Method for manufacturing a holder-integrated compound diffractive optical element

Abstract

To propose a holder integral composite diffraction optical element with which a composite diffraction optical element and other members such as a lens, etc., can be fixed in position easily with good accuracy, and positioning to a light source is facilitated and interface reflection is controlled so as to suppress performance degradation, helping to suppress performance changes regarding temperature and humidity.SOLUTION: Provided is a holder integral composite diffraction optical element in which parallel flat plates M formed from an elastic material which is sufficiently transparent in a use wavelength are secured to a holder H formed from an elastic material, and a minute structure MS to generate light diffraction is formed using an energy curable resin on at least one of the parallel flat plates M, with at least one tapered shape HT included in the inside of the holder H that allows other components to be accommodated while being positioned in place, and a substantially arc shape HR included in an outline part that can be used for positioning in assembling and forming.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a combined diffractive optical element (DOE) that converts light emitted from a laser light source or an LED light source into a specific pattern. Manufacturing method of body complex combined diffractive optical element (DOE) Manufacturing method and relates to.

Background Art

[0002] In recent years, an optical projection module that projects a specific pattern by combining a diffractive optical element with fine uneven shapes formed on a flat plate and an LED, a solid-state laser, or a vertical cavity surface emitting laser (VCSEL) and can be used for three-dimensional measurement, face recognition, guidance display, laser processing, etc. has become widely popular.

[0003] A method for creating a composite lens that accurately forms a lens shape using a transparent resin that cures with UV light or thermal energy on a glass substrate fixed to an elastic member is disclosed in Patent Document 1.

[0004] A method disclosed in Patent Document 2 uses a curable resin material to inexpensively and mass-produce lenses having the same shape, and it is difficult for defects to occur even through a singulation process such as dicing.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The diffractive optical element exhibits its function when combined with a light source. In order to combine the diffractive optical element with the light source, the fabricated diffractive optical element is fixed to a holder or the like, and is fixed to the light source via this holder. In the holder for fixing this diffractive optical element, components other than the diffractive optical element may be incorporated.

[0007] In recent years, finer and more complex projection patterns have been demanded, and between the light source and the diffractive optical element, a lens member such as a collimator lens that controls the light emitted from the light source to an approximately parallel or nearly parallel angle by a refraction action is increasingly arranged.

[0008] Furthermore, in order to realize a fine and complex projection pattern, it is necessary to precisely control the positional deviation between the diffractive optical element and the light source.

[0009] Also, when arranging members such as a collimator lens, the positions of each of the lens member, the diffractive optical element, and the light source must be precisely controlled.

[0010] In order to fabricate diffractive optical elements in large quantities and at low cost, there is also a method of forming a large number of diffractive optical elements in a wafer shape all at once, and then singulating them using a cutting method such as dicing.

[0011] The diffractive optical elements singulated by such a method have a large processing error during cutting, so after being mounted on the holder, adjustment while projecting a pattern is required when combining with the light source, resulting in enormous assembly costs.

[0012] Furthermore, when arranging other members such as a lens in the holder, it is necessary to ensure the positional accuracy between the members, but since the accuracy with respect to the outer shape of the diffractive optical element cannot be ensured, the members in the holder cannot be positioned with high precision.

[0013] Also, regarding the diffractive optical element, when dimensional changes occur due to temperature and humidity, changes in the periodic pattern of the fine structure and changes in the positional relationship with each member may occur, and as a result, the target projection pattern may not be obtained.

[0014] In order to suppress the above temperature and humidity changes, a composite diffractive optical element combining glass and a resin material has been proposed. However, when formed in a wafer shape as described above, processing errors occur in the singulation process, making it difficult to solve the problem of positioning accuracy.

[0015] The present invention has been made to solve such problems, and it is possible to precisely position a composite diffractive grating with respect to a holder and also precisely fix other members such as lenses to be incorporated later. A holder-integrated composite diffractive optical element Manufacturing method is provided.

Means for Solving the Problems

[0016] In order to solve the above problems, the holder-integrated composite diffractive optical element according to the present invention has a parallel plate M formed of an elastic material fixed to a holder H formed of an elastic material, and a fine structure MS for generating light diffraction is formed on at least one surface of the parallel plate M using an energy-curable resin. The inside of the holder H has at least one tapered shape HT that can accommodate other components while positioning them, and the outer shape has a substantially arc shape HR that can be used for positioning during assembly or molding.

[0017] The energy-curable resin used here refers to a material in which a cross-linking reaction or a polymerization reaction proceeds by receiving energy from the outside. Examples of the external energy include heat, ultraviolet rays, and electron beams. Such energy-curable resins include thermosetting types, ultraviolet-curable types, electron beam-curable types, etc. depending on the type of energy, and silicone-based, epoxy-based, and acrylic-based are generally known as material systems. Thus, although the types of energy-curable resins are diverse, any resin that is optically sufficiently transparent can be used as the resin lens material of the present invention. The limitation of transparency here means that the light absorption and scattering of the material are small enough to withstand use within the wavelength range of use.

[0018] By adopting such a configuration, the parallel flat plate M can be fixed to the holder H in advance. By using the substantially arc-shaped HR formed on the holder H for forming the fine structure pattern MS, it becomes possible to precisely align the center of the fine structure pattern MS with the center of the holder H. Since the parallel flat plate M is fixed in advance and the reference for forming the fine structure pattern MS is the substantially arc-shaped HR of the holder H, only the flat portions on both sides of the parallel flat plate M are important. Any shape can be used as long as the outer shape can be fixed to the holder H, and outer shape accuracy is not required.

[0019] By forming the holder H with the center of the tapered shape HT formed inside the holder H coinciding with the center of the substantially arc-shaped HR formed on the outer shape portion of the holder H, it becomes possible to position other members such as lenses with high precision with respect to the holder H based on the holder H.

[0020] Furthermore, since the center of the fine structure pattern MS is formed to substantially coincide with the center of the substantially arc-shaped HR of the holder H, other members such as lenses arranged at the center of the tapered shape HT can be precisely positioned and arranged with respect to the fine structure pattern MS via the holder H.

[0021] Furthermore, in the present invention, it is preferable that the number of substantially arc-shaped HRs formed on the outer shape portion of the holder H is four. When used for positioning during molding or assembly, by evenly contacting the four arc-shaped HRs with a positioning jig or the like, it becomes possible to easily align the center of the jig or the like with the center of the holder H.

[0022] Also, it is desirable that the ratio of the length of the arc-shaped HR to the circumferential length of the virtual circle circumscribing the four arc-shaped HRs is 0.01 or more. If the ratio is less than this value, the length of the arc-shaped HR is insufficient and it does not function sufficiently as a positioning means.

[0023] Furthermore, the angle formed by the taper shape HT for fixing other members formed inside the holder H and the axis perpendicular to the plane of the parallel flat plate M fixed to the holder H is preferably between 1° and 45°.

[0024] When the angle formed is 1° or less, when the holder H is created by injection molding or the like, the resistance during demolding increases, and the holder H cannot be accurately molded. Also, when the angle formed is 45° or more, the taper angle for positioning becomes poor, and it becomes difficult to precisely position other members.

[0025] It is preferable that the difference in refractive index at the wavelength of use of the material of the parallel flat plate M fixed to the holder H and the refractive index at the wavelength of use of the energy-curable resin forming the fine structure MS that causes photorefraction formed on the parallel flat plate M is 0.1 or less.

[0026] Generally, at the interface where different materials are joined, interface reflection occurs due to the difference in refractive index. In the case of the present application, it is difficult to exactly match the refractive index of the material used for the parallel flat plate M and the refractive index of the fine structure MS. However, if this difference in refractive index is 0.1 or less, the interface reflection will be at a level that is not a problem in practice. When the difference in refractive index exceeds 0.1, the interface reflection increases, the amount of light rays outside the design increases, and as a result, it becomes difficult to satisfy the design performance.

[0027] Furthermore, in the present application, at least one or more taper shapes HT are formed inside the holder H. When at least one or more lenses L having a refracting action are installed on this taper shape HT, it is desirable that the space G between the taper shape LT of the lens L and the taper shape HT of the holder H be 0.02 mm or less after the lens L is installed.

[0028] In order to fit the tapers together, the space G must be zero or greater so that the tapers do not interfere with each other. A larger clearance makes assembly easier, but if the clearance is too large, the positioning accuracy will naturally decrease. Regarding the positioning accuracy of the diffractive optical element and the refractive lens, if the numerical value of the space G is 0.02 mm, the positioning accuracy is sufficient.

[0029] The parallel flat plate M fixed to the holder H is preferably formed of a glass material.

[0030] In the present application, the fine structure M that causes photorefraction is formed of an energy-curable resin. It is known that the energy-curable resin undergoes dimensional changes with respect to temperature and humidity due to being a resin material.

[0031] As described above, the structural pattern of the fine structure M of the present application changes with temperature and humidity. If the parallel flat plate M of the present application is formed of a glass material, the fine structure M will be fixed to the glass. Since the glass material hardly undergoes dimensional changes with respect to temperature and humidity, the fine structure M formed of the energy-curable resin fixed on the glass also undergoes less dimensional changes with respect to temperature and humidity than the diffractive optical element formed of the resin alone. Therefore, performance degradation due to temperature and humidity can be suppressed.

Advantages of the Invention

[0032] According to the holder-integrated composite diffractive optical element of the present invention, based on the holder H, the composite diffractive optical element and other members such as a lens can be easily and accurately fixed, positioning to a light source is easy, performance degradation can be suppressed by controlling interface reflection, and performance changes related to temperature and humidity can be suppressed.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0034] Hereinafter, with reference to the drawings, embodiments of the present invention will be described. Each drawing illustrates a configuration example according to the present invention, and only schematically shows the cross-sectional shape, arrangement relationship, etc. of each component to the extent that the present invention can be understood, and the present invention is not limited to the illustrated examples. Further, in the following description, specific conditions or the like may be used, but these materials and conditions are only one of the preferred examples, and therefore, the present invention is not limited thereto at all.

[0035] Figure 1 is a structural diagram of the holder-integrated composite diffractive optical element of the present invention. A parallel plate M is fixed to the projection surface side of the holder H, a tapered shape HT for positioning other members is formed on the light source side, and a fine structure MS that causes optical diffraction formed of an energy-curable resin is fixed to the light source side surface MB of the parallel plate M. A substantially arc-shaped HR that serves as a positioning reference for molding and assembly is formed on the outer shape portion of the holder H.

[0036] Here, for the following drawings, when the light incident side is the light source side and the light emission side is the projection side with the composite diffractive optical element in between, the light source side surface of the parallel plate M is MB, the projection side surface is MA, and similarly, the light source side of the fine structure MS is MSB, the projection side is MSA, and the light source side of the lens member L installed in the tapered portion is LB, and the projection side is LA. When a plurality of parallel plates M are configured, they are sequentially numbered M1, M2 from the projection surface side. Similarly, when the fine structure MS, the lens member L, and the tapered shape HT are also configured in a plurality, they are sequentially numbered from the projection surface side.

Examples

[0037] Figure 2 is a configuration diagram of the holder-integrated compound diffractive optical element in the first embodiment. A parallel flat plate M is fixed inside the holder H, and a fine structure MS is formed of an energy-curable resin on the flat surface portion MB. Although the structural pattern of the fine structure MS is illustrated enlarged for convenience, it is originally a pitch and step of about several tens of nm to several μm.

[0038] On the outer shape portion of the holder H, four substantially arc-shaped HRs are formed. The four substantially arc-shaped HRs have the same shape, and the length of one substantially arc-shaped HR is 0.39 mm. The circumferential length RL of the virtual circle circumscribing this substantially arc-shaped HR is 4.71 mm. The ratio calculated from both is 0.083, satisfying the formula of claim 2. The outer shape of the parallel flat plate M is a quadrilateral. Although it is a quadrilateral for convenience, there is no restriction on its outer shape as long as it can secure a plane area sufficient to form the fine structure pattern MS and can be fixed to the holder H, such as a trapezoid or a parallelogram. One tapered shape HT is formed inside the holder H, and the angle HTA formed with the plane of the parallel flat plate M is 30°.

[0039] Here, with reference to Figure 3, a method for accurately fixing the compound diffractive optical element to the holder H will be described.

[0040] First, a parallel flat plate M formed of a substantially quadrilateral transparent elastic member is fixed to the holder H by a method such as adhesion. The substantially arc-shaped portion HR of the holder H is fixed to the first cylindrical hole JA1 of a jig JA having a precise cylindrical hole shape. UV-curable resin is dropped onto the fine structure pattern surface JB1 of a jig JB provided with a fine structure pattern surface JB1. The jig JB is inserted along the second cylindrical hole JA2 formed in the jig JA and stops at a predetermined position. The UV-curable resin contacts the light source side surface MB of the parallel flat plate M, and the resin spreads in the radial direction. After the resin spreads to a predetermined position, UV light is irradiated from the projection surface side MA of the parallel flat plate M, and the UV-curable resin cures. After the curing is completed, the jig JB is removed from the jig JA. When the holder H is taken out of the jig JA, a holder-integrated compound diffractive optical element with the fine structure MS formed is completed based on the substantially arc-shaped HR of the holder H.

[0041] Here, the composite diffractive optical element refers to a diffractive optical element formed by bonding different materials. For example, when a microstructure is formed of a thermosetting resin on a parallel flat plate formed of a UV-curable resin, it is also regarded as a composite diffractive optical element. A combination of a thermoplastic resin and an energy-curable resin can also be said to be a composite diffraction grating.

[0042] In addition, in Example 1, a UV-curable resin is used. However, when a thermosetting resin is used, jig JB may be heated. Therefore, the manufacturing example presented this time does not depend on the type of energy-curable resin.

Example

[0043] FIG. 4 is a diagram for explaining a second embodiment. The basic configuration is the same as that of Example 1, but the length of the substantially arc shape HR is 0.157 mm, and the circumferential length RL of the virtual circle circumscribing the arc shape HR is 4.71 mm. The ratio calculated from both is 0.033, which satisfies the formula of claim 2. The energy-curable resin forming the microstructure M is a thermosetting acrylic resin, and the refractive index at the used wavelength is 1.51. The material constituting the parallel flat plate M is a UV-curable epoxy resin, and the refractive index is 1.60.

[0044] The holder H is formed in a tapered shape, and the angle HTA formed between the tapered shape HT and the axis perpendicular to the parallel flat plate M is 45°. A lens member L for controlling light in parallel is fixed to the tapered shape HT, and the space G formed between the tapered shape HT and the taper of the lens member L is 0.02 mm.

[0045] By configuring in this way, the microstructure MS formed on the parallel flat plate M and the lens member L can be fixed in the holder H with high precision, and a high-performance product can be provided.

Example

[0046] Figs. 5 and 6 are diagrams for explaining the third embodiment. In the first and second embodiments, there was one fixed parallel flat plate M, but in this embodiment, two parallel flat plates M1 and M2 are used. Further, the parallel flat plate M2 is not a quadrilateral but a deformed heptagon. In the present application, as long as a sufficient planar area can be secured to form a fine structure, the outer shape of the parallel flat plate is not limited. Also, for the sake of explanation, a light source that emits light is illustrated as LS on the light source side of the holder-integrated composite diffractive optical element. As the type of the light source, as long as it is a component that emits light such as an LED or a semiconductor laser, the method is not limited.

[0047] The length of the substantially arc shape HR is 0.157 mm, and the circumferential length RL of the virtual circle circumscribing the arc shape HR is 4.71 mm. The ratio calculated from both is 0.033, which satisfies the formula of claim 2. The energy-curing resin forming the first fine structure MS1 when viewed from the projection side is a UV-curing acrylic resin, the refractive index at the used wavelength is 1.5, the material constituting the parallel flat plate M1 is a glass material, and the refractive index is 1.59. The energy-curing resin constituting the second fine structure MS2 is a UV-curing acrylic resin, the refractive index at the used wavelength is 1.5, the material constituting the parallel flat plate M1 is a glass material, and the refractive index is 1.53.

[0048] Two tapered shapes HT1 and HT2 are formed on the holder H. The angle HTA1 formed by the tapered shape HT1 and the axis perpendicular to the parallel flat plate M is 45°, and similarly, the angle HTA2 formed by the tapered shape HTA2 is 1.5°. A lens member L for controlling light in parallel is fixed to the tapered shape HT1 portion via the tapered shape HT1. A diaphragm member S having an aperture that can partially block the light emitted from the light source LS is fixed to the tapered shape HT2 portion via the tapered shape HT2.

[0049] The space G1 between the tapered shape HT1 portion of the holder and the tapered shape LT of the lens member L is 0.02 mm, and the space G2 between the tapered shape HT2 portion of the holder and the tapered shape ST of the diaphragm member S is zero.

[0050] Figure 5 illustrates an example of a light beam emitted by a dashed arrow. By configuring it in this way, among the light emitted from the light source LS, extra light beams can be accurately cut by the aperture member S as shown in the figure, so it becomes possible to select a light source with a wide emission angle. Furthermore, since only the necessary light beams can enter the lens member L, a more accurate projection pattern can be realized.

[0051] Here, a method of forming the fine structures MS1 and MS2 on two parallel flat plates M1 and M2 with an energy-curable resin will be briefly described.

[0052] First, the parallel flat plate M2 is fixed to the holder H. After that, the fine structure MS2 is formed by the same method as the method presented in FIG. 3. After forming the fine structure MS2, the next parallel flat plate M1 is fixed to the projection side of the holder H. The holder H with the parallel flat plate M1 fixed is fixed to a separately prepared jig in the direction opposite to the direction in which the fine structure MS2 was formed. After this, in the same manner as in Example 1, a UV-curable resin is dropped onto the jig in which the second fine structure MS2 is formed, the jigs are fixed to each other using the method presented in FIG. 3 for the jig in which the holder H is inserted, and UV light is applied to cure the resin. By repeating this method, in this example, it becomes possible to form a plurality of composite diffractive optical elements in order on the projection surface side. Therefore, in the present application, the number of composite diffractive optical elements fixed to the holder H is not limited.

[0053] So far, the present application has been described based on the examples. By configuring it in this way, since the composite diffractive optical element and other members can be accurately positioned based on the holder H, a complex projection pattern can be realized. Also, since the holder can be effectively used for alignment with the light source side, it becomes possible to realize the set performance.

Description of Reference Numerals

[0054] The clearance between the tapered shape HT formed on the holder G and the taper LT formed on the lens member L Clearance between the tapered shape HT1 formed on the G1 holder and the taper LT formed on the lens member L Clearance between the tapered shape HT2 formed on the G2 holder and the taper ST formed on the light shielding member LS H Holder HR Substantially arc-shaped formed on the holder H HT Tapered shape formed on the holder HTA Angle formed between the axis perpendicular to the plane of the parallel flat plate M and the tapered shape HT HT1 The first tapered shape counted from the projection plane side HT2 The second tapered shape counted from the projection plane side HTA1 Angle formed between the first tapered shape counted from the projection plane side and the axis perpendicular to the parallel flat plate M HTA2 Angle formed between the second tapered shape counted from the projection plane side and the axis perpendicular to the parallel flat plate M JA Jig for forming a fine structure pattern JB Jig with a fine structure pattern JA1 The first cylindrical hole formed in the jig JA JA2 The second cylindrical hole formed in the jig JA JB1 Fine structure surface formed on the jig JB L Lens member LT Tapered shape formed on the lens LS Light source M Parallel flat plate MS Fine structure formed on the parallel flat plate M M1 The first parallel flat plate counted from the projection plane side M2 The second parallel flat plate counted from the projection plane side MS1 The first fine structure counted from the projection plane side MS2 The second fine structure counted from the projection plane side S Diaphragm member ST Tapered shape formed on the diaphragm member S R Virtual circle circumscribing the substantially arc-shaped HR

Claims

1. A step of fixing a parallel flat plate M formed of an elastic material or glass that is sufficiently transparent at the operating wavelength to a holder H formed of an elastic material; A step of fixing a substantially arc shape HR of the holder H to a first cylindrical hole JA1 of a first jig JA; A step of dropping an energy-curable resin onto a second jig JB provided with a fine structure pattern surface JB1 and inserting the second jig JB along a second cylindrical hole JA2 formed in the first jig JA; A step of forming a fine structure MS that generates light diffraction on at least one surface of the parallel flat plate M by curing the energy-curable resin in a state where the energy-curable resin is in contact with the parallel flat plate M; A step of housing a lens member L in at least one tapered shape HT formed inside the holder H; and A method for manufacturing a holder-integrated composite diffractive optical element, characterized in that the center of the tapered shape HT, the center of the substantially arc shape HR, and the center of the fine structure MS are made to coincide.

2. The method for manufacturing a holder-integrated composite diffractive optical element according to claim 1, wherein there are four substantially arc shapes HR that can be used for positioning the outer shape portion, and they are formed at four corners of the holder H, and are configured to satisfy the following formula (1). 0.01 < HRL / RL... (1) HRL: Length of the substantially arc shape HR RL: Circumference of a virtual circle R circumscribing four points of the substantially arc shape HR

3. The method for manufacturing a holder-integrated composite diffractive optical element according to claims 1 and 2, wherein all the tapered shapes HT used for positioning formed inside the holder H are configured to satisfy the following formula (2). 1° < HTA < 45°... (2) HTA: Angle formed by the tapered shape HT and an axis perpendicular to the parallel flat plate M

4. The method for manufacturing a holder-integrated composite diffractive optical element according to claims 1 to 3, wherein the parallel flat plate M and the energy-curable resin for forming the fine structure MS are configured to satisfy formula (3). |MI - MSI| ≤ 0.1... (3) MI: Refractive index at the operating wavelength of the elastic material forming the parallel flat plate MSI:... Refractive index at the operating wavelength of the energy-curable resin

5. The method for manufacturing a holder-integrated composite diffractive optical element according to claims 1 to 4, wherein the lens member L is fixed through a tapered shape HT formed inside the holder H, and the distance between the internal tapered shape HT and the tapered shape LT of the lens member L is configured to be from zero to 0.02 mm.

6. The method for manufacturing the holder-integrated diffractive optical element according to claims 1 to 4, characterized in that the parallel flat plate M is formed of glass.

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