JP2005317168A - Optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device capable of appropriately performing shaping of a cross-sectional shape of each light flux and conversion of intensity distribution even if a light source unit is used in which a plurality of light emitting points are adjacently provided. <P>SOLUTION: The optical pickup unit 10 is configured with a light source unit 20 in which a plurality of light emitting points emitting lights in different wavelengths are adjacently provided, a beam shaping element 40 for shaping the light flux to have a divergence angle different from that at the incidence, a coupling element 12, and an objective optical element 15 for converging the emitted light flux from the coupling element on a recording face of an optical information recording medium for forming a condensing spot. The distance from each light emitting point to a surface of a protection layer for protecting the recording surface is stabilized irrespective of kinds of the optical information recording medium, and the condensing spot is formed by using a light flux of a long wavelength for the optical information recording medium with a thick protection layer while using a light flux of a short wavelength for the optical information recording medium with a thin protection layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup device having compatibility between two or more types of optical information recording media.

In recent years, light beams having different wavelengths are emitted from two or more light sources onto a recording surface of two or more types of optical information recording media (optical disks) and collected by one objective lens, thereby reading each optical disk. Various so-called compatible optical pickup devices for performing writing and writing have been proposed.
A laser diode (semiconductor laser) is generally used as the light source of the optical pickup device. Since semiconductor lasers have different vertical and horizontal ratios of the active region, the beam divergence angle (full width at half maximum) differs in the vertical and horizontal directions with respect to the bonding surface, and the cross-sectional shape in the plane perpendicular to the optical axis becomes elliptical It often has a non-uniform intensity distribution such as a Gaussian distribution.
Therefore, a technique for shaping the cross-sectional shape of the light beam from an ellipse to a circle and a technique for converting a non-uniform intensity distribution into a substantially uniform intensity distribution are disclosed (for example, see Patent Documents 1 and 2).
JP-A-6-294940 JP 2000-089161 A

By the way, with recent demands for miniaturization and high functionality of optical pickup devices, a light source (hereinafter referred to as “one unit”) in which a plurality of high-power laser diodes are arranged in close proximity to each other. "Light source unit") may be used.
In the optical pickup device using the light source unit, the light emission points of the respective light fluxes are at substantially the same position, so that the optical path lengths (distances between object images) are substantially equal, and the optical system magnification is also substantially equal.

  Here, for example, when a light beam having a wavelength of 780 nm used for a CD (compact disk) and a light beam having a wavelength of 650 nm used for a DVD (digital versatile disk) are compared, the divergence angles are almost equal, but the numerical aperture of the objective lens ( NA) is larger for DVD than for CD, so under the condition that the optical system magnification is almost equal between DVD and CD, the rim intensity of the luminous flux for DVD is the intensity required from the standard (60- The problem of being less than about 70%) arises.

  However, the technologies disclosed in Patent Documents 1 and 2 are technologies related to an incompatible optical pickup apparatus that mainly uses only one type of light beam, and is compatible with the use of two or more types of light beams having different wavelengths. It is difficult to apply to an optical pickup device having the above. In addition, Patent Document 1 describes that the present invention can be applied to an optical apparatus having one or more diode lasers. However, the above problem in the case where a light source unit in which the optical system magnification of each light beam is equal is used as a light source. It does not describe how to solve the point.

  An object of the present invention is to take the above-mentioned problems into consideration, and even when using a light source unit in which a plurality of light emitting points are provided close to each other, it is possible to appropriately shape the cross-sectional shape of each light beam and convert the intensity distribution. An optical pickup device that can be performed is provided.

In order to solve the above problems, the invention according to claim 1 is directed to a light source unit in which a plurality of light emitting points emitting light having different wavelengths are provided in close proximity, and an emitted light beam from the light source unit with respect to an optical axis. A beam shaping element that shapes a divergence angle different from the incident angle in at least one of a first direction perpendicular to the first direction and a second direction perpendicular to both the optical axis and the first direction;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point to the surface of the protective layer protecting the recording surface is set to be constant regardless of the type of the optical information recording medium,
The optical information recording medium having a thin protective layer is formed by using the first light beam having a long wavelength among the light beams emitted from the light emitting points to form an optical information recording medium having a thin protective layer. On the other hand, the condensing spot is formed by using a second light beam having a short wavelength among the light beams emitted from the respective light emitting points.

In this specification, “the distance from each light emitting point to the surface of the protective layer that protects the recording surface is constant regardless of the type of the optical information recording medium” means that the structure of the optical pickup device This means that the linear distance from the light emitting point that emits one light beam to the surface of the protective layer and the linear distance from the light emitting point that emits the second light beam to the surface of the protective layer are kept the same. Here, due to the assembly error of each light emitting point and the rotation drive device that rotatably holds the optical information recording medium, it is assumed that the distance is not the same in the strict sense. In the present specification, it is assumed that the distance is the same even when the distance is changed due to an assembly error.
Also, as a general light source unit, a type in which separate laser diodes are arranged close to each other and mounted, or a type in which a plurality of laser diodes made of different materials are formed on one substrate is known. These are included in the light source unit in this specification.

  In addition to CD and DVD, optical information recording media include optical discs of various standards having different light source wavelengths and protective substrate thicknesses, such as CD-R, RW (recordable compact disc), VD (video disc), MD ( High-density optical discs including general optical discs such as mini discs and MO (magneto-optical discs), and further using a blue-violet semiconductor laser or blue-violet SHG laser having a wavelength of about 400 nm as a light source for recording / reproducing information. Shall also be included. As a high-density optical disc, information is recorded / reproduced by an objective optical system having an NA of about 0.85. In addition to a standard optical disc having a protective layer thickness of about 0.1 mm, an objective optical system having an NA of 0.65 is used. It also includes a standard optical disc (hereinafter referred to as HD-DVD) in which information is recorded / reproduced and the thickness of the protective layer is about 0.6 mm.

The invention according to claim 2 is a light source unit in which at least two light emitting points that emit light at different wavelengths are provided close to each other;
The emitted light beam from the light source unit is incident in at least one of two directions, a first direction perpendicular to the optical axis and a second direction perpendicular to both the optical axis and the first direction. A beam shaping element that shapes the divergence angle different from the original,
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point of the two light emitting points to the surface of the protective layer that protects the recording surface is set to be constant regardless of the type of the optical information recording medium,
For the two optical information recording media having different protective layer thicknesses, the first of the light beams emitted from the two light emitting points having the longer wavelength is different from the optical information recording medium having the thicker protective layer. The condensing spot is formed using a light beam, and the second light beam having a short wavelength out of the light beams emitted from the two light emitting points is used for the optical information recording medium having the thinner protective layer. A light spot is formed.
According to the invention described in claim 1 or 2, even when the optical system magnification of each light beam becomes equal by using a light source unit in which a plurality of light emitting points are provided close to each other, the cross-sectional shape of each light beam can be arbitrarily set. It can be shaped into a shape, the quality of each light beam can be improved, and a good condensing spot can be formed.

A third aspect of the present invention is the optical pickup device according to the first or second aspect, wherein the beam shaping element and the coupling element are integrated.
The invention according to claim 4 is the optical pickup device according to claim 1 or 2, wherein the beam shaping element and the coupling element are composed of one element having both functions. It is characterized by.
According to invention of Claim 3 or 4, an optical pick-up apparatus can be reduced in size by integrating the said beam shaping element and the said coupling element.

A fifth aspect of the present invention is the optical pickup device according to any one of the first to fourth aspects, wherein the beam shaping element and the objective optical element are separated. .
Invention of Claim 6 is an optical pick-up apparatus as described in any one of Claims 1-5, Comprising: All of the said beam shaping element, the said coupling element, and the said objective optical element are plastics. It is characterized by.
According to the invention described in claim 6, by manufacturing each optical element with plastic, it becomes easier to manufacture and the manufacturing cost can be reduced as compared with the case of manufacturing with optical glass.

The invention according to claim 7 is the light source unit in which a plurality of light emitting points emitting light having different wavelengths are provided close to each other, and the outermost effective diameter outer periphery of the emitted light flux whose intensity distribution from the light source unit is substantially Gaussian. A light intensity distribution conversion element for converting the light intensity of the light beam passing through the section into a desired light intensity between 45% and 95% of the light intensity of the light beam passing through the optical axis position;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point to the surface of the protective layer protecting the recording surface is set to be constant regardless of the type of the optical information recording medium,
The optical information recording medium having a thin protective layer is formed by using the first light beam having a long wavelength among the light beams emitted from the light emitting points to form an optical information recording medium having a thin protective layer. On the other hand, the condensing spot is formed by using a second light beam having a short wavelength among the light beams emitted from the respective light emitting points.

The invention according to claim 8 is a light source unit in which at least two light emitting points that emit light at different wavelengths are provided close to each other;
Of the emitted light flux whose intensity distribution from the light source unit is approximately Gaussian distribution, the light intensity of the light flux that passes through the outermost peripheral portion of the effective diameter is between 45% and 95% of the light intensity of the light flux that passes through the optical axis position. A light intensity distribution conversion element that converts the light intensity to a desired light intensity;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
Two optical information in which the distance from each of the two light emitting points to the surface of the protective layer protecting the recording surface is set to be constant regardless of the type of the optical information recording medium, and the thickness of the protective layer is different For the recording medium, the focused spot is formed by using the first light beam having a long wavelength out of the light beams emitted from the two light emitting points with respect to the optical information recording medium having the thicker protective layer. And the focused spot is formed on the optical information recording medium with the thinner protective layer by using a second light beam having a short wavelength out of the light beams emitted from the two light emitting points. To do.

  According to the invention described in claim 7 or 8, even when the optical system magnification of each light beam becomes equal by using a light source unit in which a plurality of light emitting points are provided close to each other, non-uniform intensity distribution of each light beam. Can be converted into a substantially uniform intensity distribution, the quality of each light beam can be improved, and the formation of a good condensing spot can be realized.

The invention according to claim 9 is the optical pickup device according to claim 7 or 8, wherein the light intensity distribution conversion element and the coupling element are integrated.
A tenth aspect of the invention is the optical pickup device according to the seventh or eighth aspect, wherein the light intensity distribution conversion element and the coupling element are constituted by one element having both functions. It is characterized by being.
According to invention of Claim 9 or 10, an optical pick-up apparatus can be reduced in size by integrating the said light intensity distribution conversion element and the said coupling element.
An eleventh aspect of the invention is the optical pickup device according to any one of the seventh to tenth aspects, wherein the light intensity distribution conversion element and the objective optical element are separated. And

A twelfth aspect of the invention is the optical pickup device according to any one of the seventh to eleventh aspects, wherein the light intensity distribution conversion element, the coupling element, and the objective optical element are all made of plastic. It is characterized by being.
According to the twelfth aspect of the present invention, by manufacturing each optical element with plastic, manufacturing becomes easier and manufacturing cost can be reduced as compared with the case of manufacturing with optical glass.

The invention according to claim 13 is a light source unit in which a plurality of light emitting points that emit light at different wavelengths are provided close to each other;
The emitted light beam from the light source unit is incident in at least one of two directions, a first direction perpendicular to the optical axis and a second direction perpendicular to both the optical axis and the first direction. A beam shaping element that shapes the divergence angle different from the original,
Of the emitted light flux whose intensity distribution from the light source unit is approximately Gaussian distribution, the light intensity of the light flux that passes through the outermost peripheral portion of the effective diameter is between 45% and 95% of the light intensity of the light flux that passes through the optical axis position. A light intensity distribution conversion element that converts the light intensity to a desired light intensity;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point to the surface of the protective layer protecting the recording surface is set to be constant regardless of the type of the optical information recording medium,
The optical information recording medium having a thin protective layer is formed by using the first light beam having a long wavelength among the light beams emitted from the light emitting points to form an optical information recording medium having a thin protective layer. On the other hand, the condensing spot is formed by using a second light beam having a short wavelength among the light beams emitted from the respective light emitting points.

  According to the invention described in claim 13, even when the optical system magnification of each light beam becomes equal by using a light source unit provided with a plurality of light emitting points close to each other, the cross-sectional shape of each light beam can be set to an arbitrary shape. In addition to being able to be shaped, it is possible to convert a non-uniform intensity distribution into a substantially uniform intensity distribution, thereby improving the quality of each light beam and realizing a good focused spot formation.

The invention according to claim 14 is a light source unit in which at least two light emitting points that emit light at different wavelengths are provided close to each other;
The emitted light beam from the light source unit is incident in at least one of two directions, a first direction perpendicular to the optical axis and a second direction perpendicular to both the optical axis and the first direction. A beam shaping element that shapes the divergence angle different from the original,
Of the emitted light flux whose intensity distribution from the light source unit is approximately Gaussian distribution, the light intensity of the light flux that passes through the outermost peripheral portion of the effective diameter is between 45% and 95% of the light intensity of the light flux that passes through the optical axis position. A light intensity distribution conversion element that converts the light intensity to a desired light intensity;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point of the two light emitting points to the surface of the protective layer that protects the recording surface is set to be constant regardless of the type of the optical information recording medium,
For the two optical information recording media having different protective layer thicknesses, the first of the light beams emitted from the two light emitting points having the longer wavelength is different from the optical information recording medium having the thicker protective layer. The condensing spot is formed using a light beam, and the second light beam having a short wavelength out of the light beams emitted from the two light emitting points is used for the optical information recording medium having the thinner protective layer. A light spot is formed.

The invention according to claim 15 is the optical pickup device according to claim 13 or 14, wherein the beam shaping element, the light intensity distribution conversion element, and the coupling element are integrated. To do.
The invention according to claim 16 is the optical pickup device according to claim 13 or 14, wherein the beam shaping element, the light intensity distribution conversion element, and the coupling element have one function. It is composed of elements.
The invention according to claim 17 is the optical pickup device according to claim 13 or 14, wherein the beam shaping element and the light intensity distribution conversion element are integrated.

The invention according to claim 18 is the optical pickup device according to claim 13 or 14, wherein the beam shaping element and the light intensity distribution conversion element are constituted by one element having both functions. It is characterized by being.
A nineteenth aspect of the present invention is the optical pickup device according to the thirteenth or fourteenth aspect, wherein the beam shaping element and the coupling element are integrated.
The invention according to claim 20 is the optical pickup device according to claim 13 or 14, wherein the beam shaping element and the coupling element are constituted by one element having both functions. It is characterized by.

A twenty-first aspect of the present invention is the optical pickup device according to the thirteenth or fourteenth aspect, wherein the light intensity distribution conversion element and the coupling element are integrated.
The invention according to claim 22 is the optical pickup device according to claim 13 or 14, wherein the light intensity distribution conversion element and the coupling element are constituted by one element having both functions. It is characterized by being.
According to invention of Claim 15-22, an optical pick-up apparatus can be reduced in size by integration.

The invention according to claim 23 is the optical pickup device according to any one of claims 13 to 22, wherein the beam shaping element and the objective optical element are separated. .
A twenty-fourth aspect of the invention is the optical pickup device according to any one of the thirteenth to twenty-second aspects, wherein the light intensity distribution conversion element and the objective optical element are separated. And

Invention of Claim 25 is the optical pick-up apparatus as described in any one of Claims 13-24,
The beam shaping element, the light intensity distribution conversion element, the coupling element, and the objective optical element are all made of plastic.
According to the 25th aspect of the present invention, it is possible to manufacture each optical element with plastic, thereby facilitating the manufacturing and reducing the manufacturing cost as compared with the case of manufacturing with optical glass.
A twenty-sixth aspect of the invention is the optical pickup device according to any one of the first to twenty-fifth aspects, wherein a predetermined optical path difference is imparted to the incident light beam on the optical surface of the objective optical element. A first optical path difference providing structure is provided.
A twenty-seventh aspect of the present invention is the optical pickup device according to the twenty-sixth aspect, wherein the first optical path difference providing structure is a diffractive structure.

A twenty-eighth aspect of the present invention is the optical pickup device according to the twenty-sixth or twenty-seventh aspect, wherein the first optical path difference providing structure causes a wavefront aberration and / or due to a temperature variation of a use environment and / or a wavelength variation of an incident light beam. Alternatively, the occurrence of astigmatism degradation is suppressed.
A twenty-ninth aspect of the invention is the optical pickup device according to any one of the first to twenty-eighth aspects, wherein the objective optical element has an aperture limiting function for an emitted light beam.
The invention according to a thirty-third aspect is the optical pickup device according to the twenty-ninth aspect, wherein the aperture limiting function is formed in a predetermined region on the optical surface of the objective optical element and has a predetermined optical path with respect to an incident light beam. This is realized by a second optical path difference providing structure that flares the light flux by providing a difference.

A thirty-first aspect of the invention is the optical pickup device according to any one of the first to thirty-first aspects, wherein the focused optical spot is formed by using the first light flux. When the position in the optical axis direction is the reference position,
When forming the condensing spot using the second light flux, the objective optical element is moved relative to the reference position toward the light source unit.
According to the thirty-first aspect of the present invention, it is possible to suppress aberration that occurs due to the difference in the thickness of the protective layer of each optical information recording medium.

A thirty-second aspect of the invention is the optical pickup device according to any one of the first to third aspects, wherein the second light flux is perpendicular to the optical axis at the time when the second light flux is emitted from the light source unit. The in-plane cross-sectional shape is an elliptical shape in which the first direction is a short diameter and the second direction is a long diameter, and the rim intensity in the first direction of the second light flux is within a range of 45 to 95%. It is characterized by being.
According to the thirty-second aspect of the present invention, the second light flux can be suitably used for a DVD.

A thirty-third aspect of the invention is the optical pickup device according to any one of the first to thirty-second aspects, wherein the light emitting point that emits the second light flux is arranged so as to coincide with the optical axis. Features.
According to the thirty-third aspect of the present invention, it is possible to suppress aberration that occurs in the second light flux.
A thirty-fourth aspect of the invention is the optical pickup device according to any one of the first to thirty-third aspects, wherein the optical system magnification is in a range of 3 to 5 times.

A thirty-fifth aspect of the invention is the optical pickup device according to any one of the first to thirty-fourth aspects, wherein the light-receiving unit combines the reflected light of the first light beam and the reflected light of the second light beam. It is commonly used to receive light.
According to the thirty-fifth aspect of the present invention, the light receiving unit for the first light beam and the light receiving unit for the second light beam can be shared, so that the manufacturing cost and size reduction of the optical pickup device can be realized.
A thirty-sixth aspect of the invention is the optical pickup device according to any one of the first to thirty-fifth aspects, wherein an optical path of the first light flux and the second light flux is transmitted through the beam shaping element or the light beam. It has an optical path synthesizing means for matching at the time before entering the light intensity distribution conversion element.
According to the thirty-sixth aspect of the present invention, the oblique incidence of the light beam can be prevented and the coma aberration can be suppressed.

The invention according to claim 37 is the optical pickup device according to any one of claims 1 to 36, wherein the beam shaping element or the light intensity distribution conversion element is used for an arbitrary light flux among the passing light fluxes. It has a wavelength selectivity that gives an optical action.
According to the thirty-seventh aspect of the present invention, even when a plurality of types of light beams having different wavelengths are emitted from the light source unit due to the wavelength selectivity, cross-sectional shape shaping and light intensity distribution conversion are performed for each light beam. It can be performed.

A thirty-eighth aspect of the invention is the optical pickup device according to the thirty-seventh aspect, wherein the optical action is an action of suppressing coma generated by oblique incidence of a light beam and / or the first light beam and the second light beam. It is an action that suppresses astigmatism generated due to a wavelength difference with the light beam.
A thirty-ninth aspect of the invention is the optical pickup apparatus according to the thirty-eighth aspect, wherein the optical action is given only to the first light flux.
The invention according to claim 40 is the optical pickup device according to claim 38 or 39, wherein the wavelength selectivity is realized by a third optical path difference providing structure that provides a predetermined optical path difference to the incident light flux. It is characterized by that.

The invention according to claim 41 is the optical pickup device according to claim 40, wherein the third optical path difference providing structure is linear on the optical surface along a third direction perpendicular to the optical axis. It has a coma aberration correction structure in which the extending first optical function unit is continuously arranged in a fourth direction perpendicular to the third direction.
The invention according to claim 42 is the optical pickup device according to claim 41, wherein when the arrangement direction of the light emitting points provided in the light source unit is defined as a fifth direction, the fourth direction and the fifth direction. The absolute value of the angle formed by the direction is 30 degrees or less.

The invention according to claim 43 is the optical pickup device according to claim 40, wherein the third optical path difference providing structure is linearly formed on the optical surface along a sixth direction perpendicular to the optical axis. An astigmatism correction structure is provided in which the extending second optical function unit is continuously arranged in a seventh direction perpendicular to the sixth direction.
The invention according to claim 44 is the optical pickup device according to claim 43, wherein when the arrangement direction of the light emitting points provided in the light source unit is defined as a fifth direction, the seventh direction and the fifth direction are defined. The absolute value of the angle formed by the direction is 30 degrees or less.

The invention according to a 45th aspect is the optical pickup device according to the 40th aspect, wherein the third optical path difference providing structure is linearly formed along a third direction perpendicular to the optical axis on the optical surface. A coma correction structure in which the extending first optical function unit is continuously arranged in a fourth direction perpendicular to the third direction, and a sixth direction perpendicular to the optical axis on the optical surface. And an astigmatism correction structure in which the second optical function unit extending linearly is continuously arranged in a seventh direction perpendicular to the sixth direction.
The invention according to claim 46 is the optical pickup device according to claim 45, wherein when the arrangement direction of the light emitting points provided in the light source unit is defined as a fifth direction, the fourth direction and the fifth direction. The absolute value of the angle formed by the direction is 30 degrees or less, the absolute value of the angle formed by the seventh direction and the fifth direction is 30 degrees or less, and the fourth direction and the seventh direction are formed. The absolute value of the corner is 15 degrees or less.
When using an optical element in which the coupling element and the light intensity distribution conversion element are integrated, the two types of light beams (first light beam and second light beam) emitted from the light source unit are different in wavelength. Astigmatism occurs when the refractive index of the optical element changes, and when one of the light emitting points that emit these light beams is arranged on the optical axis, the light beam emitted from the other becomes off-axis light. Astigmatism due to the occurrence occurs. Accordingly, the coma aberration correcting structure and the astigmatism correcting structure are provided as the third optical path difference providing structure on the optical surface of the beam shaping element and the light intensity distribution converting element as in the inventions of claims 40 to 46. Thus, coma and astigmatism can be suppressed.

A 47th aspect of the present invention is the optical pickup device according to any one of the 1st to 6th and 13th to 46th aspects of the present invention, with respect to the optical axis of each light beam at the time of emission from the light source unit. The cross-sectional shape in a vertical plane is an elliptical shape in which the first direction is the short diameter and the second direction is the long diameter, and the divergence of the light beam after being shaped by the beam shaping element in the first direction When the angle is D1 and the divergence angle in the second direction is D2, 1.0 <D2 / D1 <2.0 is satisfied.
However, D1 and D2 are angles at positions where the light intensity of each light beam is 50% of the peak.
A 48th aspect of the present invention is the optical pickup device according to any one of the 7th to 46th aspects, wherein the surface is perpendicular to the optical axis of each of the luminous fluxes when the light is emitted from the light source unit. The cross-sectional shape inside is an elliptical shape in which the first direction is the short diameter and the second direction is the long diameter, and the rim intensity in the first direction of the light flux after being converted by the light intensity distribution conversion element is It is characterized by being in the range of 45-95%.

A 49th aspect of the present invention is the optical pickup device according to any one of the 1st to 6th and 13th to 47th aspects, wherein the beam shaping element is a cylindrical lens, and each of the light emission units included in the light source unit. The arrangement direction of the points is coincident with the axial direction of the beam shaping element.
The invention according to claim 50 is the optical pickup device according to any one of claims 1 to 6 and 13 to 47, wherein the light source unit includes the light emitting points with respect to a vertical direction of a plane. Then, the optical axis of the beam shaping element is inclined.
The invention according to claim 51 is the optical pickup device according to claim 50, characterized in that an inclination direction of an optical axis of the beam shaping element coincides with an arrangement direction of the light emitting points.

The invention according to Claim 52 is the optical pickup device according to any one of Claims 1-6, 13-47, wherein the beam shaping element has an exit surface relatively to the entrance surface. It is characterized by an inclined wedge shape.
The invention according to claim 53 is the optical pickup device according to claim 52, wherein a relative inclination direction of the exit surface with respect to the entrance surface coincides with an arrangement direction of the light emitting points. And

The invention according to claim 54 is the optical pickup device according to any one of claims 1 to 53, further comprising light combining means for matching at least the optical paths of the first light flux and the second light flux. Features.
The invention according to claim 55 is the optical pickup device according to claim 54, wherein the light after passing through the light combining means with respect to a vertical direction of a plane including the light emitting points provided in the light source unit. The optical paths of the first light flux and the second light flux are inclined.
The invention according to claim 56 is the optical pickup device according to claim 54 or 55, characterized in that the light synthesizing means has a wedge shape in which the exit surface is inclined relative to the entrance surface. To do.

The invention according to Claim 57 is the optical pickup device according to any one of Claims 49 to 56, wherein the beam shaping element is relative to the optical axis at the time when the light is emitted from the light source unit. Each of the light beams having an elliptical cross-sectional shape in a vertical plane is expanded and emitted.
The invention according to Claim 58 is the optical pickup device according to any one of Claims 49 to 56, wherein the beam shaping element is relative to the optical axis at the time of emission from the light source unit. Each of the light beams having an elliptical cross-sectional shape in a vertical plane is reduced in diameter and emitted.

The invention according to claim 59 is the optical pickup device according to any one of claims 37 to 58, wherein at least one of the beam shaping element and the light intensity distribution conversion element is used as the optical information. It has an actuator that moves according to the type of the recording medium.
The invention according to claim 60 is the optical pickup device according to claim 59, wherein the actuator moves at least one of the beam shaping element and the light intensity distribution conversion element along the optical axis. It is made to move to.
The invention according to claim 61 is the optical pickup device according to claim 59 or 60, wherein the actuator moves at least one of the beam shaping element and the light intensity distribution converting element with respect to the optical axis. And moving in a vertical direction.
The invention described in Item 62 is the optical pickup device described in any one of Items 59-61, wherein the actuator is a piezoelectric actuator.

The beam shaping element and the light intensity distribution conversion element are moved using an actuator as described in claim 59, so that, for example, a divergence angle change or a phase difference is applied to the light beam emitted from these optical elements. Thus, it becomes possible to correct aberrations.
The astigmatism caused by the wavelength difference of the incident light beam is corrected by moving the beam shaping element or the light intensity distribution conversion element in the direction along the optical axis using the actuator as described in claim 60. Is possible.
The light beam is obliquely incident on the optical element by moving the beam shaping element or the light intensity distribution conversion element in a direction perpendicular to the optical axis using the actuator as described in claim 61. It is possible to correct the coma aberration.

The invention according to Claim 63 is the optical pickup device according to any one of Claims 1 to 62, wherein the light source unit is configured by closely arranging three light emitting points that emit light at different wavelengths. The light emitting points are arranged on a straight line.
The invention according to claim 64 is the optical pickup device according to claim 63, wherein the light emitting point that emits the third light flux having the shortest wavelength among the three light emitting points is defined as the optical axis of the light source unit. It arrange | positions in the position nearest to.
According to the invention of claim 64, the wavefront aberration value is generally maximized by arranging the light emitting point that emits the third light flux having the shortest wavelength at the position closest to the optical axis of the light source unit. Since the light emitting point is arranged on the axis, the amount of wavefront aberration of the light beam from each light emitting point when using the actual optical pickup device can be suppressed as a whole, and the image height characteristic of the optical pickup device is excellent. Can be a thing.

  According to the present invention, even when a light source unit in which a plurality of light emitting points are provided close to each other is used, an optical pickup device capable of appropriately shaping the cross-sectional shape of each light beam and converting the intensity distribution is obtained. It is done.

  Hereinafter, an embodiment for carrying out the optical pickup device 10 of the present invention will be described in detail with reference to the drawings. The optical pickup device of the present embodiment has compatibility between DVDs / CDs. However, the optical pickup device is not limited to this, and a configuration having compatibility between high density optical disks / DVDs, and high density optical disks / DVD / CDs. The three types of optical discs may be compatible.

As shown in FIG. 1, the optical pickup device 10 includes a light source unit 20, a light intensity distribution conversion element 30, a beam shaping element 40, a beam splitter 11, a coupling element 12 (collimator in the present embodiment), 1/4. A wave plate 13, a diaphragm member 14, an objective lens 15, a cylindrical lens 16, a concave lens 17, an optical sensor 18 (light receiving unit), and the like are roughly configured.
Of the optical elements used in the optical pickup device 10, all the optical elements except the beam splitter 11 are made of plastic.

  The light source unit 20 includes a first laser diode 21 (light emitting point) that emits a light beam having a wavelength λ1 (first light beam) used for a CD, and a light beam (second light beam, λ2 <λ1) that is used for a DVD. ), And the second laser diode 22 that emits light in the Y direction. Reference numeral 23 denotes a housing for storing the laser diodes 21 and 22 therein.

When such a light source unit 20 is used, since the light emission points of the respective light beams are substantially coincident, the optical path lengths (distances between object images) are substantially equal, and the optical system magnification is also substantially equal. The optical system magnification is preferably in the range of 3 to 5 times.
Further, the first light flux from the first laser diode 21 arranged at a position slightly shifted in the Y direction with respect to the second laser diode 22 arranged on the optical axis is as shown by a dotted line in FIG. The incident light is obliquely incident on each optical element.

  Further, as shown in FIG. 2, the light beams (first light beam and second light beam) emitted from the light source unit 20 are in a first direction (Y direction) perpendicular to the optical axis L, and the optical axes L and Y. It has different divergence angles with respect to the second direction (X direction) perpendicular to both directions, and the XY cross section of the light beam has a substantially elliptical shape with the Y direction as the minor axis and the X direction as the major axis. In FIG. 2, the light source unit 20 and the light intensity distribution conversion element 30 are not shown.

FIG. 3A shows light corresponding to the height (distance in the Y direction) from the optical axis when the maximum value of the light intensity is 100% with respect to the light flux before entering the light intensity distribution conversion element 30. It is a graph which shows an example of the rate of change of intensity. It can be seen from the graph that the luminous flux has a Gaussian distribution.
Of the outgoing light flux having a Gaussian distribution, the light intensity (rim intensity) of the light flux passing through the outermost peripheral portion of the effective diameter of the light intensity distribution conversion element 30 (indicated by D in FIG. 3A) is the optical axis. It can be seen that it is about 35% of the light intensity (100%) of the light beam passing through the position.

Next, the operation of the optical pickup device 10 configured as described above will be described.
The first light flux emitted from the light source unit 20 is first converted in light intensity distribution by the light intensity distribution conversion element 30, and then emitted after the cross-sectional shape is shaped by the beam shaping element 40. In addition, the effect | action with respect to the light beam by the light intensity distribution conversion element 30 and the beam shaping element 40 in this case is mentioned later.

Next, the light beam passes through the collimator 12 via the beam splitter 11 and becomes a parallel light beam. Then, the light passes through the quarter-wave plate 13 and is narrowed by the diaphragm member 14, and a focused spot is formed on the recording surface 51 by the objective lens 15 via the CD protective substrate 50.
In this case, the position of the objective lens 15 in the optical axis direction (Z direction) is defined as a reference position P1.

Then, the light beam modulated and reflected by the information pits on the recording surface 51 passes again through the objective lens 15, the diaphragm member 14, the quarter wavelength plate 13, and the collimator 12 and is branched by the beam splitter 11. Then, astigmatism is given by the cylindrical lens 16, enters the optical sensor 18 through the concave lens 17, and a read signal of information recorded on the CD is obtained using a signal output from the optical sensor 18. It is like that.
Similarly to the first light beam, the second light beam emitted from the light source unit 20 is first converted in the light intensity distribution conversion element 30 and then output in a state in which the cross-sectional shape is shaped in the beam shaping element 40. Is done. The effect of the light intensity distribution conversion element 30 and the beam shaping element 40 on the light flux at this time will be described later.

Next, the light beam passes through the collimator 12 via the beam splitter 11 and becomes a parallel light beam. Then, the light passes through the quarter-wave plate 13 and is narrowed by the diaphragm member 14, and a focused spot is formed on the recording surface 61 by the objective lens 15 via the DVD protective substrate 60.
At this time, the objective lens 15 is moved to the light source unit 20 side (P2) with respect to the reference position P1 by an actuator (not shown). Thereby, it is the structure which suppresses the aberration which arises because the thickness of a protective layer (protective substrate) differs by CD and DVD.

  Then, the light beam modulated and reflected by the information pits on the recording surface 61 passes again through the objective lens 15, the diaphragm member 14, the quarter wavelength plate 13, and the collimator 12 and is branched by the beam splitter 11. Then, astigmatism is given by the cylindrical lens 16, passes through the concave lens 17, enters the optical sensor 18 common to the first light beam, and is recorded on the DVD using a signal output from the optical sensor 18. An information read signal can be obtained.

As shown in FIG. 1, the light intensity distribution conversion element 30 in the present embodiment is composed of a single aspheric lens.
The incident surface 31 of the light intensity distribution conversion element 30 is formed as an aspherical surface symmetrical with respect to the optical axis L, and is designed so that the paraxial radius of curvature is negative.
Similarly, the exit surface 32 of the light intensity distribution conversion element 30 is formed as an aspherical surface symmetric with respect to the optical axis L, and further the radius of curvature of the exit surface 32 so that the paraxial curvature radius is negative. Is designed to be smaller than the absolute value of the radius of curvature of the incident surface 31.

Further, regarding the light intensity distribution conversion element 30, the distance (height) from the optical axis L of the incident light beam is H1, the angle formed by the light beam passing through the position of the height H1 with the optical axis L is θ1, and the focal length is F1. When the sine condition dissatisfaction amount S1 is defined as S1 = H1 / (F1 × sin θ1) −1, it is designed so that S1> 0, that is, the sine condition is not satisfied.
A technique for changing the intensity distribution of the light beam by intentionally designing the lens group constituting the optical system so as not to satisfy the sine condition is disclosed in, for example, Japanese Patent Laid-Open No. 63-188115. Since it is well known, detailed description is omitted.

  In this way, when the light intensity distribution conversion element 30 is designed so that the unsatisfactory sine condition S1 of the light intensity distribution conversion element 30 is positive, when light beams are incident on the incident surface 31 of the light intensity distribution conversion element 30 at equal intervals, On the exit surface 32 side, the light flux is increased so that the light flux density in the region away from the optical axis L is increased (dense), and conversely, the light flux density in the region close to the optical axis L is decreased (sparsely). It will be shaped and emitted.

As a result, as shown in FIG. 3B, the rim intensity of the light beam that passes through the effective diameter outermost peripheral portion (indicated by D) of the light intensity distribution conversion element 30 among the emitted light beam having a Gaussian distribution is expressed as the optical axis. About 85% of the light intensity of the light beam passing through the position can be converted to a practically sufficient light intensity.
The rim intensity in the X direction of the second light flux is preferably in the range of 45 to 95%.

As shown in FIG. 2, the beam shaping element 40 is composed of a spherical refractive surface whose incidence surface 41 has an infinite curvature radius with respect to the YZ plane and whose curvature radius with respect to the XZ plane is represented by r (r ≠ ∞). Has been.
Further, when the divergence angle in the Y direction of the light beam shaped by the beam shaping element 40 is D1 and the divergence angle in the X direction is D2, 1.0 <D2 / D1 <2.0 is satisfied. The entrance surface 41 and the exit surface 42 of the beam shaping element 40 are designed.

  Therefore, the incident surface 41 and the exit surface 42 are refracted with respect to an incident light beam having a substantially elliptical cross section, and are emitted at a divergence angle different from that at the time of incidence in the X direction and the Y direction. It can be shaped and emitted so as to have an arbitrary shape (for example, a circle).

  As described above, according to the optical pickup device 10 shown in the present embodiment, even when the light source unit 20 in which a plurality of light emitting points are integrated and the optical system magnification of each light beam becomes equal is used, It is possible to shape the cross-sectional shape of the light beam into an arbitrary shape, and to convert a non-uniform intensity distribution into a substantially uniform intensity distribution, improving the quality of each light beam, Formation can be realized.

The optical pickup device 10 of the present invention can be changed as appropriate within the scope of the gist of the present invention.
For example, in the above-described embodiment, the optical pickup device 10 includes both the beam shaping element 40 and the light intensity distribution conversion element 30. However, the present invention is not limited to this, and may have a configuration including only one of them. .
In addition, the beam shaping element 40, the light intensity distribution conversion element 30, and the coupling element 12 are arranged as separate optical elements. However, the present invention is not limited to this. The light intensity distribution conversion element 30 and the coupling element 12 can be configured as an integral structure by also having a function of converting the divergence angle, and as shown in FIG. It can be changed as appropriate.

Also, a first optical path difference providing structure (not shown) that provides a predetermined optical path difference to the incident light beam may be formed on the optical surface of the objective lens 15. As the first optical path difference providing structure, for example, a sawtooth-shaped diffractive annular zone centered on the optical axis or a step structure in which a plurality of annular zone surfaces centered on the optical axis are continued through steps substantially parallel to the optical axis. A plurality of zonal planes centered on the optical axis are continuous through a step substantially parallel to the optical axis, and the light flux that has passed through each zonal zone is recorded on the recording surface of each optical information recording medium. Examples include a phase shift structure in which the phases are substantially aligned.
Thereby, for example, using the diffracted light from the diffraction ring zone, it is possible to suppress the deterioration of the wavefront aberration and / or astigmatism due to the temperature fluctuation of the use environment and / or the wavelength fluctuation of the light beam.

  In addition, a second optical path difference providing structure (not shown) may be provided in a predetermined region on the optical surface of the objective lens 15 so that a predetermined optical path difference is applied to the incident light beam to flare the light beam. Examples of the second optical path difference providing structure include the same diffraction structure and phase shift structure as the first optical path difference providing structure. Thereby, among the light beams incident on the objective lens 15, a light beam that passes through a predetermined region is made flare light, and a so-called aperture limiting function that does not contribute to the formation of a condensed spot can be provided.

  In the above-described embodiment, the first light beam is obliquely incident on each optical element. However, the present invention is not limited to this, and the light beam passes through the optical paths of the first light beam and the second light beam. Alternatively, optical path synthesis means (not shown) for matching at the time before entering the light intensity distribution conversion element 30 may be arranged. As the optical path combining means, for example, an optical system using an integrated prism such as a beam shaping element disclosed in Japanese Patent Laid-Open No. 11-232685 can be used. Thereby, the oblique incidence of the light beam can be prevented and the coma aberration can be suppressed.

Further, the beam shaping element 40 or the light intensity distribution conversion element 30 may have a wavelength selectivity that gives an optical action to an arbitrary light beam among the passing light beams.
Further, the optical action includes an action of suppressing coma aberration generated by oblique incidence of the light beam and an action of suppressing astigmatism generated by the wavelength difference between the first light beam and the second light beam.
The wavelength selectivity is realized, for example, by forming a third optical path difference providing structure that gives a predetermined optical path difference to the incident light beam on the optical surface of the beam shaping element 40 or the light intensity distribution conversion element 30. Examples of the third optical path difference providing structure include a diffraction structure and a phase shift structure similar to the first optical path difference providing structure.

  Moreover, as a 3rd optical path difference providing structure, as shown in FIG. 5, on the optical surface of the beam shaping element 40 or the light intensity distribution conversion element 30, it is perpendicular | vertical to the optical axis L (3rd direction). A structure (coma aberration correction structure) in which the first optical function unit 70 extending linearly along the direction is continuously arranged in a direction perpendicular to the third direction (fourth direction) can be given. In this case, as shown in FIGS. 6 and 7, the absolute angle θ formed by the arrangement direction (fifth direction) of the first laser diode 21 and the second laser diode 22 included in the light source unit 20 and the fourth direction is provided. It is preferable that the value be 30 degrees or less, that is, approximately match. As shown in FIG. 7, the counterclockwise direction with respect to the fifth direction is defined as the positive direction of the angle θ. As described above, the second laser diode 22 is arranged on the optical axis L, whereas the first laser diode 21 is arranged slightly shifted in the Y direction (fifth direction in FIG. 6). The first light flux from the first laser diode 21 is obliquely incident on each optical element, and coma aberration due to this oblique incidence occurs. Therefore, a third optical path difference providing structure is provided in the beam shaping element 40 or the light intensity distribution conversion element 30, and a predetermined optical path difference is given to the first light flux passing through the first optical function unit 70 formed continuously in the fourth direction. By providing the above-mentioned coma aberration, the coma aberration can be corrected.

Similarly, as the third optical path difference providing structure, on the optical surface of the beam shaping element 40 or the light intensity distribution conversion element 30, linearly along the direction perpendicular to the optical axis L (sixth direction). A structure (astigmatism correction structure) in which the extending second optical function unit 71 is continuously arranged in a direction perpendicular to the sixth direction (seventh direction) may be provided. In this case, it is preferable that the absolute value of the angle θ formed by the fifth direction and the seventh direction be 30 degrees or less, that is, substantially coincide. Then, by giving a predetermined optical path difference to each light beam passing through the second optical function unit 71, a wavelength difference between the first light beam from the first laser diode 21 and the second light beam from the second laser diode 22 is obtained. Astigmatism that occurs can be corrected.
The coma aberration correcting structure and the astigmatism correcting structure may be provided on the same optical surface. In this case, the absolute value of the angle formed by the fourth direction and the seventh direction is preferably 15 degrees or less. Thereby, both the coma aberration and the astigmatism can be suppressed to such an extent that no practical trouble occurs.

Alternatively, wavelength selectivity may be realized by applying a multilayer film having a function of allowing only a light beam having a predetermined wavelength to pass and reflecting another light beam to the optical surface. Or you may implement | achieve by making the shape of an optical surface into asymmetrical centering on an optical axis.
Thereby, for example, even when a plurality of types of light beams having different wavelengths are emitted from the light source unit 20, the cross-sectional shape can be shaped and the light intensity distribution can be converted for each light beam.
Further, the shape of the beam shaping element 40 can be appropriately changed, for example, a toroidal shape, a cylindrical shape, a wedge shape, or the like.

  When the shape of the optical surface of the beam shaping element 40 is a cylindrical shape, the arrangement direction of the first laser diode 21 and the second laser diode 22 provided in the light source unit 20 (fifth direction, see FIG. 6), the beam It is preferable to match the axial direction of the shaping element 40. In particular, when the optical pickup device 10 is compatible between HD-DVD / DVD, the numerical aperture NA of the objective lens 15 for HD-DVD and DVD is both about 0.65. The element 30 is not necessarily required. By aligning the axial direction of the cylindrical beam shaping element 40 and the arrangement direction (fifth direction) of the first laser diode 21 and the second laser diode 22, the coma aberration and non-existence can be reduced. Point aberration can be corrected.

Further, when the shape of the beam shaping element 40 is a wedge shape in which the exit surface is inclined relative to the entrance surface, the relative inclination direction of the exit surface with respect to the entrance surface coincides with the fifth direction. It is preferable to make it.
The optical axis of the beam shaping element 40 may be inclined with respect to the vertical direction of the plane including the fifth direction. In this case, the inclination direction of the optical axis of the beam shaping element is the fifth direction. It is preferable to match.

In the case of the optical pickup device 10 having compatibility between HD-DVD / DVD, it is preferable to dispose the collimator 12 and the beam shaping element 40 separately. As a type of the beam shaping element 40 in this case, a type in which a light beam having an elliptical cross section in a plane perpendicular to the optical axis L at the time of emission from the light source unit 20 is expanded and emitted. However, when using a type that expands the diameter, there is an advantage that astigmatism can be reduced, but the divergence angle at the time of emission from the beam shaping element 40 is increased, Since the focal length of the collimator 12 for collimating the light beam is shortened, it is preferable to provide the collimator 12 with the third optical path difference providing structure. When using a diameter reducing type, astigmatism can be reduced. However, since the divergence angle at the time of emission from the beam shaping element 40 becomes small and the focal length of the collimator 12 becomes long, the beam shaping element 40 has the above-mentioned third. It is preferable to provide a road difference providing structure.
In addition, a light combining means that at least matches the optical paths of the first light beam and the second light beam may be arranged in the optical system of the optical pickup device. In this case, the light combining is performed with respect to the vertical direction of the plane including the fifth direction. It is preferable to incline the optical paths of the first light flux and the second light flux after passing through the means. The shape of the light combining means in this case is preferably a wedge shape in which the exit surface is inclined relative to the entrance surface.

In addition, as described above, the light intensity distribution conversion element 30 or the beam shaping element 40 has an effect of suppressing coma aberration generated by the oblique incidence of the light beam, or non-generation caused by the wavelength difference between the first light beam and the second light beam. As a means for achieving the effect of suppressing the point aberration, there is a method of moving the beam shaping element 40 or the light intensity distribution conversion element 30 in a predetermined direction by an actuator.
For example, FIG. 8 shows an optical pickup device in which an actuator for moving the beam shaping element 40 in the optical axis direction is added to the configuration of the optical pickup device 10 of FIG.

Examples of the actuator include a conventional rotary motor and a piezoelectric actuator as disclosed in JP-A-6-123830.
By moving the beam shaping element 40 in the optical axis direction, astigmatism caused by the wavelength difference between the first light flux from the first laser diode 21 and the second light flux from the second laser diode 22 can be corrected. It becomes possible. The same effect can be obtained when the light intensity distribution conversion element 30 is moved in the optical axis direction.

For example, FIG. 9 shows an optical pickup device in which an actuator for moving the beam shaping element 40 in a direction perpendicular to the optical axis is added to the configuration of the optical pickup device 10 of FIG.
By moving the beam shaping element 40 in the direction perpendicular to the optical axis, it is possible to correct coma caused by the oblique incidence of the first light beam from the first laser diode 21 on each optical element. It becomes. The same effect can be obtained when the light intensity distribution conversion element 30 is moved in the optical axis direction.

  In addition, as described above, providing the third optical path difference providing structure in the beam shaping element 40 or the light intensity distribution conversion element 30 can also provide the effect of suppressing the coma and astigmatism. The effect of suppressing coma and astigmatism is further improved by moving the beam shaping element 40 or the light intensity distribution conversion element 30 provided with the structure in the optical axis direction or the optical axis vertical direction using an actuator. Can do.

  In addition, the optical pickup device 10 of the present embodiment has compatibility between DVD / CD, but when the optical pickup device has compatibility between high-density optical disc / DVD / CD, for example, A configuration as shown in FIG. 10 can be adopted.

  The optical pickup device shown in FIG. 10 includes a light source unit 20, a beam shaping element 40, a beam splitter 11, a coupling element 12 (collimator in the present embodiment), a quarter wavelength plate 13, a diaphragm member 14, and an objective lens 15. The cylindrical lens 16, the concave lens 17, the optical sensor 18 (light receiving unit), and the like are roughly configured, and the optical intensity distribution conversion element is not provided.

The light source unit 20 includes a first laser diode 21 (light emitting point) that emits a light beam having a wavelength λ1 (first light beam) used for CD and a light beam (second light beam, λ2 <λ1) that is used for DVD. ) And a third laser diode 24 that emits a light beam having a wavelength λ3 (third light beam, λ3 <λ2) that is used for HD DVD as a high-density optical disk. It is an integrated configuration by being arranged close to (Y direction). Reference numeral 23 denotes a housing for storing the laser diodes 21, 22, and 24 therein.
The third laser diode 24 that emits the third light beam having the shortest wavelength among the laser diodes 21, 22, and 24 is disposed at a position closest to the optical axis L of the light source unit 20 (on the optical axis in FIG. 10). doing.

When such a light source unit 20 is used, since the light emission points of the respective light beams are substantially coincident, the optical path lengths (distances between object images) are substantially equal, and the optical system magnification is also substantially equal.
In addition, since the third laser diode 24 having the largest wavefront aberration value is arranged on the axis, the amount of wavefront aberration of the light flux from each light emitting point when the actual optical pickup device is used is suppressed as a whole. And the image height characteristics of the optical pickup device can be improved.
In FIG. 10, reference numeral 62 indicates an HD-DVD protective substrate, and reference numeral 63 indicates an HD-DVD recording surface.

Next, examples will be described.
[Example 1]
The optical pickup device in the present embodiment has the same configuration as that shown in FIG. Specifically, the optical pickup device is compatible between CD / DVD, and emits a first laser diode that emits a first light beam with a wavelength of 785 nm for CD and a second light beam with a wavelength of 655 nm for DVD. The second laser diode is stored in the light source unit, and each light beam emitted from the light source unit passes through an element in which a beam shaping element, a light intensity distribution conversion element, and a collimator (coupling element) are integrated. Then, after passing through the beam splitter and the quarter-wave plate, the diameter of the light beam is reduced by the stop member, and the light is condensed on the recording surface of each optical disc via the objective lens.

Tables 1 and 2 show lens data of each optical element.

なお、以下に示す各表において例えば「−５．１３００Ｅ−０１」は「−５．１３００×１０^-1」を意味する。 As shown in Table 1, the second laser diode that emits the second light beam with a wavelength of 655 nm is disposed on the optical axis where the coordinates (X, Y) = (0.000, 0.000), and the second laser diode with a wavelength of 785 nm. The first laser diode that emits one light beam is disposed at a position shifted in the Y-axis direction (the fifth direction) where coordinates (X, Y) = (0.000, 0.110).
The incident surface (first surface) of the element in which the beam shaping element, the light intensity distribution conversion element, and the collimator are integrated is an anamorphic non-standard that is defined by a mathematical formula in which the coefficients shown in Table 1 and Table 2 are substituted into Formula 1. It consists of a spherical surface.

In each table shown below, for example, “−5.1300E-01” means “−5.1300 × 10 ⁻¹ ”.

Furthermore, on the first surface, as the third optical path difference providing structure, a diffractive structure defined by a mathematical formula in which the coefficients shown in Tables 1 and 2 are substituted into Formula 2 is formed.

対物レンズの入射面は、光軸を中心として光軸からの高さｈが０≦ｈ≦０．９８２の範囲内となる同心円状の中央領域（第４面）と、第４面の周囲を覆い、光軸からの高さｈが０．９８２＜ｈとなる周辺領域（第４´面）に区分されている。
第４面は、数４式に表１、表２に示す係数を代入した数式で規定される非球面で構成されている。

The exit surface (second surface) of the element in which the beam shaping element, the light intensity distribution conversion element, and the collimator are integrated is a Y toroidal defined by a mathematical formula in which the coefficients shown in Table 1 and Table 2 are substituted into Formula 3. It is composed of planes.

The entrance surface of the objective lens has a concentric central region (fourth surface) in which the height h from the optical axis is in the range of 0 ≦ h ≦ 0.982 with the optical axis as the center, and the periphery of the fourth surface. It is divided into peripheral regions (fourth surface) where the height h from the optical axis is 0.982 <h.
The fourth surface is composed of an aspheric surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 1 and 2 into Formula 4.

なお、表中、「基準波長」とあるのは、いわゆるブレーズ波長を指し、その波長の光束が入射した場合に回折構造により生じるある次数の回折光の回折効率が最大（例えば１００％）となる波長のことである。
第４´面及び対物レンズの出射面（第５面）は、数４式に表１、表２に示す係数を代入した数式で規定される非球面で構成されている。 Furthermore, a diffraction ring zone centered on the optical axis is formed on the fourth surface, and the pitch of the diffraction ring zone is defined by an equation obtained by substituting the coefficients shown in Tables 1 and 2 into the optical path difference function of Formula 5. The

In the table, “reference wavelength” refers to a so-called blaze wavelength, and the diffraction efficiency of a certain order of diffracted light generated by the diffractive structure is maximized (for example, 100%) when a light beam of that wavelength is incident. It is a wavelength.
The 4 ′ surface and the exit surface (fifth surface) of the objective lens are composed of aspheric surfaces defined by mathematical formulas obtained by substituting the coefficients shown in Tables 1 and 2 into Formula 4.

  FIG. 11 is a graph showing the radiation characteristics of the second light beam (wavelength λ = 655 nm) before passing through the element in which the beam shaping element, the light intensity distribution conversion element, and the collimator are integrated, and FIG. 12 shows the beam shaping element. 5 is a graph showing radiation characteristics of the second light flux after passing through an element in which the light intensity distribution conversion element and the collimator are integrated.

[Example 2]
The optical pickup device in the present embodiment is configured not to include a light intensity distribution conversion element. Specifically, the optical pickup device is compatible between HD-DVD / DVD, and a first laser diode that emits a first light beam with a wavelength of 655 nm for DVD and a first laser diode with a wavelength of 407 nm for HD-DVD. A second laser diode that emits two light beams is stored in the light source unit, and each light beam emitted from the light source unit sequentially passes through a beam shaping element, a beam splitter, and a collimator (coupling element), and thereby a diaphragm member The diameter of the light beam is narrowed down by this, and the light is condensed on the recording surface of each optical disk via the objective lens.

Tables 3 and 4 show lens data of each optical element.

As shown in Table 3, the second laser diode that emits the second light flux with a wavelength of 407 nm is disposed on the optical axis at coordinates (X, Y) = (0.000, 0.000), and the second laser diode with a wavelength of 655 nm. The first laser diode that emits one light beam is disposed at a position shifted in the Y-axis direction (the fifth direction) where coordinates (X, Y) = (0.000, 0.110).
The incident surface (third surface) and the exit surface (fourth surface) of the beam shaping element are configured by Y toroidal surfaces defined by mathematical expressions in which the coefficients shown in Tables 3 and 4 are substituted into Equation (3).

The exit surface (eighth surface) of the collimator is formed of an aspherical surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 3 and 4 into Formula 4.
Further, a diffraction ring zone centered on the optical axis is formed on the eighth surface, and the pitch of the diffraction ring zone is defined by a mathematical formula in which the coefficients shown in Tables 3 and 4 are substituted into the optical path difference function of Formula 5. The
The entrance surface (tenth surface) of the objective lens is formed of an aspherical surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 3 and 4 into Formula 4.

Further, a diffractive ring zone centered on the optical axis is formed on the tenth surface, and the pitch of the diffractive ring zone is defined by an equation obtained by substituting the coefficients shown in Tables 3 and 4 into the optical path difference function of Formula 5. The
The exit surface (eleventh surface) of the objective lens is composed of an aspherical surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 3 and 4 into Formula 4.

[Example 3]
As in the second embodiment, the optical pickup device in the present embodiment has a configuration that does not include the light intensity distribution conversion element. Specifically, the optical pickup device is compatible between HD-DVD / DVD, and a first laser diode that emits a first light beam with a wavelength of 655 nm for DVD and a first laser diode with a wavelength of 407 nm for HD-DVD. A second laser diode that emits two light beams is stored in the light source unit, and each light beam emitted from the light source unit sequentially passes through a beam shaping element, a beam splitter, and a collimator (coupling element), and thereby a diaphragm member The diameter of the light beam is narrowed down by this, and the light is condensed on the recording surface of each optical disk via the objective lens.

Tables 5 and 6 show lens data of each optical element.

As shown in Table 5, the second laser diode that emits the second light flux with a wavelength of 407 nm is disposed on the optical axis at coordinates (X, Y) = (0.000, 0.000), and the second laser diode with a wavelength of 655 nm. The first laser diode that emits one light beam is disposed at a position shifted in the Y-axis direction (the fifth direction) where coordinates (X, Y) = (0.000, 0.110).
The incident surface (third surface) of the beam shaping element is composed of an X toroidal surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 5 and 6 into Formula 6.

Furthermore, on the third surface, as the third optical path difference providing structure, there is formed a diffractive structure defined by a mathematical formula in which the coefficients shown in Table 5 and Table 6 are substituted into Formula 2. As shown in FIG. 5, this diffractive structure has a first optical function unit extending linearly along a direction perpendicular to the optical axis L (third direction) in a direction perpendicular to the third direction ( The fourth direction is continuously arranged, and the fourth direction and the X direction coincide with each other. In FIG. 5, each first optical function unit 70 is divided into three stages, but the number of divisions in this embodiment is five.
The exit surface (fourth surface) of the beam shaping element is composed of an X toroidal surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 5 and 6 into Formula 6.

The exit surface (eighth surface) of the collimator is formed of an aspherical surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 5 and 6 into Formula 4.
Further, a diffraction ring zone centered on the optical axis is formed on the eighth surface, and the pitch of the diffraction ring zone is defined by an equation obtained by substituting the coefficients shown in Tables 5 and 6 into the optical path difference function of Formula 5. The
The entrance surface (tenth surface) of the objective lens is formed of an aspherical surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 5 and 6 into Formula 4.
Further, a diffractive ring zone centered on the optical axis is formed on the tenth surface, and the pitch of the diffractive ring zone is defined by an equation obtained by substituting the coefficients shown in Tables 5 and 6 into the optical path difference function of Formula 5. The
The exit surface (eleventh surface) of the objective lens is composed of an aspherical surface defined by mathematical formulas in which the coefficients shown in Tables 5 and 6 are substituted into Formula 4.

[Example 4]
As in the third embodiment, the optical pickup device in the present embodiment has a configuration that does not include a light intensity distribution conversion element. Specifically, the optical pickup device has compatibility between HD-DVD / DVD / CD as shown in FIG. 10, and is a modification of the pickup device shown in FIG.
The deformation will be described. The housing 23 stores the first laser diode 21, the second laser diode 22, and the third laser diode 24. 10, the first laser diode 21 is arranged on the left side, the second laser diode 22 is arranged on the right side, and the third laser diode 24 is arranged in the center. In this embodiment, the collimator 12 and the beam shaping element 40 are arranged as separate optical elements.

  The first laser diode 21 emits a first light beam having a wavelength of 785 nm for CD. The second laser diode 22 emits a second light beam having a wavelength of 655 nm for DVD. The third laser diode 24 emits a third light flux having a wavelength of 408 nm for HD-DVD. Each light beam emitted from the light source unit 20 sequentially passes through the beam shaping element 40, the collimator 12 (coupling element), and the beam splitter 11, and the diameter of the light beam is narrowed by the diaphragm member 14. The light is condensed on the recording surfaces 51, 61, 63 of the optical disk.

表７に示すように、波長４０８nmの第３光束を出射する第３レーザダイオード２４は座標（Ｘ，Ｙ）＝（０．０００、０．０００）となる光軸上に配置され、波長６５５nmの第２光束を出射する第２レーザダイオード２２は座標（Ｘ，Ｙ）＝（０．０００，０．１１０）となるＹ軸方向（上記第５方向）にずれた位置に配置され、波長７８５nmの第１光束を出射する第１レーザダイオード２４は座標（Ｘ，Ｙ）＝（０．０００，−０．１１０）となるＹ軸方向（上記第５方向）にずれた位置に配置されている。 Tables 7 and 8 show lens data of each optical element.

As shown in Table 7, the third laser diode 24 that emits a third light flux with a wavelength of 408 nm is disposed on the optical axis at coordinates (X, Y) = (0.000, 0.000), and has a wavelength of 655 nm. The second laser diode 22 that emits the second light beam is disposed at a position shifted in the Y-axis direction (the fifth direction) where the coordinates (X, Y) = (0.000, 0.110), and has a wavelength of 785 nm. The first laser diode 24 that emits the first light flux is disposed at a position shifted in the Y-axis direction (the fifth direction) where the coordinates (X, Y) = (0.000, −0.110).

The incident surface (first surface) and the exit surface (second surface) of the beam shaping element 40 are configured by Y toroidal surfaces defined by mathematical expressions obtained by substituting the coefficients shown in Tables 7 and 8 into Equation 3. . Further, diffractive structures are formed on the third surface and the fourth surface, and are defined by mathematical formulas obtained by substituting the coefficients shown in Tables 7 and 8 into the optical path difference function of Formula 2.
The exit surface (fourth surface) of the collimator 12 is formed of an aspherical surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 7 and 8 into Formula 4.
The incident surface (sixth surface) of the objective lens 15 is composed of an aspheric surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 7 and 8 into Formula 4. Further, a diffraction ring zone centered on the optical axis is formed on the sixth surface, and the pitch of the diffraction ring zone is defined by an equation obtained by substituting the coefficients shown in Tables 7 and 8 into the optical path difference function of Formula 5. The
The exit surface (seventh surface) of the objective lens 15 is composed of an aspherical surface defined by mathematical formulas obtained by substituting the coefficients shown in Tables 7 and 8 into Formula 4.

It is a top view which shows the structure of the optical pick-up apparatus which concerns on this invention. It is a principal part perspective view which shows the shape of a beam shaping element. It is a graph (a) and (b) which shows light intensity distribution. It is a top view which shows the other structure of an optical pick-up apparatus. It is the front view (a) and top view (b) for showing the shape of the 3rd optical path difference providing structure. It is a front view for showing the structure of a light source unit. It is drawing for demonstrating angle (theta) which a 4th direction (7th direction) and a 5th direction comprise. It is a top view which shows the structure of the optical pick-up apparatus which concerns on this invention. It is a top view which shows the structure of the optical pick-up apparatus which concerns on this invention. It is a top view which shows the structure of the optical pick-up apparatus which concerns on this invention. It is a graph which shows a radiation characteristic. It is a graph which shows a radiation characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Coupling element 15 Objective optical element 18 Light-receiving part 20 Light source unit 30 Light intensity distribution conversion element 40 Beam shaping element

Claims (64)

A light source unit in which a plurality of light emitting points that emit light at different wavelengths are provided close to each other;
The emitted light beam from the light source unit is incident in at least one of two directions, a first direction perpendicular to the optical axis and a second direction perpendicular to both the optical axis and the first direction. A beam shaping element that shapes the divergence angle different from the original,
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point to the surface of the protective layer protecting the recording surface is set to be constant regardless of the type of the optical information recording medium,
The optical information recording medium having a thin protective layer is formed by using the first light beam having a long wavelength among the light beams emitted from the light emitting points to form an optical information recording medium having a thin protective layer. On the other hand, the optical pickup device is characterized in that the condensing spot is formed by using a second light beam having a short wavelength among the light beams emitted from the light emitting points. A light source unit in which at least two light emitting points emitting at different wavelengths are provided close to each other;
The emitted light beam from the light source unit is incident in at least one of two directions, a first direction perpendicular to the optical axis and a second direction perpendicular to both the optical axis and the first direction. A beam shaping element that shapes the divergence angle different from the original,
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point of the two light emitting points to the surface of the protective layer that protects the recording surface is set to be constant regardless of the type of the optical information recording medium,
For the two optical information recording media having different protective layer thicknesses, the first of the light beams emitted from the two light emitting points having the longer wavelength is different from the optical information recording medium having the thicker protective layer. The condensing spot is formed using a light beam, and the second light beam having a short wavelength out of the light beams emitted from the two light emitting points is used for the optical information recording medium having the thinner protective layer. An optical pickup device for forming a light spot. The optical pickup device according to claim 1 or 2,
An optical pickup device in which the beam shaping element and the coupling element are integrated. The optical pickup device according to claim 1 or 2,
The optical pickup device, wherein the beam shaping element and the coupling element are constituted by one element having both functions. It is an optical pick-up apparatus as described in any one of Claims 1-4,
An optical pickup device, wherein the beam shaping element and the objective optical element are separated. An optical pickup device according to any one of claims 1 to 5,
All of the beam shaping element, the coupling element, and the objective optical element are made of plastic. A light source unit in which a plurality of light emitting points that emit light at different wavelengths are provided close to each other;
Of the emitted light flux whose intensity distribution from the light source unit is approximately Gaussian distribution, the light intensity of the light flux that passes through the outermost peripheral portion of the effective diameter is between 45% and 95% of the light intensity of the light flux that passes through the optical axis position. A light intensity distribution conversion element that converts the light intensity to a desired light intensity;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point to the surface of the protective layer protecting the recording surface is set to be constant regardless of the type of the optical information recording medium,
The optical information recording medium having a thin protective layer is formed by using the first light beam having a long wavelength among the light beams emitted from the light emitting points to form an optical information recording medium having a thin protective layer. On the other hand, the optical pickup device is characterized in that the condensing spot is formed by using a second light beam having a short wavelength among the light beams emitted from the light emitting points. A light source unit in which at least two light emitting points emitting at different wavelengths are provided close to each other;
Of the emitted light flux whose intensity distribution from the light source unit is approximately Gaussian distribution, the light intensity of the light flux that passes through the outermost peripheral portion of the effective diameter is between 45% and 95% of the light intensity of the light flux that passes through the optical axis position. A light intensity distribution conversion element that converts the light intensity to a desired light intensity;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each of the two light emitting points to the surface of the protective layer protecting the recording surface is set to be constant regardless of the type of the optical information recording medium,
For the two optical information recording media having different protective layer thicknesses, the first of the light beams emitted from the two light emitting points having the longer wavelength is different from the optical information recording medium having the thicker protective layer. The condensing spot is formed using a light beam, and the second light beam having a short wavelength out of the light beams emitted from the two light emitting points is used for the optical information recording medium having the thinner protective layer. An optical pickup device for forming a light spot. The optical pickup device according to claim 7 or 8,
The optical pickup device, wherein the light intensity distribution conversion element and the coupling element are integrated. The optical pickup device according to claim 7 or 8,
The optical pick-up apparatus, wherein the light intensity distribution conversion element and the coupling element are constituted by one element having both functions. It is an optical pick-up apparatus as described in any one of Claims 7-10,
The optical pickup device, wherein the light intensity distribution conversion element and the objective optical element are separated. It is an optical pick-up apparatus as described in any one of Claims 7-11,
All of the light intensity distribution conversion element, the coupling element, and the objective optical element are made of plastic. A light source unit in which a plurality of light emitting points that emit light at different wavelengths are provided close to each other;
The emitted light beam from the light source unit is incident in at least one of two directions, a first direction perpendicular to the optical axis and a second direction perpendicular to both the optical axis and the first direction. A beam shaping element that shapes the divergence angle different from the original,
Of the emitted light flux whose intensity distribution from the light source unit is approximately Gaussian distribution, the light intensity of the light flux that passes through the outermost peripheral portion of the effective diameter is between 45% and 95% of the light intensity of the light flux that passes through the optical axis position. A light intensity distribution conversion element that converts the light intensity to a desired light intensity;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point to the surface of the protective layer protecting the recording surface is set to be constant regardless of the type of the optical information recording medium,
The optical information recording medium having a thin protective layer is formed by using the first light beam having a long wavelength among the light beams emitted from the light emitting points to form an optical information recording medium having a thin protective layer. On the other hand, the optical pickup device is characterized in that the condensing spot is formed by using a second light beam having a short wavelength among the light beams emitted from the light emitting points. A light source unit in which at least two light emitting points emitting at different wavelengths are provided close to each other;
The emitted light beam from the light source unit is incident in at least one of two directions, a first direction perpendicular to the optical axis and a second direction perpendicular to both the optical axis and the first direction. A beam shaping element that shapes the divergence angle different from the original,
Of the emitted light flux whose intensity distribution from the light source unit is approximately Gaussian distribution, the light intensity of the light flux that passes through the outermost peripheral portion of the effective diameter is between 45% and 95% of the light intensity of the light flux that passes through the optical axis position. A light intensity distribution conversion element that converts the light intensity to a desired light intensity;
A coupling element for converting a divergence angle of the emitted light beam;
An objective optical element that focuses a light beam emitted from the coupling element on a recording surface of an optical information recording medium to form a focused spot;
A light receiving unit that receives reflected light from the focused spot and converts it into an electrical signal;
The distance from each light emitting point of the two light emitting points to the surface of the protective layer that protects the recording surface is set to be constant regardless of the type of the optical information recording medium,
For the two optical information recording media having different protective layer thicknesses, the first of the light beams emitted from the two light emitting points having the longer wavelength is different from the optical information recording medium having the thicker protective layer. The condensing spot is formed using a light beam, and the second light beam having a short wavelength out of the light beams emitted from the two light emitting points is used for the optical information recording medium having the thinner protective layer. An optical pickup device for forming a light spot. The optical pickup device according to claim 13 or 14,
The optical pickup device, wherein the beam shaping element, the light intensity distribution conversion element, and the coupling element are integrated. The optical pickup device according to claim 13 or 14,
The optical pickup device, wherein the beam shaping element, the light intensity distribution conversion element, and the coupling element are constituted by one element having the respective functions. The optical pickup device according to claim 13 or 14,
The optical pickup device, wherein the beam shaping element and the light intensity distribution conversion element are integrated. The optical pickup device according to claim 13 or 14,
The optical pick-up apparatus, wherein the beam shaping element and the light intensity distribution conversion element are constituted by one element having both functions. The optical pickup device according to claim 13 or 14,
An optical pickup device, wherein the beam shaping element and the coupling element are integrated. The optical pickup device according to claim 13 or 14,
The optical pickup device, wherein the beam shaping element and the coupling element are constituted by one element having both functions. The optical pickup device according to claim 13 or 14,
The optical pickup device, wherein the light intensity distribution conversion element and the coupling element are integrated. The optical pickup device according to claim 13 or 14,
The optical pick-up apparatus, wherein the light intensity distribution conversion element and the coupling element are constituted by one element having both functions. The optical pickup device according to any one of claims 13 to 22,
An optical pickup device, wherein the beam shaping element and the objective optical element are separated. The optical pickup device according to any one of claims 13 to 22,
The optical pickup device, wherein the light intensity distribution conversion element and the objective optical element are separated. The optical pickup device according to any one of claims 13 to 24,
All of the beam shaping element, the light intensity distribution conversion element, the coupling element, and the objective optical element are made of plastic. It is an optical pick-up apparatus as described in any one of Claims 1-25,
An optical pickup device comprising a first optical path difference providing structure for providing a predetermined optical path difference to an incident light beam on an optical surface of the objective optical element. 27. The optical pickup device according to claim 26, wherein
The optical pickup device, wherein the first optical path difference providing structure is a diffractive structure. The optical pickup device according to claim 26 or 27,
The optical pickup device according to claim 1, wherein the first optical path difference providing structure suppresses the occurrence of wavefront aberration and / or astigmatism degradation due to temperature fluctuations in a use environment and / or wavelength fluctuations of an incident light beam. An optical pickup device according to any one of claims 1 to 28, wherein:
An optical pickup device, wherein the objective optical element has an aperture limiting function for an emitted light beam. The optical pickup device according to claim 29, wherein
The aperture limiting function is realized by a second optical path difference providing structure that is formed in a predetermined region on the optical surface of the objective optical element and flares the light flux by giving a predetermined optical path difference to the incident light flux. An optical pickup device. An optical pickup device according to any one of claims 1 to 30, wherein
When the position in the optical axis direction of the objective optical element when the focused spot is formed using the first light flux is a reference position,
An optical pickup device that moves the objective optical element toward the light source unit relative to the reference position when forming the focused spot using the second light flux. It is an optical pick-up apparatus as described in any one of Claims 1-31,
The cross-sectional shape in a plane perpendicular to the optical axis at the time when the second light flux is emitted from the light source unit is an elliptical shape in which the first direction has a minor axis and the second direction has a major axis. An optical pickup device, wherein the rim intensity of the second light flux in the first direction is in the range of 45 to 95%. The optical pickup device according to any one of claims 1 to 32,
An optical pickup device, wherein a light emitting point that emits the second light flux is arranged so as to coincide with an optical axis. The optical pickup device according to any one of claims 1 to 33,
An optical pickup device having an optical system magnification within a range of 3 to 5 times. The optical pickup device according to any one of claims 1 to 34,
The optical receiver is shared so as to receive both the reflected light of the first light beam and the reflected light of the second light beam. The optical pickup device according to any one of claims 1 to 35,
An optical pickup device comprising optical path combining means for matching the optical paths of the first light flux and the second light flux before the light flux enters the beam shaping element or the light intensity distribution conversion element. An optical pickup device according to any one of claims 1 to 36, wherein
The optical pick-up apparatus, wherein the beam shaping element or the light intensity distribution conversion element has wavelength selectivity for optically acting on an arbitrary light beam among the passing light beams. The optical pickup device according to claim 37, wherein
The optical action is an action of suppressing coma generated by oblique incidence of a light beam and / or an action of suppressing astigmatism generated by a wavelength difference between the first light beam and the second light beam. Optical pickup device. The optical pickup device according to claim 38, wherein
An optical pickup device, wherein the optical action is given only to the first light flux. The optical pickup device according to claim 38 or 39,
The optical pickup device, wherein the wavelength selectivity is realized by a third optical path difference providing structure that provides a predetermined optical path difference with respect to an incident light beam. The optical pickup device according to claim 40, wherein
The third optical path difference providing structure has a first optical function unit extending linearly along a third direction perpendicular to the optical axis on an optical surface in a fourth direction perpendicular to the third direction. An optical pickup device comprising a coma aberration correcting structure formed continuously. 42. The optical pickup device according to claim 41, comprising:
An optical pickup characterized in that an absolute value of an angle formed by the fourth direction and the fifth direction is 30 degrees or less when an arrangement direction of the light emitting points included in the light source unit is defined as a fifth direction. apparatus. The optical pickup device according to claim 40, wherein
The third optical path difference providing structure has a second optical function unit extending linearly along a sixth direction perpendicular to the optical axis on an optical surface in a seventh direction perpendicular to the sixth direction. An optical pickup device comprising an astigmatism correction structure arranged continuously. The optical pickup device according to claim 43, wherein
An optical pickup characterized in that an absolute value of an angle formed by the seventh direction and the fifth direction is 30 degrees or less when an arrangement direction of the light emitting points included in the light source unit is defined as a fifth direction. apparatus. The optical pickup device according to claim 40, wherein
The third optical path difference providing structure has a first optical function unit extending linearly along a third direction perpendicular to the optical axis on an optical surface in a fourth direction perpendicular to the third direction. A coma aberration correcting structure that is continuously arranged, and a second optical function unit that extends linearly along a sixth direction perpendicular to the optical axis on the optical surface, are perpendicular to the sixth direction. An optical pickup device comprising: an astigmatism correction structure continuously arranged in a seventh direction. The optical pickup device according to claim 45, wherein
When the arrangement direction of the light emitting points included in the light source unit is defined as a fifth direction, an absolute value of an angle formed by the fourth direction and the fifth direction is 30 degrees or less, and the seventh direction and the An optical pickup device characterized in that an absolute value of an angle formed by the fifth direction is 30 degrees or less and an absolute value of an angle formed by the fourth direction and the seventh direction is 15 degrees or less. It is an optical pick-up apparatus as described in any one of Claims 1-6 and 13-46,
The cross-sectional shape in a plane perpendicular to the optical axis of each luminous flux at the time of emission from the light source unit is an elliptical shape having the first direction as the minor axis and the second direction as the major axis, When the divergence angle in the first direction of the light beam after being shaped by the beam shaping element is D1, and the divergence angle in the second direction is D2,
1.0 <D2 / D1 <2.0
An optical pickup device satisfying the requirements.
However, D1 and D2 are angles at positions where the light intensity of each light beam is 50% of the peak. It is an optical pick-up apparatus as described in any one of Claims 7-46,
The cross-sectional shape in a plane perpendicular to the optical axis of each luminous flux at the time of emission from the light source unit is an elliptical shape having the first direction as the minor axis and the second direction as the major axis, An optical pickup device, wherein the rim intensity in the first direction of the light beam after being converted by the light intensity distribution conversion element is within a range of 45 to 95%. It is an optical pick-up apparatus as described in any one of Claims 1-6 and 13-47,
The optical pickup device, wherein the beam shaping element is a cylindrical lens, and an arrangement direction of the light emitting points provided in the light source unit coincides with an axial direction of the beam shaping element. It is an optical pick-up apparatus as described in any one of Claims 1-6 and 13-47,
An optical pickup device, wherein an optical axis of the beam shaping element is inclined with respect to a vertical direction of a plane including each light emitting point provided in the light source unit. The optical pickup device according to claim 50, wherein
An optical pickup device, wherein an inclination direction of an optical axis of the beam shaping element coincides with an arrangement direction of the light emitting points. It is an optical pick-up apparatus as described in any one of Claims 1-6 and 13-47,
The optical pickup device, wherein the beam shaping element has a wedge shape in which an exit surface is inclined relative to an entrance surface. The optical pickup device according to claim 52, wherein
An optical pickup device characterized in that a relative inclination direction of the emission surface with respect to the incident surface coincides with an arrangement direction of the light emitting points. 54. The optical pickup device according to any one of claims 1 to 53, wherein:
An optical pickup device comprising: a light combining unit that matches at least the optical paths of the first light beam and the second light beam. The optical pickup device according to claim 54, wherein
An optical pickup device, wherein an optical path of the first light flux and the second light flux after passing through the light synthesizing unit is inclined with respect to a vertical direction of a plane including each light emitting point included in the light source unit. The optical pickup device according to claim 54 or 55,
The optical pickup device is characterized in that the light synthesizing means has a wedge shape in which an exit surface is inclined relative to an entrance surface. 57. The optical pickup device according to any one of claims 49 to 56, wherein:
The beam shaping element emits the light beam having an enlarged diameter in a plane perpendicular to the optical axis at the time of emission from the light source unit. Pickup device. 57. The optical pickup device according to any one of claims 49 to 56, wherein:
The beam shaping element emits the light beams having a reduced diameter in a cross-sectional shape in a plane perpendicular to the optical axis at the time of emission from the light source unit. Pickup device. 59. The optical pickup device according to any one of claims 37 to 58, wherein:
An optical pickup device comprising: an actuator that moves at least one of the beam shaping element and the light intensity distribution conversion element according to a type of the optical information recording medium. The optical pickup device according to claim 59, wherein
The optical pickup device, wherein the actuator moves at least one of the beam shaping element and the light intensity distribution conversion element in a direction along an optical axis. The optical pickup device according to claim 59 or 60, wherein:
The optical pickup device, wherein the actuator moves at least one of the beam shaping element and the light intensity distribution conversion element in a direction perpendicular to an optical axis. 62. The optical pickup device according to any one of claims 59 to 61, wherein:
The optical pickup device, wherein the actuator is a piezoelectric actuator. It is an optical pick-up apparatus as described in any one of Claims 1-62,
The optical pickup device, wherein the light source unit is configured by arranging three light emitting points that emit light at different wavelengths close to each other, and the light emitting points are arranged in a straight line. An optical pickup device according to claim 63, wherein
An optical pickup device, wherein a light emitting point that emits a third light flux having the shortest wavelength among the three light emitting points is disposed at a position closest to the optical axis of the light source unit.

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