JP2008015010A - Compound optical element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound optical element which is excellent in reliability by preventing exfoliation of a joining surface between dissimilar materials. <P>SOLUTION: By using a 1st optical part 10 consisting substantially of glass, a 2nd optical part 20 consisting substantially of a photocuring resin and a 3rd optical part 30 consisting substantially of a thermoplastic resin, the 2nd optical part 20 is joined to an optical functional surface 11 of the 1st optical part 10 and the 3rd optical part 30 is joined to an optical functional surface 22 of the 2nd optical part 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a composite optical element and a manufacturing method thereof.

  Conventionally, a composite optical element formed by bonding different types of materials (for example, glass and thermosetting resin) is known (for example, see Patent Document 1).

According to such a composite optical element, for example, a relief pattern (diffraction surface) is formed on the optical functional surface of a resin that is easy to create a fine shape, while a portion requiring mechanical strength and resistance to environmental changes is made of glass. This makes it possible to improve the degree of freedom in optical design and realize a highly functional optical system.
JP 2004-177574 A

  However, when glass and thermosetting resin are joined by press molding, internal stress is generated on the joint surface between the glass and resin due to volume shrinkage accompanying the curing of the thermosetting resin, resulting in a decrease in shape accuracy and thermosetting at the joint surface. Various adverse effects such as peeling of the resin may occur.

  This invention is made | formed in view of this point, The place made into the objective is to prevent the peeling in the joint surface of dissimilar materials, and to provide the composite optical element excellent in reliability.

  That is, the composite optical element of the present invention is bonded to the first optical unit, the second optical unit bonded to the optical functional surface of the first optical unit, and the optical functional surface of the second optical unit. A third optical part, the first optical part is substantially made of glass, the second optical part is substantially made of a photocurable resin, and the third optical part is substantially thermoplastic. It is characterized by comprising resin.

  Also, the method for manufacturing a composite optical element of the present invention press-molds the second optical part substantially made of a photo-curing resin on the optical functional surface of the first optical part substantially made of glass. And a procedure for joining the third optical part substantially made of a thermoplastic resin to the optical functional surface of the second optical part by press molding. is there.

  As described above, according to the present invention, it is possible to provide a composite optical element that is excellent in reliability by preventing peeling at a joint surface between different materials.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or its application.

  FIG. 1 is a cross-sectional view showing a configuration of a composite optical element according to an embodiment of the present invention. As shown in FIG. 1, the composite optical element 1 includes a first optical unit 10, a second optical unit 20, and a third optical unit 30.

  The first optical unit 10 is composed of a biconvex lens having a convex aspherical optical function surface (lens surface) 11 and an optical function surface (lens surface) 14. Each of these optical function surfaces 11 and 14 is formed of a refractive surface having only a refractive action.

  Further, an edge plane 15 that protrudes outward in the lens circumferential direction from the optical function surface 11 is provided at the peripheral edge of the first optical unit 10.

  The second optical unit 20 functions as a bonding layer for bonding the first optical unit 10 and the third optical unit 30, and is bonded to the first optical unit 10 on the optical functional surface 11. It is comprised by the meniscus-shaped lens made. The optical functional surface 21 on the first optical unit 10 side in the second optical unit 20 is formed with a smooth surface corresponding to the optical functional surface 11. Similarly, the optical functional surface 22 facing the optical functional surface 21 is formed of a refractive surface having only a refractive action.

  The third optical unit 30 is constituted by a meniscus lens joined to the second optical unit 20 on the optical functional surface 22. The optical functional surface 31 on the second optical unit 20 side in the third optical unit 30 is formed with a smooth surface corresponding to the optical functional surface 22. Similarly, the optical function surface 32 facing the optical function surface 31 is formed of a refractive surface having only a bending action.

  Although not shown, if a fine diffractive structure such as a relief pattern is formed on the optical functional surface 32 of the third optical unit 30, it is advantageous in securing desired optical performance. For example, if a smooth surface portion is provided in the central portion and the outer peripheral portion of the optical functional surface 32 of the third optical portion 30, and an uneven surface portion constituted by a diffractive surface having a sawtooth cross section is provided adjacent to the smooth surface portion. The optical power of the optical functional surface 32 in the central region where the smooth surface portion is provided can be made different from the optical power of the optical functional surface 32 in the peripheral region where the uneven surface portion is provided. Thus, for example, by focusing light of a certain wavelength using the central region and condensing light of a different wavelength using the peripheral region, the lights having different wavelengths are focused at the same focal length. can do.

  Here, the first to third optical units 10, 20, and 30 are made of different materials. Specifically, the first optical unit 10 is made of a glass material with emphasis on hygroscopicity, heat resistance, etc. rather than fine moldability.

  The second optical unit 20 absorbs the difference in linear thermal expansion that occurs between the first optical unit 10 and the third optical unit 30, and functions to increase peeling and the element reliability after molding. It bears and is made of a photo-curing resin material. For example, in consideration of optical characteristics such as adhesive strength, refractive index, and light transmittance, it is preferable to use an epoxy-based or acrylate-based ultraviolet curable resin material.

  The thickness of the second optical unit 20 is the same as that of the first optical unit 10 in order to minimize adverse effects such as generation of internal stress due to volume shrinkage accompanying the curing of the second optical unit 20 itself. It is preferable to make the layer as thin as possible within a range in which the bonding strength with the third optical unit 30 can be secured.

  Since the third optical unit 30 forms a fine diffractive structure such as a relief pattern, the third optical unit 30 is preferably composed of a thermoplastic resin material with emphasis on formability. For example, a cycloolefin polymer material (registered trademark ZEONEX manufactured by Nippon Zeon Co., Ltd.) can be used.

  Here, for example, when the third optical unit 30 is directly bonded on the first optical unit 10, when the temperature change occurs due to the difference in contraction rate between the optical units 10 and 30, There is a possibility that a large distortion occurs between the first optical unit 10 and the third optical unit 30.

  Further, when the temperature rises or falls when the composite optical element 1 is used, distortion occurs between the first optical unit 10 and the third optical unit 30, and the third optical unit 30 becomes the first optical unit. There is a risk of peeling from 10.

  When the third optical unit 30 is a thermoplastic resin and the composite optical element 1 is produced by pressing with the first optical unit 10, the manufactured composite optical element 1 has a large strain. In addition to the remaining optical uniformity, the third optical unit 30 may be peeled off from the first optical unit 10 due to residual strain.

  On the other hand, in the present embodiment, the second optical unit 20 made of a photo-curing resin is provided between the first optical unit 10 and the third optical unit 30. For this reason, the difference between the optical parts joined to each other is small. Therefore, the problems such as peeling of the third optical unit 30 and remaining strain are effectively suppressed as described above.

  As described above, according to the composite optical element 1 according to the present embodiment, it is possible to suppress peeling at the joint surface between different materials. In addition, the degree of freedom in optical design is not only greatly expanded, but also mass productivity is improved, so that it is possible to supply inexpensive optical elements, so that it can be expected to be applied to various fields such as lenses, mirrors, and prisms. .

  Each of the first optical unit 10, the second optical unit 20, and the third optical unit 30 has substantially the same refractive index with respect to the d-line and specifically has a refractive index of 1.5 or more. It is preferable that it is comprised. Thus, NA can be enlarged by comprising with a high refractive material whose refractive index is 1.5 or more.

  Further, by configuring with a material having a light transmittance of 90% or more at a light wavelength of 400 nm or more, for example, the application range to a BD (registered trademark) apparatus having a wavelength of 405 nm of laser light to be used can be expanded. it can. In addition, the measured value of light transmittance is a value when it carries out with respect to the sample of thickness 10mm by which both surfaces were mirror-polished.

  Next, a method for manufacturing the composite optical element 1 according to the present embodiment will be described with reference to FIGS. Here, the first optical unit 10 substantially made of glass, the second optical unit 20 substantially made of a photo-curing resin, and the third optical unit 30 substantially made of a thermoplastic resin, The manufacturing method of the composite optical element 1 comprised by this will be described as an example.

  First, the first optical unit 10 is manufactured. Specifically, the first optical unit 10 is manufactured using a pair of molds (lower mold 41 and upper mold 45) shown in FIG. The lower mold 41 has a concave molding surface 42 corresponding to the shape of the optical functional surface 11 of the first optical unit 10 on the top surface. On the other hand, the upper mold 45 is constituted by a columnar body having a molding surface 46 facing the lower mold 41 as a top surface. The molding surface 46 is formed in a concave shape corresponding to the shape of the optical function surface 14.

  Then, using these lower mold 41 and upper mold 45, the glass preform 40 processed into a ball shape or a shape and dimension approximately similar to the first optical unit 10 is heated and pressed (heat pressed). Specifically, the glass preform 40 is disposed between the lower mold 41 and the upper mold 45.

  Next, the glass preform 40 is heated to near the softening temperature to be softened, and the upper mold 45 is displaced relative to the lower mold 41 in the direction of the lower mold 41 to lower the softened glass preform 40. The first optical unit 10 is obtained by pressing with the molding surface 42 of the mold 41 and the molding surface 46 of the upper mold 45 (see FIG. 2B). Then, the first optical unit 10 is completed by cooling to a predetermined temperature (for example, glass transition temperature -150 ° C. to room temperature).

  Next, as shown in FIG. 3A, a softened state is formed on the molding surface 52 using a molding die 51 having a concave molding surface 52 corresponding to the shape of the optical functional surface 22 of the second optical unit 20. The photo-curing resin 50 is disposed. Then, the photocurable resin 50 is pressed using the molding die 51 and the pressing die 55. Specifically, the first optical part 10 molded earlier is pressed with the pressing die 55, and the photo-curing resin 50 disposed on the molding surface 52 of the molding die 51 is moved to a predetermined position with the optical function surface 11. The photocurable resin 50 is cured by pressing and applying light energy (such as ultraviolet rays or electron beams) to the photocurable resin 50 in this state.

  In this step, the photocurable resin 50 in a softened state before applying light energy is very soft compared to the first optical unit 10, so the photocurable resin 50 is used as the optical function of the first optical unit 10. Even if the surface 11 is pressed, the shape of the optical functional surface 11 does not substantially change. In addition, the photocurable resin 50 flows in accordance with the shape of the optical function surface 11, and the shape of the optical function surface 11 is suitably transferred. Thereby, the 2nd optical part 20 is joined to the optical function surface 11 of the 1st optical part 10 (refer FIG.3 (b)).

  Next, as shown in FIG. 4A, a molding die 61 having a molding surface 62 corresponding to the shape of the optical function surface 32 of the third optical unit 30 is used, and the molding surface 62 is in a softened state. A thermoplastic resin 60 is disposed.

  Then, the thermoplastic resin 60 is pressed using the molding die 61 and the pressing die 65. Specifically, the first optical unit 10 and the second optical unit 20 that have been molded are pressed with the pressing die 65, and the thermoplastic resin 60 disposed on the molding surface 62 of the molding die 61 is added to the second optical unit 20. The thermoplastic resin 60 is cured by pressing the optical functional surface 22 of the optical unit 20 to a predetermined position and applying heat to the thermoplastic resin 60 in this state.

  In this way, the first optical unit 10, the second optical unit 20 joined to the first optical unit 10 on the optical functional surface 11, and the second optical unit 20 on the optical functional surface 22. It is possible to obtain a composite optical element 1 including the third optical unit 30 bonded to the substrate (see FIG. 4B).

  In addition, the manufacturing procedure of the composite optical element 1 is not limited to that described above, and various other procedures can be considered. Hereinafter, another method for manufacturing the composite optical element 1 according to this embodiment will be described.

  First, the first optical unit 10 is manufactured. Note that the manufacturing procedure of the first optical unit 10 is the same as the procedure described with reference to FIG.

  Next, as shown in FIG. 5, the third optical unit 30 is manufactured. The third optical unit 30 is manufactured using a pair of molds (lower mold 71 and upper mold 75) shown in FIG. The lower mold 71 has a concave molding surface 72 corresponding to the shape of the optical functional surface 32 of the third optical unit 30 on the top surface. On the other hand, the upper die 75 is constituted by a columnar body having a forming surface 76 facing the lower die 71 as a top surface. The molding surface 76 is formed in a convex shape corresponding to the shape of the optical function surface 31.

  Then, the thermoplastic resin 60 in a softened state is disposed on the molding surface 72 of the lower mold 71, and the upper mold 75 is displaced relative to the lower mold 71 in the direction of the lower mold 71, thereby making the thermoplastic resin 60. Press. In this state, the third optical unit 30 is produced by applying heat to the thermoplastic resin 60 and curing it (see FIG. 5B).

  Next, the photo-curing resin 50 in a softened state is disposed on the optical functional surface 31 of the third optical unit 30 molded earlier. And the 1st optical part 10 shape | molded previously is pressurized with the press type | mold 85, the photocurable resin 50 is pressed to the predetermined position with the optical function surface 11 of the 1st optical part 10, and the state Then, the photocurable resin 50 is cured by applying light energy to the photocurable resin 50.

  In this way, the first optical unit 10, the second optical unit 20 joined to the first optical unit 10 on the optical functional surface 11, and the second optical unit 20 on the optical functional surface 22. It is possible to obtain a composite optical element 1 including the third optical unit 30 bonded to the substrate (see FIG. 4B).

  In general, glass has a higher softening temperature and higher hardness than resin, so that, for example, as described here, the first optical unit 10 is substantially made of glass, and the second optical unit 10 When the part 20 is substantially made of a photo-curing resin, the glass first optical part 10 molded into a desired shape as described above is used as a molding die to press and soften the resin in a softened state. By joining them together, it can be molded easily and with high shape accuracy. The same applies to the molding of the third optical unit 30.

  Further, since the third optical unit 30 is made of a thermoplastic resin, it is possible to form a fine diffractive structure such as a complex aspherical shape or a relief pattern on the optical functional surface 32 that is difficult to realize with a glass material. Thus, the composite optical element 1 having excellent optical characteristics can be obtained.

  Moreover, by forming the 2nd optical part 20 comprised with the photocurable resin between the 1st optical part 10 comprised with glass, and the 3rd optical part 30 comprised with the thermoplastic resin, In addition, it is possible to strengthen the bonding between different materials such as glass and thermoplastic resin. This is advantageous in improving the mechanical strength and reliability of the composite optical element 1 with respect to the usage environment.

  Moreover, when photocuring resin, such as an ultraviolet curable resin, is used as a material of the 2nd optical part 20, since it can be hardened in a short time, productivity can be improved. When a thermoplastic resin is used as the material of the third optical unit 30, the composite optical element 1 can be obtained easily and inexpensively by heating without requiring a large apparatus for irradiating ultraviolet rays or the like.

  In the present embodiment, the example in which the optical functional surface 32 of the third optical unit 30 is configured by an aspherical surface has been described. However, the present invention is not limited to this configuration. For example, a flat surface, a spherical surface, a cylindrical surface, An elliptical surface, a toric surface, etc. may be sufficient. In addition, when the diffractive structure is formed on the optical function surface 32, in addition to a diffractive surface having a sawtooth cross section, for example, a diffractive surface having a rectangular cross section or a sinusoidal cross section, or a plurality of convex or concave lens surfaces is used. Forms a lens array surface, a phase step surface, or a light reflection preventing structure (for example, a structure composed of a plurality of cone-shaped protrusions or cone-shaped recesses arranged at a pitch equal to or less than the wavelength of light whose reflection is to be suppressed). It may be a light reflection preventing surface.

  Further, the second and third optical units 20 and 30 are not limited to those formed by press molding. For example, the second and third optical units 20 and 30 are formed on the optical functional surfaces 11 and 22 by a coating method such as a spin coating method or a squeezing method. You may form by making it harden | cure after apply | coating a resin material. In addition, when a diffractive structure is formed on the optical functional surface 32 of the third optical unit 30, it may be formed by etching.

  In this embodiment, a biconvex lens is described as an example of a composite optical element. However, the present invention is not limited to this form. For example, a binary optical element, a microlens array element, and a phase step are formed. An optical element or an optical element having SWS (Subwavelength Structure Surface) may be used.

<Modification>
FIG. 7 is a sectional view showing a modification of the composite optical element of the present invention. In the following, the same parts as those in the above embodiment are denoted by the same reference numerals, and only differences will be described.

  As shown in FIG. 7, the composite optical element 2 according to this modification is configured by a biconvex lens, and has a convex aspherical optical function surface (lens surface) 11 and an optical function surface (lens surface) 14. The second optical unit 20 and the third optical unit 30 are stacked and bonded to each other.

  That is, the second optical unit 20 is bonded to the optical functional surface 11 of the first optical unit 10, and the third optical unit 30 is bonded to the optical functional surface 22 of the second optical unit 20. Although it is the same as that of embodiment, in this modification, the 2nd optical part 20 is further joined also to the optical function surface 14 of the 1st optical part 10, and the optical function surface 22 of this 2nd optical part is joined. The third optical unit 30 is bonded.

  The optical functional surface 32 of the third optical unit 30 joined to the optical functional surface 14 side of the first optical unit 10 is formed of a bent surface having only a bending action. Although not shown, a fine diffractive structure such as a relief pattern may be formed on the optical function surface 32.

  As described above, according to the composite optical element 2 according to the modified example of the present invention, the second and third optical units 20 and 30 are laminated and bonded to both convex surfaces of the first optical unit 10, respectively. Therefore, a more complicated optical system can be realized.

  As described above, the present invention is extremely useful because it provides a highly practical effect that a composite optical element having excellent reliability can be provided by preventing separation of the joint surfaces between different materials. And industrial applicability is high. In particular, it is useful as a composite optical element used in an optical system of an optical disk device and an imaging system such as a digital still camera or a mobile phone.

It is sectional drawing which shows the structure of the composite optical element which concerns on embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of a 1st optical part. It is sectional drawing for demonstrating the manufacturing method of a 2nd optical part. It is sectional drawing for demonstrating the manufacturing method of a 3rd optical part. It is sectional drawing for demonstrating another manufacturing method of a 3rd optical part. It is sectional drawing for demonstrating another manufacturing method of a 2nd optical part. It is sectional drawing which shows the modification of the composite optical element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Composite optical element 2 Composite optical element 10 1st optical part 11 Optical functional surface 14 Optical functional surface 20 2nd optical part 21 Optical functional surface 22 Optical functional surface 30 3rd optical part 31 Optical functional surface 32 Optical functional surface 40 glass preform 50 photo-curing resin 60 thermoplastic resin

Claims (8)

A first optical unit;
A second optical unit bonded to the optical functional surface of the first optical unit;
A third optical unit joined to the optical functional surface of the second optical unit,
The first optical unit is substantially made of glass,
The second optical part is substantially composed of a photo-curing resin,
The composite optical element, wherein the third optical unit is substantially made of a thermoplastic resin. In claim 1,
The optical functional surfaces of the first optical unit are respectively provided on both surfaces of the first optical unit,
The composite optical element, wherein the second optical unit and the third optical unit are laminated and bonded to each of the optical functional surfaces. In claim 1,
An optical functional surface of the third optical unit is formed on a diffractive surface. In claim 1,
Each of the first to third optical units is made of a material having substantially the same refractive index with respect to the d-line. In claim 1,
Each of the first to third optical units is composed of a material having a refractive index with respect to d-line of 1.5 or more. In claim 1,
Each of the first to third optical units is composed of a material having a light transmittance of 90% or more at a light wavelength of 400 nm or more. In claim 1,
A composite optical element used as a lens, a mirror, or a prism. A procedure of joining the second optical part substantially composed of a photo-curing resin to the optical functional surface of the first optical part substantially composed of glass by press molding;
A method of manufacturing a composite optical element, comprising: a step of bonding a third optical part substantially made of a thermoplastic resin to the optical functional surface of the second optical part by press molding.

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