JP2012088643A - Holographic optical element and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holographic optical element having favorable element characteristics while dissolving harmful effects brought by drying of a photosensitive material for forming a photosensitive recording layer; and to provide a method for manufacturing the same.SOLUTION: A holographic optical element 10 includes: a substrate 110 having translucency; a photosensitive recording layer 120 which is provided on the substrate 110 and on which an interference fringe is formed; a substrate 140 provided on the other side of the substrate 110 with respect to the photosensitive recording layer 120 and having the translucency; and an adhesion layer 130 provided between the photosensitive recording layer 120 and the substrate 140 and having the translucency. The refraction index of the adhesion layer 130 is substantially equal to the refraction index of the photosensitive recording layer 120.

Description

  The present invention relates to a hologram optical element and a method for manufacturing the same.

  With respect to a conventional hologram optical element, for example, Japanese Patent Laid-Open No. 8-21822 aims to prevent deformation of the hologram photosensitive material during interference fringe recording, to have high diffraction efficiency, and to facilitate the manufacture of the hologram. A hologram photosensitive material is disclosed (Patent Document 1). In the hologram photosensitive material disclosed in Patent Document 1, a photosensitive layer for forming a hologram is formed on the front side surface of a substrate film. An anti-bending layer having a shrinkage rate and an expansion rate equal to those of the photosensitive layer is formed on the back surface of the substrate film to the extent that the hologram photosensitive material can be prevented from being bent.

Japanese Patent Application Laid-Open No. 8-21822

  In recent years, a hologram optical element is considered to be used not only as a high-density recording element but also as a three-dimensional display or a light modulation element, and has been actively studied.

  33 to 36 are cross-sectional views showing the steps of the method for manufacturing a hologram optical element. A method for manufacturing the hologram optical element will be briefly described. First, a photosensitive material is applied on a substrate 560 and dried to obtain a photosensitive recording layer 520 (FIG. 33). After the drying step, another substrate 510 is arranged so that the photosensitive recording layer 520 is sandwiched between the substrate 510 and the substrate 560 (FIG. 34).

  The substrate 510 and the substrate 560 must be transparent so that the coherent light 570 for recording can be transmitted. Two-beam interference exposure is performed on the photosensitive recording layer 520 using the coherent light 570. By this exposure step, interference fringes are formed in the exposure region 521 of the photosensitive recording layer 520 (FIG. 35). Post-cure is performed by exposing a portion other than the exposure region 521 using post-cure light 571 having no coherence. (FIG. 36). As the post-cure light 571, for example, lamp light or LED (Light Emitting Diode) light is used. The hologram optical element is completed through the above steps.

  However, in the above method for manufacturing a hologram optical element, when the photosensitive material coated on the substrate 560 is dried, the photosensitive material shrinks due to heat, force, or the like. When the influence of this contraction is large, the deformation of the photosensitive material accompanying the contraction affects the performance of the hologram optical element.

  That is, as shown in FIGS. 33 and 34, when the photosensitive material applied on the substrate 560 is dried, a compressive stress 580 is generated in the surface of the photosensitive recording layer 520 due to evaporation of the solvent and polymerization. Remains. As shown in FIG. 35, when the exposure process is performed on the photosensitive recording layer 520 in this state, the compressive stress 580 is released only in the exposure region 521. As a result, the photosensitive region 520 is deformed by compressing the exposed area 521 from the surrounding unexposed portion. In this case, there is a concern that the diffraction efficiency of the hologram optical element is lowered or the wave front of the diffracted light or transmitted light is distorted, which is not preferable in terms of the performance of the hologram optical element. Further, the curved photosensitive recording layer 520 may hinder the handling of the hologram optical element.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and a hologram optical element capable of obtaining good element characteristics while eliminating the adverse effects associated with drying of a photosensitive material for forming a photosensitive recording layer, and The manufacturing method is provided.

  A hologram optical element according to the present invention includes a first substrate having translucency, a photosensitive recording layer provided on the first substrate, on which interference fringes are formed, and the first substrate with respect to the photosensitive recording layer. And a second substrate having translucency, and a buffer layer having translucency provided between the photosensitive recording layer and the second substrate. The refractive index of the buffer layer and the refractive index of the photosensitive recording layer are substantially the same.

  According to the hologram optical element configured as described above, at the time of manufacturing the hologram optical element, the buffer layer may have a function of bringing both into close contact without providing a gap between the photosensitive recording layer and the second substrate. It is possible to provide a function of absorbing internal stress generated in the photosensitive recording layer. At this time, since the refractive index of the buffer layer and the refractive index of the photosensitive recording layer are substantially the same, it is possible to suppress the reflection of light at the boundary between the buffer layer and the photosensitive recording layer. As a result, good element characteristics can be obtained while eliminating the adverse effects caused by the drying of the photosensitive material for forming the photosensitive recording layer.

  Preferably, the hologram optical element is provided on the first substrate and is disposed between the first substrate and the photosensitive recording layer, and another photosensitive recording layer on which interference fringes are formed, and another photosensitive property. Another buffer layer provided between the recording layer and the photosensitive recording layer and having translucency is further provided. The refractive index of another buffer layer and the refractive index of another photosensitive recording layer are substantially the same as the refractive index of the buffer layer and the photosensitive recording layer.

  According to the hologram optical element configured as described above, it is possible to form a plurality of interference fringes by light having different wavelengths on a single hologram optical element while exhibiting the above effects.

  Preferably, the first substrate and the second substrate have higher gas barrier properties than the photosensitive recording layer. According to the hologram optical element configured as described above, the formation of interference fringes is hindered during exposure of the photosensitive recording layer due to oxygen transmitted through the substrate, or due to moisture transmitted through the substrate. Deterioration of the recording layer can be suppressed.

  Preferably, the first substrate and the second substrate have higher hardness than the photosensitive recording layer. According to the hologram optical element configured as described above, it is possible to improve impact resistance and scratch resistance by ensuring the mechanical strength of the hologram optical element.

  The method for manufacturing a hologram optical element according to the present invention includes a step of forming a photosensitive recording layer by applying a photosensitive material on a temporary substrate and drying the material; A step of providing the photosensitive recording layer between the first substrate, a step of forming interference fringes on the photosensitive recording layer by irradiation with coherent light, and forming an interference fringe on the photosensitive recording layer A step of peeling the temporary substrate from the photosensitive recording layer, a buffer layer having translucency and a second substrate are prepared, and the buffer layer is formed on the surface of the photosensitive recording layer from which the temporary substrate has been peeled off. And a step of superimposing the second substrate through the substrate. The thermal expansion coefficient of the temporary substrate and the thermal expansion coefficient of the photosensitive material are substantially the same.

  According to the method for manufacturing a hologram optical element configured as described above, the thermal expansion coefficient of the temporary substrate and the thermal expansion coefficient of the photosensitive material are substantially the same, so the photosensitive material applied on the temporary substrate is dried. In this case, the temporary substrate can be deformed following the deformation accompanying the temperature change of the photosensitive material. Thereby, it can suppress that an internal stress generate | occur | produces in the photosensitive recording layer.

  Further, by laminating the second substrate on the surface of the photosensitive recording layer from which the temporary substrate has been peeled off via a buffer layer, the photosensitive recording layer can be exposed without providing a gap between the photosensitive recording layer and the second substrate. The second substrate can be overlaid on the recording layer. At this time, the step of superimposing the second substrate via the buffer layer is performed after the step of forming the interference fringes on the photosensitive recording layer, so that the shape of the photosensitive recording layer deformed by the irradiation of coherent light is followed. Thus, a buffer layer can be provided.

  Therefore, good element characteristics can be obtained while eliminating the adverse effects caused by the drying of the photosensitive material for forming the photosensitive recording layer.

  As described above, according to the present invention, there is provided a hologram optical element capable of obtaining good element characteristics and a method for producing the same while eliminating the adverse effects associated with drying of the photosensitive material for forming the photosensitive recording layer. Can be provided.

It is sectional drawing which shows the hologram optical element in Embodiment 1 of this invention. It is sectional drawing which shows the 1st process of the manufacturing method of the hologram optical element in Embodiment 1 of this invention. It is sectional drawing which shows the 2nd process of the manufacturing method of the hologram optical element in Embodiment 1 of this invention. It is sectional drawing which shows the 3rd process of the manufacturing method of the hologram optical element in Embodiment 1 of this invention. It is sectional drawing which shows the 4th process of the manufacturing method of the hologram optical element in Embodiment 1 of this invention. It is sectional drawing which shows the 5th process of the manufacturing method of the hologram optical element in Embodiment 1 of this invention. It is a table | surface which shows the kind of board | substrate material, and the measurement result of diffraction efficiency and a beam pattern. In comparative example 1, it is a figure which shows the mode of an exposure area | region. It is sectional drawing which shows the hologram optical element in Embodiment 2 of this invention. It is sectional drawing which shows the process of the manufacturing method of the hologram optical element in Embodiment 2 of this invention. It is sectional drawing which shows the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 1st process of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 2nd process of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 3rd process of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 4th process of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 5th process of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 6th process of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. FIG. 12 is a cross-sectional view showing a modification of the hologram optical element in FIG. 11. It is sectional drawing which shows the 1st process of the modification of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 2nd process of the modification of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 3rd process of the modification of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 4th process of the modification of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 5th process of the modification of the manufacturing method of the hologram optical element in Embodiment 3 of this invention. It is sectional drawing which shows the 1st process of the manufacturing method of the hologram optical element in Embodiment 4 of this invention. It is sectional drawing which shows the 2nd process of the manufacturing method of the hologram optical element in Embodiment 4 of this invention. It is sectional drawing which shows the 3rd process of the manufacturing method of the hologram optical element in Embodiment 4 of this invention. It is sectional drawing which shows the 4th process of the manufacturing method of the hologram optical element in Embodiment 4 of this invention. It is sectional drawing which shows the hologram optical element in Embodiment 5 of this invention. It is sectional drawing which shows the 1st process of the manufacturing method of the hologram optical element in Embodiment 5 of this invention. It is sectional drawing which shows the 2nd process of the manufacturing method of the hologram optical element in Embodiment 5 of this invention. It is sectional drawing which shows the 3rd process of the manufacturing method of the hologram optical element in Embodiment 5 of this invention. It is sectional drawing which shows the 4th process of the manufacturing method of the hologram optical element in Embodiment 5 of this invention. It is sectional drawing which shows the 1st process of the manufacturing method of a hologram optical element. It is sectional drawing which shows the 2nd process of the manufacturing method of a hologram optical element. It is sectional drawing which shows the 3rd process of the manufacturing method of a hologram optical element. It is sectional drawing which shows the 4th process of the manufacturing method of a hologram optical element.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

(Embodiment 1)
1 is a cross-sectional view showing a hologram optical element according to Embodiment 1 of the present invention. Referring to FIG. 1, hologram optical element 10 in the present exemplary embodiment includes substrate 110, substrate 140, photosensitive recording layer 120, adhesion layer 130, and spacer 151.

  The board | substrate 110 and the board | substrate 140 are arrange | positioned at intervals. Substrate 110 and substrate 140 each have main surface 110a and main surface 140a as side surfaces having the largest area among the plurality of side surfaces of each substrate. Substrate 110 and substrate 140 are arranged such that main surface 110a and main surface 140a face each other.

  The photosensitive recording layer 120 is provided on the substrate 110. The photosensitive recording layer 120 is provided on the main surface 110 a of the substrate 110. The photosensitive recording layer 120 is disposed between the substrate 110 and the substrate 140.

  Interference fringes are formed in the exposure region 121 of the photosensitive recording layer 120 by irradiation of the recording light (signal light / reference light) to the photosensitive recording layer 120. At the time of reproduction, the exposure area 121 is irradiated with reproduction light, and the data recorded on the photosensitive recording layer 120 is reproduced by reading the light pattern diffracted by the interference fringes.

  The adhesion layer 130 is disposed between the photosensitive recording layer 120 and the substrate 140. The adhesion layer 130 is provided on the main surface 140 a of the substrate 140. The adhesion layer 130 is provided in contact with the photosensitive recording layer 120. The photosensitive recording layer 120 and the adhesion layer 130 are sandwiched between the substrate 110 and the substrate 140.

  The spacer 151 is sandwiched between the substrate 110 and the substrate 140. Spacer 151 is provided in contact with main surface 110 a of substrate 110 and main surface 140 a of substrate 140. The spacer 151 is provided so as to keep the distance between the substrate 110 and the substrate 140 constant. The spacer 151 is not an essential component of the hologram optical element 10.

  The photosensitive recording layer 120 is formed from a photosensitive material. That is, the photosensitive recording layer 120 is formed from a resin that undergoes a physical or chemical change by the action of light. For example, the photosensitive recording layer 120 is formed of a photosensitive resin obtained by adding an additive such as a polymerization initiator and a sensitizer to a base such as acrylic or polyethylene terephthalate (PET).

  The adhesion layer 130 is formed from a resin material. The adhesion layer 130 has translucency so that recording light and reproduction light for the photosensitive recording layer 120 can pass through the adhesion layer 130. The adhesion layer 130 is formed of a resin having a characteristic that interference fringes are not formed even when coherent light is irradiated.

  In hologram optical element 10 in the present embodiment, the refractive index of photosensitive recording layer 120 and the refractive index of adhesive layer 130 are substantially the same. As one example, when the photosensitive recording layer 120 is formed from a photosensitive resin obtained by adding various additives to acrylic as a base, the adhesion layer 130 forms the photosensitive recording layer 120. It is formed from the same acrylic as the base of the photosensitive resin. As another example, the refractive index of the photosensitive recording layer 120 and the refractive index of the adhesive layer 130 are made the same by adding an additive for adjusting the refractive index to the resin material forming the adhesive layer 130. Adjusted.

  The substrate 110 and the substrate 140 are made of an inorganic material such as glass. The substrate 110 and the substrate 140 have translucency so that recording light and reproduction light for the photosensitive recording layer 120 can pass through each substrate.

  Subsequently, assuming the case where the hologram optical element 10 in FIG. 1 is manufactured, the steps of the method for manufacturing the hologram optical element in the present embodiment will be described. 2 to 6 are cross-sectional views showing the steps of the method for manufacturing the hologram optical element in the first embodiment of the present invention.

  Referring to FIG. 2, first, a substrate 160 is prepared. In the present embodiment, the substrate 160 is used as a temporary substrate for supporting the photosensitive material during the drying process of the photosensitive material for obtaining the photosensitive recording layer 120. The substrate 160 is made of a resin material. The substrate 160 is formed from a resin film. The substrate 160 is made of, for example, acrylic, PET (polyethylene terephthalate), or PEN (polyethylene naphthalate).

  A photosensitive material is applied on the substrate 160. In this embodiment mode, a photosensitive material is applied onto the substrate 160 by bar coating. Next, the photosensitive material is dried by heating the substrate 160 in an oven, and the photosensitive recording layer 120 is obtained.

  Referring to FIG. 3, next, a substrate 110 made of an inorganic material such as glass is disposed so that the photosensitive recording layer 120 is sandwiched between the substrate 110 and the substrate 160. At this time, a spacer 152 is disposed beside the photosensitive recording layer 120 between the substrate 110 and the substrate 160. In this state, the substrate 110 and the substrate 160 are heated and pressed in a direction in which they are brought close to each other. Thereby, the photosensitive recording layer 120 is softened and molded, and the film thickness of the photosensitive recording layer 120 is adjusted and the accuracy of the surface shape of the photosensitive recording layer 120 is ensured.

  The spacer 152 was used to adjust the film thickness of the photosensitive recording layer 120. However, the film thickness can be adjusted according to the coating conditions at the time of applying the photosensitive material and the heating press conditions after drying the photosensitive material. If there is, it can be omitted.

  Next, two-beam interference exposure using coherent light 170 is performed on the base material thus manufactured. By irradiating the photosensitive recording layer 120 with the coherent light 170 through the substrate 110, interference fringes are formed in the exposure region 121 of the photosensitive recording layer 120. Thereafter, a post-cure process is performed by exposing a portion other than the exposure region 121 using post-cure light having no coherence.

  Referring to FIG. 4, after performing the post-cure process, the substrate 160 is peeled from the photosensitive recording layer 120. By this peeling step, the photosensitive recording layer 120 has a surface 120a from which the substrate 160 has been peeled off.

  Referring to FIG. 5, a substrate 140 made of an inorganic material such as glass is prepared. A resin material for forming the adhesion layer 130 is applied on the substrate 140. The substrate 140 is overlaid on the substrate 110 so that the adhesion layer 130 contacts the surface 120 a of the photosensitive recording layer 120. At this time, the spacer 151 is disposed beside the photosensitive recording layer 120 and the adhesion layer 130 between the substrate 110 and the substrate 140.

  Although described in detail later with reference to FIG. 6, in the present embodiment, the adhesion layer 130 is formed from a photocurable resin. In this step, the adhesion layer 130 is cured using a curing light 171 having a wavelength capable of curing the material forming the adhesion layer 130. The material for forming the adhesion layer 130 is selected in consideration of the fact that the curing process of the adhesion layer 130 does not affect the characteristics of the photosensitive recording layer 120. The hologram optical element 10 in FIG. 1 is completed through the above steps.

  In the present embodiment, the photosensitive material is supported by the substrate 160 formed of a resin film during the drying process of the photosensitive material shown in FIG. With such a configuration, the phenomenon that the photosensitive recording layer 120 is deformed during the exposure step shown in FIG. 3 can be avoided, and the hologram optical element 10 having high diffraction efficiency and good wavefront accuracy can be produced.

  The reason will be described in detail. When a substrate having a small thermal expansion coefficient (for example, a glass substrate) is used as the substrate 160 used when forming the photosensitive recording layer 120, the photosensitive material is dried or the film thickness is adjusted. Residual stress is generated inside the photosensitive recording layer 120 at the time of hot pressing. This is because, even though the solvent contained in the photosensitive material volatilizes and the photosensitive recording layer 120 shrinks in volume, the heated substrate hardly deforms and compressive stress is applied to the surface of the photosensitive recording layer 120. This is because of remaining. Such compressive stress acts in the direction of compressing the exposure region 121 during the exposure process shown in FIG. 3 and causes deformation of the photosensitive recording layer 120.

  In contrast, in the method for manufacturing a hologram optical element in the present embodiment, a substrate having a large thermal expansion coefficient, such as a resin film, is used as the substrate 160. As a result, when the photosensitive material shrinks with drying, the substrate 160 easily deforms following the deformation of the photosensitive material, so that the residual stress generated in the photosensitive recording layer 120 obtained after drying. Can be reduced. In particular, when the photosensitive material is heated and dried using an oven or the like, the substrate 160 expands during heating, and the substrate 160 contracts in the same manner as the photosensitive material during cooling. It is possible to further reduce the residence stress generated in the.

  From this point of view, the thermal expansion coefficient of the substrate 160 and the thermal expansion coefficient of the photosensitive material for forming the photosensitive recording layer 120 are substantially the same during the drying process of the photosensitive material shown in FIG. It is preferable to select such a substrate 160. For example, when the photosensitive recording layer 120 is formed of a photosensitive resin in which various additives are added to acrylic as a base, the substrate 160 forms a photosensitive recording layer 120. It is formed from the same acrylic as the base of the conductive resin. As another example, by adding an additive for adjusting the thermal expansion coefficient to the resin material forming the substrate 160, the thermal expansion coefficient of the photosensitive recording layer 120 and the thermal expansion coefficient of the substrate 160 are the same. Adjusted to

  On the other hand, when the substrate 160 formed of a resin film is disposed as it is on the side surface of the hologram optical element, such a substrate generally lacks rigidity, so that the mechanical strength of the hologram optical element is sufficiently secured. The problem of not being done arises. In this case, not only the scratch resistance and impact resistance of the hologram optical element are not sufficiently ensured, but also the function of the element may be lowered due to deformation of the hologram optical element in use. Further, there is a concern that the deformation of the hologram recording layer causes a decrease in the angle selectivity of the diffracted light.

  In addition, the substrate 160 formed from a resin film is inferior in gas barrier properties as compared to a substrate formed from an inorganic material such as glass. This is disadvantageous in terms of forming interference fringes and maintaining the function of the hologram optical element. For example, in the case where the reaction in the exposure region 121 is advanced using radical polymerization to form interference fringes, when oxygen passes through the substrate, the surface of the photosensitive recording layer 120 is inhibited from curing and the polymerization reaction proceeds. do not do. Further, when the substrate has a hygroscopic property, the moisture reacts with the photosensitive recording layer 120, so that the hologram optical element is deteriorated with time.

  In order to solve these problems, in the present embodiment, a substrate formed from a resin film is performed by performing the peeling process of the substrate 160 shown in FIG. 4 and the overlapping process of the substrate 140 shown in FIG. 160 is replaced with a substrate 140 formed of an inorganic material such as glass.

The materials for forming the substrate 110, the substrate 140, and the substrate 160 will be described. The substrate 110 and the substrate 140 preferably have higher hardness than the photosensitive recording layer 120. Hardness is determined by Vickers hardness. The Vickers hardness of the substrate 110 and the substrate 140 is preferably set to 1000 N / mm ² or more.

  The substrate 110 and the substrate 140 preferably have a higher gas barrier property than the photosensitive recording layer 120. Further, the substrate 160 preferably has a higher gas barrier property than the photosensitive recording layer 120.

In the method for manufacturing a hologram optical element in the present embodiment, the moisture permeability of the substrate 110 and the substrate 140 disposed on the side surface of the hologram optical element after completion of the element is preferably 1 g · mm / m ² / day or less. . The oxygen permeability of the substrate 160 used in the element formation process is preferably 1000 cm ³ · mm / m ² / day / MPa or less. As the substrate 160, it is preferable to use a PET film or a PEN film having a high gas barrier property against oxygen. Further, from the viewpoint of improving the gas barrier property against oxygen, an inorganic material such as glass can be used for the substrate 160.

  The substrate 110 and the substrate 140 are preferably formed of a material having a high light transmittance in order to suppress light absorption during exposure and reproduction and to increase the diffraction efficiency of the hologram. The substrate 110 and the substrate 140 are preferably formed of a material having a light transmittance of 90% or more at the wavelength of recording light and reproducing light, for example, quartz.

  Considering the above contents and the element characteristics and cost of the hologram optical element, it is most preferable to use a transparent inorganic material such as a glass substrate as the substrate 110 and the substrate 140.

  Next, the role played by the adhesion layer 130 will be described. In the present embodiment, the adhesion layer 130 is interposed between the substrate 140 and the photosensitive recording layer 120 in the overlapping process of the substrate 140 shown in FIG. According to such a configuration, the adhesion layer 130 is deformed following the surface shape of the surface 120a of the photosensitive recording layer 120, and thus is mainly due to the shape accuracy of the surface 120a that is considered to deteriorate in the exposure process. It is possible to prevent a gap from being generated between the photosensitive recording layer 120 and the substrate 140. In addition, bubbles can be prevented from being mixed on the surface 120a when the substrate 140 is stacked.

  Furthermore, when the shrinkage ratio of the photosensitive material forming the photosensitive recording layer 120 is high, the relief along the interference fringes is caused by the compressive stress inside the photosensitive recording layer 120 during the peeling process of the substrate 160 shown in FIG. There is a concern that unnecessary diffracted light is generated as a result. The adhesion layer 130 also serves to prevent the generation of such unnecessary diffracted light.

  In the hologram optical element 10 in the present embodiment, the material for forming the adhesion layer 130 is selected so that the refractive index of the adhesion layer 130 and the refractive index of the photosensitive recording layer 120 are substantially the same. With such a configuration, it is possible to prevent a light reflection component from being generated at the boundary surface between the adhesion layer 130 and the photosensitive recording layer 120 to form a noise hologram.

For the above reason, the difference between the refractive index of the photosensitive recording layer 120 and the refractive index of the adhesive layer 130 is preferably as small as possible. The refractive index of the photosensitive recording layer 120 is n ₁ and the refractive index of the adhesive layer 130 is refraction. It is also possible to set the refractive index of each layer so as to satisfy the relationship of | n ₁ −n ₂ | ≦ 0.1n ₁ when the rate is n ₂ . Regarding the relationship between the refractive index of the adhesive layer 130 and the refractive index of the substrate 140, and the relationship between the refractive index of the photosensitive recording layer 120 and the refractive index of the substrate 110, the refractive index of the photosensitive recording layer 120 and the refractive index of the adhesive layer 130 are also shown. This is the same as the relationship with the refractive index.

  The adhesion layer 130 is preferably formed from a photocurable resin. In this case, by applying an uncured material to the substrate 140 during the manufacturing process of the hologram optical element, the adhesive layer 130 is provided following the shape change of the photosensitive recording layer 120 when the substrate 160 is peeled off. be able to. Further, when a thermosetting resin is used, there is a risk that the interference fringes formed on the photosensitive recording layer 120 may be deformed when the adhesion layer 130 is heat-cured. Can eliminate concerns.

  The structure of the hologram optical element according to the first embodiment of the present invention described above will be described together. The hologram optical element 10 according to the present embodiment includes a substrate 110 as a first substrate having translucency, and a substrate. 110, a photosensitive recording layer 120 on which interference fringes are formed, a substrate 140 as a second substrate that is provided on the opposite side of the substrate 110 with respect to the photosensitive recording layer 120 and has translucency, An adhesion layer 130 is provided between the photosensitive recording layer 120 and the substrate 140 and serves as a light-transmitting buffer layer. The refractive index of the adhesive layer 130 and the refractive index of the photosensitive recording layer 120 are substantially the same.

  Further, the steps of the method for manufacturing a hologram optical element according to Embodiment 1 of the present invention will be described together. In the method for manufacturing a hologram optical element according to the present embodiment, a photosensitive material is applied onto a substrate 160 as a temporary substrate. Then, by drying the material, the step of forming the photosensitive recording layer 120 and the substrate 110 as the first substrate are arranged so that the photosensitive recording layer 120 is disposed between the substrate 160 and the substrate 110. After the step of providing, the step of forming interference fringes in the photosensitive recording layer 120 by irradiation of the coherent light 170, and the step of forming interference fringes in the photosensitive recording layer 120, the substrate 160 is removed from the photosensitive recording layer 120. The photosensitive recording layer 12 from which the peeling process, the adhesion layer 130 as the light-transmitting buffer layer, and the substrate 140 as the second substrate are prepared and the substrate 160 is peeled off are prepared. On the surface 120a, and a step of superimposing the substrate 140 via an adhesion layer 130.

  Preferably, the thermal expansion coefficient of the substrate 160 and the thermal expansion coefficient of the photosensitive material for forming the photosensitive recording layer 120 are substantially the same.

  According to the hologram optical element 10 and the method for manufacturing the hologram optical element according to Embodiment 1 of the present invention configured as described above, the adverse effects caused by drying of the photosensitive material for forming the photosensitive recording layer 120 are eliminated. However, good device characteristics can be obtained.

  Next, an example performed for confirming the function and effect exhibited by the hologram optical element 10 in FIG. 1 will be described. FIG. 7 is a table showing the types of substrate materials and the measurement results of diffraction efficiency and beam pattern.

Referring to FIG. 7, in this example, first, hologram optical element 10 was manufactured by the manufacturing steps shown in FIGS. At this time, a PET film was used as the substrate 160, and glass substrates were used as the substrate 110 and the substrate 140. The heating conditions in the drying process shown in FIG. 2 were set at a temperature of 80 ° C. for 30 minutes. The conditions of the hot press process shown in FIG. 3 were 5 minutes at a pressure of 0.4 MPa and a temperature of 70 ° C. The height of the spacer 152 was set to 20 μm. In the exposure process shown in FIG. 3, a He—Ne laser having a wavelength of 633 nm was used as the exposure light source. The exposure angle of the signal light was 0 °, and the exposure angle of the reference light was 30 °. The exposure area 121 was set to a range of φ4 mm, and the exposure amount was set to 300 mJ / cm ² .

  Furthermore, the hologram optical elements in Comparative Example 1 and Comparative Example 2 were produced by the manufacturing steps shown in FIGS. In Comparative Example 1, glass substrates were used as the substrate 160 and the substrate 110. In Comparative Example 2, a PET film was used as the substrate 160 and a glass substrate was used as the substrate 110.

  After producing the hologram optical elements in Examples, Comparative Example 1 and Comparative Example 2, each hologram optical element is irradiated with laser light from the same angle as during exposure, and the wavefront shapes of transmitted light and diffracted light are observed, The diffraction efficiency was measured. Further, in order to evaluate the gas barrier properties, a humidity resistance test was performed using a constant temperature and humidity tester for 160 hours under a temperature condition of 40 ° C. and a humidity of 90% RH for 160 hours.

  FIG. 8 is a diagram showing the state of the exposure area in Comparative Example 1. In Comparative Example 1, there was no change in diffraction efficiency due to the moisture resistance test. From this result, it has confirmed that it had high gas-barrier property.

  On the other hand, in the exposure process shown in FIG. 3, since the exposure region was deformed by compressive stress, the wavefronts of the diffracted light and transmitted light were distorted. After forming the hologram optical element under the same conditions as in Comparative Example 1, the substrate 160 was peeled off, and the vicinity of the exposure region was observed with a microscope. As shown in FIG. 8, in the region 101 surrounded by the dotted line, deformation of the hologram layer itself on which interference fringes were formed was confirmed. As a result of measuring the height of the dotted line portion in FIG. 8, it was confirmed that the deformed portion was raised by about 1 μm as compared with the surrounding area.

  In Comparative Example 2, the wavefronts of transmitted light and diffracted light were uniform, and no deformation in the exposure region was observed. From this result, it was confirmed that the compressive stress generated in the photosensitive recording layer 120 was smaller than that in Comparative Example 1 by using a PET film as the substrate 160 that supports the photosensitive material during the drying process. . The external diffraction efficiency η was η> 45%.

  On the other hand, as a result of performing a moisture resistance test on the hologram optical element of Comparative Example 2, the external diffraction efficiency changed by about 14% compared to the original value. This is presumably because the hologram film reacted with moisture and changed in quality because the PET film used as the substrate 160 permeated water vapor.

  In the examples, neither changes in the beam intensity distributions of transmitted light and diffracted light nor changes in diffraction efficiency due to the moisture resistance test were observed. The external diffraction efficiency was η> 50%. From this result, it was confirmed that both the shape change of the exposure region 121 due to the compressive stress and the adverse effect due to the permeation of moisture to the substrate were improved, and the function of the hologram optical element was good.

(Embodiment 2)
The hologram optical element in the present embodiment basically has the same structure as that of the hologram optical element 10 in the first embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  FIG. 9 is a cross-sectional view showing a hologram optical element according to Embodiment 2 of the present invention. Referring to FIG. 9, hologram optical element 20 in the present embodiment includes substrate 110, substrate 140, photosensitive recording layer 120, adhesion layer 130, spacer 151, and substrate 160. The hologram optical element 20 is different from the hologram optical element 10 in the first embodiment in that it further includes a substrate 160.

  The substrate 160 is the substrate 160 prepared in the step in FIG. 2 in Embodiment 1, and is formed from a light-transmitting resin material. The substrate 160 is interposed between the photosensitive recording layer 120 and the adhesion layer 130. The substrate 160 is provided in contact with the photosensitive recording layer 120. In the hologram optical element 20 according to the present embodiment, an adhesion layer 130 and a substrate 160 are provided as a light-transmitting buffer layer provided between the photosensitive recording layer 120 and the substrate 140.

  Subsequently, assuming the case where the hologram optical element 20 in FIG. 9 is manufactured, the steps of the method for manufacturing the hologram optical element in the present embodiment will be described. FIG. 10 is a cross-sectional view showing the steps of the method for manufacturing a hologram optical element in the second embodiment of the present invention.

  First, by performing the steps in FIGS. 2 and 3 in the first embodiment, the substrate 160, the substrate 110 disposed opposite to the substrate 160, and the substrate 110 and the substrate 160 are disposed, and an exposure region is formed. A base material having a photosensitive recording layer 120 in which interference fringes are formed on 121 is prepared.

  Referring to FIG. 10, next, a substrate 140 made of an inorganic material such as glass is prepared. A resin material for forming the adhesion layer 130 is applied on the substrate 140. The substrate 140 is overlaid on the substrate 110 so that the adhesion layer 130 is in contact with the substrate 160. Next, the holographic optical element 20 in FIG. 9 is completed by performing the curing step in FIG. 6 in the first embodiment.

  That is, in the method for manufacturing a hologram optical element according to Embodiment 2 of the present invention, the photosensitive recording layer 120 is formed by applying a photosensitive material on the substrate 160 and drying the material. Are provided such that the photosensitive recording layer 120 is disposed between the substrate 160 and the substrate 110, a step of forming interference fringes in the photosensitive recording layer 120 by irradiation of the coherent light 170, and a photosensitive property. After the step of forming interference fringes in the recording layer 120, a step of preparing a light-transmitting adhesive layer 130 and a substrate 140 and superimposing the substrate 140 on the substrate 160 via the adhesive layer 130 is provided.

  In this embodiment, the adhesion layer 130 and the substrate 140 are overlapped with the substrate 160 in the step illustrated in FIG. Thereby, the process of the manufacturing method of a hologram optical element can be simplified. In the process shown in FIG. 10, the adhesion layer 130 plays a role of bringing the two into close contact without causing a gap between the substrate 160 and the substrate 140.

  In the hologram optical element 20 according to the present embodiment, the adhesive layer 130 is provided between the substrate 160 and the substrate 140. However, the substrate 140 is disposed directly on the substrate 160 without providing the adhesive layer 130. It is good. In this case, the substrate 160 is provided as a light-transmitting buffer layer provided between the photosensitive recording layer 120 and the substrate 140. In such a method for manufacturing a hologram optical element, after the step of forming interference fringes in the photosensitive recording layer 120, the step of processing the surface of the substrate 160 disposed on the side opposite to the photosensitive recording layer 120 into a planar shape. And a step of preparing a light-transmitting substrate 140 and superimposing the substrate 140 on the surface of the substrate 160 processed to be planar.

  According to the hologram optical element 20 and the method of manufacturing the hologram optical element according to the second embodiment of the present invention configured as described above, the adverse effects caused by drying of the photosensitive material for forming the photosensitive recording layer 120 are eliminated. However, good device characteristics can be obtained.

(Embodiment 3)
The hologram optical element in the present embodiment basically has the same structure as that of the hologram optical element 10 in the first embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  FIG. 11 is a sectional view showing a hologram optical element according to Embodiment 3 of the present invention. Referring to FIG. 11, hologram optical element 30 in the present embodiment includes substrate 110, substrate 140, photosensitive recording layer 120, stress absorption layer 135, and spacer 151. The hologram optical element 30 has a stress absorbing layer 135 instead of the adhesion layer 130 in FIG. 1 when compared with the hologram optical element 10 in the first embodiment.

  The stress absorbing layer 135 is disposed between the photosensitive recording layer 120 and the substrate 140. The stress absorption layer 135 is provided on the main surface of the substrate 140. The stress absorbing layer 135 is provided in contact with the photosensitive recording layer 120. The photosensitive recording layer 120 and the stress absorption layer 135 are sandwiched between the substrate 110 and the substrate 140.

  The stress absorption layer 135 is formed from a resin material. The stress absorbing layer 135 has translucency so that recording light and reproducing light for the photosensitive recording layer 120 can pass through the stress absorbing layer 135. The stress absorbing layer 135 is made of a resin having a characteristic that interference fringes are not formed even when coherent light is irradiated. The refractive index of the photosensitive recording layer 120 and the refractive index of the stress absorption layer 135 are substantially the same.

  In the hologram optical element 30 in the present embodiment, a stress absorbing layer 135 is provided as a light-transmitting buffer layer provided between the photosensitive recording layer 120 and the substrate 140.

  Next, assuming the case where the hologram optical element 30 in FIG. 11 is manufactured, the steps of the method for manufacturing the hologram optical element in the present embodiment will be described. 12 to 17 are sectional views showing the steps of the method for manufacturing the hologram optical element in the third embodiment of the present invention.

  Referring to FIG. 12, first, dummy substrate 180 is prepared. The dummy substrate 180 has a larger thermal expansion coefficient than the resin material forming the stress absorbing layer 135. A resin material for forming the stress absorbing layer 135 is applied on the surface of the dummy substrate 180 and dried. During drying, the resin material forming the stress absorbing layer 135 contracts, while the dummy substrate 180 having a larger thermal expansion coefficient than the resin material contracts more than the stress absorbing layer 135. At this time, a tensile stress is generated inside the stress absorbing layer 135 as indicated by an arrow in the figure.

  Next, the substrate 140 made of an inorganic material such as glass is disposed so that the stress absorption layer 135 is sandwiched between the dummy substrate 180 and the substrate 140. Next, referring to FIG. 13, the dummy substrate 180 is peeled from the stress absorbing layer 135.

  Referring to FIG. 14, stress absorbing layer 135 is transferred from dummy substrate 180 to substrate 140 by the peeling process shown in FIG. 13. In the stress absorbing layer 135, a state in which a tensile stress is generated is taken over as indicated by an arrow in the figure.

  Referring to FIG. 15, a photosensitive recording layer 120 is obtained by applying a photosensitive material on the stress absorbing layer 135 and drying it. At this time, since a tensile stress is generated in the stress absorption layer 135 in advance, the photosensitive recording layer 120 can be deformed by following the photosensitive material that shrinks with drying. This prevents the residual stress from being generated inside the photosensitive recording layer 120.

  In the present embodiment, the stress absorbing layer 135 provided as a buffer layer plays a role of absorbing internal stress generated when the photosensitive material for forming the photosensitive recording layer 120 is dried.

  Referring to FIG. 16, a substrate 110 made of an inorganic material such as glass is overlaid on the photosensitive recording layer 120. Referring to FIG. 17, two-beam interference exposure using coherent light 170 is performed. By irradiating the photosensitive recording layer 120 with the coherent light 170 through the substrate 110, interference fringes are formed in the exposure region 121 of the photosensitive recording layer 120. Thereafter, a post-cure process is performed by exposing a portion other than the exposure region 121 using post-cure light having no coherence. The hologram optical element 30 in FIG. 11 is completed through the above steps.

  That is, in the method for manufacturing a hologram optical element according to Embodiment 3 of the present invention, the step of forming the stress absorbing layer 135 on the substrate 140, the photosensitive material is applied on the stress absorbing layer 135, and the material is dried. Thus, by the step of forming the photosensitive recording layer 120, the step of providing the substrate 110 so that the photosensitive recording layer 120 is disposed between the substrate 140 and the substrate 110, and the irradiation of the coherent light 170, Forming an interference fringe on the photosensitive recording layer 120.

  The step of forming the stress absorbing layer 135 on the substrate 140 includes the step of forming the stress absorbing layer 135 such that a tensile stress in a direction parallel to the main surface of the substrate 140 is generated inside the stress absorbing layer 135.

  A modification of the hologram optical element 30 in FIG. 11 will be described. FIG. 18 is a cross-sectional view showing a modification of the hologram optical element in FIG.

  Referring to FIG. 18, hologram optical element 40 in the present modification includes substrate 110, substrate 140, photosensitive recording layer 120, stress absorption layer 135, and spacer 151.

  When the length in the direction in which the substrate 110 and the substrate 140 face each other is referred to as a thickness, the stress absorbing layer 135 has a thickness H1, and the photosensitive recording layer 120 has a thickness H2. In this modification, the photosensitive recording layer 120 and the stress absorption layer 135 are formed so as to satisfy the relationship of H1> H2.

  Next, assuming a case where the hologram optical element 40 in FIG. 18 is manufactured, a process of a modified example of the method for manufacturing a hologram optical element in the present embodiment will be described. 19 to 23 are cross-sectional views showing steps of a modification of the method for manufacturing a hologram optical element according to Embodiment 3 of the present invention.

  Referring to FIG. 19, first, a resin material for forming stress absorbing layer 135 is applied on the surface of substrate 140 made of an inorganic material such as glass and dried. At this time, the stress absorbing layer 135 is formed so as to be thicker than the photosensitive recording layer 120 formed in a later step.

  Referring to FIG. 20, a photosensitive recording layer 120 is obtained by applying a photosensitive material on the stress absorbing layer 135 and drying it. Referring to FIG. 21, at this time, since the stress absorbing layer 135 is formed in a thick film, the stress absorbing layer 135 can be easily deformed by following a photosensitive material that shrinks with drying. This prevents the residual stress from being generated inside the photosensitive recording layer 120. The stress absorbing layer 135 is deformed following the shrinkage of the photosensitive material, so that the stress absorbing layer 135 is formed into a shape that tapers toward the photosensitive recording layer 120.

  Also in this modification, the stress absorbing layer 135 provided as a buffer layer plays a role of absorbing internal stress generated when the photosensitive material for forming the photosensitive recording layer 120 is dried.

  Referring to FIG. 22, next, a substrate 110 made of an inorganic material such as glass is overlaid on the photosensitive recording layer 120. Referring to FIG. 23, two-beam interference exposure using coherent light 170 is performed. By irradiating the photosensitive recording layer 120 with the coherent light 170 through the substrate 110, interference fringes are formed in the exposure region 121 of the photosensitive recording layer 120. Thereafter, a post-cure process is performed by exposing a portion other than the exposure region 121 using post-cure light having no coherence. Through the above steps, the hologram optical element 40 in FIG. 18 is completed.

  That is, in the method for manufacturing a hologram optical element according to this modification, in the step of forming the stress absorption layer 135 on the substrate 140, the thickness H1 of the stress absorption layer 135 is larger than the thickness H2 of the photosensitive recording layer 120. And a step of forming the stress absorption layer 135.

  In this modification, the stress absorbing layer 135 has a function of absorbing internal stress generated when the photosensitive material is dried through the film thickness adjustment of the stress absorbing layer 135. However, the present invention is not limited to this configuration. By using a stress absorbing layer 135 having a Young's modulus lower than that of the photosensitive recording layer 120, the stress absorbing layer 135 may have such a function.

  According to the hologram optical element 40 and the hologram optical element manufacturing method according to the third embodiment of the present invention configured as described above, the adverse effects caused by drying of the photosensitive material for forming the photosensitive recording layer 120 are eliminated. However, good device characteristics can be obtained.

(Embodiment 4)
24 to 27 are sectional views showing the steps of the method for manufacturing a hologram optical element in the fourth embodiment of the present invention. Hologram optical element 50 in the present embodiment has the same structure as hologram optical element 10 in the first embodiment. Hereinafter, a method for manufacturing the hologram optical element 50 in the present embodiment will be described.

  First, by performing the steps shown in FIG. 2 in Embodiment Mode 1, a laminate in which the photosensitive recording layer 120 is formed on the main surface of the substrate 160 is obtained. Referring to FIG. 24, next, a substrate 110 made of an inorganic material such as glass is disposed so that the photosensitive recording layer 120 is sandwiched between the substrate 110 and the substrate 160. Next, referring to FIG. 25, the substrate 160 is peeled from the photosensitive recording layer 120. By this peeling step, the photosensitive recording layer 120 has a surface 120a from which the substrate 160 has been peeled off.

  The substrate 160 is made of a resin material. As a material for forming the substrate 160, a material that is easily peeled off from the photosensitive recording layer 120 and has the same or similar thermal expansion coefficient as that of the photosensitive material for forming the photosensitive recording layer 120 is selected. In this embodiment mode, the substrate 160 does not need to have a light-transmitting property.

  Referring to FIG. 26, next, a substrate 140 made of an inorganic material such as glass is prepared. A resin material for forming the adhesion layer 130 is applied on the substrate 140. The substrate 140 is overlaid on the substrate 110 so that the adhesion layer 130 contacts the surface 120 a of the photosensitive recording layer 120. At this time, the adhesion layer 130 serves to prevent a gap from being formed between the photosensitive recording layer 120 and the substrate 140 and to bring them into close contact.

  Referring to FIG. 27, next, two-beam interference exposure with coherent light 170 is performed on the base material thus manufactured. By irradiating the photosensitive recording layer 120 with the coherent light 170 through the substrate 110, interference fringes are formed in the exposure region 121 of the photosensitive recording layer 120. Thereafter, a post-cure process is performed by exposing a portion other than the exposure region 121 using post-cure light having no coherence. The hologram optical element 10 in FIG. 1 is completed through the above steps.

  As described above, in this embodiment, the substrate 160 made of a resin film is used as a substrate for supporting the photosensitive material in the drying step shown in FIG. This suppresses the generation of compressive stress in the photosensitive recording layer 120 obtained after drying. When the drying process is completed, the photosensitive recording layer 120 is transferred from the substrate 160 to the substrate 110 made of an inorganic material such as glass. Since the internal stress generated in the photosensitive recording layer 120 is small, the photosensitive recording layer 120 is not greatly deformed during the exposure process shown in FIG.

  That is, in the method for manufacturing a hologram optical element according to Embodiment 4 of the present invention, the photosensitive recording layer 120 is formed by applying a photosensitive material onto the substrate 160 made of a resin material and drying the material. And a step of providing the substrate 110 so that the photosensitive recording layer 120 is disposed between the substrate 160 and the substrate 110, a step of peeling the substrate 160 from the photosensitive recording layer 120, and a light-transmitting adhesion After the step of preparing the layer 130 and the substrate 140 and superimposing the substrate 140 on the surface 120a of the photosensitive recording layer 120 from which the substrate 160 has been peeled through the adhesion layer 130 and the step of superimposing the substrate 140, it is possible. Forming interference fringes in the photosensitive recording layer 120 by irradiation with the interference light 170.

  According to the hologram optical element manufacturing method according to the fourth embodiment of the present invention configured as described above, it is possible to eliminate the adverse effects caused by drying of the photosensitive material for forming the photosensitive recording layer 120, and to improve Element characteristics can be obtained.

(Embodiment 5)
The hologram optical element in the present embodiment basically has the same structure as that of the hologram optical element 10 in the first embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  FIG. 28 is a cross-sectional view showing a hologram optical element according to Embodiment 5 of the present invention. Referring to FIG. 28, hologram optical element 60 in the present embodiment includes substrate 110, substrate 140, photosensitive recording layer 120, photosensitive recording layer 210 as another photosensitive recording layer, and buffer layer. As an adhesion layer 130, a substrate 160 as another buffer layer, and a spacer 151.

  On the substrate 110, the photosensitive recording layer 210 and the photosensitive recording layer 120 are stacked in the order given. The photosensitive recording layer 210 is disposed between the photosensitive recording layer 120 and the substrate 110. The substrate 160 is disposed between the photosensitive recording layer 210 and the photosensitive recording layer 120. The substrate 160 is provided in contact with the photosensitive recording layer 210 and the photosensitive recording layer 120. The adhesion layer 130 is disposed between the photosensitive recording layer 120 and the substrate 140. The adhesion layer 130 is provided in contact with the photosensitive recording layer 210 and the substrate 140.

  The substrate 160 is the substrate 160 prepared in the step in FIG. 2 in Embodiment 1, and is formed from a light-transmitting resin material. The substrate 160 and the adhesion layer 130 are made of a resin material. The substrate 160 and the adhesion layer 130 are translucent so that recording light and reproduction light for the photosensitive recording layer 210 and the photosensitive recording layer 120 can pass through the substrate 160 and the adhesion layer 130.

  The photosensitive recording layer 120 is formed with interference fringes having a first width, and the photosensitive recording layer 210 is formed with interference fringes having a second width different from the first width.

  In hologram optical element 60 in the present embodiment, the refractive index of photosensitive recording layer 120, the refractive index of photosensitive recording layer 210, the refractive index of adhesion layer 130, and the refractive index of substrate 160 are substantially the same. is there.

  With such a multilayer structure of the photosensitive recording layer, it is possible to form a plurality of interference fringes with light having different wavelengths on a single hologram optical element 60. In the present embodiment, the photosensitive recording layer has a two-layer structure, but the hologram optical element may have a multilayer structure of two or more layers.

  Subsequently, assuming the case where the hologram optical element 60 in FIG. 28 is manufactured, the steps of the method for manufacturing the hologram optical element in the present embodiment will be described. 29 to 32 are cross-sectional views showing the steps of the method for manufacturing the hologram optical element in the fifth embodiment of the present invention.

  Referring to FIG. 29, first, by performing the steps in FIGS. 2 and 3 in the first embodiment, substrate 160, substrate 110 arranged to face substrate 160, substrate 110 and substrate 160 are separated. A base material having a photosensitive recording layer 210 disposed between them and having interference fringes formed in the exposure region 121 is produced. Since the photosensitive material for forming the photosensitive recording layer 210 is supported by the substrate 160 made of a resin material, generation of internal stress in the photosensitive recording layer 210 as the photosensitive material is dried can be suppressed. .

  Referring to FIG. 30, next, a photosensitive material is applied onto substrate 160 and dried to obtain photosensitive recording layer 120. At this time, since the photosensitive material for forming the photosensitive recording layer 120 is supported by the substrate 160 made of a resin material, generation of internal stress in the photosensitive recording layer 120 can be suppressed.

  Referring to FIG. 31, next, a substrate 140 made of an inorganic material such as glass is prepared. A resin material for forming the adhesion layer 130 is applied on the substrate 140. The substrate 140 is overlaid on the substrate 110 such that the adhesion layer 130 is in contact with the photosensitive recording layer 120. At this time, the adhesion layer 130 serves to prevent a gap from being formed between the photosensitive recording layer 120 and the substrate 140 and to bring them into close contact.

  Referring to FIG. 32, two-beam interference exposure using coherent light 170 is performed on the base material thus manufactured. By irradiating the photosensitive recording layer 120 with the coherent light 170 through the substrate 140, interference fringes are formed in the exposure region 121 of the photosensitive recording layer 120. Thereafter, a post-cure process is performed by exposing a portion other than the exposure region 121 using post-cure light having no coherence. The hologram optical element 60 in FIG. 28 is completed through the above steps.

  Thus, in the method for manufacturing a hologram optical element in the present embodiment, as a substrate disposed in the uppermost layer, an inorganic material such as glass is used, and as a substrate disposed between layers of the photosensitive recording layer, A substrate made of a resin material is used from the viewpoint of the thermal expansion coefficient.

  It is possible to configure a new hologram optical element and a method for manufacturing a hologram optical element by appropriately combining the structure of the hologram optical element described in the first to fifth embodiments and the steps of the method for manufacturing the hologram optical element.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is mainly applicable to a multi-wavelength hologram optical element for a pickup diffraction grating, and can also be effectively used industrially as a method for producing a hologram optical element.

  10, 20, 30, 40, 50, 60 Hologram optical element, 101 region, 110 substrate, 110a main surface, 120, 210 photosensitive recording layer, 120a surface, 121 exposure region, 130 adhesion layer, 135 stress absorption layer, 140 Substrate, 140a main surface, 151, 152 spacer, 160 substrate, 170 coherent light, 171 cure light, 180 dummy substrate, 210 photosensitive recording layer.

Claims (5)

A first substrate having translucency;
A photosensitive recording layer provided on the first substrate, on which interference fringes are formed;
A second substrate which is provided on the opposite side of the first substrate with respect to the photosensitive recording layer and has translucency;
A light-transmitting buffer layer provided between the photosensitive recording layer and the second substrate;
A hologram optical element, wherein a refractive index of the buffer layer and a refractive index of the photosensitive recording layer are substantially the same. Another photosensitive recording layer provided on the first substrate, disposed between the first substrate and the photosensitive recording layer, wherein interference fringes are formed;
Further comprising another buffer layer provided between the another photosensitive recording layer and the photosensitive recording layer and having translucency,
2. The hologram optical element according to claim 1, wherein the refractive index of the another buffer layer and the refractive index of the another photosensitive recording layer are substantially the same as the refractive indexes of the buffer layer and the photosensitive recording layer. .   The hologram optical element according to claim 1, wherein the first substrate and the second substrate have a higher gas barrier property than the photosensitive recording layer.   4. The hologram optical element according to claim 1, wherein the first substrate and the second substrate have a hardness higher than that of the photosensitive recording layer. 5. A step of forming a photosensitive recording layer by applying a photosensitive material on a temporary substrate and drying the material;
Providing a first substrate such that the photosensitive recording layer is disposed between the temporary substrate and the first substrate;
Forming interference fringes in the photosensitive recording layer by irradiation with coherent light; and
After the step of forming interference fringes on the photosensitive recording layer, the step of peeling the temporary substrate from the photosensitive recording layer;
Preparing a light-transmitting buffer layer and a second substrate, and superimposing the second substrate on the surface of the photosensitive recording layer from which the temporary substrate has been peeled, via the buffer layer;
A method for manufacturing a hologram optical element, wherein a thermal expansion coefficient of the temporary substrate and a thermal expansion coefficient of the photosensitive material are substantially the same.