WO2007145119A1

WO2007145119A1 - Composite optical device

Info

Publication number: WO2007145119A1
Application number: PCT/JP2007/061478
Authority: WO
Inventors: Jun Murata; Toshiaki Takano
Original assignee: Panasonic Corporation
Priority date: 2006-06-13
Filing date: 2007-06-06
Publication date: 2007-12-21

Abstract

Disclosed is a composite optical device, particularly a composite optical device wherein a second optical unit and a third optical unit are joined to a first optical unit. This composite optical device is improved in optical characteristics. Specifically disclosed is a composite optical device (1) comprising first, second and third optical units (10, 20, 30). The first optical unit (10) has lens surfaces (12, 13). The second optical unit (20) is joined to the first optical unit (10) on the lens surface (12), and has a lens surface (22) which is opposite to a first contact surface (21). The third optical unit (30) is joined to the second optical unit (20) on the lens surface (22), and has a lens surface (32) which is opposite to a second contact surface (31). A part of the lens surface (22) has a first rough surface portion (22a), and a part of the lens surface (32) has a second rough surface portion (32a).

Description

Specification

Compound optical element

Technical field

The present invention relates to a composite optical element, and more particularly to a composite optical element in which a second optical part and a third optical part are joined to a first optical part.

Background art

Conventionally, a composite optical element having two or more optical parts is known. For example, in a composite optical element having two optical parts, a second optical part is bonded to the first optical part. Such composite optical elements are used in various optical systems. For example, they can be used as lenses by forming a diffractive structure on the joint surface.

[0003] As disclosed in Patent Document 1, for example, the diffractive structure formed on the joint surface is a slit-like or groove-like shape having a fine equidistant interval of several tens to several hundreds per minute interval (about 1 mm). When light is incident on such a diffractive structure, which is often a grating structure, a diffracted light beam is generated in a direction determined by the pitch (interval) of the slits and grooves and the wavelength of the light. Then, by collecting the diffracted light flux at one point, the composite optical element having such a diffractive structure can be used as a lens.

[0004] When the composite optical element is used as a lens, for example, a composite optical element in which a second optical part made of a resin is joined to a first optical part made of glass is used. This structure makes it possible to use the h-line (404. (7nm) force is also possible to increase the diffraction efficiency to 90% or more in a wide wavelength range up to C-line (656.3 nm).

Patent Document 1: Japanese Patent Laid-Open No. 11-287904

Disclosure of the invention

Problems to be solved by the invention

[0005] The composite optical element has two or more optical parts as described above, and each optical part often has a different material force, which may lead to deterioration of optical characteristics. [0006] The present invention has been made in view of efforts, and an object of the present invention is to provide a composite optical element capable of improving optical characteristics.

Means for solving the problem

[0007] The present invention includes first, second and third optical units. The first optical unit has a first optical functional surface. The second optical unit is bonded to the first optical unit on the first optical functional surface, and has the second optical functional surface on the side opposite to the first bonding surface bonded to the first optical unit. The third optical unit is bonded to the second optical unit on the second optical functional surface, and has the third optical functional surface on the side opposite to the second bonding surface bonded to the second optical unit. The first and second uneven surface portions are present on a part of each of the second and third optical function surfaces.

The invention's effect

[0008] According to the present invention, it is possible to improve optical characteristics.

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view of a composite optical element according to a first embodiment.

FIG. 2 (a) Force (f) in FIG. 2 is a cross-sectional view showing a method for manufacturing a composite optical element according to Embodiment 1.

FIG. 3 is a schematic cross-sectional view of a composite optical element that is useful for the first modification of Embodiment 1.

FIG. 4 is a schematic cross-sectional view of a composite optical element that works on the second modification of Embodiment 1.

FIG. 5 is a schematic cross-sectional view of a composite optical element that can be applied to the third modification of the first embodiment.

FIG. 6 is a schematic cross-sectional view of a composite optical element that works on the fourth modification of Embodiment 1.

FIG. 7 is a schematic cross-sectional view of a composite optical element according to the second embodiment.

FIG. 8 is a schematic cross-sectional view of a composite optical element according to Embodiment 3.

Explanation of symbols [0010] 1, 2, 101, 201, 301, 401 Compound optical element

10, 40 1st optical part

12 Lens surface (first optical function surface)

13, 43 Lens surface (4th optical function surface)

20 Second optical part

21 First joint surface

22 Lens surface (second optical function surface)

22a First uneven surface

30 Third optical section

31 Second joint surface

32 Lens surface (third optical function surface)

32a Second uneven surface

43a 3rd uneven surface

50 4th optical part

51 3rd joint surface

52 Lens surface (5th optical function surface)

52a 4th uneven surface

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

[Embodiment 1 of the Invention]

In Embodiment 1, a composite lens is given as an example of a composite optical element, and its structure and its manufacturing method are shown.

FIG. 1 is a schematic cross-sectional view showing a configuration of a composite optical element 1 according to the present embodiment.

The composite optical element 1 according to the present embodiment includes first, second and third optical units 10, 20 and 30. The first optical unit 10 has a lens surface (first optical functional surface) 12 and a lens surface (fourth optical functional surface) 13. The second optical unit 20 is bonded to the first optical unit 10 at the lens surface 12, and a lens surface (second optical function surface) 22 is provided on the side opposite to the first bonding surface 21. Have. The third optical unit 30 is bonded to the second optical unit 20 at the lens surface 22, and has a lens surface (third optical functional surface) 32 on the side opposite to the second bonding surface 31. A first uneven surface portion 22a exists on a part of the lens surface 22, and a second uneven surface portion 32a exists on a part of the lens surface 32.

[0015] Generally, in order for an uneven surface portion to function as a diffractive portion or the like, it is necessary to accurately form the uneven surface portion. In the composite optical element 1 according to the present embodiment, the first and second concavo-convex surface portions 22a and 32a are present on part of the lens surfaces 22 and 32, respectively. For this reason, the composite optical element 1 that is effective in this embodiment has the uneven surface portion formed into a desired shape with high accuracy compared to the composite optical element in which the uneven surface portion exists on the entire lens surface. Degradation of optical characteristics (such as aberration and light collection rate) can be prevented.

[0016] The composite optical element 1 according to the present embodiment is shown in detail. The first optical unit 10 is made of a first resin, and the first resin may be an energy curable resin or a thermoplastic resin. Here, the energy curable resin is, for example, a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, or the like, and is cured by applying predetermined energy (heat, ultraviolet ray, electron beam, etc.). It is fat. Further, the lens surfaces 12 and 13 are each formed as an aspheric surface and are formed smoothly.

[0017] The second optical unit 20 comprises a second resin, and the second resin may be an energy curable resin or a thermoplastic resin, but the melting temperature thereof is the melting of the first resin. Lower than temperature. The lens surface 22 includes a first uneven surface portion 22a and smoothly formed first and second smooth surface portions (both not shown). Specifically, the lens surface 22 has a first smooth surface portion, a first uneven surface portion 22a, and a second smooth surface portion in a direction from the optical axis toward the periphery, and is centered on one point on the optical axis. Are arranged on a concentric circle. Therefore, in the lens surface 22, the optical power is different between the first and second smooth surface portions and the first uneven surface portion 22a.

[0018] The third optical unit 30 is composed of a third resin, and the third resin may be an energy curable resin or a thermoplastic resin, but the melting temperature thereof is the first and second resins. It is lower than the melting temperature of fat. The melting temperature of this resin will be shown when explaining the molding method of the composite optical element 1 described later. Further, the lens surface 32 includes a second uneven surface portion 32a and a smoothly formed third smooth surface portion (not shown). Specifically, the lens surface 32 has a third smooth surface portion and The second concavo-convex surface portion 32a exists in the direction from the optical axis toward the periphery, and is disposed on a concentric circle centered on one point on the optical axis. Therefore, in the lens surface 32, the optical power differs between the third smooth surface portion and the second uneven surface portion 32a.

[0019] As the entire composite optical element 1, the second concavo-convex surface portion 32a exists in the periphery of the first concavo-convex surface portion 22a without overlapping the first concavo-convex surface portion 22a in the optical axis direction of the composite optical element 1. ing. That is, in the optical axis direction of the composite optical element 1, the first smooth surface portion overlaps a part of the third smooth surface portion, and the first uneven surface portion 22a overlaps the remaining portion of the third smooth surface portion. 2 The smooth surface portion overlaps the second uneven surface portion 32a. Therefore, since the composite optical element 1 as a whole has three portions having different optical powers, three types of light having different wavelengths can be condensed.

FIGS. 2A to 2F are cross-sectional views showing a method for manufacturing the composite optical element 1 according to the present embodiment. In the method of manufacturing the composite optical element 1, the first optical member 155 is press-molded in the steps shown in FIGS. 2 (a) and (b), and the press-molding method is used in the steps shown in FIGS. 2 (c) and (d). The second optical member 165 is bonded to the first optical member 155, and the third optical member 185 is bonded to the second optical member 165 using a press molding method in the steps shown in FIGS. 2 (e) and (f). If you let it, it is a natural thing. Since the composite optical element 1 is manufactured by using the press molding method in this way, the aspherical lens surface and the uneven surface portion having a sawtooth cross section can be molded by one molding, and can be easily and molded. It can be molded with high accuracy. Specifically,

First, as shown in FIG. 2 (a), a first resin preform 150 and a molding apparatus are prepared.

The first resin preform 150 may be an energy-cured resin or a thermoplastic resin, preferably melted in advance before being set in the molding apparatus. The molding apparatus includes an upper mold 71 and a lower mold 72, and the upper mold 71 is used to mold the upper lens surface of the first optical member 155 (the lens surface serving as the lens surface 13 of the first optical unit 10). The lower mold 72 has a molding surface 72a for molding the lower lens surface of the first optical member 155 (the lens surface serving as the lens surface 12 of the first optical unit 10). ing. Then, after setting the lower mold 72 with the molding surface 72a facing upward, the molten first resin preform 150 is set on the molding surface 72a, and the molding surface 71a is placed on the first resin preform 150. Set the upper die 71 downward.

Next, as shown in FIG. 2 (b), the molding surfaces 71a and 72a of the upper die 71 and the lower die 72 are pressed. Are transferred to the surface of the first slag preform 150, respectively. When pressing, the upper mold 71 and the lower mold 72 can be pressed against the surface of the first resin preform 150 by pressing the lower mold 72 against the surface of the first resin preform 150. May be pressed against the surface of the first resin preform 150, respectively. Then, it is solidified. As a result, the first optical member 155 can be molded.

[0023] Subsequently, a second resin preform 160 and a molding apparatus shown in Fig. 2 (c) are prepared. The second resin preform 160 is preferably melted in advance before being set in the molding apparatus, and the soft resin temperature thereof is made of a resin lower than the soft resin temperature of the first resin preform 150. It is preferable. The molding apparatus includes a lower mold 81. The molding surface 81a of the lower mold 81 is for molding the lens surface of the second optical member 165. Therefore, a part of the molding surface 81a is the first mold. It is formed to be uneven so as to correspond to the uneven surface portion. Then, after setting the lower mold 81 with the molding surface 81a facing upward, the softened second resin preform 160 is set on the molding surface 81a, and the first optical member is placed on the second resin preform 160. Set 155. When setting the first optical member 155, if the first optical member 155 is set on the lower die 81 so that the optical axis of the first optical member 155 coincides with the central axis of the molding surface 81a of the lower die 81, the light The second optical member 165 can be joined to the first optical member 155 with the axial direction aligned.

Subsequently, as shown in FIG. 2 (d), the first optical member 155 is pressed against the lower mold 81 and pressed.

At this time, since the soft temperature of the second resin preform 160 is lower than that of the first resin preform 150, the molten second resin preform 160 is used as the first optical member. Even when bonded to 155, melting of the first optical member 155 at the bonded surface can be prevented, and as a result, deformation of the lower lens surface of the first optical member 155 can be prevented. Further, the second resin preform 160 flows in accordance with the shape of the lens surface of the second optical member 165 and enters the irregularities of the molding surface 81a, and the shape of the molding surface 81a is the same as that of the second resin preform 160. It is suitably transferred to the surface. Thereby, the joined body 175 in which the second optical member 165 is joined to the first optical member 155 can be molded.

[0025] Subsequently, a third resin preform 180 and a molding apparatus shown in Fig. 2 (e) are prepared. It is preferable that the third resin preform 180 is melted in advance before being set in the molding apparatus. The soft temperature of the third resin preform 180 is higher than that of the first and second resin preforms 150 and 160. Is also low It is preferable that it consists of rosin. The molding apparatus includes a lower mold 91, and the lower mold 91 has a molding surface 91a. The molding surface 91a is used to mold the lens surface of the third optical member 186. Therefore, a part of the molding surface 91a is formed to be uneven so as to correspond to the second uneven surface portion. Then, after setting the lower die 91 with the molding surface 91a facing upward, the softened third resin preform 180 is set on the molding surface 91a, and the joined body 175 is set on the third resin preform 180. To do. When setting the joined body 175, if the joined body 175 is set on the lower mold 91 so that the optical axis of the joined body 175 coincides with the center axis of the molding surface 91a of the lower mold 91, the optical axis directions are aligned and joined. The third optical member 185 can be joined to the body 175.

Then, as shown in FIG. 2 (f), the joined body 175 is pressed against the lower die 91 and pressed. At this time, since the soft temperature of the third resin preform 180 is lower than the soft temperature of the second resin preform 160, the molten third resin preform 180 is bonded to the bonded body 175. However, it is possible to prevent the third resin preform 180 from melting on the joint surface, and as a result, it is possible to prevent the lens surface of the second optical member 165 from being deformed. In addition, the third resin preform 180 flows in accordance with the shape of the lens surface of the third optical member 185 and enters into the irregularities of the molding surface 91a, and the shape of the molding surface 91a is the same as the second resin preform 160. It is preferably transferred onto the surface of the third resin preform 180. Thereby, the composite optical element 1 shown in FIG. 1 can be molded.

As described above, in the composite optical element 1 according to the present embodiment, the first and second concave convex surface portions 22a and 32a are present on a part of each of the lens surfaces 22 and 32. Compared to the case where the entire surface is present, the shape of the concavo-convex portion can be accurately formed into a desired shape. That is, since the concave and convex shape that functions as the diffractive portion can be accurately formed, it is possible to prevent deterioration of the optical characteristics.

[0028] In addition, since the composite optical element 1 that works according to the present embodiment is molded using a press molding method, even an aspheric lens can be molded with high accuracy. Further, the first and second uneven surface portions 22a and 32a can be formed by devising the shape of the molding surface of the mold.

[0029] Furthermore, since the melting temperature of the resin is designed to be lower in the molding order, it is possible to prevent deformation of the already molded optical member during pressing. [0030] Such a composite optical element 1 can be mounted on an optical apparatus such as an imaging device, an illuminating device, or an optical disc recording / reproducing device. The imaging device is a device for photographing a subject, for example, a digital still camera or a digital video camera. The illumination device is a device for irradiating light on an object to be illuminated, and is, for example, a projector. Optical disk recording / playback devices include digital versatile discs (hereinafter referred to as DVD), compact discs (hereinafter referred to as CD), Blu-ray discs (registered trademark, hereinafter referred to as BD (registered trademark)), etc. Is a device for recording and reproducing. Generally, DVDs, CDs, and BDs have different light source wavelengths and optical disc thicknesses for recording and playback, so that a single optical disc recording and playback device can record and playback DVDs, CDs, and BDs. However, it is necessary to devise an optical system. However, if the composite optical element 1 which is effective in the present embodiment is used, an optical disc recording / reproducing apparatus compatible with a plurality of types of information recording media can be realized.

Note that the shapes of the first, second, and third optical units are not limited to the above shapes, and may be the shapes described in the following first to fourth modifications. Further, the shapes of the first and second uneven surface portions are not limited to the above shapes, and may be the shapes described in the following first to fourth modifications.

[0032] (First modification)

FIG. 3 is a schematic cross-sectional view of the composite optical element 101 that works on the first modification. In the composite optical element 101 according to this modification, the first optical unit 110 is formed in a plate shape, and the first and second uneven surface portions 122a and 132a are diffractive portions formed in a stepped cross section.

Specifically, the first optical unit 110 has a planar lens surface 112 and a lens surface 113, and the second optical unit 120 is joined to the first optical unit 110 at the lens surface 112. . The second optical unit 120 has a lens surface 122 on the side opposite to the first bonding surface 121, and the third optical unit 130 is bonded to the second optical unit 120 on the lens surface 122. The third optical unit 130 has a lens surface 132 on the side opposite to the second joint surface 131. The first uneven surface portion 122a exists on a part of the lens surface 122 of the second optical unit 120, and the second uneven surface portion 132a exists on a part of the lens surface 132 of the third optical unit 130. ing.

[0034] The composite optical element 101 that works in this modification functions as a diffractive portion, as in the first embodiment. Since the first and second uneven surface portions 122a and 132a are provided, the same effects as those of the first embodiment can be obtained.

[0035] (Second modification)

FIG. 4 is a schematic cross-sectional view of a composite optical element 201 that works on the second modification. In the composite optical element 201 according to the present modification, the first optical unit 110 is plate-like, as with the composite optical element 101 that works according to the first modification, but the first and second uneven surface parts 122a, 132a Are both lens array portions in which a plurality of concave lenses are arranged.

[0036] Thus, in the composite optical element 201 that is effective in the present modification, the first and second uneven surface portions 122a

, 132a is a lens array part, so that light having a wavelength is incident on the first uneven surface part 122a to be condensed, and light having a wavelength (≠ λ) is incident on the second uneven surface part 132a to be condensed.

twenty one

Can do.

[0037] (Third Modification)

FIG. 5 is a schematic cross-sectional view of a composite optical element 301 that works on the third modification. The composite optical element 301 according to the present modification is formed substantially the same as the composite optical element 1 according to the first embodiment, but the first and second uneven surface portions 322a and 332a are phase step portions having a stepped cross section. It is.

[0038] In the composite optical element 301 that works in this modification as described above, since both the first and second uneven surface portions 322a and 332a are phase step portions, the first and second uneven surface portions 322a and 332a The phase of the incident light flux is changed at the first and second uneven surface portions 322a and 332a, respectively.

[0039] (Fourth modification)

FIG. 6 is a schematic cross-sectional view of a composite optical element 401 that works on the fourth modification. The composite optical element 401 according to this modification is formed substantially the same as the composite optical element 1 according to the first embodiment, but the first and second uneven surface portions 422a and 433a are antireflection portions. Specifically, each of the first and second uneven surface portions 422a and 433a has a plurality of cone-shaped projections, and the pitch between the projections is substantially the same as the wavelength for preventing reflection.

In this way, in the composite optical element 401 that is effective in this modified example, the first and second uneven surface portions 422a and 433a are antireflection portions, so that reflection of light having a wavelength of about the pitch is prevented. In addition, if the pitch on the first uneven surface portion 422a is different from the pitch on the second uneven surface portion 433a, reflection of two lights having different wavelengths can be prevented.

[Embodiment 2 of the Invention]

FIG. 7 is a schematic sectional view of the composite optical element 2 according to the second embodiment. In the composite optical element 2 according to the present embodiment, the third uneven surface portion 43 a exists on the lens surface (fourth optical function surface) 43 of the first optical portion 40. The third uneven surface portion 43a may be a diffractive portion having a sawtooth cross section as described in the first embodiment, or may have the shape described in the first to fourth modifications. .

[Embodiment 3 of the Invention]

FIG. 8 is a schematic sectional view of the composite optical element 3 according to the third embodiment. In the composite optical element 3 according to the present embodiment, the fourth optical unit 50 is bonded to the lens surface 13 of the composite optical element 1 of the first embodiment. The fourth optical unit 50 has a lens surface (fifth optical function surface) 52 on the side opposite to the third bonding surface 51, and the lens surface 52 has a fourth uneven surface portion 52 a. The fourth concavo-convex surface portion 52a may be a diffractive portion formed in the shape of a sawtooth cross section as described in the first embodiment, the same as the third concavo-convex surface portion 43a of the second embodiment, and the first to fourth The shape described in the modification may be used.

[0043] The fourth optical unit 50 is composed of a fourth resin. The soft temperature of the 4th resin is lower than the soft temperature of the 1st resin, but regarding the high and low of the soft temperature of the 2nd resin and the 3rd resin Depends on the order. For example, when the first optical member is molded, then the second and third optical members are formed, and when the fourth optical member is finally formed, the soft temperature of the fourth resin is the second and third optical members. The temperature is preferably lower than the soft temperature of the third resin. Conversely, after the first optical member is molded, the fourth optical member is molded and the force is applied. When the second and third optical members are molded, the soft temperature of the fourth resin is the second and third. It is preferable that the temperature is higher than the soft temperature of the resin. If molding is performed using a resin preform having a low softening temperature in the molding order, the composite optical element 4 can be molded without softening the already molded optical member.

<< Other Embodiments >>

The present invention may have the following configurations for the first to third embodiments. [0045] The lens surface may be an aspherical surface, a flat surface, or a spherical surface, a cylindrical surface, an elliptical surface, or a toric surface.

[0046] The material of the optical part is not limited to the above description! The material may be!, And the deviation may be glass. Some optical parts may have glass power and the remaining optical parts may be made of resin. For example, when the first, second, and third optical parts are made of glass, the glass transition temperature only needs to be designed so as to decrease in the molding order. Further, an impurity that does not affect the optical characteristics may be mixed in the optical unit.

[0047] The first optical part is not limited to one formed by a press molding method, and may be one formed by etching or one formed by injection molding. Further, the second optical part may be one that is applied to the lens surface of the first optical part by a coating method such as spin coating or squeezing, and then cured.

[0048] The position of the uneven surface portion on the lens surface is not limited to the above description. Further, two or more types of uneven surface portions may exist on the same lens surface.

[0049] In the third embodiment, the fourth optical unit may be bonded to the first optical unit while being connected to the lens surface where the third uneven surface portion exists.

Industrial applicability

[0050] As described above, the present invention can be mounted on an optical disc recording / reproducing apparatus. In addition, an image pickup apparatus (digital still camera, digital video camera, etc.) or a display apparatus (projector, etc.) can be used. It can be installed.

Claims

The scope of the claims

[1] a first optical unit having a first optical functional surface;

A second optical unit that is bonded to the first optical unit on the first optical functional surface and has a second optical functional surface on the opposite side of the first bonding surface bonded to the first optical unit; A third optical unit that is bonded to the second optical unit on the second optical functional surface and has a third optical functional surface on the opposite side of the second bonding surface bonded to the second optical unit;

A composite optical element characterized in that first and second uneven surface portions are present on a part of each of the second and third optical functional surfaces.

[2] The first optical unit has the fourth optical functional surface on a side opposite to the first optical functional surface,

2. The composite optical element according to claim 1, wherein a third uneven surface portion is present on the fourth optical function surface.

[3] The first optical unit has the fourth optical functional surface on a side opposite to the first optical functional surface,

A fourth optical unit that is bonded to the first optical unit on the fourth optical functional surface and has a fifth optical functional surface on the side opposite to the third bonding surface bonded to the first optical unit is further provided. In preparation for

2. The composite optical element according to claim 1, wherein a fourth uneven surface portion is present on a part of the fifth optical function surface.

[4] Each of the first and second concavo-convex surface portions is at least one of a diffraction portion, a lens array portion composed of a plurality of convex or concave lenses, a phase step portion, and a light reflection preventing portion. The composite optical element according to claim 1, wherein:

[5] The composite optical element according to [1], wherein the first, second, and third optical units are respectively composed of first, second, and third resins.

[6] The softening temperature of the second resin may be lower than the softening temperature of the first resin but higher than the softening temperature of the third resin. Composite optical element.

[7] The first, second and third resins are all energy-cured resins. The composite optical element according to claim 5.