JP2734547B2 - Optical pickup head device and optical information device using the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup head device capable of recording / reproducing or erasing optical information stored on an optical medium or a magneto-optical medium such as an optical disk or an optical card and the optical pickup device. The present invention relates to an optical information device using a pickup head device.

2. Description of the Related Art Optical memory technology using a pit-shaped pattern as a high-density, large-capacity storage medium has been put to practical use while expanding its applications to digital audio disks, video disks, document file disks, and data files. . The mechanism by which recording and reproduction of information is successfully performed with high reliability via a light beam focused on the order of microns depends solely on the optical system.

The basic functions of an optical pickup head device (hereinafter abbreviated as OPU) are (I) light-collecting ability to form a diffraction-limited small spot, (II) focus control of the optical system and pit signal detection, and (III) The tracking control is roughly classified into three types.

These are realized by combinations of various optical systems and photoelectric conversion detection systems according to the purpose and application.

FIG. 10 is a schematic diagram showing an example of a conventional OPU. Usually, diverging wavefront from the semiconductor laser light source 1 that oscillates at TE ₀₀ mode: the parallel beam (electric field horizontally polarized wave) by the collimator lens 2, quarter-wave plate on the left side by the polarizing beam splitter 107 (1 / 4.lamda Selectively reflected on the plate 18). The circularly polarized wavefront that has passed through the 1 / 4λ plate 18 is narrowed down to a spot of approximately 1 μm by the lens 3, reaches the optical storage medium surface 4, and irradiates the pit-shaped pattern 40.

The light beam reflected and diffracted on the medium surface travels backward through the lens 3 again, passes through the 1 / 4λ plate 18, becomes a vertically polarized parallel beam, passes through the polarizing beam splitter 107, and passes through the beam splitter 19 in two directions. Divided. One reflected light is a condenser lens 20 and a cylindrical lens that gives astigmatism
The light enters the four-divided photodetector 559 through 21 and is converted into a focus error (hereinafter abbreviated as FE) signal. The other transmitted light enters the two-part photodetector 22 for detecting a tracking error (hereinafter abbreviated as TE) signal as a far-field pattern.

Here, the 1 / 4λ plate 18 is combined with the polarization beam splitter 107 to increase the efficiency of using the light amount, and at the same time, suppresses the return light to the semiconductor laser so that unnecessary noise in the signal light component does not increase. Ingenuity. However, with the read-only disk OPU, there is room in the light intensity design, and it is possible to omit the 1 / 4λ plate and the polarizing beam splitter. Is planned.

Problems to be Solved by the Invention However, even in a read-only OPU, it is necessary to independently or separately combine a beam splitting unit, a focus control unit using astigmatism or a knife edge method, and a tracking control unit. For this reason, it is not easy to manufacture, assemble, and adjust a large number of optical components that have been used in the past, such as beam splitters, lenses, and prisms. In terms of miniaturization, low cost, mass productivity, and high reliability, There was a problem.

One of the common reasons that these problems occur is that, first, optical parts that require high-precision planes or aspherical surfaces can be processed in a desired manner only after many steps. Second, it requires a lot of time and complicated inspection and measurement equipment to assemble and adjust to achieve a given overall performance by combining a large number of components. Third, miniaturization of components However, there is a great restriction on miniaturization of all optical systems because of its limitations.

As a solution to the above problem, a technique has been recently disclosed in which a predetermined wavefront for focus and tracking control is recorded on one hologram element, and each wavefront reproduced by a read beam of an optical pickup head device is guided to a photodetector. ^{1) to 5)} .

1) JP-A-54-43005; Oigami, Nagai 2) JP-A-62-188032; Oigami, Nagai 3) JP-A-62-236145; Matsushita, Tatsumi 4) Y.Kimura et al, " High Performance Optical Head
using Optimized Holo graphic Optical Element ", Proceeding of the International Symposium on Optical Memory (Proc. of the Inte
rnational Symposium on Optical Memory), Tokyo, Sep
t.16-18,1987 (p.131) 5) K. Tatsumi et al, "A Multi-functional Reflectio
n Type Grating Lens for the CD Optical Head ", Proceeding of the International Symposium on Optical Memory (Proc. of the In
ternational Symp osium on Optical Memory), Tokyo, S
ept. 16-18, 1987 (p. 127) 4) The FE signal was obtained by the double knife edge method, and the TE signal was obtained by the diffraction light intensity from the slit grating provided on the far field (hologram element surface). The other method is to detect the FE signal and the TE signal by calculating the astigmatism surfaces 140, 141, and 142 from the signals received by the four-division photodetector 555 as shown in FIG. For example, the FE signal is obtained by adding the outputs of the detectors of the quadrant detector by the adder circuits 31 and 32, obtaining the difference by the differential circuit 33, and performing signal processing by the signal processing circuit.

However, when the wavelength of the light source deviates from the design reference wavelength λ by δλ as a serious problem in each system,
Each beam on the photodetector moves (for example, 140 → 1401), and as a result, the FE signal is mixed with the tracking signal component, the FE signal is offset, etc., and accurate focus control can be performed. It will be difficult.

In a normal semiconductor laser, the operating environment temperature is, for example, 60 ° C.
When it changes, the laser oscillation wavelength is about 12 nm and the drive current
A change of 40 mA causes a wavelength change of about 8 nm.

As a stable FE signal detection method capable of coping with a change in the diffraction angle from the hologram element caused by such a wavelength variation, Japanese Patent Application No. 62-251026 discloses a Fresnel zone plate off-axis to the hologram element surface. Is formed to generate a beam having two different focal points for a photodetector to detect an FE signal. At this time, since the photodetector has a light receiving portion formed radially with the light source at the center, a stable FE signal can be detected without any influence even if a wavelength change occurs in the light source.

However, in the configuration disclosed in Japanese Patent Application No. 62-251026, since two off-axis Fresnel zone plates are formed on the hologram element surface, unnecessary diffraction depending on the superposition of two patterns is performed. When light is generated, an offset is generated in the FE signal, or a TE signal or a signal having the same cycle as the TE signal but having a different phase is mixed into the FE signal, so that there is a problem that focus control cannot be stably performed.

Means for Solving the Problems In order to solve the above-mentioned problems, an optical pickup head device of the present invention comprises a light source for emitting a beam, and a beam emitted from the light source, receiving the beam, and converging the beam onto an optical storage medium. A light-collecting optical system, a hologram element that receives a beam reflected by the optical storage medium to generate diffracted light, and a photodetector that receives a diffracted light from the hologram element and outputs a signal corresponding to the amount of light received. The hologram region of the hologram element has a plurality of spatially divided regions, and the plurality of regions are two diffracted light beams focused at different positions in the optical axis direction with respect to a light receiving surface of the photodetector. And a first pattern or a second pattern in each of the divided hologram regions of the hologram element. Is one recording of the second pattern, the first said pattern recording area of the second pattern is an arrangement was configured to mutually sandwich each other and a recording area.

Further, an optical information device according to the present invention includes a drive mechanism for an optical storage medium, an optical pickup head device according to the present invention, and a focus servo mechanism using each of a focus error signal and a tracking error signal obtained from the optical pickup head device. And a tracking servo mechanism, and an electric circuit for realizing the servo mechanism,
It has a configuration having at least a power supply or a connection portion to an external power supply.

According to the present invention, only the independent pattern is recorded in each of the plurality of divided hologram areas of the hologram element by the above-described means. Therefore, only the diffracted light corresponding to the pattern recorded in each area is recorded from the hologram area. Since no diffraction light is generated, that is, there is no diffraction light depending on the recording of the hologram patterns superimposed on each other, and there is no influence of the diffraction light, a stable focus error signal without offset can be detected.

Further, the optical information device constituted by using this optical pickup head device can perform stable focus control.

Embodiment FIG. 1A shows a schematic configuration of an OPU device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a semiconductor laser that emits a coherent beam (for example, TE at a wavelength λ ₂ = 800 nm).
(Oscillation in ₀₀ mode), 2 is a collimating lens (for example, focal length f _C = 20 mm), 3 is a focusing objective lens, 4 is an optical storage medium (optical disk), and a beam emitted from the light source 1 is a collimating lens. The beam is converted into a parallel beam by the lens 2 and is focused on the disk 4 by the lens 3.

Reference numeral 6 denotes a hologram element capable of reproducing a wavefront having two pairs of conjugate focal points, which is obtained by recording two divergent or convergent wavefronts on the hologram element. The hologram element 6 is interposed between the lenses 2 and 3, and its 0th-order diffracted light is focused on the disk 4 on the outward path. In the disk 4, reference numeral 42 denotes a substrate, and reference numeral 41 denotes a protective film.

The beam reflected on the disk 4 passes through the lens 3 again on the return path and becomes almost parallel light, and then becomes a hologram element 6
To generate diffracted lights 71 and 73 and 72 and 74 having two pairs of conjugate focal points for obtaining an off-axis FE signal, in addition to the zero-order diffracted light. These diffracted lights 71 to 74 are converged via the collimating lens 2.

When the focal points of the diffracted lights 71 to 74 are correctly focused on the disk 4, the convergence point of the zero-order diffracted light (the emission point of the light source 1)
Focusing in directions perpendicular to the two surfaces at positions before and after the surface 111 perpendicular to the optical axis of the lens 2 including 10),
At this time, the distance between each focal plane and the plane 111 is designed to be δ1 = δ2 = δ. Diffracted light 71-74 is photodetector unit 5
To receive light.

FIG. 1B shows the photodetector unit 5 arranged on the surface 111 and the states of the diffracted lights 71 and 72 on the surface of the photodetector unit 5.
The photodetector unit 5 includes a photodetector 51 and
The photodetector 51 includes photodetectors 511, 512, and 513, and the photodetector 52 includes photodetectors 521, 522, and 523. This figure shows a reproduced image corresponding to a state where the focus is correctly focused on the disk. FE signal, TE signal,
The details of the method of detecting the RF signal and the hologram element 6 will be described later.

FIG. 2 is a conceptual diagram showing another embodiment of the present invention.
In the first embodiment, a transmission hologram element is used, whereas in this embodiment, a reflection hologram element 660 is used to bend the optical axis at α = 90 °. Further, an image forming optical system is constituted only by the objective lens system 30 without using a collimating lens, thereby achieving miniaturization and reducing the number of parts.

FIG. 3 illustrates yet another embodiment of the present invention. FIG. 1A shows a schematic configuration of an OPU device, in which a beam emitted from a light source 1 is converted into a parallel beam by a collimator lens 2, reflected by a polarizing beam splitter 106, and then turned on by a wave plate 9.
Then, the optical path is bent by the mirror 8 and then focused on the disk 4 by the lens 3.

The beam reflected on the disk 4 passes through the lens 3 again on the return path and becomes almost parallel light, then passes through the wave plate 9 to be vertically polarized, and passes through the polarizing beam splitter 106. The transmitted light from the polarizing beam splitter 106 is incident on the hologram 666, generates off-axis diffracted light wavefronts 71 to 74 in addition to the 0th-order diffracted light, and condenses this diffracted light with the lens 20,
The light is received by the photo detector unit 55.

FIG. 7B shows the state of the photodetector unit 55 and the diffracted light on the surface of the photodetector unit. The difference between the photodetector unit 55 and the photodetector unit 5 in the above two examples is that the 0th-order diffracted light 70 can be received because the outward path from the light source and the return path to the photodetector unit are separated. That is, the photodetector 50 is formed. By detecting the zero-order light, a good RF signal can be easily detected.

Here, the wave plate 9 is a polarizing beam splitter 10.
The design is about λ / 5 to facilitate the balance of performance with 6, and the S / N ratio for signal detection is maximized by optimizing the amount of return light.

Now, the signal detection method in the above embodiment will be described in detail. FIG. 4 shows, for example, the photodetector regions 511 to 51 of the photodetector unit 5 shown in FIG.
The relationship between the diffracted lights 71, 72 detected at 3,521 to 523 and the light emitting point 10 is schematically and generally represented. FIG. 4B shows a case where a focused spot is formed on the disk.
FIGS. 4 (a) and 4 (c) each show a state in which the disk is defocused in the opposite direction.

The FE signal is obtained by, for example, performing a differential operation on signals output from the photodetectors 512 and 522. The method of detecting the FE signal by this calculation is called a spot size discrimination method and is a well-known technique. Here, for example, the differential output is increased by adding the signal output from the photodetectors 521 and 523 to the signal output from the photodetector 512 and the signal output from the photodetectors 511 and 513 to the signal output from the photodetector 522, respectively.

When the wavelength λ of the light source changes by δλ to the longer wavelength side, the diffracted lights 71 and 72 on the photodetector 5 move to 710 and 720, respectively, as shown in FIG. At this time, each photodetector 511-513, 521-523
Is formed radially around the convergence point of the 0th-order diffracted light (the light-emitting point 10 of the light source 1), even if the diffracted light moves due to the wavelength fluctuation of the light source, a constant diffracted light always enters each photodetector. Therefore, extremely stable FE signal detection becomes possible.

Furthermore, if the light source and the photodetector unit are displaced from each other during the assembly process, the FE signal can be detected stably with only a slight rotation of the hologram element, and the adjustment accuracy is significantly greater than before. Be improved. Also, the RF signal is, for example, photodetectors 511 to 51
It is obtained by summing the signals output from 3,521 to 523.

FIG. 5 is a conceptual diagram showing still another embodiment of the present invention. FIG. 7A shows the functional area division of the hologram element 6, and the hologram areas 671 and 672 are areas in which a wavefront having a pair of conjugate focal points can be reproduced.

As shown, a plurality of hologram regions 671 and 672 are formed alternately. That is, in this embodiment, eight regions 671 and 672 are provided, and different off-axis Fresnel zone plates are formed in the functional regions 671 and 672 in order to generate diffracted light having different focal points. doing.

FIG. 2B shows a wavefront on the photodetector 5 of the OPU using the hologram element 6 as shown in FIG. 1A, for example.
, The diffracted light 73 is obtained from the functional area 672 of the hologram element 6.

When this hologram element is used, no matter where the hologram element is inserted with respect to the reflected beam from the disk, the FE signal has a TE signal or a signal with a different phase in the same cycle as the TE signal. Does not occur.

Also, two Fresnel zone plates were added to areas 671 and 672
Therefore, the diffracted light generated depending on the superposition of the two patterns does not occur.

Therefore, the FE generated depending on the unnecessary diffracted light
It does not occur that the signal offset or the TE signal or the signal with the same cycle but the same phase as the TE signal is mixed into the FE signal.
Stable focus control becomes possible.

In this embodiment, the regions 671 and 672 are provided for each of the eight regions. However, the above effects can be obtained by providing two or more regions. Also, areas 671, 67
Regardless of the off-axis Fresnel zone plate or the interference pattern obtained by the two-beam interference method, the pattern to be recorded on 2 is a problem if it is diffracted light that focuses on a position different from the light receiving surface of the photodetector in the optical axis direction. Thus, the FE signal can be detected, and there is no particular restriction on the pattern recorded on the hologram element in the optical pickup head device of the present invention.

FIG. 6 is a conceptual diagram showing still another embodiment of the present invention. FIG. 11A shows the functional area division of the hologram element 61, and hologram areas 673 and 674 are areas where a wavefront having a pair of conjugate focal points can be reproduced. FIG. 2B shows an OPU as shown in FIG. 1A, for example.
The wavefront reproduced from the hologram element 61 on the photodetector unit 5 obtained when the hologram element 61 is used is shown.
The diffracted light 721 is obtained from the functional area 674 of the hologram element 61 from the functional area 673 of FIG.

The method of detecting the FE signal is the same as that of the fourth embodiment, and is obtained, for example, by performing a differential operation on the signals output from the photodetectors 512 and 522. In addition, photo detectors
Photodetectors 521 and 523 are applied to the signal output from 512.
By adding the signal output from the photodetectors 511 and 513 to the signal output from the photodetector 522, the output intensity of the FE signal increases.

In any case, in the FE signal detection method shown in the present embodiment, omitting the photodetectors 513 and 523 or 511 and 521 is no problem at all, and the intensity of the obtained FE signal is sufficient. In such a case, the configuration can be simplified by omitting the photodetector.

On the other hand, if the obtained FE signal is not strong enough,
The sensitivity can be increased by detecting also the conjugate lights 72 and 74 of the first-order diffracted lights 71 and 73.

FIG. 7 is a conceptual diagram showing still another embodiment of the present invention. FIG. 7A shows the functional area division of the hologram element 60. The areas 675 and 676 where wavefronts having two pairs of conjugate focal points can be reproduced for detecting the FE signal, and a simple grating pattern for detecting the TE signal are respectively shown. Area recorded in a different direction from the other
681 and 682, and a region 691 that does not generate first-order or higher order diffracted light (hereinafter referred to as a non-hologram region) 691. This is, for example, a part of the hologram element 6 of the fifth embodiment,
Diffraction grating 681,682 and non-hologram area 6 for TE signal detection
91 is formed.

Far-field patterns 401 and 402 relating to the tracks of the disk included in the beam reflected by the disk
Is made incident on the hologram element 60 as shown in FIG.

FIG. 2B shows an OP as shown in FIG. 1A, for example.
U, hologram element 60 and photo detector unit 500
Photodetector unit 50 obtained by using
FIG. 7 shows a wavefront reproduced from the hologram element 60 on the hologram element 60.
From, the diffracted light 722 from the functional area 676 of the hologram element 60, the diffracted light 752 from the functional area 681 of the hologram element 60,
Diffracted light 762 is obtained from each of the functional areas 682 of the hologram element.

The photodetector unit 500 includes a plurality of photodetectors 51, 52, 53, and 54, and furthermore, the photodetector 51 has 511, 512, 513, and the photodetector 52 has 5
21,522,523 respectively. In this case, the FE signal can be detected in exactly the same manner as in the fourth embodiment. On the other hand, the TE signal is obtained by performing a differential operation on the signals output from the photodetectors 53 and 54.

At this time, even when a seek operation is performed or tracking control is performed on an eccentric disk, even when the image of the lens on the hologram element 60 is moved due to a shift of the focusing lens, the offset is not affected. No good TE signal can be detected.

There are no particular restrictions on the shapes and sizes of the diffraction gratings 681 and 682 and the non-hologram region 691 for detecting the TE signal. The diffraction grating for detecting a TE signal can be implemented in other embodiments without any problem.

Further, the hologram elements of the present invention shown in the fifth to seventh embodiments can be easily manufactured by a general method such as two-beam interference method, pattern generation by a computer, and the like, and the explanation on the manufacturing method is omitted.

FIG. 8 shows an embodiment of an optical information device constituted by using the optical pickup head device described above. The optical storage medium (optical disk 4) is rotated by the drive mechanism 81. The optical pickup head device 80 sends a signal corresponding to the positional relationship with the optical disc 4 to the electric circuit 83. The electric circuit 83 amplifies or calculates this signal and outputs a signal for finely moving the optical pickup head device 80 or the objective lens in the optical pickup head device. Reference numeral 82 denotes a driving device for the optical pickup head device, and reference numeral 85 denotes a driving device for the objective lens in the optical pickup head device. Focus servo and tracking servo are performed on the optical disc 4 by the signal and the driving device 82 or 85,
Reading, writing, or erasing of information is performed on the optical disc 4. Reference numeral 84 denotes a connection portion to a power supply or an external power supply, and supplies electricity to the electric circuit 83, the drive device 82 of the optical pickup head device, the drive mechanism 81 of the optical disk, and the objective lens drive device 85 from the connection portion. It should be noted that there is no problem even if a connection terminal for a power supply or an external power supply is provided in each drive circuit.

The optical information device configured by using the optical pickup head device of the present invention performs stable focus control because there is no occurrence of an offset in the FE signal and no mixing of the TE signal or a signal having the same cycle as the TE signal with a different phase. be able to.

In addition, by providing a diffraction grating in a part of the hologram element area, the focusing lens is displaced when a seek operation is performed or when tracking control is performed on an eccentric disk, etc. Even if the image of the lens moves, it is possible to detect a good TE signal without offset, so that stable tracking control can be performed. That is, the optical information device can read information recorded on the optical storage medium with high reliability. Further, since the configuration of the optical pickup head device is simplified, the optical information device is inexpensive and small.

Effect of the Invention As described above, the optical pickup head device of the present invention includes a light source that emits a beam, and a condensing optical system that receives the beam emitted from the light source and converges the beam on an optical storage medium. A hologram element that receives the beam reflected by the optical storage medium and generates diffracted light; and a photodetector that receives a diffracted light from the hologram element and outputs a signal corresponding to the amount of light received and received. The hologram region has a plurality of regions that are spatially divided into a plurality of regions, and the plurality of regions generates two diffracted lights that are focused on different positions in the optical axis direction with respect to a light receiving surface of the photodetector. The hologram element is composed of a first pattern and a second pattern. One region is recorded, and a region where the first pattern is recorded and a region where the second pattern is recorded are arranged so as to sandwich each other, so that diffracted light having two different focal points is provided. Generate different 2
Since one pattern is formed in each of the spatially independent regions, no diffracted light is generated due to the superposition of the two patterns.

Therefore, the FE generated depending on the unnecessary diffracted light
An optical pickup head device that outputs a focus error signal capable of performing stable focus control without causing a signal offset and / or a TE signal or a signal having the same cycle as the TE signal and having a different phase from being mixed into the FE signal; Become.

Further, a plurality of photodetectors for receiving diffracted light other than at least the 0th-order diffracted light from the hologram element have a band-like shape, and the region dividing line of the photodetector has a radial direction centered on the convergence point of the 0th-order diffracted light from the hologram element. By extending the shape almost in parallel along the shape, even if the diffraction angle from the hologram element changes due to the wavelength variation in the light source, a constant diffracted light always enters each photodetector, All of the focus error signal, tracking error signal, and high frequency information signal can be detected extremely stably.

Further, the position adjustment of the photodetector is simplified to such an extent that almost no adjustment is made by slightly rotating the hologram element. As a result, the position accuracy of the photodetector is reduced, so that the FE signal and the TE signal can be detected stably, the adjustment when assembling the optical pickup head device is simplified, and the inexpensive optical pickup is used. A head device can be provided.

In addition, since the allowable range for the wavelength variation of the light source and the position adjustment of the photodetector is expanded, the pickup head device according to the present invention uses a semiconductor laser as a light source, and is stable and reliable even in an environment where temperature changes are extremely severe. An optical pickup head device capable of high operation is obtained.

Further, by providing a diffraction grating or a diffraction grating different from the hologram pattern and a non-hologram region that does not generate first-order or higher diffracted light in a part of the hologram element spatially separated from the region where the hologram pattern is recorded. Thus, the optical pickup head device can detect a stable focus error signal and tracking error signal.

In addition, even when a seek operation is performed or when tracking control is performed on an eccentric disk, even when the image of the lens on the hologram element moves due to displacement of the focusing lens, there is no offset. Good TE
Since signals can be detected, stable tracking control can be performed.

As a result, an optical information device using the present optical pickup head device is an optical information device capable of reading information recorded on an optical storage medium with high reliability. Further, since the configuration of the optical pickup is simplified, the optical information device is inexpensive and small.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram of an optical pickup head device showing one embodiment of the present invention, and FIG. 1B is a diagram showing the relationship between a photodetector and diffracted light in the optical pickup head device shown in FIG. FIG. 2 is a conceptual diagram of an optical pickup head device showing another embodiment of the present invention, and FIG. 3 (a) is a conceptual diagram of an optical pickup head device showing another embodiment of the present invention, and FIG. FIG. 4A is a diagram showing the relationship between a photodetector and diffracted light in the optical pickup head device shown in FIG.
FIGS. 4 (a), (b) and (c) are general principle diagrams for explaining the present invention, and FIG. 5 (a) is a configuration diagram of a hologram element for explaining an embodiment of the present invention, and FIG. FIG. 6A shows the relationship between the diffracted light and the photodetector in the optical pickup head device using the hologram element shown in FIG.
FIG. 9 is a configuration diagram of a hologram element for explaining another embodiment of the present invention, and FIG. 10B is a diagram showing the relationship between diffracted light and a photodetector in an optical pickup head device using the hologram element shown in FIG. FIG. 7A is a configuration diagram of a hologram element for explaining another embodiment of the present invention, and FIG. 7B is a relation between a diffracted light and a photodetector in an optical pickup head device using the hologram element shown in FIG. FIGS. 8 and 9 are schematic sectional views of an optical information device according to an embodiment of the present invention, and FIGS. 9A, 9B and 9C show a method of detecting a focus error signal of an optical system of a conventional optical pickup head device. FIG. 10 is a configuration diagram showing an example of an astigmatism wavefront detection system of an optical system of a conventional optical pickup head device. 1. Semiconductor laser or equivalent coherent light source,
2 ... collimating lens, 3 ... lens, 4 ... optical storage medium (optical disk), 5 ... photodetector unit, 6 ... hologram element, 10 ... light emitting point, 41 ... protective film, 42 ... substrate, 50-54 …… photodetector, 55 ……
Photo detector unit, 60 ... Hologram element, 61
… Hologram element, 70… 0-order diffracted light, 71-74… 1
Next-order diffracted light, 401,402 ... Farfield pattern, 671
~ 676 …… hologram area, 681 …… diffraction grating, 682 ……
Diffraction grating, 691 ... non-hologram area.

Claims (4)

(57) [Claims] 1. A light source for emitting a beam, a condensing optical system for receiving a beam emitted from the light source and converging the beam onto an optical storage medium, and a diffracted light for receiving a beam reflected by the optical storage medium. A hologram element to be generated, and a photodetector that receives a diffracted light from the hologram element and outputs a signal corresponding to the amount of light received, and the hologram area of the hologram element is obtained by spatially dividing a plurality of areas into a plurality of areas. The plurality of regions include a first pattern and a second pattern that generate two diffracted lights focused on different positions in an optical axis direction with respect to a light receiving surface of the photodetector, and the hologram element Either the first pattern or the second pattern is recorded in each of the divided hologram areas, and the area where the first pattern is recorded is Optical pick-up head, characterized in that are arranged and the second pattern is recorded areas such that each mutually scissors together. 2. A photodetector for receiving at least diffracted light other than the 0th-order diffracted light from the hologram element has a plurality of band-like shapes, and a region dividing line of the photodetector is centered on a converging point of the 0th-order diffracted light from the hologram element. 2. The optical pickup head device according to claim 1, wherein the optical pickup head device has a shape that extends substantially parallel to the radial direction. 3. A part of the hologram element which is spatially separated from a region where a hologram pattern is recorded is provided with a diffraction grating or a diffraction grating different from the hologram pattern and a non-hologram region which does not generate first or higher order diffracted light. The optical pickup head device according to claim 1, wherein the optical pickup head device is formed. 4. A drive mechanism for an optical storage medium, an optical pickup head device according to claim 1, and a focus error signal and a tracking error signal obtained from the optical pickup head device. An optical information device including at least a focus servo mechanism and a tracking servo mechanism, an electric circuit for realizing the servo mechanism, and a connection part to a power supply or an external power supply.