JP2012128319A - Laminated diffractive optical element and manufacturing method of laminated diffractive optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated diffractive optical element capable of preventing surface shape deterioration of a lens substrate of the laminated diffractive optical element due to deformation of the lens substrate by cure shrinkage of a second resin layer during a step of jointing a second lens substrate of the laminated diffractive optical element.SOLUTION: A laminated diffractive optical element is composed of a flat plate glass 1 for forming a grating, a fluorine resin 2, an acrylic resin 3, and a flat plate glass 4 for jointing which are laminated in this order. The fluorine resin 2 includes dispersed ITO fine particles and has an outer periphery provided with a resin accumulation part 6. The flat plate glass 4 for jointing has the outer periphery with a size larger than an optical effective diameter of the flat plate glass 4 for jointing and smaller than the inner size of the resin accumulation part 6. Consequently, when molding the laminated diffractive optical element, the contour of the flat plate glass 4 for jointing has no contact with the resin accumulation part 6, so that deformation of the flat plate glass 1 for forming a grating and the flat plate glass 4 for jointing can be prevented.

Description

  The present invention relates to a laminated diffractive optical element used in an optical apparatus such as a camera or a video, and a method for manufacturing the laminated diffractive optical element.

  Conventionally, a laminated diffractive optical element (Patent Document 1) has a structure in which a first lens substrate, a first resin layer, a second resin layer, and a second lens substrate are sequentially laminated. .

  The first lens substrate and the second lens substrate have a spherical or aspherical lens shape. The diffraction grating is a concentric annular zone pattern and is formed between the first resin layer and the second resin layer. A photocurable resin or a thermosetting resin is used for the first resin layer and the second resin layer.

  Conventionally, a method for manufacturing a laminated diffractive optical element includes a step of forming a first resin layer having a diffraction grating with a first optical material on one surface of a first lens substrate, as described in Patent Document 1, The process consists of a step of bonding the first resin layer and the second lens substrate through the second resin layer. The step of forming the first resin layer includes a step of filling the first optical material between the mold and the first lens substrate, a step of curing the first optical material with light, It consists of the process of releasing the optical material from the mold. The step of bonding the first resin layer and the second lens substrate includes the step of filling the second optical material between the first resin layer and the second lens substrate, and the second optical material by light. It consists of a curing process.

  In recent years, a resin containing metal oxide fine particles is used for a laminated diffractive optical element in order to improve its optical characteristics. However, a resin containing metal oxide fine particles has a lower visible light transmittance than a normal resin. Therefore, in order to increase the visible light transmittance of the laminated diffractive optical element, it is necessary to reduce the thickness of the resin layer containing the metal oxide fine particles. However, if the resin layer is made thin, unfilling of the resin into the mold is likely to occur, and the problem of sink marks due to cure shrinkage of the resin becomes significant.

  Therefore, conventionally, a resin reservoir groove has been formed on the outer periphery of the laminated diffractive optical element by providing a resin reservoir groove for storing excess resin on the outer periphery of the mold. It was. Thereby, it is possible to fill the diffraction grating shape portion between the mold and the first lens substrate. Moreover, since the shrinkage of curing of the resin forming the diffraction grating within the optical effective diameter can be supplemented by the resin in the resin reservoir outside the optical effective diameter, sink marks occurring in the diffraction grating can be prevented.

JP 2007-212547 A

  However, in the case of a multilayer diffraction grating having a conventional resin reservoir, the second lens substrate is deformed in the step of bonding the first resin layer and the second lens substrate via the second resin layer. There was a problem. That is, when the first resin layer is formed on the first lens substrate and then the first resin layer and the second lens substrate are bonded, the second optical material is cured and contracted. At this time, due to the resin reservoir formed in the first resin layer, the amount of the second optical material that cures and shrinks is large in the central portion of the second lens substrate and small in the outer peripheral portion. Therefore, the second lens substrate is deformed in the direction in which the central portion is recessed. As a result, a difference in curvature in the direction from the optical axis toward the outer periphery, referred to as “As”, occurs, or unevenness formed in a bell shape, referred to as “K”.

  It is an object of the present invention to provide a laminated diffractive optical element with less deformation of the second lens substrate and a manufacturing method for producing the laminated diffractive optical element.

  In the laminated diffractive optical element of the present invention, a first lens substrate, a first resin layer, a second resin layer, and a second lens substrate are laminated in this order, and the first resin layer contains metal oxide fine particles. The outer periphery of the first resin layer is provided with a resin reservoir, and the outer shape of the second lens substrate is larger than the optical effective diameter of the second lens substrate, and It is characterized by being smaller than the inner shape of the resin reservoir.

  The method for manufacturing a laminated diffractive optical element of the present invention includes a laminated diffractive optical element in which a first lens substrate, a first resin layer, a second resin layer, and a second lens substrate are laminated in order. A step of positioning the first resin layer in which metal oxide fine particles are dispersed between the first lens substrate and a mold; and the first resin layer on the mold. The first lens substrate placed on the mold is pressed to fill the first resin layer up to the groove for the resin reservoir provided in the mold to form a resin reservoir in the first resin layer A step of irradiating the filled first resin layer with light to cure the first resin layer, and the cured first resin layer together with the first lens substrate from the mold. A step of releasing, the first resin layer, an outer diameter larger than the optical effective diameter, and the first resin layer The step of positioning the second resin layer between the second lens substrate smaller than the inner diameter of the oil reservoir, and the first resin layer placed on the first resin layer via the second resin layer A step of pressing the second lens substrate to fill the second resin layer to an optically effective diameter, the first lens substrate, the first resin layer, the second resin layer, and the second And a step of aligning the lens substrate and a step of irradiating the filled second resin layer with light to cure the second resin layer.

  In the laminated diffractive optical element of the present invention, the outer shape of the second lens substrate is formed larger than the optical effective diameter of the second lens substrate and smaller than the inner shape of the resin reservoir. Interference between the first lens substrate and the second lens substrate is avoided. For this reason, the laminated diffractive optical element of the present invention has little deformation of the first lens substrate and the second lens substrate, and the surface shape of both substrates is good, so that the optical performance of an optical device such as a camera or video is obtained. Can be improved.

  In the method for manufacturing a laminated diffractive optical element of the present invention, the outer diameter of the second lens substrate and the first resin layer are smaller than the effective optical diameter and smaller than the inner diameter of the resin reservoir of the first resin layer. There is a step of positioning the second resin layer between them. For this reason, the manufacturing method of the present invention can avoid the interference between the first lens substrate and the second lens substrate at the time of manufacturing, and the first lens substrate and the second lens substrate are less deformed. A laminated diffractive optical element can be manufactured. Further, the manufacturing method of the present invention improves the production yield of the laminated diffractive optical element by preventing deformation of the first lens substrate and the second lens substrate, thereby producing the laminated diffractive optical element. Cost can be reduced.

1 is a cross-sectional view of a multilayer diffractive optical element according to a first embodiment of the present invention. It is a figure of the metal mold | die used for shaping | molding of the lamination type diffractive optical element of 1st Embodiment and 1st Example of this invention. (A) is a top view. (B) is a sectional view. It is a figure for demonstrating the manufacturing process of the laminated | stacked diffractive optical element of 1st Embodiment and 1st Example of this invention. It is sectional drawing of the lamination type diffractive optical element of 2nd Embodiment of this invention. It is a figure of the metal mold | die used for shaping | molding of the lamination | stacking type | mold diffractive optical element of 2nd Embodiment and 2nd Example of this invention. (A) is a top view. (B) is a sectional view. It is a figure for demonstrating the manufacturing process of the lamination type diffractive optical element of 2nd Embodiment and 2nd Example of this invention.

  Hereinafter, a laminated diffractive optical element according to an embodiment of the present invention and a method of manufacturing the laminated diffractive optical element will be described with reference to the drawings.

[First Embodiment]
An apparatus for manufacturing a laminated diffractive optical element according to a first embodiment of the present invention and a process of forming a laminated diffraction grating will be described.

  FIG. 1 is a cross-sectional view of the multilayer diffractive optical element 7 according to the first embodiment of the present invention.

  The laminated diffractive optical element 7 has a structure in which a first lens substrate 1, a first resin layer 2, a second resin layer 3, and a second lens substrate 4 are laminated in order.

  The first resin layer 2 has a diffraction grating portion in which metal oxide fine particles are dispersed. A resin reservoir 6 is formed on the outer periphery of the first resin layer 2. The resin reservoir 6 is formed in a convex shape on the outer periphery or part of the first lens substrate 1 outside the optical effective diameter. The resin reservoir 6 is an area for storing the first optical material 2a in the manufacturing process of the first resin layer 2 described later. The second resin layer 3 also has a diffraction grating part. The second lens substrate 4 is formed so that the outer diameter is not less than the optical effective diameter of the laminated diffractive optical element 7 and less than the inner diameter of the resin reservoir 6 formed in the first resin layer 2. The thickness of the resin reservoir 6 in the optical axis direction is larger than the thickness of the diffraction grating portion made of the first resin layer 2 in which metal oxide fine particles are dispersed.

  FIG. 2A is a plan view of a mold 9 used for manufacturing a laminated diffractive optical element. FIG. 2B is a cross-sectional view of the mold 9. FIG. 3 is a diagram for explaining a manufacturing process of the laminated diffractive optical element.

  In FIG. 3, reference numeral 13 denotes a holding member that holds the first lens substrate 1.

  First, as shown in FIG. 3A, an appropriate amount of unsolidified first optical material 2a in which metal oxide fine particles are dispersed is dropped onto one surface 1a of the first lens substrate 1. Next, as shown in FIG. 3B, the first lens substrate 1 placed on the mold 9 is pressed, and the first optical material 2 a in which the metal oxide fine particles are dispersed is removed from the outer periphery of the mold 9. It reaches to the groove 10 for the resin reservoir provided in. The resin reservoir groove 10 is a region for storing the first optical material 2 a in the manufacturing process of the first resin layer 2, and is formed in the mold 9. At this time, the first optical material 2a in which the metal oxide fine particles are dispersed is uniformly filled in the diffraction grating portion within the optical effective diameter without deficiency, and further, the outer circumference or one of the grooves 10 for the resin reservoir outside the optical effective diameter. The part is also filled.

  Next, the first optical material 2a in which the filled metal oxide fine particles are dispersed is irradiated with light for curing the material. Next, as shown in FIG. 3C, the first optical material 2 a (first resin layer 2) in which the cured metal oxide fine particles are dispersed is released from the mold 9 together with the first lens substrate 1. To do.

  On the first lens substrate 1, a diffraction grating portion and a resin reservoir portion 6 made of the first resin layer 2 in which metal oxide fine particles are dispersed are formed. The resin reservoir 6 is formed in a convex shape on the outer periphery or part of the first lens substrate 1 outside the optical effective diameter. The thickness of the resin reservoir 6 in the optical axis direction is larger than the thickness of the diffraction grating portion made of the first resin layer 2 in which metal oxide fine particles are dispersed.

  In FIG. 3D, reference numeral 14 indicates a holding member that holds the first lens substrate 1.

  Hereinafter, a process of bonding the second lens substrate 4 to the first resin layer 2 through the second optical material 3a (second resin layer 3) is described with reference to FIGS. To explain.

  First, as shown in FIG. 3D, an appropriate amount of the second optical material 3a that is not solidified is dropped onto one surface of the second lens substrate 4. Next, as shown in FIG. 3E, the second lens substrate 4 placed on the first resin layer 2 in which the metal oxide fine particles are dispersed is pressed, and the second optical material 3a is laminated. Fill to the effective optical diameter of the diffractive optical element. Next, the laminated first lens substrate 1, the first resin layer 2 in which the metal oxide fine particles are dispersed, the uncured second resin layer 3 formed of the second optical material 3a, and the second The optical axis with the lens substrate 4 is aligned by alignment means (not shown). Next, the filled second optical material 3a is irradiated with light for curing the material. At this time, the outer peripheral end of the second lens substrate 4 is not in contact with the resin reservoir 6 on the first lens substrate 1. Finally, the laminated diffractive optical element is cured by heating.

  That is, the manufacturing method of the laminated diffractive optical element 7 of the first embodiment includes the first lens substrate 1, the first resin layer 2, the second resin layer 3, and the second lens substrate 4. Is a manufacturing method of the laminated diffractive optical element 7 which is laminated in order.

[Second Embodiment]
An apparatus for manufacturing a laminated diffractive optical element according to a second embodiment of the present invention and a process of forming a diffraction grating will be described.

  Since the manufacturing apparatus of the laminated diffractive optical element of the second embodiment and the process of forming the diffraction grating are substantially the same as those of the first embodiment, portions different from the first embodiment will be described in detail, and the other The portion will be described briefly.

  FIG. 4 is a sectional view of the laminated diffractive optical element 27 according to the second embodiment. The laminated diffractive optical element 27 has a structure in which a first lens substrate 21, a first resin layer 22, a second resin layer 23, and a second lens substrate 25 are laminated in order.

  The first resin layer 22 has a diffraction grating portion in which metal oxide fine particles are dispersed. The second resin layer 23 also has a diffraction grating part. The resin reservoir 26 is formed on the first resin layer 22 in which metal oxide fine particles are dispersed. In the second lens substrate 25, a relief portion 25 b that avoids interference with the resin reservoir portion 26 is formed in a portion of the first resin layer 22 that faces the resin reservoir portion 26. The resin reservoir 26 is formed on the first resin layer 22 in which metal oxide fine particles are dispersed.

  FIG. 5A is a plan view of a mold 29 used for manufacturing the laminated diffractive optical element. FIG. 5B is a cross-sectional view of the mold 29.

  In the method of manufacturing the laminated diffractive optical element 27 of the second embodiment, the first lens substrate 21, the first resin layer 22, the second resin layer 23, and the second lens substrate 25 are sequentially formed. Laminate.

  The manufacturing method of the laminated diffractive optical element 27 according to the second embodiment includes the following steps.

  A step of positioning the first optical material 22a in which metal oxide fine particles are dispersed between the first lens substrate 21 and the mold 29 (FIG. 6A). The first lens substrate 21 placed on the mold 29 via the first optical material 22 a is pressed to fill the first optical material 22 a up to the resin reservoir groove 30 provided on the mold 29, A step of forming a resin reservoir 26 in one resin layer 22; A process of forming the first resin layer 22 by irradiating the cured first optical material 22a with light to cure (FIG. 6B). A step of separating the cured first resin layer 22 from the mold 29 together with the first lens substrate 21 (FIG. 6C). A step of positioning the second optical material 23a between the second lens substrate 25 and the first resin layer 22 (FIG. 6D). In the second lens substrate 25, an escape portion 25 b that avoids interference with the resin reservoir portion 26 is formed at a portion of the first resin layer 22 that faces the resin reservoir portion 26. A step of pressing the second lens substrate 25 placed on the first resin layer 22 via the optical material 23a to fill the second optical material 23a to the optical effective diameter. A step of aligning the optical axes of the first lens substrate 21, the second resin layer 23 formed by curing the first resin layer 22 and the second optical material 23a, and the second lens substrate 25; A step of forming the second resin layer 23 by irradiating the cured second optical material 23a with light to cure (FIG. 6E). A step of heating and curing the laminated diffractive optical element 27 formed by the above steps.

Example 1
A laminated diffractive optical element according to Example 1 of the present invention and a method of manufacturing the laminated diffractive optical element will be described.

  The laminated diffractive optical element 7 (FIG. 1) of this example is composed of a flat plate glass 1 for forming a lattice, a fluororesin 2 in which ITO (indium oxide) fine particles are dispersed, an acrylic resin 3, and a flat plate glass 4 for bonding. It is configured.

  The lattice-forming flat glass (first lens substrate) 1 is shaped like a disk having a diameter of 34 mm and a thickness of 3 mm. The fluororesin (first optical material) 2 in which ITO fine particles as metal oxide fine particles are dispersed has photocurability, and nano-sized ITO fine particles are uniformly dispersed at 20 vol% in the fluororesin. It is dark blue. Similarly, the acrylic resin (second optical material) 3 has photocurability. The joining flat glass (second lens substrate) 4 is formed in a disc shape having a diameter of 30 mm and a thickness of 2 mm.

  The diffraction grating between the fluororesin 2 and the acrylic resin 3 in which ITO fine particles are dispersed is a blazed diffraction grating having a grating height of 10 μm and a grating width of 1 mm to 5 mm, and is formed concentrically with a convex shape toward the center. Yes. The resin reservoir 6 is made of the fluororesin 2 in which ITO fine particles are dispersed, and is formed in a range of 10 μm to 40 μm in height and 20 μm to 500 μm in width on the outer periphery or a part outside the optical effective diameter. The height (H1) of the resin reservoir 6 is the height from the trough of the diffraction grating. The width (W1) of the resin reservoir 6 is the distance from the outer periphery of the diffraction grating to the outer periphery of the fluororesin 2. The diameter of the bonding flat glass 4 is not less than the optical effective diameter and less than the inner diameter of the resin reservoir 6.

  The metal mold | die used for the manufacturing method of the lamination type diffractive optical element 7 of a present Example is demonstrated based on FIG.

  The mold 9 has a desired reversal shape of the diffraction grating and a resin reservoir groove 10 formed on its molding surface 9a. The resin reservoir groove 10 is formed in a ring shape (endless shape) in plan view along the outer periphery of the mold 9 and has a groove shape formed lower than the molding surface 9a of the mold.

  The diffraction grating on the molding surface 9a of the mold 9 is a blazed diffraction grating having a grating height of 10 μm and a grating width of 1 mm to 5 mm, and is formed concentrically with a concave shape toward the center. The resin reservoir groove 10 is concentrically formed with a depth of 40 μm and a width of 500 μm on the outer periphery outside the optical effective diameter. The depth (V1) of the resin reservoir groove 10 is the depth from the peak of the diffraction grating formed in the mold 9. The width (W2) of the resin reservoir groove 10 is the width from the outer periphery of the diffraction grating to the outer periphery of the groove shape. The molding surface 9a of the mold 9 is formed by a cutting method or a polishing method on the mold base material.

  A method for manufacturing the laminated diffractive optical element 7 will be described with reference to FIG.

  First, a silane coupling process is performed on one surface 1a of the lattice-forming flat glass 1 in order to strengthen the close contact with the fluororesin 2 in which ITO fine particles are dispersed.

  Next, as shown in FIG. 3 (A), a fluororesin in which ITO fine particles are dispersed by a dispenser (not shown) near the center of the silane coupling surface of the flat glass for forming a lattice (first lens substrate) 1. 2 is dropped in an appropriate amount. The fluororesin 2 in which the ITO fine particles are dispersed may be dropped on the molding surface of the mold 9. That is, the fluororesin 2 in which metal oxide fine particles are dispersed is positioned between the lattice-forming flat glass 1 and the mold 9.

  Next, as shown in FIG. 3 (B), the grid-forming flat glass 1 placed on the mold 9 via the fluororesin 2 is pressed, and the fluororesin 2 in which ITO fine particles are dispersed is removed from the mold 9. The resin reservoir groove 10 provided on the outer periphery is filled. By pressing the grid-forming flat glass 1, the thickness of the fluororesin 2 in which the ITO fine particles are dispersed excluding the diffraction grating portion is extended to 1 μm. The fluororesin 2 in which the ITO fine particles are dispersed has a deep blue color, and can be used for a laminated diffractive optical element by extending the thickness to 1 μm to enhance transparency. The portion of the fluororesin 2 in which the ITO fine particles are dispersed is extended to the outer periphery outside the optical effective diameter, and is accumulated and accumulated in the resin reservoir groove 10 on the molding surface 9 a of the mold 9. The amount accumulated and accumulated in the resin reservoir groove 10 of the fluororesin 2 in which ITO fine particles are dispersed is uneven in the circumferential direction. For this reason, the resin reservoir 6 formed in the resin reservoir groove 10 has a height and width that are non-uniform in a range of 10 μm to 40 μm in height and 20 μm to 500 μm in width.

Next, the fluorine resin 2 in which the filled ITO fine particles are dispersed is irradiated with 20 J (40 [mW / cm ² ] × 500 seconds) of ultraviolet light from an unillustrated ultraviolet irradiation lamp to fluorinate the ITO fine particles dispersed therein. Resin 2 is cured.

  Next, as shown in FIG. 3C, the holding member 13 is raised to separate (release) the fluororesin 2 in which the hardened ITO fine particles are dispersed from the mold 9 together with the flat plate glass 1 for lattice forming. .

  Next, the silane coupling process for strengthening the close contact with the acrylic resin 3 is performed on one surface 4 a of the flat glass 4 for bonding.

  Next, as shown in FIG. 3D, an appropriate amount of acrylic resin 3 is dropped in the vicinity of the center of the silane coupling surface of the joining flat glass 4 with a dispenser (not shown). The acrylic resin 3 may be dropped on the diffraction grating made of the fluororesin 2 in which the ITO fine particles formed in the previous step are dispersed. That is, the acrylic resin 3 in which ITO fine particles are dispersed is positioned between the flat glass 4 for bonding having a diameter larger than the optical effective diameter and smaller than the inner diameter of the resin reservoir 6 of the fluororesin 2 and the fluororesin 2. .

  Next, the bonding flat glass 4 placed on the fluororesin 2 in which ITO fine particles are dispersed is pressed to fill the acrylic resin 3 to the optically effective diameter. By pressing the bonding flat glass 4, the thickness of the acrylic resin 3 excluding the diffraction grating portion is extended to 50 μm. Since the acrylic resin 3 has high transparency, it can be used in a laminated diffractive optical element with a thickness of 50 μm. Since the diameter of the bonding flat glass 4 is formed to be equal to or larger than the optical effective diameter of the bonding flat glass 4 and smaller than the inner diameter of the resin reservoir 6, the bonding flat glass 4 and the resin reservoir 6 do not come into contact with each other. . For this reason, the flat glass 1 for lattice formation and the flat glass 4 for joining do not deform | transform by hardening shrinkage | contraction of the acrylic resin 3 of a post process.

  On the other hand, when the diameter of the bonding flat glass 4 is equal to or larger than the inner diameter of the resin reservoir 6, the bonding flat glass 4 and the resin reservoir 6 face each other due to curing shrinkage of the acrylic resin 3 in the subsequent process. Abut. As a result, the lattice forming flat glass 1 and the bonding flat glass 4 are deformed.

  Next, the optical eccentricity of the laminated lattice forming flat glass 1, the fluororesin 2 in which ITO fine particles are dispersed, the acrylic resin 3, and the bonding flat glass 4 is adjusted.

Next, as shown in FIG. 3E, the filled acrylic resin 3 is irradiated with 9 J (30 [mW / cm ² ] × 300 seconds) of ultraviolet light from an unillustrated ultraviolet irradiation lamp, and acrylic resin is irradiated. Resin 3 is cured. At this time, the acrylic resin 3 contracts by about 9% by volume due to the curing reaction.

  Finally, the laminated multilayer diffractive optical element 7 is heated and cured at 80 ° C. for 24 hours to relieve the internal stress remaining in the fluororesin 2 or acrylic resin 3 in which the ITO fine particles are dispersed, thereby removing the uncured portion. Harden.

  The manufacturing method described above is a method for manufacturing a lens having a perfect circle on the outer periphery, but can also be applied to manufacturing a non-circular lens such as a polygonal lens or an elliptic lens on the outer periphery. In this case, the resin reservoir groove 10 and the resin reservoir 6 are formed in a non-round shape in plan view, and the outer shape of the bonding flat glass 4 is larger than the optical effective diameter of the bonding flat glass 4 and the resin. The shape needs to be smaller than the inner shape of the reservoir 6. And the external shape of the flat glass 4 for joining needs to be formed in the magnitude | size required in order to press the acrylic resin 3. FIG.

  The standard value of the as shape and the habit shape within the effective optical diameter of the flat glass 4 for bonding of the laminated diffractive optical element of this example is 0.5 or less in Newton rings. On the other hand, the measured values of the as-shaped shape and the habit-shaped shape within the effective optical diameter of the laminated diffractive optical element of this example were 0.2 and 0.3 good surface shapes, respectively. In addition, the measured values of the as-shaped shape and the habit-shaped shape within the optical effective diameter of the flat glass 4 for bonding of the laminated diffractive optical element of this example were 0.3 and 0.4 good surface shapes, respectively. It was.

  The shape of the lens and the shape of the lens substrate of the laminated diffractive optical element were measured using a Fizeau interferometer. The vertical shape was evaluated by excluding the tilt component, curvature component, and measurement noise from the measured surface shape data. The habit shape was evaluated by excluding the tilt component, curvature component, asphalt component and measurement noise from the measured surface shape data.

  As described above, in the laminated diffractive optical element of the first embodiment, the outer shape of the flat glass for bonding (second lens substrate) is larger than the optical effective diameter of the flat glass for bonding, and the flat glass for lattice forming It is formed smaller than the inner shape of the resin reservoir of the (first lens substrate). For this reason, the laminated diffractive optical element of the first embodiment is formed by avoiding the interference between the lattice forming flat glass and the bonding flat glass and reducing the deformation of the surfaces of both glasses. Therefore, this laminated diffractive optical element can improve the optical performance of an optical device such as a camera or a video to be mounted.

  Also, according to the method for manufacturing a laminated diffractive optical element, a laminated diffractive optical element having a good lens substrate surface shape can be produced, and thus a laminated diffractive optical element having excellent optical performance can be produced. Further, since the production yield is improved by improving the surface shape of the lattice-forming flat glass or the bonding flat glass, the manufacturing cost of the laminated diffractive optical element can be reduced.

(Comparative Example 1)
Comparative Example 1 is different from Example 1 only in the diameter of the flat glass for bonding, and the other configurations are the same. The diameter of the flat glass for bonding is less than the effective optical diameter of the laminated diffractive optical element and is smaller than that of Example 1.

  In the joining process of the laminated diffractive optical element of Comparative Example 1, as in Example 1, the joining flat glass and the resin reservoir 6 do not face each other, so that the joining flat glass is not deformed. However, the laminated diffractive optical element of Comparative Example 1 cannot satisfy the desired optical performance of the laminated diffractive optical element because, for example, effective light rays are reduced because the diameter of the flat glass for bonding is less than the effective optical diameter.

(Comparative Example 2)
In Comparative Example 2, the diameter of the flat glass for bonding is only different from that of Example 1, and the other configurations are the same. The diameter of the joining flat glass is equal to or larger than the diameter of the resin reservoir 6 on the lattice forming flat glass 1 and is larger than that of the first embodiment.

  In the joining process of the laminated diffractive optical element of Comparative Example 2, the joining flat glass and the resin reservoir 6 face each other, so that the lattice forming flat glass 1 and the joining flat glass are formed by curing shrinkage of the acrylic resin 3 in the subsequent process. Transforms. The measured values of the as-shaped shape and the habit-shaped shape within the optical effective diameter of the grating-forming flat glass 1 of the laminated diffractive optical element of Comparative Example 2 were 0.8 and 1.0, respectively. Further, the measured values of the as-shaped shape and the habit-shaped shape within the optical effective diameter of the flat glass for bonding of the laminated diffractive optical element of Comparative Example 2 were 1.2 and 1.7, respectively.

  Since the standard value of the as-shaped shape and the hazy shape within the optical effective diameter of the lattice-forming flat glass 1 and the bonding flat glass of the laminated diffractive optical element is 0.5 or less, the laminated diffractive optical element of Comparative Example 2 is The desired optical performance cannot be satisfied.

(Second embodiment)
A laminated diffractive optical element according to a second embodiment of the present invention and a method of manufacturing the laminated diffractive optical element will be described.

The laminated diffractive optical element 27 (FIG. 4) of this example includes a lattice-forming flat glass 21, a fluororesin 22 in which TiO ₂ (titanium oxide) fine particles are dispersed, an epoxy resin 23, and a bonding flat glass 25. It consists of

The lattice-forming flat glass (first lens substrate) 21 is formed in a disk shape having a diameter of 100 mm and a thickness of 5 mm. The fluororesin (first resin layer) 22 in which TiO ₂ microparticles as metal oxide microparticles are dispersed has photocurability, and nano-sized TiO ₂ microparticles are uniformly dispersed at 10 vol% in the fluororesin. White. Similarly, the epoxy resin (second resin layer) 23 has photocurability. The flat glass for bonding (second lens substrate) 25 is formed in a disk shape with a diameter of 100 mm and a thickness of 8 mm, and a relief portion 25b having a depth of 1 mm and a width of 3 mm is formed concentrically on the outer periphery of one side 25a. Has been.

The diffraction grating between the fluororesin 22 and the epoxy resin 23 in which TiO ₂ fine particles are dispersed is a blazed diffraction grating having a grating height of 20 μm and a grating width of 0.1 mm to 15 mm, and is formed concentrically with a concave shape at the center. Has been. The resin reservoir 26 is made of a fluororesin 22 in which TiO ₂ fine particles are dispersed, and is formed in a range of 20 μm to 70 μm in height and 20 μm to 300 μm in width on the outer periphery or a part outside the optical effective diameter. The height (H2) of the resin reservoir 26 is the height from the valley of the diffraction grating. The width (W3) of the resin reservoir 26 is the distance from the outer periphery of the diffraction grating to the outer periphery of the fluororesin 22. A relief portion 25b provided on the outer peripheral portion of one surface 25a of the bonding flat glass 25 faces the resin reservoir portion 26 so as to avoid interference with the resin reservoir portion. That is, by forming the relief portion 25b, the outer shape D1 (FIG. 6D) of the remaining projection 25a is formed smaller than the inner diameter D2 of the resin reservoir 26.

  The metal mold | die used for the manufacturing method of the lamination type diffractive optical element 27 of a present Example is demonstrated based on FIG.

  The mold 29 has a desired reversal shape of the diffraction grating and a resin reservoir groove 30 formed on the molding surface 29a thereof.

  The diffraction grating on the molding surface 29a of the mold 29 is a blazed diffraction grating having a grating height of 20 μm and a grating width of 0.1 mm to 15 mm, and is formed concentrically with a convex shape toward the center. The resin reservoir groove 30 is concentrically formed with a height of 70 μm and a width of 300 μm on the outer periphery outside the optically effective diameter. The molding surface 29a of the mold 29 is formed by a cutting method or a polishing method on the mold base material.

  A method for manufacturing the laminated diffractive optical element 27 will be described in order.

First, a silane coupling process is performed on one surface 21a of the lattice-forming flat glass 21 in order to strengthen the close contact with the fluororesin 22 in which TiO ₂ fine particles are dispersed.

Next, as shown in FIG. 6A, an appropriate amount of fluororesin 22 in which TiO ₂ fine particles are dispersed is dropped in the vicinity of the center of the silane coupling treatment surface of the lattice-forming flat glass 21 with a dispenser. Note that the fluororesin 22 in which the TiO ₂ fine particles are dispersed may be dropped on the molding surface of the mold 29. That is, the fluororesin 22 in which metal oxide fine particles are dispersed is positioned between the lattice forming flat glass 21 and the mold 29.

Next, as shown in FIG. 6 (B), the grid forming flat glass 21 placed on the mold 29 via the fluororesin 22 is pressed, and the fluororesin 22 in which TiO ₂ fine particles are dispersed is molded into the mold 29. To the groove 30 for the resin reservoir provided on the outer periphery. By pressing the grid-forming flat glass 21, the thickness excluding the diffraction grating portion of the fluororesin 22 in which the TiO ₂ fine particles are dispersed is extended to 3 μm. The fluororesin 22 in which TiO ₂ fine particles are dispersed is white for light scattering, and can be used for a laminated diffractive optical element by extending the thickness to 3 μm to weaken the light scattering property. The portion of the fluororesin 22 in which the TiO ₂ fine particles are dispersed is extended to the outer periphery outside the optical effective diameter, and accumulates and accumulates in the resin reservoir groove 30 on the molding surface 29 a of the mold 29. The amount accumulated and accumulated in the resin reservoir groove 30 of the fluororesin 22 in which the TiO ₂ fine particles are dispersed is uneven in the circumferential direction. For this reason, the resin reservoir 26 formed in the resin reservoir groove 30 is formed with a nonuniform height and width within a range of 20 μm to 70 μm in height and 20 μm to 300 μm in width. The depth of the resin reservoir groove 30 is the depth (V2) from the peak of the diffraction grating formed in the mold 29. The width of the resin reservoir groove 30 is a width (W4) from the outer periphery of the diffraction grating to the outer periphery of the groove shape.

Next, the fluorine resin 22 in which the filled TiO ₂ fine particles are dispersed is irradiated with 30 J (40 [mW / cm ² ] × 750 seconds) of ultraviolet light from an unillustrated ultraviolet irradiation lamp to disperse the TiO ₂ fine particles. The obtained fluororesin 22 is cured.

Next, as shown in FIG. 6C, the holding member 33 is lifted to release the fluororesin 22 in which the hardened TiO ₂ fine particles are dispersed together with the grid forming flat glass 21.

  Next, a silane coupling process for strengthening the close contact with the epoxy resin 23 is performed on the one surface 25 a having the relief portion 25 b of the bonding flat glass 25.

Next, as shown in FIG. 6 (D), an appropriate amount of epoxy resin 23 is dropped in the vicinity of the center of the silane coupling surface of the joining flat glass 25 with a dispenser. The epoxy resin 23 may be dropped on the diffraction grating made of the fluororesin 22 in which the TiO ₂ fine particles formed in the previous step are dispersed. That is, the epoxy resin 23 is positioned between the lattice forming flat glass 21 and the fluororesin 22.

Next, the bonding flat glass 25 placed on the fluororesin 22 in which the TiO ₂ fine particles are dispersed is pressed to fill the epoxy resin 23 to the optically effective diameter. By pressing the bonding flat glass 25, the thickness of the epoxy resin 23 excluding the diffraction grating portion is extended to 30 μm. Since the epoxy resin 23 has high transparency, it can be used for a laminated diffractive optical element with a thickness of 30 μm. The escape portion 25b provided on the outer peripheral portion of the one side 25a of the bonding flat glass 25 faces the resin reservoir portion 26 but does not come into contact therewith. For this reason, the lattice-forming flat glass 21 and the bonding flat glass 25 do not come into contact with each other and are not deformed by the curing shrinkage of the epoxy resin 23 in the subsequent step.

  On the other hand, when the escape portion 25b is not provided on the outer peripheral portion of the one surface 25a of the bonding flat glass 25, the bonding flat glass 25 and the resin reservoir portion 26 face each other. For this reason, the lattice-forming flat glass 21 and the bonding flat glass 25 are deformed by the curing shrinkage of the epoxy resin 23 in the subsequent step.

Next, the optical eccentricity of the laminated lattice forming flat glass 21, the fluororesin 22 in which TiO ₂ fine particles are dispersed, the epoxy resin 23, and the bonding flat glass 25 is adjusted.

Next, as shown in FIG. 6E, the filled epoxy resin 23 is irradiated with ultraviolet light from an ultraviolet irradiation lamp by 15 J (30 [mW / cm ² ] × 500 seconds), and the epoxy resin 23 is applied. Harden. At this time, the epoxy resin 23 contracts by about 5% by volume due to the curing reaction.

Finally, the laminated multilayer diffractive optical element 27 is heated and cured at 60 ° C. for 48 hours to relieve internal stress remaining in the fluororesin 22 or epoxy resin 23 in which the TiO ₂ fine particles are dispersed, thereby uncured parts. Is cured.

  The manufacturing method described above is a manufacturing method of a lens having a perfect circle on the outer periphery, but can also be applied to manufacturing a non-circular lens such as a polygonal lens or an elliptic lens on the outer periphery. In this case, the resin reservoir portion 26 is formed in a non-circular shape in plan view, and the outer shape of the remaining portion of the relief portion 25b of the one surface 25a of the second lens substrate is smaller than the inner shape of the resin reservoir portion 26. In addition, it is necessary to be formed in a size necessary for pressing the epoxy resin 23.

  The standard values of the as-shaped shape and the habit-shaped shape within the optical effective diameter of the grating-forming flat glass 21 and the bonding flat glass 25 of the laminated diffractive optical element of this example are 0.5 or less in Newton rings. On the other hand, the measured values of the as-shape and the habit-shape within the effective optical diameter of the grating-forming flat glass 21 of the laminated diffractive optical element of this example are 0.3 and 0.5, respectively. It was a surface shape. In addition, the measured values of the as-shaped shape and the habit-shaped shape within the optical effective diameter of the flat glass 25 for bonding of the laminated diffractive optical element of this example were 0.2 and 0.4 good surface shapes, respectively. It was. In addition, the same method as Example 1 was used for the measurement of the shape of the stack and the habit of the laminated diffractive optical element of this example.

  As described above, the laminated diffractive optical element of the second embodiment is provided with a relief portion on the bonding flat glass to avoid interference with the resin reservoir portion at a portion facing the resin reservoir portion. Interference between the grating lens substrate and the bonding flat glass is avoided during manufacture. Therefore, the laminated diffractive optical element of the present invention can be formed with less deformation of the surface of the grating-forming flat glass (first lens substrate) and the joining flat glass of the laminated diffractive optical element. Therefore, this laminated diffractive optical element can improve the optical performance of an optical device such as a camera or a video to be mounted.

  Further, according to the method for manufacturing a laminated diffractive optical element, the gap between the flat glass for bonding and the fluororesin layer in which a relief portion is formed in a portion facing the resin reservoir of the fluororesin layer (first resin layer). There is a step of positioning the acrylic resin (second resin layer). For this reason, the manufacturing method of the present invention can avoid interference between the flat glass for lattice and the flat glass for bonding at the time of manufacturing, and the laminated diffraction with little deformation between the flat glass for lattice forming and the flat glass for bonding. An optical element can be manufactured. Furthermore, the manufacturing method of the present invention improves the production yield of the laminated diffractive optical element by not causing deformation in the lattice forming flat glass and the bonding flat glass, and the manufacturing cost of the laminated diffractive optical element. Can be lowered.

(Comparative Example 3)
Comparative Example 3 has the same configuration except for the shape of the outer peripheral portion of the flat glass for bonding, which is different from Example 2. The flat glass for bonding of Comparative Example 3 has a convex portion having a height of 0.1 mm and a width of 3 mm concentrically on the outer peripheral portion of one surface.

  In the joining step of the laminated diffractive optical element of Comparative Example 3, the convex portion on the outer peripheral portion of the joining flat glass and the resin reservoir portion 26 face each other and come into contact with each other. The flat glass 21 for bonding and the flat glass for bonding are deformed. The measured values of the as-shape and the habit-shape within the effective optical diameter of the grating-forming flat glass 21 of the laminated diffractive optical element of Comparative Example 3 were 1.1 and 1.9, respectively. Further, the measured values of the as-shaped shape and the habit-shaped shape within the optical effective diameter of the flat glass for bonding of the laminated diffractive optical element of Comparative Example 3 were 0.9 and 1.5, respectively.

  Since the standard value of the as-shaped shape and the habit shape within the optical effective diameter of the first lens substrate 21 of the laminated diffractive optical element and the flat glass for bonding is 0.5 or less, the laminated diffractive optical element of Comparative Example 3 The desired optical performance cannot be satisfied.

1, 21: First lens substrate (lattice forming flat glass), 2, 22: First resin layer (fluororesin), 2a, 22a: First resin layer (first optical material), 3, 23: second resin layer (acrylic resin), 3a, 23a: second resin layer (second optical material), 4, 25: second lens substrate (flat glass for bonding), 6, 26: resin Reservoir, 7, 27: Laminated diffractive optical element, 9, 29: Mold, 10, 30: Resin reservoir groove, 25b: Relief

Claims (4)

In the laminated diffractive optical element laminated in the order of the first lens substrate, the first resin layer, the second resin layer, and the second lens substrate,
Metal oxide fine particles are dispersed in the first resin layer, a resin reservoir is provided on the outer periphery of the first resin layer, and the outer shape of the second lens substrate is the second Larger than the optical effective diameter of the lens substrate and smaller than the shape inside the resin reservoir,
A laminated diffractive optical element. In the laminated diffractive optical element laminated in the order of the first lens substrate, the first resin layer, the second resin layer, and the second lens substrate,
Metal oxide fine particles are dispersed in the first resin layer, a resin reservoir is provided on the outer periphery of the first resin layer, and the second lens substrate is opposed to the resin reservoir. An escape portion that avoids interference with the resin reservoir is provided in the portion to be,
A laminated diffractive optical element. In the manufacturing method of the laminated diffractive optical element in which the first lens substrate, the first resin layer, the second resin layer, and the second lens substrate are sequentially laminated,
Positioning the first resin layer in which metal oxide fine particles are dispersed between the first lens substrate and a mold;
The first lens substrate placed on the mold through the first resin layer is pressed to fill the first resin layer into the resin reservoir groove provided in the mold, and Forming a resin reservoir in one resin layer;
Irradiating light to the filled first resin layer to cure the first resin layer;
Releasing the cured first resin layer from the mold together with the first lens substrate;
Between the first resin layer and the second lens substrate, the outer diameter of which is larger than the optical effective diameter and smaller than the inner diameter of the resin reservoir of the first resin layer. A step of positioning
Pressing the second lens substrate placed on the first resin layer via the second resin layer to fill the second resin layer to an optically effective diameter;
Aligning the first lens substrate, the first resin layer, the second resin layer, and the second lens substrate;
Irradiating light to the filled second resin layer to cure the second resin layer,
A method for producing a laminated diffractive optical element. In the manufacturing method of the laminated diffractive optical element in which the first lens substrate, the first resin layer, the second resin layer, and the second lens substrate are sequentially laminated,
Positioning the first resin layer in which metal oxide fine particles are dispersed between the first lens substrate and a mold;
The first lens substrate placed on the mold through the first resin layer is pressed to fill the first resin layer into the resin reservoir groove provided in the mold, and Forming a resin reservoir in one resin layer;
Irradiating light to the filled first resin layer to cure the first resin layer;
Releasing the cured first resin layer from the mold together with the first lens substrate;
Between the first resin layer and the second lens substrate in which a relief portion that avoids interference with the resin reservoir portion is formed in a portion facing the resin reservoir portion of the first resin layer, Positioning the second resin layer;
Pressing the second lens substrate placed on the first resin layer via the second resin layer to fill the second resin layer to an optically effective diameter;
Aligning the first lens substrate, the first resin layer, the second resin layer, and the second lens substrate;
Irradiating light to the filled second resin layer to cure the second resin layer,
A method for producing a laminated diffractive optical element.

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