JP2007264408A - Method for manufacturing optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease changes in a shape caused by exterior temperature changes, to improve adhesion durability and to improve quality of an optical element. <P>SOLUTION: A method for manufacturing an optical element is disclosed for manufacturing a hologram optical element by adhering a first optical base and a second optical base L2 comprising materials having the same coefficients of linear expansion. The method includes a heating step of the second optical base to heat the second optical base with the same thermal energy quantity as the first optical base to equalize the thermal energy quantities added to the first optical base and to the second optical base, in order to form the first optical base and the second optical base, to be adhered, under almost identical thermal conditions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical element.

  2. Description of the Related Art In recent years, a manufacturing method for manufacturing an optical element by integrating a plurality of members by bonding them has been developed.

For example, as a method of manufacturing an optical element having a diffraction grating in a partial region, an optical element composed of two prisms and a parallel plate disposed between the slopes of the prism, the slope of the prism and the prism A method is disclosed in which a diffraction grating is applied to one of the surfaces of a parallel flat plate in contact with a slope, and the prism slope and the parallel flat plate are bonded together with an adhesive (see Patent Document 1).
JP-A-10-39120

  However, as in Patent Document 1, when some kind of processing such as processing for forming a diffraction grating is performed on at least one member, the amount of heat energy given to each member may be different. is there.

  Since the residual stress inside the member differs depending on the amount of heat energy given, if members with different amounts of heat energy given before bonding are bonded and integrated, Residual stress inside the member is released to change the shape of the member, and the shape may be different before and after the temperature change. Due to such a shape change, there may be a problem that a gap is generated between the bonded members or the adhesive is peeled off, and the bonded portion is broken and the integrated member is separated. There is.

  In particular, as an optical element provided in a video display device (wearable display) such as a head-mounted type (head-mounted type) or a spectacle type that is worn on a part of the body such as the head that has been developed recently. In addition, a hologram optical element (HOE) is provided, and the image light irradiated from the display unit is diffracted and reflected by the hologram optical element so that the image light is incident on the pupil of the wearer. It has become.

FIG. 4 shows an example of a hologram optical element.
As shown in FIG. 4, the hologram optical element L has a U-shape in which a first optical base material L1 on which the hologram element 2 is formed and a concave notch for joining to the first optical base material L1 are formed. And the second optical base material L2 are bonded together to produce a single hologram optical element L.

  Since the hologram optical element L as shown in FIG. 4 has a plurality of bonded surfaces and a complicated shape, the amount of heat energy given to the first optical base L1 and the second optical base L2 are given. When bonding and integration are performed in a state where there is a difference in the amount of heat energy generated, the bonded surfaces 110a, 110b, and 110c are broken according to changes in the external temperature, and the integrated first optical base material There is a fear that L1 and the second optical base material L2 are separated, and there is a fear that the quality of the hologram optical element L is deteriorated.

  Therefore, in view of the above-described problems, an object of the present invention is to reduce a shape change caused by a temperature change in the outside world, improve adhesion durability, and improve the quality of an optical element.

  According to a first aspect of the present invention, in the method of manufacturing an optical element in which a plurality of members are bonded to manufacture an optical element, the heating step of forming the plurality of members to be bonded under substantially equal thermal conditions. It is the manufacturing method of the optical element containing.

  According to a second aspect of the present invention, in the optical element manufacturing method according to the first aspect, the member is formed of a material having the same linear expansion coefficient.

  A third aspect of the present invention is the method of manufacturing an optical element according to the first or second aspect, wherein the heating step is performed such that the amount of heat energy given to each member is equal. Yes.

  According to a fourth aspect of the present invention, in the method of manufacturing an optical element according to the third aspect, in the heating step, when the amount of applied heat energy is different for each member, the most applied amount of heat energy is The other member is heated so as to be equal to a high heat energy amount of the member.

  Invention of Claim 5 is a manufacturing method of the optical element as described in any one of Claim 1 to 3, In the said heating process, when heating the said member, the thermal history for every said member becomes equal It is characterized by heating.

  According to a sixth aspect of the present invention, in the method of manufacturing an optical element according to the first or second aspect, when the heating step is different in the amount of thermal energy applied to each member, the most applied thermal energy. When the amount of thermal energy of the member having a large amount is within the range of the amount of thermal energy in which the rate of change in shape before and after heating is constant, the rate of change in shape before and after heating is constant with respect to the other members. The heat energy amount within the range of the heat energy amount is given.

  According to the first aspect of the present invention, the plurality of members to be bonded are subjected to a heating process that is formed under substantially equal thermal conditions, thereby making the amount of thermal energy given to each member substantially equal. The residual stress inside each member before bonding can be made equal. Therefore, even if the residual stress inside each member is released according to the temperature change of the outside after being bonded and integrated, the same shape change can be caused in each member. It is possible to reduce a possibility that a problem occurs that a gap is generated or an adhesive is peeled off and a bonded portion is broken and an integrated member is separated. For this reason, it is possible to reduce the shape change caused by the temperature change in the outside world, improve the adhesion durability, and improve the quality of the optical element.

  According to the invention described in claim 2, since the same effect as that of claim 1 can be obtained, the materials forming the members are materials having the same linear expansion coefficient. It is possible to equalize the shape change according to.

  According to the third aspect of the present invention, the same effect as that of the first or second aspect can be obtained, and the amount of thermal energy given to each member to be bonded is made equal, so that The residual stress inside each member can be made equal. Therefore, even if the residual stress inside each member is released according to the temperature change of the outside after being bonded and integrated, it is possible to reduce the possibility that the integrated member is separated.

  According to the fourth aspect of the present invention, the same effect as in the third aspect can be obtained, and the other members are heated so as to be equal to the thermal energy amount of the member having the highest thermal energy amount. Thereby, the thermal energy given to each member to be bonded can be made equal.

  According to the fifth aspect of the present invention, it is possible to obtain the same effect as that of any one of the first to third aspects, as well as adhesion by heating so that the thermal history of each member becomes equal. The thermal energy applied to each member to be performed can be made equal, the internal structure of each member can be made equal, and the quality of each member can be made uniform.

  According to the sixth aspect of the present invention, the same effect as in the first or second aspect can be obtained, and the amount of thermal energy given to the member having the largest amount of thermal energy is changed in shape before and after heating. When the rate is within the range of the amount of heat energy that is constant, by giving the other member the amount of heat energy within the range of the amount of heat energy that the shape change rate before and after the heating is constant The residual stress of each member to be bonded can be made equal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the embodiment of the present invention, an example in which the method of manufacturing an optical element of the present invention is applied to a method of manufacturing a hologram optical element on which a hologram element is formed will be described. However, the scope of the invention is not limited to the illustrated example. .

  First, the manufacturing process of the hologram optical element will be described with reference to FIG. In the present embodiment, an example of manufacturing a hologram optical element applicable to a glasses-type image display device is shown. As shown in FIG. 1, the hologram optical element is an optical substrate processing step in which a first optical substrate and a second optical substrate are formed in a predetermined shape, and an inclined surface is formed at one end of the first optical substrate. A), an optical substrate forming step (B) for forming a hologram element on an inclined surface formed at one end of the first optical substrate, and an integration for integrating the first optical substrate with the second optical substrate. And the step (C).

Hereinafter, each step will be described in detail.
For the sake of simplicity, the hologram optical element is attached to the spectacle frame, and the direction in which the eye is present when the spectacle frame is worn by a human is defined as the back direction, and the direction in which the human-visible image is present is defined as the front direction. Further, the vertical direction of the hologram optical element is defined as the Y direction, the horizontal direction is defined as the X direction, and the thickness direction is defined as the Z direction.

A. Optical base material processing step The optical base material processing step includes a first optical base material processing step (A-1) and a second optical base material processing step (A-2) as shown in FIG. It consists of a molding die process, an injection compression molding process, a cutting process, a polishing process, and the like.

  A 1st optical base material processing process (A-1) forms the inclined surface which affixes a hologram sensitive material on one end of the 1st optical base material L1, and forms in a hologram element, A 2nd optical base material processing process (A -2) forms the shape of the 2nd optical base material L2 corresponding to the external shape of the 1st optical base material L1.

FIG. 2 shows an example of the external shape of the first optical base material L1 and the second optical base material L2.
As shown in FIG. 2, the first optical base material L1 is fitted to the recessed portion 106 of the second optical base material L2 on the lower and both sides of the outer shape of the first optical base material L1. The outer peripheral surfaces 102a, 102b, and 102c to be joined are formed. The outer peripheral surface 102a is inclined at a preset inclination angle so that the image light from the display unit projected from the upper surface 102d side can be guided to the eyes of the user via a hologram element described later, and the hologram sensitive material 20 The outer peripheral surfaces 102b and 102c are formed corresponding to the shapes of the inner peripheral surfaces 105b and 105c of the second optical base material L2.

  In the second optical base material L2, a concave portion 106 corresponding to the outer peripheral surfaces 102a, 102b, 102c of the outer shape of the first optical base material L1 is formed near the center. The recessed portion 106 is formed of corresponding inner peripheral surfaces 105a, 105b, and 105c so as to be joined to the outer peripheral surfaces 102a, 102b, and 102c, respectively.

  Each of the outer peripheral surfaces 102b and 102c and the inner peripheral surfaces 105b and 105c is flat or curved as long as the first optical base material L1 can be fitted into the recess 106 of the second optical base material L2. The outer peripheral surfaces 102b and 102c and the inner peripheral surfaces 105b and 105c are preferably formed so as to be inclined so as to spread in a fan shape from the pupil.

  Moreover, the shape of the recessed part 106 is not particularly limited, but is preferably a polygonal and / or semicircular shape. By this, the adhesive force of the 1st optical base material L1 and the 2nd optical base material L2 can be strengthened.

  As a material for forming the first optical base material L1 and the second optical base material L2, light transmissive glass, resin, or the like can be used, but they are formed of materials having the same linear expansion coefficient.

  Since the materials forming the first optical base material L1 and the second optical base material L2 are materials having the same linear expansion coefficient, it is possible to equalize the shape change according to the temperature change of the outside world.

  Although it does not restrict | limit to the material as glass, Soda lime glass, borosilicate glass, ultra high purity glass, crystal glass etc. can be mentioned, These can be used preferably.

  As the resin material, cellulose triacetate, cellulose diacetate, cellulose acetate propionate or cellulose ester such as cellulose acetate butyrate, polyester such as polyethylene terephthalate or polyethylene naphthalate, polyolefin such as polyethylene or polypropylene, Polyvinylidene chloride, polyvinyl chloride, polyvinyl alcohol, ethylene vinyl alcohol copolymer, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide, polyether sulfone, polysulfone, polyetherimide, polyamide, fluorine Resin, polymethyl acrylate, acrylate copolymer, etc. .

B. Optical base material forming step Next, the optical base material forming step (B) will be described. As shown in FIG. 1, the optical base material forming step includes a laminated sheet forming step (B-1), a cutting step (B-2), a pasting step (B-3), an exposure step (B-4), and heating. Including the step (B-5), the hologram sensitive material 20 is attached to the first outer peripheral surface 102a of the first optical base material L1, and the hologram sensitive material 20 is formed on the hologram element 2.

B-1. Laminated sheet forming step In the laminated sheet forming step, a hologram sensitive material is detachably bonded between a pair of protective sheets to generate a laminated sheet formed in a cross-sectional sandwich shape. In addition, when there exists a lamination sheet according to the objective previously, you may abbreviate | omit a lamination sheet formation process.

  The laminated sheet used in the present embodiment has a four-layer structure. From the bottom, the cover sheet that is the first protective sheet, the hologram photosensitive material, the barrier sheet that is the third protective sheet, and the base sheet that is the second protective sheet. Become. Between these sheets, a pressure-sensitive adhesive that can be peeled off and applied between the sheets is applied.

B-2. Cutting process In the cutting process, an island-shaped part is cut into the laminated sheet using a cutting mechanism (not shown). The incision outline of the island-shaped part is composed of a semi-cut part and a cut part. Hereinafter, the laminated sheet around each island-like part is referred to as a ladder-like part. The shape of the island-shaped portion may be a polygonal shape, an elliptical shape, or the like, but a shape corresponding to the outer peripheral surface 102a of the first optical base material L1 is preferable, and by using such a shape, the hologram element does not shift. An image can be formed.

  Examples of the material for the cover sheet, barrier sheet, and base sheet include plastic, glass, and metal. Paper or plastic that is flexible and can be made into a roll shape or a flat shape depending on the situation and has a strength that does not easily damage the internal hologram photosensitive material is preferable. Here, examples of the plastic include polyester, polystyrene, polycarbonate, polyether sulfone, polyimide, polycyclopentadiene, polynorbornene, nylon, and cellulose acetate.

B-3. First, when the cover sheet of the laminated sheet is peeled off, the first optical base material L1 is attached in a state where the island-shaped portion of the hologram sensitive material is attached to the base sheet which is the other protective sheet. Pressure is applied to the outer peripheral surface 102a. The sticking mechanism includes a sticking roller, a support member that supports the sticking roller, an elastic member that adjusts the pressure of the sticking roller, a roller shaft, and the like. A roller shaft for rotating the pasting roller is provided at the center of the pasting roller. Support members for supporting the adhering roller are provided on both sides of the roller shaft, and an elastic member is provided at the center of the support member. This elastic member makes it possible to adjust the pressurization when the island-shaped portion of the hologram sensitive material is pressed from above via the base sheet.

  At the time of pasting, only the island-shaped portion of the hologram sensitive material is disposed at a position where it adheres to the outer peripheral surface 102a of the first optical base material L1, and the hologram feel from the direction of the base sheet by the pasting roller above the base sheet. It rolls forward and backward while applying pressure so that the island-shaped portion of the material and the outer peripheral surface 102a of the first optical base L1 are brought into close contact with each other. Thereby, the island-shaped portion of the hologram sensitive material and the outer peripheral surface 102a of the first optical substrate L1 are in close contact with each other. And the island-shaped part of a hologram sensitive material is left on the outer peripheral surface 102a of the 1st optical base material L1, and the base sheet which is a protective sheet, and the ladder-shaped part of a hologram sensitive material are peeled.

B-4. Exposure Step In the exposure step, laser exposure is performed with reference light and object light emitted from the laser transmitter on the island-shaped portion of the hologram sensitive material affixed to the outer peripheral surface 102a of the first optical substrate L1. Laser light emitted from the laser transmitter is split into reference light and object light by a variable beam splitter, and is incident on the main surface of the island-shaped portion of the hologram sensitive material by various mirrors. As a result, the interference fringes generated by the interference between the reference light and the object light are recorded at predetermined positions on the island-shaped portion of the hologram sensitive material as a change in refractive index on the photosensitive layer of the island-shaped portion of the hologram sensitive material. Is formed.

  The exposure mechanism used in the exposure step is configured by a laser exposure unit that irradiates laser light. The laser exposure unit exposes the laser beam from the RGB laser transmitter for exposing interference fringes to the front and back of the island-shaped portion of the hologram sensitive material and the laser from the laser transmitter at a predetermined position of the island-shaped portion of the hologram sensitive material with laser light. For example, a reflecting mirror, a shutter, and a beam splitter are provided.

B-5. Heating Step The heating step B-5 includes a first optical substrate heating step (B-5a) and a second optical substrate heating step (B-5b), as shown in FIG.

B-5a. First optical substrate heating step The first optical substrate heating step is a step of greatly increasing the refractive index modulation by the hologram element after the exposure step (B-4) is completed. In this step, the first optical base material L1 on which the hologram element is formed by a thermostat is put into a heating device maintained at a preset temperature (for example, a temperature of about 85 ° C.) for a predetermined time (for example, Heat for about 6 hours.

  In this way, by heating the hologram element on which the interference fringes are recorded, the diffraction efficiency due to the interference fringes can be improved, and the sharpness of the reflected (diffracted) image and the improvement of the image quality can be realized. be able to. Here, the heating temperature is preferably a temperature at which the composition of the first optical substrate L1 and the hologram element does not change, and is equal to or lower than the glass transition temperature of the first optical substrate L1, or the first optical substrate L1. And it is preferable that it is below the lowest temperature among the glass transition temperatures of a hologram element. In the first optical base material heating step in the present embodiment, heating is performed at a temperature lower than the lowest temperature among the glass transition temperatures of the latter first optical base material L1 and hologram sensitive material.

  The first optical base material L1 needs to be heated in the first optical base material heating step in order to greatly increase the refractive index modulation by the hologram element after the optical base material processing step and before the integration step. Accordingly, the amount of heat energy given to the first optical base material L1 is higher than that of the second optical base material L2, and the thermal energy given to the first optical base material L1 and the second optical base material L2, respectively. There will be a difference in quantity. When the first optical base material L1 and the second optical base material L2 are subjected to the integration process while the difference in the amount of heat energy is generated, the shape changes according to the temperature change of the outside world, and the adhesive durability is lowered. As a result, the quality of the optical element may be degraded.

  Therefore, in the present embodiment, the heating process includes a second optical base material heating process to solve this problem.

B-5b. Second optical substrate heating step The second optical substrate heating step is a heating step in which the first optical substrate L1 and the second optical substrate L2 to be bonded are formed under substantially equal thermal conditions.

  In order to form the first optical substrate L1 and the second optical substrate L2 to be bonded under substantially equal thermal conditions, the optical substrate having the highest amount of applied thermal energy (first optical substrate L1) The other optical base material (second optical base material L2) is heated so as to be equal to the thermal energy amount of the first optical base material L1 and the second optical base material L2, respectively. The second optical substrate is heated as described above.

  In addition, the upper limit of the temperature at the time of heating the 2nd optical base material L2 and giving the amount of thermal energy equal to the 1st optical base material L1 depends on the physical property (softening point) of the raw material of the 2nd optical base material L2. The heating time is set based on the upper limit value of this temperature and the amount of heat energy given to the first optical base material L1.

  That is, by heating the second optical substrate L2 so as to be equal to the amount of heat energy applied to the first optical substrate L1, it is applied to the first optical substrate L1 and the second optical substrate L2 to be bonded. The thermal energy applied can be made equal, and the residual stresses inside the first optical substrate L1 and the second optical substrate L2 before bonding can be made equal. Therefore, even if the residual stress inside each member is released according to the temperature change of the outside after being bonded and integrated, the integrated first optical base material L1 and second optical base material L2 are separated. The risk of problems can be reduced.

  Furthermore, in the second optical substrate heating step, when the second optical substrate L2 is heated so as to be equal to the thermal energy amount of the first optical substrate L1, the first optical substrate L1 and the second optical substrate are heated. Heating is preferably performed so that the thermal histories of L2 (temperature changes with time) are equal.

  For example, in the second optical base material heating step, when the first optical base material L1 passes through the first optical base material heating step, the second optical base material L2 is put into the heating device simultaneously with the first optical base material L1. The first optical base material L1 and the first optical base material L1 are heated at the same temperature and for the same time so that the thermal history of the first optical base material L1 and the second optical base material L2 is equal.

  The first optical base material L1 and the second optical base material to be bonded by heating so that the thermal histories (temperature changes with time) of the first optical base material L1 and the second optical base material L2 become equal. The thermal energy applied to L2 can be made equal, the internal structure of each member can be made equal, and the quality of each member can be made uniform.

B-5b. Other Examples of Second Optical Base Material Heating Step In the second optical base material heating step, the thermal energy amount of the optical base material (first optical base material L1) having the highest applied heat energy amount is about before and after heating. When the shape change rate is within the range of the amount of heat energy at which the shape change rate is constant, the amount of heat energy at which the shape change rate before and after heating is constant with respect to the other optical base material (second optical base material L2). It is good also as giving the amount of heat energy in the range.

  In addition, the upper limit of the temperature at the time of giving the heat energy amount within the range of the heat energy amount where the shape change rate before and after heating is constant is the physical property of the material of the first optical base material L1 and the second optical base material L2 ( It is limited according to the softening point.

  In the following, when the amount of heat energy applied to the first optical substrate L1 is within the range of the amount of heat energy that gives a constant rate of change in shape before and after heating, the heat energy that can be applied to the second optical substrate L2 An example of quantity estimation will be described.

In FIG. 3, the example of the graph of the shape change rate with respect to the heat energy amount of the 2nd optical base material L2 is shown.
The graph shown in FIG. 3 is an example of a graph when PMMA is used as the material of the second optical substrate L2. The horizontal axis shows the amount of heat energy [° C · h] when the heating time is set to a predetermined time (here 1 hour) and the heating temperature is changed, and the vertical axis shows the amount of heat energy as the shape change rate. The change rate [%] of the opening width W of the recessed part 106 before and after heating is given.

  As shown in FIG. 3, the shape change rate of the second optical base material L2 increases as the amount of thermal energy increases. However, when the amount of heat energy passes around 70 [° C. · h], the shape change rate becomes It becomes constant. This indicates that the amount of heat energy necessary for removing the residual stress in the second optical base material L2 is given. In addition, since the first optical base material L1 and the second optical base material L2 are formed of the same linear expansion coefficient material, the shape change rate with respect to the heat energy amount of the first optical base material L1 is also as shown in FIG. Almost equal.

  Therefore, when the upper limit temperature that can be heated based on the physical properties of the material of the first optical base material and the second optical base material L2 is 100 [° C.], the range of the amount of thermal energy in which the shape change rate before and after heating is constant As, it can be estimated as 70 to 100 [° C · h].

  Therefore, when the amount of heat energy given to the first optical base material L1 is within the range of the amount of heat energy in which the shape change rate before and after heating is constant (here, 70 to 100 [° C. · h]), Instead of giving the thermal energy amount equal to the thermal energy amount given to the first optical base material L1 to the two optical base materials L2, the range of the thermal energy amount where the shape change rate before and after this heating is constant It is good also as giving the amount of heat energy in.

  That is, when the amount of thermal energy applied to the first optical base material L1 is within the range of the amount of thermal energy in which the shape change rate before and after heating is constant (here, 70 to 100 [° C. · h]). When the thermal energy amount equal to the thermal energy amount given to the first optical substrate L1 is given to the second optical substrate L2, and the thermal energy amount with a constant shape change rate before and after the heating is The case where the amount of heat energy within the range is given has the common effect that the residual stress of the first optical base material L1 and the second optical base material L2 to be bonded can be made equal by removing the residual stress. It is possible to obtain the same effect that there is no fear that the quality of the optical element is deteriorated due to a change in shape according to a change in the temperature of the external environment after the integration step or a decrease in adhesion durability.

C. Integration Step Next, an integration step for integrating the first optical substrate L1 with the second optical substrate L2 will be described. As shown in FIG. 1, the integration step includes an adhesive application step (C-1) for applying a photocurable adhesive to the recessed portion 106 of the second optical base material L2, and the first optical base material L1. A joining step (C-2) for joining the outer peripheral surfaces 102a, 102b, and 102c in a state in which the outer peripheral surfaces 102a, 102b, and 102c are fitted to the recessed portion 106 of the second optical substrate L2, and the first optical substrate L1 and the second optical substrate L2. An adhesive removing step (C-3) for removing the light-curing adhesive protruding from the joint surface, and light-irradiating the joint surface between the first optical substrate L1 and the second optical substrate L2 to form a photo-curing adhesive A curing step (C-4) for curing the agent is included. Hereinafter, each process of the integration process will be described.

C-1. Adhesive Application Step In the adhesive application step, a photocurable adhesive is applied to the recessed portion 106 of the second optical base material L2. The application amount of the photocurable adhesive at this time is a sufficient amount that protrudes from the joint surface when the first optical substrate L1 and the second optical substrate L2 are pressed.

  In the adhesive application step in the present embodiment, the photocurable adhesive is applied to the recessed portion 106 of the second optical base material L2, but the outer peripheral surface 102a of the first optical base material L1, 102b, 102c may be a step of applying a photo-curing adhesive, and the photo-curing type is applied to the joint outer peripheral surface 102a, 102b, 102c of the first optical base material L1 and / or the recessed portion 106 of the second optical base material L2. What is necessary is just the process of apply | coating an adhesive agent.

  As a photocurable adhesive, what has a refractive index comparable as the refractive index of the 1st optical base material L1 and the 2nd optical base material L2 when hardened | cured is preferable, and an ultraviolet curable adhesive is especially preferable.

  The ultraviolet curable adhesive is preferable because it can be cured by irradiating light energy such as ultraviolet rays and can be selected in the range of the optical refractive index of the first optical base material L1 and the second optical base material L2. It is preferable because the surfaces of the first optical substrate L1 and the second optical substrate L2 are less likely to erode.

  As the ultraviolet curable adhesive, a polymerizable monomer having at least one double bond in the molecule such as vinyl, acrylic or methacrylic can be used. Specifically, as a monofunctional monomer, in addition to acrylic acid and methacrylic acid, alkyl acrylates such as methyl acrylate and ethyl acrylate, alkyl methacrylates including methyl methacrylate, butyl methacrylate or hydroxy compounds thereof are also included. Or a styrene monomer, an acrylonitrile monomer, or the like can be used. In addition, polyfunctional monomers include acrylics such as ethylene glycol dimethacrylate and allyls such as diallyl phthalate, and a crosslinked structure can be obtained during the polymerization and curing process to improve the durability and thermal stability of the bonded part. Is preferably used.

  The photopolymerization agent added to the ultraviolet curable adhesive is not particularly limited as long as it can be radically polymerized by ordinary ultraviolet rays, and examples thereof include acetophenone-based, nenephenyl-based, benzoin-based, thioxanthone-based, and azylphosphine oxide-based compounds. .

  Specific examples of the ultraviolet curable adhesive include Norland product NOA series or EMI product OPTOCAST 3400 series which are included in the refractive index range of the first optical base material L1 and the second optical base material L2.

C-2. Bonding process The bonding process moves at least one of the first optical base material L1 or the second optical base material L2 in the front direction or the back direction, and the outer peripheral surfaces 102a, 102b, 102c of the first optical base material L1 and the second optical base material. The recesses 106 of the base material L2 are combined and fitted and joined. At the time of joining, the outer peripheral surfaces 102a, 102b, and 102c and the recessed portion 106 are brought into pressure contact with each other, and excess photo-curing adhesive protrudes.

  Hereinafter, the surface where the outer peripheral surface 102a of the first optical base material L1 and the inner peripheral surface 105a of the second optical base material L2 are bonded is referred to as an adhesive surface 110a, and the outer peripheral surface 102b of the first optical base material L1 and the second optical base. The surface where the inner peripheral surface 105b of the material L2 is bonded is the bonding surface 110b, and the surface where the outer peripheral surface 102c of the first optical substrate L1 and the inner peripheral surface 105c of the second optical substrate L2 are bonded is the bonding surface 110c. And

C-3. Adhesive Removal Step The adhesive removal step removes the photocurable adhesive that protrudes from the adhesive surface between the first optical base material L1 and the second optical base material L2. In addition, as a removal method of a photocurable adhesive agent, suppose that the well-known technique according to the characteristic of a photocurable adhesive agent is used.

C-4. Curing Step The curing step cures the photocurable adhesive by irradiating light onto the adhesive surface between the first optical substrate L1 and the second optical substrate L2, and the first optical substrate L1 and the second optical substrate. The material L2 is integrated.

  Examples of the light source for irradiating light for curing the photocurable adhesive include a low / high pressure mercury lamp, an ultraviolet lamp, a black light, and a light emitting diode that irradiate light of a specific wavelength capable of curing the photocurable adhesive. Can do.

  Through these various steps, the outer peripheral surfaces 102a, 102b, 102c of the first optical base material L1 and the recessed portion 106 of the second optical base material L2 are bonded via the photo-curing adhesive. A hologram optical element L as shown in FIG. 4 is formed.

  As described above, according to the present embodiment, the plurality of members to be bonded are subjected to a heating process that is formed under substantially the same thermal conditions, so that the amount of thermal energy given to each member is substantially equal. The residual stress inside each member before bonding can be made equal. Therefore, even if the residual stress inside each member is released according to the temperature change of the outside after being bonded and integrated, the same shape change can be caused in each member. It is possible to reduce a possibility that a problem occurs that a gap is generated or an adhesive is peeled off and a bonded portion is broken and an integrated member is separated. For this reason, it is possible to reduce the shape change caused by the temperature change in the outside world, improve the adhesion durability, and improve the quality of the optical element.

  Further, the present invention is not limited to the contents of the above embodiment, and can be appropriately changed without departing from the gist of the present invention.

It is a flowchart which shows the manufacturing process of a hologram optical element. It is an example of the external appearance shape of the 1st optical base material L1 and the 2nd optical base material L2. It is an example of the graph of the shape change rate with respect to the amount of thermal energy of the 2nd optical base material L2. It is an example of the external appearance of a hologram optical element.

Explanation of symbols

2 Hologram element 20 Hologram sensitive material 102a, 102b, 102c Outer peripheral surface 102d Upper surface 106 Recessed portion 105a, 105b, 105c Inner peripheral surface 110a, 110b, 110c Adhesive surface L Hologram optical element L1 First optical base material L2 Second optical base Material W Opening width X Left-right direction Y Up-down direction Z Thickness direction

Claims (6)

In the method of manufacturing an optical element for manufacturing an optical element by bonding a plurality of members,
Including a heating step of forming the plurality of members to be bonded under substantially equal thermal conditions;
A method for producing an optical element characterized by the above. The member is formed of a material having the same linear expansion coefficient;
The method of manufacturing an optical element according to claim 1. The heating step includes
Heating so that the amount of heat energy given to each member becomes equal;
The method of manufacturing an optical element according to claim 1 or 2. The heating step includes
When the amount of heat energy given to each member is different,
Heating the other member such that the most given amount of heat energy is equal to the amount of heat energy of the member being high,
The method of manufacturing an optical element according to claim 3. The heating step includes
When heating the member, heating so that the thermal history of each member becomes equal,
The method for manufacturing an optical element according to any one of claims 1 to 3. The heating step includes
When the amount of heat energy given to each member is different,
When the amount of heat energy of the member having the largest amount of heat energy given is within the range of the amount of heat energy in which the rate of change in shape before and after heating is constant, before and after the heating with respect to the other member Giving an amount of heat energy within the range of the amount of heat energy in which the rate of change in shape of the material is constant,
The method of manufacturing an optical element according to claim 1 or 2.

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