Holographic optical element manufacturing apparatus and holographic optical element manufacturing method

Abstract

To provide a holographic optical element manufacturing device capable of realizing a target function in the entire visible light region, and capable of being manufactured at low cost, and to provide its manufacturing method.SOLUTION: A holographic optical element manufacturing method includes: changing angles of a plane mirror 114 for reference light and a plane mirror 117 for signal light, to change a relative irradiation angle of signal parallel light 118 and cylindrical wave-like reference light 123 with respect to a recording medium 124, thereby making a plurality of interference fringes multiple-exposed onto the recording medium 124 while generating the plurality of interference fringes with different intervals.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a holographic optical element, and a holographic optical element manufacturing apparatus and method for manufacturing the holographic optical element, and more particularly to a holographic optical element provided with a holographic diffraction grating, and a manufacturing apparatus and method for the same. [Background technology]

[0002] Conventionally, holographic optical elements such as holographic diffraction gratings using hologram technology and manufacturing devices thereof have been put to practical use (for example, Non-Patent Document 1). In particular, in recent years, various display devices such as transparent head-mounted displays (hereinafter referred to as "HMDs") and head-up displays have been proposed to realize augmented reality (AR) (for example, Patent Document 1). By applying holographic optical elements to these types of display devices, it is expected that high-quality, low-cost display devices can be realized while realizing a wide viewing angle.

[0003] Conventional holographic diffraction gratings are manufactured using a so-called two-beam interferometer, in which a source beam for exposure emitted from a light source is split into S-polarized signal light and P-polarized reference light by a polarizing beam splitter (PBS), the signal light that passes through the PBS is converted to S-polarized light by a λ / 2 plate, the polarization direction is aligned, and the signal light and reference light are irradiated onto a recording medium made of a photosensitive material, causing the signal light and reference light to interfere with each other and exposing the interference fringes on the recording medium (for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Sigma Koki Co., Ltd., "Grating exposure device" search [searched April 21, 2019], Internet<URLhttps: / / www.global-optosigma.com / jp / category / opt / opt07.html> [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-12259 Summary of the Invention [Problem to be solved by the invention]

[0006] However, holographic optical elements manufactured using the conventional two-beam interferometer described above generally function correctly only at the wavelength used for exposure. Using a wavelength other than that used for exposure results in a different function than intended. Therefore, to manufacture a holographic optical element capable of achieving the intended function at wavelengths throughout the entire visible light range, wavelength-multiplexed exposure across the entire visible light range is required. However, photosensitive materials constituting recording media are not sensitive to the entire visible light range, but are only sensitive to certain wavelengths. While it is possible to use a recording medium containing multiple photosensitive materials to achieve sensitivity across the entire visible light range, this requires changing the wavelength of the exposure source beam across the entire visible light range, necessitating the use of very large-scale manufacturing equipment and making it difficult to reduce manufacturing costs.

[0007] The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a holographic optical element that can achieve a desired function over the entire visible light range and can be manufactured at low cost, as well as a manufacturing apparatus for the same. [Means for solving the problem]

[0008] (1) In order to solve the above-mentioned problems, the holographic optical element of the present invention has a configuration in which a plurality of holographic diffraction gratings each having a different grating spacing and grating curved surface, or a plurality of holographic diffraction gratings each including a diffraction plane with a different orientation, are formed by overlapping each other.

[0009] As a result, the holographic optical element of the present invention can achieve the desired function over the entire visible light range because multiple holographic diffraction gratings with different grating intervals and grating curves, or holographic diffraction gratings with diffraction planes oriented in different directions, each achieve the desired function for light of different wavelengths. Furthermore, multiple holographic diffraction gratings with different grating intervals and grating curves, or holographic diffraction gratings with diffraction planes oriented in different directions, can be formed by changing the relative angles when the signal beam and the reference beam are irradiated onto the recording medium, so that they can be manufactured using a source beam of a single wavelength, thereby achieving low costs.

[0010] (2) In the above configuration, the plurality of holographic diffraction gratings may have a layer structure in which the layers have different refractive indices and are stacked three-dimensionally.

[0011] With this configuration, the holographic optical element of the present invention can construct a three-dimensional layer structure on a single recording medium by irradiating the signal light and the reference light while changing the irradiation angle relative to the recording medium, thereby achieving the desired function over the entire visible light range.

[0012] (3) Furthermore, in the configuration described in claim 2, a configuration may be adopted in which the number of layers varies depending on the corresponding wavelength, and when parallel light of the corresponding wavelength is irradiated, the parallel light is diffracted and line-focused.

[0013] With this configuration, the holographic optical element of the present invention can function as an ideal cylindrical lens with uniaxial curvature, preventing the occurrence of aberrations that occur in ordinary cylindrical lenses and improving focusing accuracy.

[0014] (4) In the configuration described in claim 3, the layer may have a shape corresponding to the position where the diffracted light is focused and the direction of the diffracted light.

[0015] With this configuration, the holographic optical element of the present invention can focus parallel light so that line foci are formed at different positions when parallel light of wavelengths corresponding to each layer is irradiated. This allows the functions of multiple cylindrical lenses to be realized with a single holographic optical element, resulting in a low-cost, space-saving optical element.

[0016] (5) In addition, in the configuration described in claim 3 or 4, the layer may have a shape that, when irradiated with light spreading from the line focus, diffracts the light spreading from the line focus and generates parallel light having a direction corresponding to the position and direction of the line focus.

[0017] The shapes of the layers constituting the holographic optical element of the present invention can be changed by changing the relative angles at which the signal beam and the reference beam are irradiated onto the recording medium. This allows the element to be manufactured using a source beam of a single wavelength without using large-scale manufacturing equipment, and this configuration improves the versatility of the optical element.

[0018] (6) The present invention also provides an apparatus for manufacturing a holographic optical element, which is used to manufacture a holographic optical element by exposing a recording medium made of a photosensitive material having sensitivity to a predetermined wavelength range, and includes a light source that emits an exposure source beam of a single wavelength, a beam splitter that splits the source beam into signal light and reference light, a signal light irradiation unit that irradiates the recording medium with the signal light via a first optical path, and a reference light irradiation unit that irradiates the recording medium with the reference light via a second optical path, thereby causing interference between the signal light and the reference light irradiated by the signal light irradiation unit to generate interference fringes and exposing the generated interference fringes to the recording medium. and an irradiation means, wherein the signal light irradiation means has a signal light irradiation angle adjusting means that adjusts the irradiation angle of the signal light with respect to the recording medium, and the reference light irradiation means has a reference light irradiation angle adjusting means that adjusts the irradiation angle of the reference light with respect to the recording medium, and the signal light irradiation angle adjusting means adjusts the irradiation angle of the signal light in accordance with the interval of the interference fringes to be generated, and the reference light irradiation angle adjusting means adjusts the irradiation angle of the reference light with respect to the recording medium in accordance with the adjusted irradiation angle of the signal light, thereby changing the interval of the interference fringes, thereby generating a plurality of interference fringes each having a different interval, and multiplex-exposing the generated plurality of interference fringes onto the recording medium.

[0019] With this configuration, the holographic optical element manufacturing apparatus of the present invention can perform multiple exposure on the recording medium to form multiple holographic diffraction gratings each having a different grating spacing and grating curved surface, or multiple holographic diffraction gratings each having a diffraction plane oriented in a different direction, by adjusting the relative irradiation angle of the signal beam and the reference beam with respect to the recording medium, thereby making it possible to expose holographic diffraction gratings compatible with multiple wavelengths using a source beam of a single wavelength. Therefore, the holographic optical element manufacturing apparatus of the present invention can achieve the desired function over the entire visible light range and can manufacture holographic optical elements at low cost without employing a complex device configuration.

[0020] (7) In addition, in the configuration described in claim 6, a configuration may be adopted in which the signal light irradiation angle adjustment means changes the irradiation angle of the signal light with respect to the recording medium by a predetermined value, and the reference light irradiation angle adjustment means changes the relative irradiation angle of the reference light with respect to the signal light in accordance with the change in the irradiation angle of the signal light with respect to the recording medium, thereby generating multiple interference fringes with different intervals, and the generated multiple interference fringes are multiple-exposed onto the recording medium.

[0021] With this configuration, the relative irradiation angles of the signal light and the reference light with respect to the recording medium are sequentially changed by a predetermined value to generate interference fringes with different intervals multiple times, and the multiple interference fringes are multiple-exposed to produce the holographic optical element of the present invention, which is composed of multiple holographic diffraction gratings, each having a different grating interval and grating curved surface, or multiple holographic diffraction gratings, each having diffraction planes oriented in different directions, stacked on top of each other.

[0022] (8) In the configuration of claim 6 or 7, the signal light irradiation angle adjusting means may be configured to change the irradiation angle of the signal light with respect to the recording medium two-dimensionally or three-dimensionally.

[0023] With this configuration, the holographic optical element manufacturing apparatus of the present invention can change the angle of irradiation of the signal light onto the recording medium two-dimensionally or three-dimensionally, thereby making it possible to finely adjust the shape of the interference fringes exposed onto the recording medium and manufacture holographic optical elements that can realize various functions.

[0024] (9) Furthermore, in the configuration described in claim 8, a recording medium position adjustment means may be further provided for adjusting the position of the recording medium in accordance with the irradiation angle of the signal light adjusted by the signal light irradiation angle adjustment means.

[0025] With this configuration, the holographic optical element manufacturing apparatus of the present invention can adjust the position of the recording medium so that the signal light is irradiated at the desired position on the recording medium, even when the irradiation angle of the signal light is changed two-dimensionally or three-dimensionally, and can manufacture the holographic optical element of the present invention with high precision.

[0026] (10) Furthermore, in the configuration described in claim 9, the recording medium position adjustment means may include a recording medium linear movement means for moving the recording medium linearly in a predetermined direction, and a recording medium height adjustment means for moving the recording medium in a height direction, and the signal light irradiation angle adjustment means may adjust the position of the recording medium in accordance with the irradiation angle of the signal light adjusted by changing the irradiation angle of the signal light relative to the recording medium in three dimensions.

[0027] With this configuration, the holographic optical element manufacturing apparatus of the present invention can move the recording medium in two axial directions, so that even when the irradiation angle of the signal light onto the recording medium is changed three-dimensionally, the position of the recording medium can be precisely adjusted so that the signal light is irradiated onto the desired position on the recording medium, thereby enabling the holographic optical element of the present invention to be manufactured with high precision.

[0028] (11) Furthermore, in the configuration described in claim 9, the recording medium position adjustment means may include a recording medium plane movement means that moves the recording medium two-dimensionally within a predetermined plane, and a recording medium height adjustment means that moves the recording medium in a height direction, and the signal light irradiation angle adjustment means may adjust the position of the recording medium in accordance with the irradiation angle of the signal light that is adjusted by changing the irradiation angle of the signal light relative to the recording medium three-dimensionally.

[0029] With this configuration, the holographic optical element manufacturing apparatus of the present invention can adjust the position of the recording medium in three dimensions. Therefore, even when the irradiation angle of the signal light onto the recording medium is changed in three dimensions, the position of the recording medium can be precisely adjusted so that the signal light is irradiated onto the desired position on the recording medium, thereby enabling the holographic optical element of the present invention to be manufactured with high precision.

[0030] (12) Furthermore, in the configuration described in claim 9, the recording medium position adjustment means may include a recording medium plane movement means that moves the recording medium two-dimensionally within a predetermined plane, and a recording medium tilt angle change means that changes the tilt of the recording medium, and the signal light irradiation angle adjustment means changes the irradiation angle of the signal light with respect to the recording medium two-dimensionally, and the reference light irradiation angle adjustment means adjusts the irradiation angle of the reference light with respect to the recording medium in accordance with the adjusted irradiation angle of the signal light, and the recording medium tilt angle change means changes the tilt of the recording medium in accordance with the irradiation angles of the signal light and the reference light, thereby three-dimensionally changing the relative irradiation angles of the signal light and the reference light with respect to the recording medium.

[0031] With this configuration, even when the holographic optical element manufacturing apparatus of the present invention employs a simple adjustment mechanism (such as the signal light rotation stage 115 described below) that can change the irradiation angle of the signal light only two-dimensionally as the signal light irradiation angle adjustment means, it is possible to adjust the relative irradiation angle of the signal light and reference light with respect to the recording medium in three dimensions by changing the tilt of the recording medium, while making adjustments so that the signal light and reference light are irradiated at desired positions on the recording medium, and to multiplex-expose the recording medium to multiple holographic diffraction gratings, each having different grating spacings and grating curved surfaces, or multiple holographic diffraction gratings having diffraction planes with different orientations, and the holographic optical element of the present invention can be manufactured with high precision using a simple apparatus configuration.

[0032] (13) In the configuration described in claim 12, the recording medium position adjusting means may further include a recording medium height adjusting means for moving the recording medium in a height direction.

[0033] With this configuration, the holographic optical element manufacturing apparatus of the present invention can adjust the position of the recording medium in three dimensions while changing the inclination of the recording medium, thereby three-dimensionally adjusting the relative irradiation angles of the signal light and reference light with respect to the recording medium, thereby facilitating device setup and enabling the manufacturing of holographic optical elements with high precision.

[0034] (14) In addition, in the configuration described in any one of claims 6 to 13, the reference light irradiation means may have a cylindrical lens having a curvature in one axis, and after the reference light is line-focused by the cylindrical lens, the reference light (cylindrical wave-like reference light) spreading from the line focus may be irradiated onto the recording medium.

[0035] With this configuration, the holographic optical element manufacturing apparatus of the present invention can manufacture a holographic optical element that can achieve the same function as an ideal cylindrical lens having a uniaxial curvature.

[0036] (15) Furthermore, the present invention provides a method for manufacturing a holographic optical element, which comprises irradiating a recording medium made of a photosensitive material having sensitivity to a predetermined wavelength region with signal light and reference light generated by branching a source beam of a single wavelength, each of which is passed through a different optical path, thereby causing the signal light and the reference light to interfere with each other, and exposing the recording medium to interference fringes generated by the interference. The method is configured to produce a holographic optical element by varying the relative irradiation angle of the signal light and the reference light with respect to the recording medium, thereby varying the spacing between the interference fringes and generating a plurality of interference fringes each having a different spacing, and then multiplex-exposing the generated plurality of interference fringes onto the recording medium. [Effects of the Invention]

[0037] The holographic optical element and the manufacturing apparatus and method thereof of the present invention can provide a holographic optical element capable of achieving the intended function over the entire visible light range at low cost. [Brief explanation of the drawings]

[0038] [Figure 1] 1 is a system configuration diagram showing the configuration of a manufacturing system for a holographic optical element according to a first embodiment of the present invention. [Figure 2] 4A and 4B are diagrams for explaining interference fringes formed by interference between signal parallel light formed in the manufacturing apparatus of the first embodiment and cylindrical wave-like reference light spreading from a line focus. [Figure 3] 10 is a graph showing the relationship between the rotation angle of the signal beam rotation stage and the wavelength when the exposure wavelength is 532 nm and the vertical angle is 10° in the manufacturing apparatus of the first embodiment. [Figure 4] 10 is a graph showing the relationship between the rotation angle of the goniostage and the vertical angle when the exposure wavelength is 532 nm and the vertical angle is between −10° and 10° in the manufacturing apparatus of the first embodiment. [Figure 5] FIG. 10 is a diagram showing the resulting horizontal angle range of a parallel signal light beam in the manufacturing apparatus of the first embodiment. [Figure 6] 10 is a graph showing the relationship between the rotation angle of the reference beam rotation stage and the wavelength when the exposure wavelength is 532 nm and the vertical angle is 10° in the manufacturing apparatus of the first embodiment. [Figure 7] 1 is a flowchart (part 1) showing a process executed by an information processing device in the manufacturing system according to the first embodiment. [Figure 8] 10 is a flowchart (part 2) illustrating the process executed by the information processing device in the manufacturing system according to the first embodiment. [Figure 9] FIG. 1 is a diagram (part 1) showing a changing state of the optical system of the manufacturing device when manufacturing a holographic diffraction grating corresponding to one wavelength in the manufacturing system of the first embodiment. [Figure 10]FIG. 2 is a diagram (part 2) showing a changing state of the optical system of the manufacturing device when manufacturing a holographic diffraction grating corresponding to one wavelength in the manufacturing system of the first embodiment. [Figure 11] 1A and 1B show an example of the three-dimensional structure of a holographic diffraction grating manufactured by the manufacturing system of the first embodiment. FIGS. 1A and 1B show an example of the structure of a holographic diffraction grating when white parallel light is irradiated onto the holographic diffraction grating, and the line focus is located near the center of the holographic diffraction grating in the vertical direction of the drawing. FIGS. 1C and 1D show an example of the structure of a holographic diffraction grating when the line focus is located toward the bottom of the holographic diffraction grating HG. [Figure 12] FIG. 10 is a diagram (part 1) showing an example of the configuration of a head-mounted display using a holographic light guide plate according to Modification 2 of the present invention. [Figure 13] FIG. 10 is a diagram (part 2) showing a configuration example of a head-mounted display using a holographic light guide plate in Modification 2. [Figure 14] FIG. 10 is a diagram (part 3) showing a configuration example of a head-mounted display using a holographic light guide plate in Modification 2. [Figure 15] FIG. 10 is a system configuration diagram showing the configuration of a manufacturing system for a holographic optical element according to a second embodiment of the present invention. [Figure 16] 10A and 10B are diagrams showing an example of a changing state of an optical system of a manufacturing apparatus when a holographic diffraction grating is manufactured in a manufacturing system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are embodiments in which the present invention is applied to a holographic diffraction grating as a holographic optical element and to an apparatus for manufacturing the holographic diffraction grating. However, the embodiments described below do not unduly limit the content of the present invention as defined in the claims, and not all of the configurations described in the present embodiments are necessarily essential components of the present invention.

[0040] [A] First embodiment [A.1] Overall configuration of holographic optical element manufacturing system 1A First, the configuration of a holographic optical element manufacturing system 1A (hereinafter referred to as "manufacturing system 1A") according to one embodiment of the present invention will be described using Figure 1. Figure 1 is a diagram showing the configuration of manufacturing system 1A according to this embodiment. In Figure 1, the directions of the xyz axes are indicated by arrows to define directions in the xyz space within manufacturing system 1A.

[0041] The manufacturing system 1A of this embodiment includes a manufacturing apparatus 10A including an optical system for recording (exposing) a holographic diffraction grating HG (described later) on a recording medium 124 (described later), and an information processing device 20 that is connected to the manufacturing apparatus 10A via a wired communication interface such as IEEE (Institute of Electrical and Electronics Engineers) 488 or a wireless interface such as IEEE802.11a, b, g, n, or ac and that performs adjustment processing and the like related to a stage (described later) of the optical system in the manufacturing apparatus 10A. The manufacturing system 1A is for manufacturing a reflective volume holographic diffraction grating HG (hereinafter referred to as a "holographic diffraction grating HG") that can achieve a desired function for light in the entire visible light range, using the recording medium 124 made of a photosensitive material that is sensitive only to light in a predetermined wavelength range and light of a single wavelength (for example, wavelength λ0) to which the photosensitive material is sensitive (i.e., source beam SB in FIG. 1).

[0042] Here, as described above, when a holographic diffraction grating HG is formed on recording medium 124 using a source beam SB of a single wavelength, the desired function cannot be realized for light of wavelengths (e.g., λ1, λ2, λ3, etc.) other than the wavelength corresponding to the source beam SB (e.g., λ0 when a source beam SB of wavelength λ0 is used), and it is difficult to manufacture a holographic diffraction grating HG that can achieve the desired function over the entire visible light range.

[0043] Generally, the diffraction phenomenon in a diffraction grating follows the diffraction grating equation, and the following relationship holds for both transmission type and reflection type diffraction gratings.

[0044] (1) In the case of a transmission grating,

[0045]

number

[0046] (2) In the case of a reflective diffraction grating,

[0047]

number

[0048] In these equations, α is the angle between the incident light and the normal to the diffraction grating (i.e., the incident angle), β is the angle between the diffracted light and the normal to the diffraction grating (i.e., the diffraction angle), d is the grating spacing, λ is the wavelength, and m is the order of the diffracted light.

[0049] As described above, the diffraction of light at a diffraction grating for light of wavelength λ depends on the grating spacing d of the diffraction grating. Therefore, in order to achieve the desired function with white light having wavelengths across the entire visible light range, it is necessary to devise a structure for the holographic diffraction grating HG.

[0050] Therefore, the manufacturing system 1A of this embodiment performs multiple exposure on a recording medium 124 to form a plurality of holographic diffraction gratings, each with a different grating spacing d, thereby achieving the function of manufacturing a holographic diffraction grating HG that can achieve a desired function for light across the entire visible light range. The holographic diffraction grating HG manufactured by the manufacturing system 1A of this embodiment achieves the same function as a cylindrical lens: when white parallel light is incident, the parallel light is diffracted and line-focused, and when divergent light from the line-focused white light is incident, the divergent light is diffracted and generates parallel light. The manufacturing method and specific structure of the holographic diffraction grating HG manufactured by the manufacturing system 1A of this embodiment will be described in detail later.

[0051] [A.2] Specific configuration of manufacturing equipment 10A In order to manufacture the holographic diffraction grating HG, manufacturing apparatus 10A of this embodiment has light source 111 formed of a single-wavelength laser, and is configured so that source beam SB is incident from light source 111 on beam splitter 112. Beam splitter 112 splits source beam SB incident from light source 111 into two beams, signal beam SL and reference beam RL, and causes signal beam SL to be incident on signal beam plane mirror 117, while causing reference beam RL to be incident on reference beam plane mirror 114.

[0052] In this manner, the signal light SL and the reference light RL split by the beam splitter 112 are incident on the signal light plane mirror 117 and the reference light plane mirror 114, so that the heights (i.e., positions in the z-axis direction) of (a) the beam splitter 112, (b) the signal light plane mirror 117, and (c) the reference light plane mirror 114 are aligned. The beam splitter 112 may be configured to split the source beam SB using, for example, a half mirror so that the signal light SL and the reference light RL have a 1:1 intensity ratio. Alternatively, the beam splitter 112 may be configured using a PBS to split the P-polarized light into the signal light SL and the S-polarized light into the reference light RL according to the polarization direction. In this case, a λ / 2 plate (not shown) may be provided between the beam splitter 112 and the signal light plane mirror 117 to align the polarization directions of the signal light SL and the reference light RL. Furthermore, the wavelength of the source beam SB is arbitrary, and any wavelength may be used as long as the photosensitive material that constitutes the recording medium 124 has sensitivity to that wavelength.

[0053] The signal light plane mirror 117 reflects the signal light SL incident from the beam splitter 112, causing it to be incident as signal collimated light 118 on the recording medium 124. This signal light plane mirror 117 is placed on a goniostage 116 provided on the signal light rotation stage 115, and by rotating the signal light rotation stage 115 about the z-axis, the angle of the signal light plane mirror 117 with respect to the incident direction of the signal light SL can be changed, and the emission direction (i.e., reflection direction) of the signal collimated light 118 can be changed in the xy plane, and by changing the tilt of the signal light plane mirror 117 with the goniostage 116, the emission direction of the signal collimated light 118 can be changed in the z-axis direction. For example, the signal light plane mirror 117, the signal light rotation stage 115, and the goniostage 116 of this embodiment work in conjunction with a stage drive circuit 130 and an information processing device 20, which will be described later, to form the "signal light irradiation means" of the present invention, and the signal light rotation stage 115 and the goniostage 116 work in conjunction with the stage drive circuit 130 and the information processing device 20 to form the "signal light irradiation angle adjustment means" of the present invention.

[0054] With this configuration, the manufacturing apparatus 10A of this embodiment can change the emission direction of the signal light SL (i.e., the signal parallel light 118) reflected by the signal light plane mirror 117 to an intended direction in the xyz space, and can change the irradiation angle of the signal parallel light 118 with respect to the recording medium 124 in three dimensions.

[0055] Generally, the viewing angle in the vertical direction (the z-axis direction in FIG. 1 ) achieved when a holographic diffraction grating HG is used in a transmissive display panel (for example, a display panel for a transmissive HMD or an optical combiner for a head-up display) depends on the amount of angular displacement in the z-axis direction when signal collimated light 118 is irradiated onto recording medium 124 during exposure of the holographic diffraction grating HG, and is approximately twice the amount of angular displacement in the z-axis direction. Therefore, when exposing holographic diffraction grating HG on recording medium 124 using manufacturing system 1 of this embodiment, a transmissive display panel with a viewing angle of approximately 20° in the vertical direction can be achieved by displacing the angle of signal collimated light 118 in the z-axis direction by approximately 10° using goniostage 116.

[0056] On the other hand, when the emission direction of the signal collimated light 118 is changed in the z-axis direction by the goniostage 116 or the signal light plane mirror 117 is rotated by the signal light rotation stage 115, it becomes difficult to make the signal collimated light 118 incident on a desired position on the recording medium 124. Therefore, in the manufacturing apparatus 10A of this embodiment, a height adjustment stage 126 is provided on the recording medium linear movement stage 125, and a configuration is adopted in which the recording medium 124 is placed on this height adjustment stage 126.

[0057] This recording medium linear movement stage 125 is configured to be able to move the recording medium 124 linearly in a predetermined direction (for example, the y-axis direction) in the xy plane, and the height adjustment stage 126 is configured to be able to move the recording medium 124 in the z-axis direction (i.e., height direction). When the signal light rotation stage 115 rotates the signal light plane mirror 117 or the goniostage 116 changes the inclination of the signal light plane mirror 117 to change the emission direction of the signal collimated light 118 three-dimensionally in the xyz space, the recording medium linear movement stage 125 and the height adjustment stage 126 are moved in conjunction with the signal light rotation stage 115 and the goniostage 116 to move the position of the recording medium 124 in the xyz space, and the position of the recording medium 124 is adjusted so that the signal collimated light 118 is irradiated at a desired position on the recording medium 124. The rotation angles of the signal beam rotation stage 115 and the goniostage 116 and the movement amount of the recording medium linear movement stage 125 during the manufacture of the holographic diffraction grating HG will be described in detail later. Furthermore, the recording medium linear movement stage 125 and height adjustment stage 126 of this embodiment work in conjunction with the stage drive circuit 130 and the information processing device 20 to constitute, for example, the "recording medium position adjustment means" of the present invention, and also work in conjunction with the stage drive circuit 130 and the information processing device 20 to constitute the "recording medium linear movement means" and "recording medium height adjustment means" of the present invention, respectively. Furthermore, in order to finely adjust the position of the recording medium 124, it is desirable to use a stage capable of adjusting the position of the recording medium 124 in two axial directions, the x-axis and the y-axis, as the linear movement stage for the recording medium 125, and to use this stage and the height adjustment stage 126 to adjust the position of the recording medium 124 in three axial directions, the x-axis, the y-axis, the z-axis. However, since this would complicate the device configuration and position adjustment, in this embodiment, to make the explanation easier to understand, the explanation will be given assuming that the linear movement stage for the recording medium 125 is configured to be adjustable in position only in a specified direction (specifically, the y-axis direction), and the case where a stage adjustable in two axial directions (the planar movement stage for the recording medium 140 described later) is used will be explained in the third embodiment.

[0058] Next, the reference beam plane mirror 114 reflects the reference beam RL incident from the beam splitter 112, causing it to be incident on the cylindrical lens system 122 as reference collimated beam 119. This reference beam plane mirror 114 is placed on a reference beam rotation stage 113 provided on a reference beam linear movement stage 121, and by rotating the reference beam rotation stage 113 about the z-axis, the emission direction of the reference beam 119 can be changed within the xy plane. Note that, for example, the reference beam rotation stage 113 and the reference beam linear movement stage 121 of this embodiment, in conjunction with the cylindrical lens linear movement stage 120, the stage drive circuit 130, and the information processing device 20, constitute a "reference beam irradiation angle adjustment means" of the present invention.

[0059] Here, in order to determine the focusing position of the diffracted light relative to the direction of the incident plane wave, it is necessary to control the direction of the signal light SL and the position of the line focus 127. Therefore, in the manufacturing apparatus 10A of this embodiment, a configuration is adopted in which the reference light rotation stage 113 is provided on the reference light linear movement stage 121, and when the recording medium linear movement stage 125 is moved in accordance with the direction of the signal collimated light 118, the reference light linear movement stage 121 is moved in the xy plane accordingly, so that the signal light plane mirror 117 and the reference light plane mirror 114 are moved to positions symmetrical with respect to the recording medium 124. The rotation angle of the reference light rotation stage 113 and the movement amount of the recording medium linear movement stage 125 during manufacturing of the holographic diffraction grating HG will be described in detail later.

[0060] The cylindrical lens system 122 may be configured, for example, as a single lens having a uniaxial curvature or as a combination of multiple similar lenses. When the reference collimated light 119 reflected by the reference light plane mirror 114 is incident on the cylindrical lens system 122, the cylindrical lens system 122 focuses the reference collimated light 119 and irradiates the recording medium 124 with the cylindrical wave-like reference light 123. At this time, the cylindrical wave-like reference light 123 is once focused linearly at the back focal position of the cylindrical lens system 122 to form a line focus 127, and then diverges again while being irradiated with the recording medium 124. Note that the cylindrical lens system 122 may be configured with a general cylindrical lens; however, when a general cylindrical lens is used, aberration may occur, making it impossible to focus the cylindrical wave-like reference light 123 accurately linearly. Therefore, it is preferable to use a lens having the above-mentioned shape. In addition, in this embodiment, the cylindrical lens system 122 is installed at the same height as the reference light plane mirror 114 so that the reference collimated light 119 from the reference light plane mirror 114 is irradiated with a desired position on the cylindrical lens system 122. That is, in the manufacturing apparatus 10A of this embodiment, (a) the beam splitter 112, (b) the plane mirror 117 for the signal light, (c) the plane mirror 114 for the reference light, and (d) the cylindrical lens system 122 are all set to the same height.

[0061] Here, if the inclination of signal light plane mirror 117 is adjusted using goniostage 116 and the height of recording medium 124 is adjusted accordingly using height adjustment stage 126, recording medium 124 will shift vertically (in the z-axis direction) relative to the installation position of cylindrical lens system 122. However, since cylindrical wave-like reference light 123 is irradiated onto recording medium 124 with a sufficient divergence angle from line focus 127 behind cylindrical lens system 122, even if the height of recording medium 124 is adjusted in accordance with the change in inclination of signal light plane mirror 117, cylindrical wave-like reference light 123 is maintained in a state where it is reliably irradiated onto recording medium 124.

[0062] At this time, if the recording medium 124 is positioned above the line focus 127, the cylindrical wave-like reference beam 123 is irradiated onto the recording medium 124 from below in the z-axis direction and is reflected upward by the recording medium 124. At this time, the signal beam plane mirror 117 is tilted upward by the goniostage 116, so the signal collimated beam 118 is also irradiated onto the recording medium 124 from below in the z-axis direction and is reflected upward.

[0063] On the other hand, when the recording medium 124 is positioned below the line focus 127, the cylindrical wave-like reference beam 123 is irradiated onto the recording medium 124 from above downward in the z-axis direction and is reflected downward by the recording medium 124. At this time, the signal beam plane mirror 117 is tilted downward by the goniostage 116, so the signal collimated beam 118 is also irradiated onto the recording medium 124 from above downward in the z-axis direction and is reflected downward.

[0064] In this embodiment, the cylindrical lens system 122 is placed on a cylindrical lens linear movement stage 120, and the position of the cylindrical lens system 122 can be moved in the xy plane by the cylindrical lens linear movement stage 120 in conjunction with the rotation of the reference light rotation stage 113. In this embodiment, the reference light plane mirror 114, the reference light rotation stage 113, the cylindrical lens linear movement stage 120, the reference light linear movement stage 121, and the cylindrical lens system 122 cooperate with the stage drive circuit 130 and the information processing device 20 to constitute, for example, the "reference light irradiation means" of the present invention.

[0065] In the manufacturing apparatus 10A of this embodiment, when the reference light plane mirror 114 is rotated around the z-axis by the reference light rotation stage 113, the emission direction of the reference parallel light 119 changes within the xy plane. However, with the above configuration, the cylindrical lens system 122 can be moved to a desired position within the xy plane, so that the reference parallel light 119 can be irradiated to a desired position on the cylindrical lens system 122 while maintaining a constant distance between the reference light plane mirror 114 and the cylindrical lens system 122.

[0066] Furthermore, when cylindrical lens system 122 moves in accordance with the rotation of reference beam plane mirror 114, the focusing position of cylindrical wave-like reference beam 123 (i.e., the position of line focus 127) changes in the x-axis direction or the y-axis direction, and the irradiation position of divergent light from line focus 127 on recording medium 124 changes. For this reason, manufacturing apparatus 10A of this embodiment employs a configuration in which recording medium linear movement stage 125 is moved parallel to cylindrical lens linear movement stage 120, and adjustment is made so that divergent light from line focus 127 is irradiated at a desired position on recording medium 124.

[0067] With this configuration, the manufacturing apparatus 10A of this embodiment can adjust the position so that the signal parallel light 118 and the cylindrical wave-like reference light 123 spreading from the line focus 127 are always irradiated onto the desired position on the recording medium 124, even when the orientation of the signal light plane mirror 117 and the reference light plane mirror 114 is changed using the signal light rotation stage 115, the goniostage 116, and the reference light rotation stage 113, and can reliably expose the interference fringes generated by the signal parallel light 118 and the cylindrical wave-like reference light 123 onto the recording medium 124.

[0068] The signal beam rotation stage 115, goniostage 116, reference beam rotation stage 113, cylindrical lens linear movement stage 120, reference beam linear movement stage 121, recording medium linear movement stage 125, and height adjustment stage 126 are all automatic stages having stepping motors or piezoelectric actuators (not shown), and under the control of the information processing device 20, adjust the angles of the reference beam plane mirror 114 and the signal beam plane mirror 117, or adjust the positions of the reference beam plane mirror 114, cylindrical lens system 122, and recording medium 124 in the xy plane, based on drive signals supplied from a stage drive circuit 130 via control lines (not shown). Note that the wavelength range of visible light is within a range of approximately 400 to 700 nm, and the longest wavelength is approximately twice the shortest wavelength. Therefore, it is sufficient that the reference beam rotation stage 113, signal beam rotation stage 115, and goniostage 116 are each rotatable within a range of approximately 10 to 20°. Furthermore, the specific configurations of the signal light rotation stage 115, gonio stage 116, linear movement stage 125, and height adjustment stage 126 are the same as those of conventional automatic stages, and therefore will not be described in detail.

[0069] The recording medium 124 is formed by applying a photosensitive material having sensitivity to the wavelength of the source beam SB to a predetermined thickness on a flat substrate made of a highly transmittance material such as glass, or by solely using a photosensitive material having a predetermined thickness, and when the signal parallel light 118 and the cylindrical wave-like reference light 123 are irradiated, the recording medium 124 records interference fringes generated by the interference between the two.

[0070] The stage driving circuit 130 generates driving signals based on control signals supplied from the information processing device 20 and supplies them to each of the stages 113, 115, 116, 120, 121, 125, and 126 to adjust the angles of the reference beam plane mirror 114 and the signal beam plane mirror 117, or to adjust the positions in the xy plane of the reference beam plane mirror 114, the cylindrical lens system 122, and the recording medium 124. The driving signals supplied by the stage driving circuit 130 to each of the stages 113 and the like may be in any format, and for example, a configuration may be adopted in which driving signals in a PWM (pulse wide modulation) format are supplied to drive motors and the like mounted on each of the stages 113, 115, 116, 120, 121, 125, and 126.

[0071] The information processing device 20 is a device such as a PC (personal computer), and when manufacturing a holographic diffraction grating HG using the manufacturing device 10A, it executes processing to control the operation of each stage and outputs a control signal to the stage driving circuit 130 according to the processing results.

[0072] In this embodiment, the stage drive circuit 130 is configured to drive the signal beam rotation stage 115, the goniostage 116, the reference beam rotation stage 113, the cylindrical lens linear translation stage 120, the reference beam linear translation stage 121, the recording medium linear translation stage 125, and the height adjustment stage 126 based on control signals supplied from the information processing device 20. By adjusting the positions and angles of these stages, the relative irradiation angles of the signal collimated beam 118 and the cylindrical wave-like reference beam 123 with respect to the recording medium 124 are changed, and the optical paths and optical path lengths of the signal beam SL and the reference beam RL are changed, thereby changing the spacing of the interference fringes formed by the signal collimated beam 118 and the cylindrical wave-like reference beam 123 spreading from the line focus 127 on the recording medium 124, thereby generating multiple interference fringes with different spacings, and multiplex-exposing the generated multiple interference fringes onto the recording medium 124. With this configuration, the manufacturing system 1A of this embodiment exposes multiple holographic diffraction gratings with different grating spacings onto the recording medium 124 while superimposing them. The extent and manner in which each stage is moved to achieve the grating spacing corresponding to each holographic diffraction grating will be described in detail later.

[0073] [A.3] Manufacturing principle of holographic diffraction grating HG in manufacturing equipment 10A Next, the manufacturing principle of the holographic diffraction grating HG in the manufacturing system 1A of this embodiment will be described with reference to Figures 1 and 2. Note that Figure 2 is a diagram for explaining interference fringes formed by interference between signal collimated light 118 formed in the manufacturing apparatus 10A of this embodiment and cylindrical wave-like reference light 123 spreading from a line focus 127.

[0074] First, when an arbitrary point on line focus 127 is defined as point 2 in xyz space, consider line 3, which is an arbitrary line in signal collimated light 118 within plane 1 (not shown) that includes point 2 and has the line of line focus 127 as its normal (see FIG. 2). Also, in xyz space, consider intersection 7 between line 4 extending from point 2 and line 6, which extends from an arbitrary point 5 on line 3 and is one of the perpendicular lines to line 3, as shown in FIG. 2. When the position of point 5 is changed while maintaining the orientation of line 6, point 7 moves on curve 9 such that the value (hereinafter referred to as "value 8") obtained by dividing the difference between the distance between point 2 and point 7 and the distance between point 5 and point 7 by the wavelength remains constant. When the value 8 is changed, a different curve 9' (not shown) is drawn, but each curve 9 included in the group of all curves 9, 9', 9", 9"', 9""... drawn when the value 8 is changed multiple times represents a curve that is equiphase in the interference fringes generated by the signal parallel light 118 generated from the source beam SB of a predetermined wavelength λ0 and the cylindrical wave-like reference light 123 spreading from the line focus 127.

[0075] Now, consider drawing the same group of curves 9, 9', 9", 9"', 9""... at different wavelengths λ'. By changing the orientation of lines 4 and 6 in the depth direction of plane 1, the same group of curves can be drawn at different wavelengths. This shows that even when a source beam SB of a wavelength λ' different from λ0 is used, interference fringes corresponding to wavelength λ0 can be formed simply by changing the orientations of lines 4 and 6. In other words, this shows that interference fringes corresponding to multiple wavelengths can be formed using a source beam SB of a single wavelength simply by adjusting the orientations of lines 4 and 6. In this case, if plane 1 is displaced in a direction perpendicular to plane 1, the locus drawn by point 2 will coincide with line focus 127, and the plane drawn by line 3 will coincide with a portion of the signal collimated light 118.

[0076] 2 is a part of the cylindrical wave-like reference light 123 spreading from an arbitrary point 2 on the line focus 127, the direction of the line 4 can be changed by rotating the reference light plane mirror 114 using the reference light rotation stage 113. On the other hand, the line 6 in FIG. 2 is parallel to the direction of the signal collimated light 118, so the direction of the line 6 can be changed by changing the direction of the signal light plane mirror 117 using the signal light rotation stage 115 and the goniostage 116.

[0077] From the above viewpoints, in the manufacturing apparatus 10A of this embodiment, the reference light rotation stage 113 is used to rotate the reference light plane mirror 114 to adjust the direction of the straight line 4, and the signal light rotation stage 115 and the goniostage 116 are used to change the direction of the signal light plane mirror 117 to adjust the direction of the straight line 6, and the relative irradiation angle of the cylindrical wave-like reference light 123 and the signal parallel light 118 spreading from the line focus 127 to the recording medium 124 is changed, thereby generating multiple interference fringes each having different intervals using a source beam SB of a single wavelength, and the generated multiple interference fringes are subjected to multiple exposure on the recording medium 124.

[0078] [A.4] Adjustment method for signal light rotation stage 115 and goniostage 116 Next, with reference to Figures 3 to 5, the relationship between the rotation angles of the signal light rotation stage 115 and the goniostage 116 in the manufacturing system 1A of this embodiment and the signal collimated light 118 will be explained, and a method for adjusting the signal light rotation stage 115 and the goniostage 116 will be explained. Note that Figure 3 shows the relationship between the rotation angles of the signal light rotation stage 115 and the goniostage 116 and the signal collimated light 118, with the exposure wavelength (i.e., the wavelength of the source beam SB) set to 532 nm, and the vertical angle θ v 3 is a graph showing the relationship between the rotation angle of the signal light rotation stage 115 and wavelength when the rotation angle is set to 10°. In FIG. 3, the horizontal angle θ hThe figure shows the relationship between the rotation angle of the signal light rotation stage 115 and the wavelength when the angle is set to 75°, 60°, 45°, 30°, and 15°, and also shows the relationship between the horizontal angle θ of the signal light and the horizontal angle θ of the diffracted light over the entire range of the corresponding wavelength λ, 400 nm to 700 nm. h 4 shows the driving range of the signal light rotation stage 115 when the signal light is rotated in the vertical direction at an angle θ = 30°. v 4A and 4B are diagrams showing the relationship between the rotation angle of the goniostage 116 for matching the vertical angle of the diffracted light and the horizontal angle θ h = 15°, and (b) λ = 400 nm, horizontal angle θ h = 60°, the rotation angle of the goniometer stage 116 and the vertical angle θ v The relationship between the wavelengths of the diffracted light and the vertical angle θ of the signal light is shown in the entire range of 400 to 700 nm. v = -10° to 10°. Furthermore, FIG. 5 shows the horizontal angle of the diffracted light in relation to the horizontal angle θ of the signal light over the entire range of the corresponding wavelength λ. h , vertical angle θ v 5 is a diagram showing the horizontal angle range of the signal collimated light 118 that changes as a result when the vertical angle θ v 10°, horizontal angle θ h The figure also shows the relationship between the horizontal angle θ of the corresponding wavelength λ and the wavelength when the angle is set to 75°, 60°, 45°, 30°, and 15°, and the horizontal angle θ of the signal light that changes when the signal light rotation stage 115 and the goniostage 116 are driven so that the horizontal angle of the diffracted light in the entire range of the corresponding wavelength λ, 400 nm to 700 nm, is 30 degrees. h The range is shown by shading. h It can be seen that when is changed from 15° to 60°, the horizontal angle range of the diffracted light over the entire corresponding wavelength λ range of 400 nm to 700 nm becomes approximately 20° to 40°.

[0079] First, the coordinates of the reference point in the recording medium 124 in the xyz space are set to (x0, y0, z0), the coordinates of the reference point in the line focus 127 to (x1, y1, z1), the coordinates of the rotation center in the signal light plane mirror 117 to (x2, y2, z2), the coordinates of the reference point in the cylindrical lens system 122 to (x3, y3, z3=z1), the coordinates of the rotation center in the reference light plane mirror 114 to (x4, y4, z4=z1), and the coordinates of the reference point in the beam splitter 112 to (x5, y5, z5=z1), and the traveling direction vector of the signal light SL is set to When the rotation angle of the signal beam rotation stage 115 and the goniostage 116 is set to 0°, the normal vector of the signal beam plane mirror 117 is set to (1,0,0), the normal vector of the reference beam plane mirror 114 is set to (-1,0,0) when the rotation angle of the reference beam rotation stage 113 is set to 0°, and y1=y2 is set, the optical path length l in the x-axis direction from the rotation center of the signal beam plane mirror 117 to the reference point on the recording medium 124 is x and the optical path length in the z-axis direction l z are expressed by the following equations 3 and 4, respectively.

[0080]

number

[0081]

number

[0082] In addition, the optical path length in the x direction (i.e., x0-x1) between the reference point coordinates (x1, y1, z1) on the line focus 127 and the reference point coordinates (x0, y0, z0) on the recording medium 124, and the above l z The optical path length d is defined by the following equations 5 to 7, which show the difference between the above values.

[0083]

number

[0084]

number

[0085]

number

[0086] Here, d indicates a fixed condition for obtaining curve 9, and represents the projection of the optical path difference onto plane 1. In this case, the optical path length l, which is normalized as 1 when the projection of the optical path difference from the rotation center (x2, y2, z2) of the signal light plane mirror 117 to the reference point (x0, y0, z0) of the recording medium 124 onto plane 1, can be calculated using the following equations 8 and 9.

[0087]

number

[0088]

number

[0089] Here, z' is a parameter for moving point 5 on line 3, and when z'=0, it indicates the rotation center (x2, y2, z2) of signal light plane mirror 117. In addition, if y=y0 is set at this time, the positions x and z through which curve 9 formed by the surface at any y=y0 passes are each expressed by the following formula 10, and form a uniform curved surface in the y direction.

[0090]

number

[0091] Here, when the z-axis rotation angle of the reference light plane mirror 114 by the reference light rotation stage 113 is Δφ1, the z-axis rotation angle of the signal light plane mirror 117 by the signal light rotation stage 115 is Δφ2, and the rotation angle of the goniostage 116 is Δθ, the direction vector of the signal collimated light 118 is expressed by Equation 11, while the direction vector of the cylindrical wave-like reference light 123 spreading from the line focus 127 is expressed by Equation 12.

[0092]

number

[0093]

number

[0094] Furthermore, if it is desired to generate interference fringes for a wavelength different from that of the source beam SB used for exposure, the cylindrical wave-like reference light 123 and the signal parallel light 118 from the line focus 127 must be rotated around the rotation axis shown in the following equation 13.

[0095]

number

[0096] Here, when changing the direction of the signal parallel light 118 to the direction expressed by equations 14 and 15, it is necessary to change the rotation angle Δφ2 of the signal light rotation stage 115 according to equation 16, and it is also necessary to change the rotation angle Δθ of the goniostage 116 according to equation 17.

[0097]

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[0098]

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[0099]

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[0100]

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[0101] Therefore, in the manufacturing system 1A of this embodiment, the information processing device 20 calculates the rotation angles Δφ2 and Δθ of the signal light rotation stage 115 and the goniostage 116 based on the above equations 16 and 17, and supplies a control signal to the stage driving circuit 130 so that the angles of the signal light rotation stage 115 and the goniostage 116 are set to these angles, thereby adjusting the angles of the signal light rotation stage 115 and the goniostage 116.

[0102] At this time, in the manufacturing system 1A, the rotation angle Δφ2 of the signal light rotation stage 115 and the wavelength are v is set to 10°, and the horizontal angle θ h When the horizontal angle θ in Fig. 3 is set to 75°, 60°, 45°, 30°, and 15°, h Therefore, the rotation angle Δφ2 of the signal beam rotation stage 115 is adjusted so that it is on the corresponding curve according to the corresponding wavelength of the holographic diffraction grating to be manufactured.

[0103] At this time, in the manufacturing system 1A, the rotation angle Δθ of the goniostage 116 and the vertical angle θ of the signal light v The relationship shown in Figure 4 holds when the corresponding wavelength range is 400 to 700 nm and the vertical angle of the diffracted light is -10° to 10°. Therefore, depending on the corresponding wavelength of the holographic diffraction grating to be manufactured, λ = 400 nm, θ h = 60° line and λ = 700 nm, θ h The rotation angle Δθ of the goniostage 116 is adjusted so that the wavelength falls on a line (not shown) of the corresponding wavelength between the lines of Δθ = 15°.

[0104] Here, as shown in FIG. 5, for example, θ h When the signal light rotation stage 115 and the goniostage 116 are driven so that the angle of the diffracted light in the corresponding wavelength λ range of 400 nm to 700 nm is within the range of 15° to 60°, h The inventors' simulation experiments have revealed that the angular range of the signal beam rotation stage 115 and the goniostage 116 is approximately 20° between 20° and 40°, and by changing the rotation angles of the signal beam rotation stage 115 and the goniostage 116 within this angular range, a holographic diffraction grating HG having the desired characteristics can be manufactured.

[0105] Furthermore, as shown in FIG. 4, for the goniostage 116, by displacing the angle of the signal light plane mirror 117 within an angle range of about 10° (approximately −7° to 7°), a holographic diffraction grating HG having the desired characteristics can be manufactured.

[0106] Within this angle range, when the goniostage 116 is used to displace the irradiation angle of the signal collimated light 118 in the z-axis direction while exposing interference fringes onto the recording medium 124 to produce a holographic diffraction grating HG, a transmissive display panel using the produced holographic diffraction grating HG can ensure a viewing angle of approximately 20° in the vertical direction.

[0107] The wavelength range is 400 to 700 nm, and the vertical angle is θ v =10°, horizontal angle θ h Considering that a holographic diffraction grating for diffracting parallel light at θ = 30° is exposed with a source beam SB of 532 nm wavelength, the driving ranges of the signal beam rotation stage 115 and the reference beam rotation stage 113 are as shown by the shaded areas in FIGS. 3 and 6 for the corresponding wavelengths of 400 to 700 nm, and the driving range of the goniostage 116 is as shown by the shaded areas in FIG. 4. v λ = 400 nm, θ = 10° h = 60° and λ = 700 nm, θ hThe inventor's simulation results have revealed that the angle is between the lines of θ = 15° (approximately 5° to 7°). Therefore, when each stage 115 and gonio-stage 116 are driven within the shaded area in FIG. 3 and the range of approximately 5° to 7°, the horizontal angle range of the signal collimated light 118 is approximately 20° to 40°, as shown by the shaded area in FIG. 5. In other words, this means that for a wavelength of 532 nm, a diffraction grating is multiplexed to diffract collimated light within a horizontal angle range of approximately 20° to 40°. If it is desired to diffract collimated light with angles within this range for all light with wavelengths of 400 to 700 nm, attention should be paid to the upper limit (40°) of light with the shortest wavelength (400 nm) and the lower limit (20°) of light with the longest wavelength (700 nm) in FIG. 5. When the angle θ is near the upper limit (40°) of light with the shortest wavelength (400 nm) in FIG. 5, h = 60° curve, and the θ h = 60°. Therefore, the horizontal angle range of the diffracted light is approximately 20° to 40°, and if the angle range of the signal collimated light 118 with a wavelength of 532 nm is determined to satisfy this value, it will be approximately 15° to 60°, and the corresponding drive range of each of the stages 113, 115, and 116 is determined. Furthermore, the drive range of each of the stages 113, 115, and 116 can be determined in a similar manner for other vertical angles.

[0108] [A.5] Adjustment method for reference beam rotation stage 113 Next, a method for adjusting the reference beam rotation stage 113 will be described with reference to Fig. 6, which explains the relationship between the cylindrical wave-like reference beam 123 spreading from the line focus 127 in the manufacturing system 1A of this embodiment and the rotation angle of the reference beam rotation stage 113. Note that Fig. 6 assumes that the wavelength of the source beam SB is 532 nm and the vertical angle θ v 1 is a graph showing the relationship between the rotation angle Δφ1 of the reference beam rotation stage 113 and the corresponding wavelength when the horizontal angle θ h 6 shows the relationship between the rotation angle and the wavelength when the rotation angle θ is set to 75°, 60°, 45°, 30°, and 15°. hThe driving range of each reference beam rotary stage 113 when the angle .theta.=30.degree. is indicated by hatching.

[0109] In the manufacturing apparatus 10A of this embodiment, in order to change the direction of the optical axis of the cylindrical wave-like reference light 123 spreading from the line focus 127 to the direction shown by equations 18 to 20, it is necessary to change the rotation angle Δφ1 of the reference light rotation stage 113 in accordance with equation 21.

[0110]

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[0111]

number

[0112]

number

[0113]

number

[0114] Therefore, in the manufacturing system 1A of this embodiment, a configuration is adopted in which the information processing device 20 calculates the rotation angle Δφ1 of the reference light rotation stage 113 according to equation 21, and supplies a control signal to the stage driving circuit 130 so that the rotation angle of the reference light rotation stage 113 is set to the rotation angle Δφ1, thereby adjusting the angle of the reference light rotation stage 113.

[0115] At this time, in the manufacturing system 1A, the rotation angle Δφ1 of the reference beam rotation stage 113 and the wavelength are determined by the vertical angle θ v is set to 10°, and the horizontal angle θ h When the horizontal angle θ is set to 75°, 60°, 45°, 30°, and 15°, hSince a relationship shown by the curve corresponding to the equations (18) and (20) holds, the rotation angle Δφ1 of the reference beam rotation stage 113 is adjusted so that it lies on the corresponding curve depending on the wavelength of the holographic diffraction grating to be manufactured. With this configuration, in the manufacturing apparatus 10A of this embodiment, the direction of the cylindrical wave-like reference beam 123 spreading from the line focus 127 can be adjusted to the direction shown by equations (18) to (20). Note that the horizontal angle range of the reference beam rotation stage 113 is also approximately 10°, that is, from 3° to 13°, as shown in FIG. 6 . Therefore, by adjusting the horizontal angles of the signal beam rotation stage 115, the goniostage 116, and the reference beam rotation stage 113 within a range of approximately 10° to 20°, a holographic diffraction grating HG that achieves the desired function can be manufactured.

[0116] [A.6] Exposure method When manufacturing a holographic diffraction grating HG using the manufacturing system 1A of this embodiment, first, the relative position of the line focus 127 with respect to the recording medium 124 is determined, and then the direction of the diffracted light generated when the manufactured holographic diffraction grating HG is irradiated with light is determined in order to set the characteristics of the holographic diffraction grating HG manufactured by the manufacturing system 1A. For example, the horizontal angle θ of the diffracted light in the holographic diffraction grating HG is determined. h and the vertical angle θ v When is determined as in the following equations 22 and 23, the direction of the signal collimated light 118 is determined as in equation 24. The direction of the diffracted light may be set by an operator using the information processing device 20.

[0117]

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[0118]

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[0119]

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[0120] From this, the reference direction (u2, 0, w2) and the rotation axis (n x ,n y ,n z ), the angle θ0 of the diffracted light seen from this reference direction can be calculated using Equation 25.

[0121]

number

[0122] The wavelength of the source beam SB used for exposure is λ0, and the signal parallel light 118 and the cylindrical wave-like reference light 123 spreading from the line focus 127 are superimposed and irradiated onto the recording medium 124, thereby exposing the recording medium 124 to interference fringes.

[0123] When a cylindrical wave-like reference light 123 expanding from a line focus 127 is irradiated onto a holographic diffraction grating HG manufactured by this method, light having the same optical axis as the optical axis of the signal parallel light 118 is diffracted, whereas when light having the same optical axis as the signal parallel light 118 but traveling in the opposite direction is irradiated onto the diffraction grating, the light is focused on the same straight line as the line focus 127.

[0124] For example, when the above function is to be provided for an arbitrary wavelength λ, the information processing device 20 calculates the direction of the signal collimated light 118 based on Equation 26 so that Equation 26 is satisfied.

[0125]

number

[0126] Next, in the manufacturing system 1A of this embodiment, the information processing device 20 calculates the rotation angle Δφ2 of the signal light rotation stage 115 according to the above equation 16 so that the signal parallel light 118 is irradiated in the direction calculated by equation 26, and calculates the rotation angle Δθ of the goniostage 116 according to equation 17.

[0127] Then, in order to align the angles of the signal light rotation stage 115 and the goniostage 116 with the rotation angle Δφ2 of the signal light rotation stage 115 and the rotation angle Δθ of the goniostage 116 calculated in this manner, the information processing device 20 outputs a control signal to the stage driving circuit 130 to change the rotation angle of the signal light rotation stage 115 to the calculated Δφ2 as described above, and change the rotation angle of the goniostage 116 to Δθ.

[0128] Next, the information processing device 20 sets the direction of the cylindrical wave-like reference light 123 spreading from the line focus 127, as shown in Equation 12, as u1 = -u2, v1 = v2, and w1 = -w2. At this time, the cylindrical wave-like reference light 123 spreading from the line focus 127 can be rotated in the opposite direction to the signal collimated light 118. That is, if the direction of the signal collimated light 118 is θ1 and the direction of the cylindrical wave-like reference light 123 is θ2, then θ1 = -θ2 can be set. To achieve this, the information processing device 20 calculates the rotation angle Δφ1 of the reference beam rotation stage 113 according to Equation 21.

[0129] After calculating the rotation angle Δφ1 of the reference beam rotation stage 113 in this way, the information processing device 20 outputs a control signal to the stage driving circuit 130 to change the rotation angle of the reference beam rotation stage 113 to Δφ1.

[0130] Next, the information processing device 20 executes processing for adjusting the positions of the recording medium linear movement stage 125, the height adjustment stage 126, the cylindrical lens linear movement stage 120, and the reference light linear movement stage 121. At this time, the information processing device 20 calculates the movement distances of the recording medium linear movement stage 125, the height adjustment stage 126, the cylindrical lens linear movement stage 120, and the reference light linear movement stage 121, respectively, by the following method, and adjusts the positions of the linear movement stages 120, 121, 125, and the height adjustment stage 126 based on the calculated values.

[0131] (1) Adjustment method for the recording medium linear movement stage 125 and the height adjustment stage 126 With regard to the recording medium linear movement stage 125, the information processing device 20 calculates Δy0 shown in equation 27-1, and then outputs a control signal to the stage driving circuit 130 to move the position of the recording medium linear movement stage 125 in the y-axis direction by Δy0, and with regard to the height adjustment stage 126, calculates Δz0 shown in equation 27-2, and then outputs a control signal to the stage driving circuit 130 to move the height of the height adjustment stage 126 in the z-axis direction by Δz0.

[0132]

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[0133]

number

[0134] (2) Adjustment method for the linear translation stage 120 for cylindrical lenses Furthermore, with regard to the linear movement stage 120 for the cylindrical lens, the information processing device 20 calculates Δy3 shown in Equation 28, and then outputs a control signal to the stage driving circuit 130 to move the position of the linear movement stage 125 for the recording medium in the y-axis direction by Δy3.

[0135]

number

[0136] (3) Adjustment method of the reference beam linear movement stage 121 In response to this, the information processing device 20 calculates Δx4 shown in Equation 29 for the reference light linear movement stage 121, and then outputs a control signal to the stage driving circuit 130 to move the position of the recording medium linear movement stage 125 by Δx4 in the x-axis direction and by Δy4 in the y-axis direction.

[0137]

number

[0138] When the position adjustment of each stage 113, 115, 120, 125, 126, and 121 is completed by the above method, the optical system in manufacturing apparatus 10A moves to an arrangement state, for example, as shown in Fig. 9, and signal parallel light 118 and cylindrical wave-like reference light 123 spreading from line focus 127 are irradiated onto recording medium 124 at a relative irradiation angle determined by the arrangement state, and interference fringes generated by interference between the two light beams 118 and 123 are exposed onto recording medium 124. As a result, a holographic diffraction grating corresponding to one wavelength (for example, λ1) is formed on recording medium 124.

[0139] [A.7] Operation during manufacturing of holographic diffraction grating HG in manufacturing system 1A Next, the operation of manufacturing the holographic diffraction grating HG in the manufacturing system 1A of this embodiment will be described with reference to Figures 7 to 10. Figures 7 and 8 are flowcharts showing the processing executed by the information processing device 20 in the manufacturing system 1A of this embodiment, and Figures 9 and 10 are diagrams showing the changing state of the optical path system of the manufacturing apparatus 10A when exposing two types of holographic diffraction gratings with different grating spacings.

[0140] First, in the manufacturing system 1A of this embodiment, an operator determines the relative position of the line focus 127 with respect to the recording medium 124 and the direction of the diffracted light generated when a predetermined light is irradiated onto the holographic diffraction grating HG manufactured by the manufacturing system 1A, and inputs the necessary information into the information processing device 20. In order to expose a holographic diffraction grating corresponding to a wavelength λ1 in the visible light region onto the recording medium 124, the information processing device 20 sets λ to the shortest wavelength λ1 in the visible light region (e.g., 400 nm) (step S1).

[0141] Next, the information processing device 20 determines the direction of the signal collimated light 118 according to the above equation 26 (step S2).

[0142] Once the direction of the signal collimated light 118 has been determined in this manner, the information processing device 20 calculates the rotation angles Δφ2 and Δθ of the signal light rotation stage 115 and the goniostage 116 based on the determined direction and the above equations 16 and 17 (step S3), and supplies a control signal to the stage driving circuit 130 based on the calculated rotation angles Δφ2 and Δθ to adjust the rotation angles of the signal light rotation stage 115 and the goniostage 116 to the calculated rotation angles Δφ2 and Δθ (step S4).

[0143] Next, the information processing device 20 calculates the rotation angle Δφ1 of the reference light rotation stage 113 based on the above equation 21 (step S5), and supplies a control signal to the stage driving circuit 130 based on the calculated rotation angle Δφ1 to adjust the rotation angle of the reference light rotation stage 113 to the calculated rotation angle Δφ1 (step S6).

[0144] Next, the information processing device 20 executes a process of calculating the movement amounts of the linear movement stages 120, 121, and 125 and the height adjustment stage 126 (step S7). At this time, the information processing device 20 calculates the movement amount Δy0 of the recording medium linear movement stage 125 based on the above equation 27-1, and calculates the movement amount Δz0 of the height adjustment stage 126 based on equation 27-2. At this time, the information processing device 20 also calculates the movement amount Δy3 of the cylindrical lens linear movement stage 120 based on equation 28, and further calculates the movement amounts Δx4 and Δy4 of the reference beam linear movement stage 121 based on equation 29 (step S7).

[0145] After calculating the values ​​of Δy0, Δz0, Δy3, Δx4, and Δy4 in this manner, the information processing device 20 outputs a control signal to the stage driving circuit 130 based on the calculated movement amounts Δy0, Δy3, Δx4, and Δy4, and (1) moves the recording medium linear movement stage 125 in the y-axis direction by Δy0, (2) moves the height adjustment stage 126 in the height direction (z-axis direction) by Δz0, (3) moves the cylindrical lens linear movement stage 120 in the y-axis direction by Δy3, and (4) moves the reference light linear movement stage 121 in the x-axis direction by Δx4 and in the y-axis direction by Δy4, thereby adjusting the positions of the recording medium 124, the reference light plane mirror 114, and the cylindrical lens system 122 to the corresponding positions (step S8).

[0146] When the above procedure brings the optical system of the manufacturing apparatus 10A into a state that matches the exposure of the holographic diffraction grating corresponding to wavelength λ1, the information processing apparatus 20 outputs a control signal to the light source 111 to irradiate the source beam SB for a predetermined exposure time, generating interference fringes corresponding to wavelength λ1 and exposing the holographic diffraction grating corresponding to wavelength λ1 onto the recording medium 124 (step S9).

[0147] Next, the information processing device 20 is in a state where it determines whether or not exposure of the holographic diffraction gratings corresponding to all interference fringes to be multiple-exposed on the recording medium 124 has been completed (step S10). If it determines that exposure has not been completed (step S10: No), it changes the wavelength to be exposed by Δλ by λ n =λ n-1 +Δλ (step S11). For example, when the exposure of the holographic diffraction grating corresponding to the wavelength λ1 is completed, λ n =λ1+Δλ. The specific value of Δλ is arbitrary and may be set to, for example, 10 nm. The point is that an appropriate value should be set depending on the wavelength at which the function of the holographic diffraction grating HG is desired to be realized.

[0148] In this way, in step S11, λ n =λ n-1After setting it to +Δλ, the information processing device 20 returns the process to step S2 and repeats the processes of steps S2 to S9 to expose a holographic diffraction grating corresponding to the next wavelength (for example, λ1+Δλ) onto the recording medium 124.

[0149] Then, the information processing device 20 determines whether exposure of the holographic diffraction gratings corresponding to all wavelengths has been completed (step S10), and repeats the processing of steps S2 to S11 described above until exposure of the holographic diffraction gratings corresponding to all wavelengths has been completed, and ends the processing when exposure of the holographic diffraction gratings corresponding to all wavelengths has been completed.

[0150] At this time, in the optical system of the manufacturing apparatus 10A of this embodiment, the positions and angles of the reference beam plane mirror 114, the signal beam plane mirror 117, the cylindrical lens system 122, and the recording medium 124 change to match the wavelength of the holographic diffraction grating to be exposed, as shown in Figures 9 and 10, and while the state of the optical system changes, a holographic diffraction grating corresponding to that state is exposed onto the recording medium 124.

[0151] In the manufacturing system 1A of this embodiment, by performing such processing, a plurality of holographic diffraction gratings, each having a different grating spacing and each realizing a target function for a different wavelength, are multiplexed and exposed onto the recording medium 124.

[0152] As described above, in the manufacturing system 1A of this embodiment, a single-wavelength source beam SB is split into a signal beam SL and a reference beam RL by a beam splitter 112, and each of these beams is irradiated onto a recording medium 124 via a different optical path. The cylindrical wave-like reference beam 123 spreading from a line focus 127 interferes with the signal parallel beam 118, generating interference fringes that are then exposed onto the recording medium 124, thereby manufacturing a holographic diffraction grating HG.

[0153] Furthermore, manufacturing system 1A of this embodiment is configured to perform multiple exposure of multiple holographic diffraction gratings, each having a different grating spacing, on recording medium 124 while changing the relative angle at which signal collimated beam 118 and cylindrical wave-like reference beam 123 are irradiated onto recording medium 124 by adjusting the rotation angles of reference beam rotation stage 113, signal beam rotation stage 115, and goniostage 116. With this configuration, manufacturing system 1A of this embodiment can manufacture holographic diffraction gratings HG that can achieve a desired function over the entire visible light range using source beam SB of a single wavelength. As a result, manufacturing system 1A of this embodiment can manufacture holographic diffraction gratings HG that can achieve a desired function over the entire visible light range at low cost, without the need to provide manufacturing apparatus 10A with light sources that emit source beams SB of multiple wavelengths and optical systems for those wavelengths.

[0154] [A.8] Structure of the holographic diffraction grating HG manufactured by the manufacturing system 1A of this embodiment Next, a specific structure of the holographic diffraction grating HG manufactured by the manufacturing system 1A of this embodiment will be described with reference to FIG. 11. Note that FIG. 11 illustrates an example of the three-dimensional structure of the holographic diffraction grating HG manufactured by the manufacturing system 1A of this embodiment. (A) and (B) show examples of the structure of holographic diffraction gratings HG1 and HG2 when irradiated with white parallel light and line-focused near the center of the holographic diffraction grating HG in the vertical direction (i.e., the z-axis direction) of the drawing, and (C) and (D) show examples of the structure of holographic diffraction gratings HG3 and HG4 when line-focused toward the bottom of the holographic diffraction grating HG (note that in this specification, each of the holographic diffraction gratings HG1 to HG4 will be referred to as the "holographic diffraction grating HG" unless otherwise specified). Furthermore, the combination of (A) and (B) and the combination of (C) and (D) each illustrate an example of the structure of a holographic diffraction grating HG corresponding to a different wavelength.

[0155] (1) Example of a structure in which white parallel light is focused near the center of the holographic diffraction grating HG 11(A) and 11(B), the holographic diffraction gratings HG1 and 2 in this case are formed by stacking multiple parabolic cylindrical layers centered on the center of the holographic diffraction gratings HG1 and 2 along a cross section in the vertical direction (i.e., the z-axis direction) (i.e., the cross section seen in the foreground in each of the views in FIG. 11), and exhibit a layer structure reminiscent of the growth rings of a tree stump. Each layer has a different refractive index and is nearly identical in shape, with similar interference fringes formed continuously across the entire surface of each layer.

[0156] In particular, when focusing white parallel light near the center, in order to achieve this function, a three-dimensional structure is formed in which layers having approximately parabolic cylindrical shapes with different curvatures are stacked on top of each other from the focusing position (i.e., a position a predetermined distance away from the center of the holographic diffraction gratings HG1 and HG2 in the z direction).

[0157] (2) Example of a structure in which white parallel light is focused downward on the holographic diffraction grating HG In this case, the holographic diffraction gratings HG3 and HG4 have a structure in which multiple parabolic cylindrical layers, each of which has a nearly identical shape along the vertical cross section, are stacked one on top of the other, as shown in Figures 11(C) and 11(D).

[0158] However, in this case, because the light-focusing position is below the holographic diffraction gratings HG3 and 4, the shape of each layer differs from that in the case where the light is focused near the center as described above, and the center of the parabolic cylindrical layer is shifted below the holographic diffraction gratings HG3 and 4 so that the white collimated light is focused below the holographic diffraction grating HG. Furthermore, because each layer has a shape that forms part of a substantially cylindrical shape, each layer functions as a cylindrical lens, and the holographic diffraction grating HG as a whole functions as a cylindrical lens with a uniaxial curvature.

[0159] The holographic diffraction grating HG of this embodiment, having the above structure, has a layer shape corresponding to any of the focusing positions, and when the number of layers is changed, focusing characteristics for light on the short wavelength side are realized when the number of layers is large (for example, holographic diffraction gratings HG1 and 3 in the example shown in FIG. 11), and when the number of layers is small (for example, holographic diffraction gratings HG2 and HG4 in the example shown in FIG. 11), focusing characteristics for light on the long wavelength side are realized. Then, in the manufacturing system 1A of this embodiment, holographic diffraction gratings corresponding to a plurality of interference fringes corresponding to different wavelengths are multiple-exposed, thereby manufacturing a holographic diffraction grating HG having a structure in which multiple layers are stacked as shown in FIG. 11.

[0160] With this configuration, the holographic diffraction grating HG manufactured by manufacturing system 1A of this embodiment is configured so that when white parallel light is incident from the same direction as the optical axis of signal parallel light 118, the light is focused on line focus 127, and when white light is incident from the same direction as cylindrical wave-like reference light 123 spreading from line focus 127, light having the same optical axis as the optical axis of signal parallel light 118 is diffracted. In other words, the holographic diffraction grating HG manufactured by manufacturing system 1A of this embodiment achieves a function similar to that of a cylindrical lens having a uniaxial curvature. Note that a method for manufacturing holographic diffraction gratings HG with different layer shapes (i.e., holographic diffraction gratings HG with different focusing positions) will be described in the section on Modification Example 3.

[0161] [B] Variation [B.1] Variation 1 In the first embodiment described above, the manufacturing apparatus 10A and the information processing apparatus 20 are configured as separate devices and are connected to each other by wire or wirelessly. However, the manufacturing apparatus 10A may be provided with a control unit including a CPU (Central Processing Unit) and ROM / RAM, and the control unit may perform the same functions as the information processing apparatus 20. In this case, an operation unit including a keyboard or the like may be provided, and the control unit may execute the same processes as those shown in FIGS. 7 and 8 while setting the direction of diffracted light in the holographic diffraction grating HG to be manufactured in response to input operations made by an operator on the operation unit. With this configuration, the manufacturing apparatus 10A alone can manufacture a holographic diffraction grating HG that exhibits the desired function across the entire visible light range.

[0162] [B.2] Variation 2 In the above embodiment, the case of manufacturing a holographic diffraction grating HG has been described as an example, but the present invention can also be applied to the manufacture of a light guide plate having a holographic diffraction grating HG.

[0163] In this case, the recording medium 124 may be provided in a transparent substrate, and the holographic diffraction grating HG may be multiple-exposed onto the recording medium 124 in the substrate. In this case, a prism may be placed on the first height adjustment stage 126 together with the recording medium 124, and the prism may be used to irradiate the recording medium 124 with the signal collimated beam 118 and the cylindrical wave-like reference beam 123. Note that other configurations and operations are similar to those of the first embodiment, and therefore will not be described in detail.

[0164] The holographic light guide plate HGLP manufactured by this method can be used as an optical combiner for a transmission-type HMD or head-up display. For example, a configuration example in which this holographic light guide plate HGLP is used in a transmission-type HMD 30 is shown in Figures 12 to 14.

[0165] As shown in FIG. 12, in a transmission-type HMD 30 using this holographic light guide plate HGLP, a prism-shaped light entrance portion LE is provided at the end of the holographic light guide plate HGLP, and image light VL is irradiated from this light entrance portion LE by a projector P.

[0166] The image light VL emitted from the projector P is repeatedly totally reflected at the boundary surfaces of the holographic light guide plate HGLP, travels through the holographic light guide plate HGLP, and reaches the edge. During the repeated total reflection process, the image light VL is diffracted by the holographic diffraction grating HG formed inside the holographic light guide plate HGLP and enters the user's eye EY. The external light OL passes through the holographic light guide plate HGLP and enters the user's eye EY as is. As a result, the user visually recognizes the external scenery and the information (text, images, colors, etc.) displayed by the image light VL superimposed on each other, and the user perceives the information as a virtual image.

[0167] Here, the transmissive HMD 30 uses a lens L to focus image light VL from a projector P at infinity, thereby enabling the user's eye EY to see a virtual image from infinity. A certain distance is required between the user's eye EY and the transmissive HMD 30. To achieve a wide FOV (Field of View), the area (eyebox) where the image light VL guided through the holographic light guide plate HGLP is reflected toward the eye EY must be widened. As shown in FIG. 13 , if a diffractive optical element functioning as a plane mirror is configured inside the holographic light guide plate HGLP using an existing method, it is easy to widen the eyebox because the diffractive optical element simply reflects a portion of the image light VL in the waveguiding direction. However, widening the eyebox in a direction perpendicular to the waveguiding direction requires two-stage diffraction or another function.

[0168] By employing the method of this modification, a holographic diffraction grating HG functioning as a curved mirror can be fabricated within the holographic light guide plate HGLP, as shown in FIG. 14 . In this case, a method can be employed in which the image light VL from the projector P is imaged horizontally with a cylindrical lens CL to form an image at infinity. The vertical direction spreads from the pixel position and also spreads within the waveguide. Thus, by fabricating the holographic light guide plate HGLP having the holographic diffraction grating HG functioning as the curved mirror of FIG. 14 using the method of this modification (i.e., a method of fabricating the holographic light guide plate HGLP by mounting a prism together with the recording medium 124 on the height adjustment stage 126), the light can be spread within the waveguide in the vertical direction. Furthermore, the light spread within the waveguide is diffracted into parallel light with a vertical angle corresponding to the vertical pixel position due to the diffraction characteristics of the holographic diffraction grating HG, making it possible to fabricate a see-through HMD 30 with a wide eyebox, a wide FOV, and high practicality.

[0169] [B.3] Variation 3 In the above embodiment, in order to achieve the desired function for light across the entire visible light range, a configuration was adopted in which a plurality of interference fringes, each with a different grating interval, were generated and the plurality of interference fringes were multiple-exposed onto recording medium 124 to manufacture the holographic diffraction grating HG, but a plurality of holographic diffraction gratings HG each achieving a different function may also be multiple-exposed onto recording medium 124. For example, a configuration may be adopted in which holographic diffraction gratings HG with different light-focusing positions, such as holographic diffraction gratings HG1 and 2 and holographic diffraction gratings HG3 and 4 in FIG. 11 above, are multiple-exposed onto recording medium 124.

[0170] In this case, when the operator determines the diffraction direction of the diffracted light before starting the process of Figure 7, the operator sets the direction of the diffracted light to be set to match the focusing position, and once using this setting, the holographic diffraction grating HG (e.g., holographic diffraction grating HG1 or 2) is exposed onto recording medium 124. Then, after exposure of the holographic diffraction grating HG is completed, the direction of the diffracted light corresponding to the new focusing position is set again to expose a holographic diffraction grating HG with a different focusing position (e.g., holographic diffraction grating HG3 or 4), and the holographic diffraction grating HG corresponding to the direction of the diffracted light is once again exposed onto recording medium 124. Thereafter, multiple interference fringes are generated while repeatedly resetting the direction of the diffracted light corresponding to each focusing position, and the generated multiple interference fringes are multiple-exposed onto recording medium 124.

[0171] In this case, a holographic diffraction grating HG is manufactured that has a structure in which a plurality of holographic diffraction gratings HG having different layer shapes depending on the light-collecting position are multiplex-exposed, as shown in FIG.

[0172] In this modified example, the holographic diffraction grating HG may be multiple-exposed with different focusing positions for only some wavelengths, or the holographic diffraction grating HG may be multiple-exposed with different focusing positions for the entire visible light range.

[0173] To impart the characteristic of focusing only light of certain wavelengths at different positions, the value of λ in Equation 26 can be fixed at the wavelengths in question, while changing the direction of the diffracted light to generate interference fringes multiple times and perform multiple exposures on the holographic diffraction grating HG.

[0174] On the other hand, if it is desired to have the property of focusing light in the entire visible light range at different focusing positions, the processes of FIGS. 7 and 8 can be repeated each time the direction of the diffracted light is reset, so that multiple holographic diffraction gratings HG corresponding to the focusing positions are multiple-exposed onto the recording medium 124.

[0175] [B.4] Variation 4 In the above embodiment, as shown in FIG. 11 , an example of a structure in which a plurality of parabolic cylindrical layers functioning as grating curved surfaces are formed within the recording medium 124 has been described. However, even if a configuration is adopted in which a plurality of diffraction planes, each having a different refractive index and each oriented in a different direction, are exposed onto the recording medium 124, it is possible to achieve the same function as the holographic diffraction grating HG configured as shown in FIG. 11 .

[0176] In this case, the manufacturing apparatus 10A does not need to be provided with a cylindrical lens system 122, but the reference parallel light 119 is irradiated directly onto the recording medium 124, and the reference parallel light 119 and the signal parallel light 118 are made to interfere with each other while changing the irradiation angle, and the resulting multiple interference fringes are exposed onto the recording medium 124.

[0177] Furthermore, a plurality of holographic diffraction gratings HG corresponding to the respective wavelengths may be configured to be formed two-dimensionally on the surface of the recording medium 124 .

[0178] [C] Second embodiment [C.1] Configuration of manufacturing system 1B according to the second embodiment Next, a second embodiment of a holographic optical element manufacturing apparatus according to the present invention will be described with reference to Figure 15. Figure 15 is a system configuration diagram showing the configuration of a manufacturing system 1B of this embodiment. In Figure 15, the same components as in Figure 1 are designated by the same reference numerals. Therefore, unless otherwise specified, the components in Figure 15 designated by the same reference numerals as in Figure 1 will be described as having the same configuration and function as those in the first embodiment and performing the same operations.

[0179] The manufacturing apparatus 10B constituting the manufacturing system 1B of this embodiment employs a configuration in which the beam splitter 112 is configured using a PBS and splits P-polarized light into signal light SL and S-polarized light into reference light RL according to the polarization direction. Furthermore, the manufacturing apparatus 10B of this embodiment employs a configuration in which a λ / 2 plate (not shown) is provided between the beam splitter 112 and the signal light plane mirror 117, and the signal light SL is irradiated onto the signal light plane mirror 117 while the reference light RL is irradiated onto the reference light plane mirror 114 while aligning the polarization directions of the signal light SL and the reference light RL. Incidentally, the beam splitter 112 of the manufacturing apparatus 10B of this embodiment may also be configured using a half mirror.

[0180] Furthermore, the manufacturing apparatus 10B of this embodiment employs a configuration in which a slit member (not shown) is added between the cylindrical lens system 122 and the recording medium 124, and the cylindrical wave-like reference light 123 generated after passing through the cylindrical lens system 122 forms a line focus 127 when passing through a slit portion provided in this slit member, and is configured to irradiate the recording medium 124 while spreading from the slit portion (i.e., the line focus 127). With this configuration, the manufacturing apparatus 10B of this embodiment can create a narrow line focus 127, thereby improving the accuracy of irradiating the recording medium 124 with the cylindrical wave-like reference light 123.

[0181] In the manufacturing apparatus 10B of this embodiment, as in the manufacturing apparatus 10A of the first embodiment, a plane mirror 114 for reference light is provided on the optical path of the reference light RL branched by the beam splitter 112, and this plane mirror 114 for reference light is placed on a rotation stage 113 for reference light provided on a linear movement stage 121 for reference light.By linearly moving the linear movement stage 121 for reference light within the xy plane and rotating the rotation stage 113 for reference light along the z-axis, the irradiation direction of the reference parallel light 119 can be adjusted within the xy plane. In addition, in the manufacturing apparatus 10B of this embodiment, a cylindrical lens system 122 placed on a linear movement stage 120 for a cylindrical lens is arranged on the optical path of the reference parallel light 119, and this linear movement stage 120 for a cylindrical lens can be driven in conjunction with the linear movement stage 121 for a reference light and the rotation stage 113 for a reference light to adjust the position of the cylindrical lens system 122 to match the irradiation direction of the reference parallel light 119.However, since the optical path configuration on the reference light RL side is the same as that of the manufacturing apparatus 10A of the first embodiment, details will be omitted.

[0182] Here, the manufacturing apparatus 10A of the first embodiment above employs a configuration in which a goniostage 116 is provided on a signal light rotation stage 115, and a signal light plane mirror 117 is placed on the goniostage 116, and the signal light rotation stage 115 is rotated about the z-axis and the goniostage 116 is used to adjust the tilt of the signal light plane mirror 117, thereby three-dimensionally changing the irradiation angle of the signal collimated light 118 with respect to the recording medium 124. Furthermore, the manufacturing apparatus 10A of the first embodiment employs a configuration in which the recording medium 124 is placed on a height adjustment stage 126 provided on a recording medium linear movement stage 125, and the position of the recording medium 124 is adjusted by the recording medium linear movement stage 125 and the height adjustment stage 126 in accordance with the irradiation angle of the signal collimated light 118, thereby irradiating the signal collimated light 118 at a desired position on the recording medium 124.

[0183] In contrast, in the manufacturing apparatus 10B of this embodiment, the signal light plane mirror 117 is placed directly on the signal light rotation stage 115, and the goniostage 116 is omitted. As a result, in the manufacturing apparatus 10B of this embodiment, the signal light rotation stage 115 changes the irradiation angle of the signal collimated light 118 only two-dimensionally within the same plane, and does not change it in the z-axis direction. Note that the signal light rotation stage 115 of this embodiment works in conjunction with the stage drive circuit 130 and the information processing device 20 to constitute, for example, the "signal light irradiation angle adjusting means" of the present invention.

[0184] In particular, in the manufacturing apparatus 10B of this embodiment, instead of the linear movement stage 125 for the recording medium that can move the position of the recording medium 124 in a predetermined direction (for example, the y-axis direction), a planar movement stage 140 for the recording medium that can move the position of the recording medium 124 two-dimensionally in the xy plane (i.e., in two axial directions of the x-axis and y-axis) is provided, and a goniostage 150 for the recording medium is provided on this planar movement stage 140 for the recording medium, and the recording medium 124 is placed on the goniostage 150 for the recording medium, resulting in a configuration in which the height adjustment stage 126 is omitted. Note that the specific configuration of the planar movement stage 140 for the recording medium is the same as that of the linear movement stage 125 for the recording medium, except that it is configured to be linearly movable in two axial directions by a piezoelectric actuator or a stepping motor, similar to the linear movement stage 125 for the recording medium.

[0185] In the manufacturing apparatus 10B of this embodiment, the recording medium goniostage 150 is used to change the tilt of the recording medium 124 relative to the signal collimated light 118 and the cylindrical wave-like reference light 123, so that the recording medium goniostage 150 alone achieves a function equivalent to the combination of the goniostage 116 and height adjustment stage 126 in the first embodiment. For example, the recording medium planar movement stage 140 and recording medium goniostage 150 of this embodiment cooperate with the stage drive circuit 130 and the information processing device 20 to constitute the "recording medium planar movement means" and the "recording medium tilt angle change means" of the present invention. The specific configuration of the recording medium goniostage 150 is the same as that of the goniostage 116 of the first embodiment, except for the object to be adjusted.

[0186] Here, as in the first embodiment, manufacturing apparatus 10B of this embodiment also manufactures a holographic diffraction grating HG (see FIG. 11) that, when white parallel light is incident, diffracts the parallel light and line-focuses it, while when divergent light from the line-focused white light is incident, diffracts the divergent light and generates parallel light, thereby achieving a function similar to that of a cylindrical lens. For example, when signal parallel light 118 is incident on holographic diffraction grating HG manufactured by manufacturing apparatus 10B of this embodiment, signal parallel light 118 diffracted by holographic diffraction grating HG is line-focused in a form that coincides with line focus 127, while when cylindrical wave-like reference light 123 diverging from line focus 127 is incident on holographic diffraction grating HG, the parallel light generated by diffraction has the same optical axis as signal parallel light 118.

[0187] When manufacturing such a holographic diffraction grating HG, the tilt of the recording medium 124 is adjusted by the recording medium goniostage 150, thereby changing the relative tilt of the recording medium 124 with respect to the signal collimated light 118 and the cylindrical wave-like reference light 123 (i.e., changing the relative irradiation angle of the signal collimated light 118 and the cylindrical wave-like reference light 123 with respect to the recording medium 124), and the recording medium goniostage 150 alone can achieve a function equivalent to the combination of the goniostage 116 and the height adjustment stage 126 in the manufacturing apparatus 10A of the first embodiment. Note that, in the manufacturing apparatus 10B of the present embodiment, as described above, the irradiation direction of the signal collimated light 118 is not changed in the z-axis direction, and the irradiation angle of the signal collimated light 118 is changed only two-dimensionally within the same plane. Therefore, even if the height adjustment stage 126 is omitted, the recording medium planar moving stage 140 alone can irradiate the signal collimated light 118 and the cylindrical wave-like reference light 123 at desired positions on the recording medium 124.

[0188] [C.2] Adjustment method for each stage Next, a method for adjusting each stage in the manufacturing apparatus 10B of this embodiment having the above-described configuration will be described.

[0189] First, in the manufacturing apparatus 10B of this embodiment, when the rotation angle of the reference beam rotation stage 113 is Δφ1, the rotation angle of the signal beam rotation stage 115 is Δφ2, and the tilt rotation angle of the recording medium goniostage 150 is Δθ2, the direction vector of the signal parallel beam 118 is expressed by the following formula 30, which is different from formula 11 in the first embodiment.

[0190]

number

[0191] At this time, the value of the rotation angle Δφ2 of the signal beam rotation stage 115 is expressed by the following equation 31, unlike equation 16 in the first embodiment.

[0192]

number

[0193] At this time, the rotation angle Δθ2 of the recording medium goniostage 150 is expressed by the following equation 32.

[0194]

number

[0195] Furthermore, at this time, (1) the movement amount Δy0 of the planar movement stage 140 for the recording medium in the y-axis direction is expressed by equation 27-1, as in the first embodiment above, while (2) the movement amount Δx0 in the x-axis direction is expressed by equation 33 below.

[0196]

number

[0197] In the manufacturing apparatus 10B of this embodiment, the information processing device 20 calculates Δφ2, Δθ2, Δx0, and Δy0 based on the above relationships, and based on the calculation results, adjusts the angles of the signal light rotation stage 115 and the recording medium goniostage 150 to Δφ2 and Δθ2, and moves the recording medium planar movement stage 140 by Δx0 in the x-axis direction and Δy0 in the y-axis direction.

[0198] In this embodiment, the method for calculating the rotation angle Δφ1 of the reference beam rotation stage 113 is the same as in the first embodiment, and is calculated based on the above-mentioned formula 21. Also, in this embodiment, as in the first embodiment, (i) the movement amount Δy3 of the cylindrical lens linear movement stage 120 is calculated based on formula 28, and (ii) the movement amounts Δx4 and Δy4 of the reference beam linear movement stage 121 are calculated based on formula 29. Then, based on the calculation results, the information processing device 20 works in conjunction with the stage driving circuit 130 to adjust the angles and positions of the stages 113, 115, 120, 121, 140, and 150, similarly to the first embodiment.

[0199] When the adjustment of each stage 113, 115, 120, 121, 140, and 150 is completed by the above-described method, in manufacturing apparatus 10B of this embodiment, the optical system is arranged, for example, as shown in Fig. 15, and signal parallel light 118 and cylindrical wave-like reference light 123 spreading from line focus 127 are irradiated onto recording medium 124 at a relative irradiation angle determined by this arrangement, and interference fringes generated by interference between the two light beams 118 and 123 are exposed onto recording medium 124. As a result, a holographic diffraction grating corresponding to one wavelength (for example, λ1) is formed on recording medium 124.

[0200] [C.3] Operation during manufacturing of holographic diffraction grating HG in manufacturing system 1B Next, the operation of manufacturing a holographic diffraction grating HG in manufacturing system 1B of this embodiment will be described, but since manufacturing system 1B of this embodiment also manufactures a holographic diffraction grating HG based on processes basically similar to those shown in Figures 7 and 8 above, the following description will focus on the differences in the processes executed in manufacturing system 1B of this embodiment from the first embodiment. However, since this embodiment employs a configuration in which goniostage 116 and height adjustment stage 126 are omitted as described above and their functions are replaced by recording medium goniostage 150, the references to goniostage 116 in Figures 7 and 8 should be read as recording medium goniostage 150.

[0201] First, in the manufacturing system 1B of this embodiment, the information processing device 20 sets λ to the shortest wavelength (e.g., 400 nm) in the visible light range in step S1 in order to expose a holographic diffraction grating corresponding to a wavelength λ1 in the visible light range onto the recording medium 124.

[0202] Next, the information processing device 20 determines the direction of the signal collimated light 118 according to Equation 26 (step S2). Note that the processes of steps S1 and S2 are the same as those in the first embodiment.

[0203] In particular, in this embodiment, unlike the first embodiment, the information processing device 20 calculates the rotation angle Δφ2 of the signal beam rotation stage 115 and the rotation angle Δθ2 of the recording medium goniostage 150 in step S3 based on the above equations 31 and 32, and in step S4 supplies a control signal to the stage drive circuit 130 based on the calculated rotation angles Δφ2 and Δθ2 to adjust the rotation angles of the signal beam rotation stage 115 and the recording medium goniostage 150 to the calculated rotation angles Δφ2 and Δθ2, and then adjusts the angle of the reference beam rotation stage 113 by processing similar to that in the first embodiment (steps S5 and S6).

[0204] In this embodiment, the information processing device 20 calculates the movement amount Δy3 of the cylindrical lens linear movement stage 120 and the movement amounts Δx4 and Δy4 of the reference light linear movement stage 121 in step S7, as in the first embodiment (step S7).

[0205] However, in this embodiment, unlike the first embodiment, the information processing device 20 is configured to execute processing to calculate the movement amount of the recording medium planar movement stage 140 in addition to calculating the movement amounts of the linear movement stages 120 and 121 in step S7. At this time, the information processing device 20 calculates the movement amount Δy0 of the recording medium planar movement stage 140 in the y-axis direction based on the above equation 27-1, and calculates the movement amount Δx0 of the recording medium planar movement stage 140 in the x-axis direction based on equation 33. Note that, since the manufacturing apparatus 10B of this embodiment is configured to omit the height adjustment stage 126, the information processing device 20 is configured to omit the processing to calculate the movement amount Δz0 of the height adjustment stage 126 in step S7.

[0206] In this manner, after calculating the values ​​of Δx0, Δy0, Δy3, Δx4, and Δy4, in this embodiment, unlike the first embodiment, in step S8, the information processing device 20 outputs a control signal to the stage driving circuit 130 based on the movement amounts Δx0, Δy0, Δy3, Δx4, and Δy4 calculated in step S7, and (1) moves the recording medium planar movement stage 140 in the x-axis direction by Δx0 and in the y-axis direction by Δy0, (2) moves the cylindrical lens linear movement stage 120 in the y-axis direction by Δy3, and (3) moves the reference beam linear movement stage 121 in the x-axis direction by Δx4 and in the y-axis direction by Δy4, thereby adjusting the positions of the recording medium 124, the reference beam plane mirror 114, and the cylindrical lens system 122 to the corresponding positions. Note that, since the height adjustment stage 126 is omitted in the manufacturing apparatus 10B of this embodiment, the height adjustment of the height adjustment stage 126 is not performed in step S8.

[0207] Once the above procedure has been performed and the optical system of manufacturing apparatus 10B is in a state that matches the exposure of the holographic diffraction grating corresponding to wavelength λ1, information processing apparatus 20 outputs a control signal to light source 111 to irradiate source beam SB for a predetermined exposure time, generating interference fringes corresponding to wavelength λ1 and exposing the holographic diffraction grating corresponding to wavelength λ1 onto recording medium 124 (step S9).

[0208] Next, the information processing device 20 determines whether or not exposure of the holographic diffraction gratings corresponding to all interference fringes to be multiple-exposed on the recording medium 124 (i.e., holographic diffraction gratings corresponding to all wavelengths) is complete (step S10). If it determines that exposure is not complete (step S10: No), the information processing device 20 changes the wavelength to be exposed by Δλ by λ n =λ n-1 +Δλ (step S11), the process returns to step S2, and the processes of steps S2 to S9 are repeated to expose a holographic diffraction grating corresponding to the next wavelength (for example, λ1+Δλ) onto the recording medium 124.

[0209] Then, the information processing device 20 determines whether exposure of the holographic diffraction gratings corresponding to all wavelengths has been completed (step S10), and repeats the processing of steps S2 to S11 described above until exposure of the holographic diffraction gratings corresponding to all wavelengths has been completed, ending the processing at the time when exposure of the holographic diffraction gratings corresponding to all wavelengths has been completed. Note that the operations in steps S9 to S11 described above are the same as those in the first embodiment, and therefore details will be omitted.

[0210] At this time, in the optical system of the manufacturing apparatus 10 of this embodiment, the positions and angles of the reference beam plane mirror 114, the signal beam plane mirror 117, the cylindrical lens system 122, and the recording medium 124 are changed, for example, as shown in Figures 15 and 16, in accordance with the wavelength of the holographic diffraction grating to be exposed, and holographic diffraction gratings corresponding to the changed states (i.e., holographic diffraction gratings each having a different grating spacing and corresponding to a different wavelength) are sequentially exposed onto the recording medium 124, and a holographic diffraction grating HG that achieves the intended function over the entire visible light range is exposed onto the recording medium 124.

[0211] With the above configuration, manufacturing apparatus 10B of this embodiment realizes the functions of goniostage 116 and height adjustment stage 126 using recording medium goniostage 150 alone, while adjusting the relative irradiation angles of signal collimated light 118 and cylindrical wave-like reference light 123 spreading from line focus 127 with respect to recording medium 124 using recording medium goniostage 150, and can multiplex-expose a plurality of holographic diffraction gratings, each having a different grating spacing, onto recording medium 124.This makes it possible to simplify the apparatus configuration and manufacture holographic diffraction gratings HG that can achieve the desired function over the entire visible light range at low cost.

[0212] In particular, assuming that adjustments to the apparatus will be made when actually manufacturing the holographic diffraction grating HG, it is desirable that the laser light (i.e., signal light SL, signal collimated light 118, reference light RL, reference collimated light 119, etc.) pass through the same plane as much as possible. For example, checking whether the laser light is traveling in a predetermined direction is first performed by, for example, comparing the height from a reference position between two points separated by as much distance as possible. However, in the configuration in which the height adjustment stage 126 and the goniostage 116 are combined to adjust the irradiation angles of the signal collimated light 118 and the cylindrical wave-like reference light 123 with respect to the recording medium 124, the height in the z-axis direction through which the laser light passes changes, making it difficult to establish a reference position and potentially requiring severe adjustments. On the other hand, when the method of this embodiment is adopted, the center of the laser light always passes through the same plane, which facilitates adjustments when actually manufacturing the holographic diffraction grating HG.

[0213] While the second embodiment described above employs a configuration in which the height adjustment stage 126 is omitted, it is also possible to provide the height adjustment stage 126 on the recording medium planar movement stage 140, and then provide the recording medium goniostage 150 on which the recording medium 124 is placed. In this case, the method for adjusting the height adjustment stage 126 is the same as in the first embodiment. A configuration may be adopted in which the movement amount Δz0 of the height adjustment stage 126 is calculated in step S7 based on Equation 27-2, and the height of the height adjustment stage 126 is adjusted in step S8 based on the calculation result. In the method of the second embodiment described above, the angle of the signal collimated light 118 in the z-axis direction must be adjusted during initial setup, which can make the initial setup difficult. However, with this configuration, the angle of the signal collimated light 118 in the z-axis direction does not need to be adjusted during initial setup, which can simplify the setup of the device.

[0214] [D] Third embodiment In the manufacturing apparatus 10A of the first embodiment described above, a height adjustment stage 126 on which the recording medium 124 is placed is provided on a linear movement stage 125 for the recording medium, and the linear movement stage 125 for the recording medium moves the position of the recording medium 124 in a predetermined direction (for example, the y-axis direction), while the height adjustment stage 126 moves the recording medium 124 in the z-axis direction, thereby adopting a configuration in which the recording medium 124 can be moved in two axial directions in accordance with the three-dimensional irradiation angle of the signal collimated light 118.

[0215] In contrast to this, in this embodiment, the planar movement stage 140 for the recording medium in the second embodiment is used instead of the linear movement stage 125 for the recording medium, and a height adjustment stage 126 on which the recording medium 124 is placed is provided on this planar movement stage 140 for the recording medium, thereby adopting a configuration in which the position of the recording medium 124 can be adjusted in the three axial directions of x, y and z.

[0216] In this embodiment, the movement amount Δy0 of the planar moving stage 140 for the recording medium in the y-axis direction is expressed by the above formula 27-1, and the movement amount Δx0 of the planar moving stage 140 in the x-axis direction is expressed by the above formula 33, which is the same as in the second embodiment, and the movement amount Δz0 of the height adjustment stage 126 in the z-axis direction is expressed by the above formula 27-2, which is the same as in the first embodiment.

[0217] 7 and 8. In other words, in this embodiment as well, the information processing device 20 executes the same processes as steps S1 to S6 in the first embodiment to adjust the angles of the signal beam rotation stage 115, the goniostage 116, and the reference beam rotation stage 113 to match the exposure of the holographic diffraction grating corresponding to λ1.

[0218] 8, the information processing device 20 calculates (1) the movement amount of the linear movement stages 120 and 121, (2) the movement amount of the height adjustment stage 126, and (3) the movement amount of the recording medium planar movement stage 140. At this time, the information processing device 20 (a) calculates the movement amount Δy0 of the recording medium planar movement stage 140 in the y-axis direction based on the above equation 27-1, (b) calculates the movement amount Δx0 of the recording medium planar movement stage 140 in the x-axis direction based on equation 33, and (c) calculates the movement amount Δz0 of the height adjustment stage 126 based on equation 27-2. At this time, the information processing device 20 also (d) calculates the movement amount Δy3 of the cylindrical lens linear movement stage 120 based on equation 28, and (e) further calculates the movement amounts Δx4 and Δy4 of the reference beam linear movement stage 121 based on equation 29.

[0219] After calculating the values ​​of Δx0, Δy0, Δz0, Δy3, Δx4, and Δy4 in this manner, in step S8, the information processing device 20 of this embodiment outputs a control signal to the stage driving circuit 130 based on the movement amounts Δx0, Δy0, Δy3, Δx4, and Δy4 calculated in step S7, to (1) move the recording medium planar movement stage 140 in the x-axis direction by Δx0 and in the y-axis direction by Δy0, and (2) move the height adjustment stage 126 by Δz0. Also in step S8, the information processing device 20 (3) moves the cylindrical lens linear movement stage 120 in the y-axis direction by Δy3, and (4) moves the reference beam linear movement stage 121 in the x-axis direction by Δx4 and in the y-axis direction by Δy4, thereby adjusting the positions of the recording medium 124, the reference beam plane mirror 114, and the cylindrical lens system 122 to the corresponding positions.

[0220] When the optical system of the manufacturing apparatus 10 reaches a state matching the exposure of a holographic diffraction grating corresponding to the predetermined wavelength λ1 using the above method, the information processing apparatus 20 outputs a control signal to the light source 111 to irradiate the source beam SB for a predetermined exposure time, generating interference fringes corresponding to the wavelength λ1, and exposing the holographic diffraction grating corresponding to the wavelength λ1 onto the recording medium 124 (step S9).

[0221] Then, information processing device 20 enters a state where it determines whether exposure of holographic diffraction gratings corresponding to all interference fringes to be multiple-exposed on recording medium 124 has been completed (step S10), and repeats the processing of steps S2 to S11 above until exposure of holographic diffraction gratings corresponding to all interference fringes (i.e., holographic diffraction gratings corresponding to all wavelengths) has been completed, and ends the processing when exposure of holographic diffraction gratings corresponding to all wavelengths has been completed. Note that the operations in steps S9 to S11 above are the same as in the first embodiment, and therefore details will be omitted.

[0222] At this time, in the optical system of the manufacturing apparatus 10 of this embodiment, the positions and angles of the reference beam plane mirror 114, the signal beam plane mirror 117, the cylindrical lens system 122, and the recording medium 124 are changed in accordance with the wavelength of the holographic diffraction grating to be exposed, and the holographic diffraction gratings corresponding to these states are sequentially exposed onto the recording medium 124, and a holographic diffraction grating HG that achieves the intended function over the entire visible light range is exposed onto the recording medium 124.

[0223] As described above, according to this embodiment, the position of the recording medium 124 can be adjusted in the three axial directions of x, y, and z. Therefore, the position of the recording medium 124 can be adjusted with high precision in accordance with the irradiation angle of the signal collimated light 118, and the holographic diffraction grating HG can be manufactured with high precision. [Explanation of symbols]

[0224] 1, 1A, 1B... Manufacturing system, 10, 10A, 10B... Manufacturing apparatus, 111... Light source, 112... Beam splitter, 113... Rotating stage for reference light, 114... Plane mirror for reference light, 115... Rotating stage for signal light, 116... Gonio stage, 117... Plane mirror for signal light, 118... Signal parallel light, 119... Reference parallel light, 120... Linear movement stage for cylindrical lens, 121... Linear movement stage for reference light, 122... Cylindrical lens, 123... Cylindrical wave-like reference light, 124... Recording Medium, 125...linear movement stage for recording medium, 126...height adjustment stage, 127...line focus, 130...stage drive circuit, 140...planar movement stage for recording medium, 150...goniostage for recording medium, 20...information processing device, SL...signal light, RL...reference light, 30...HMD, VL...image light, OL...external light, P...projector, HGLP...holographic light guide plate, HG...holographic diffraction grating, LE...light entrance portion, L...lens, CL...cylindrical lens

Claims

1. 1. A holographic optical element manufacturing apparatus for manufacturing a holographic optical element by exposing a recording medium made of a photosensitive material having sensitivity to a predetermined wavelength range, comprising: a light source that emits an exposure source beam of a single wavelength; a beam splitter that splits the source beam into a signal beam and a reference beam; a signal light irradiation means for irradiating the signal light onto the recording medium via a first optical path; a reference light irradiating means for irradiating the recording medium with the reference light via a second optical path, thereby causing interference between the signal light irradiated by the signal light irradiating means and the reference light to generate interference fringes, and exposing the generated interference fringes to the recording medium; and The signal light irradiation means a signal light irradiation angle adjusting means for three-dimensionally adjusting the irradiation angle of the signal light with respect to the recording medium, and changing the irradiation angle of the signal light with respect to the recording medium three-dimensionally by a predetermined value in accordance with the interval of the interference fringes to be generated; The reference light irradiation means (1) A reference beam irradiation angle adjusting means for adjusting the irradiation angle of the reference beam with respect to the recording medium is provided, and (2) a cylindrical lens having a curvature on one axis is provided, and after the reference beam is line-focused by the cylindrical lens, the irradiation angle of the reference beam spreading from the line focus with respect to the storage medium is adjusted in accordance with a change in the irradiation angle of the signal beam with respect to the recording medium, and the reference beam after the irradiation angle adjustment is irradiated onto the recording medium, and the relative irradiation angle of the reference beam with respect to the signal beam is changed, thereby forming a layer in which a plurality of layered interference fringes, each having a parabolic cylindrical shape with a different curvature, are three-dimensionally stacked. a holographic optical element manufacturing apparatus for manufacturing a holographic optical element, the apparatus comprising: a holographic optical element that, when irradiated with parallel light of a corresponding wavelength, diffracts the parallel light and produces a line focus; a holographic optical element that diffracts the parallel light and produces a line focus when irradiated with the parallel light of a corresponding wavelength ... of a corresponding wavelength and produces a line focus when irradiated with the parallel light of a corresponding wavelength; a holographic optical element that diffracts the parallel light of a corresponding wavelength and produces a line focus when irradiated with the parallel light of a corresponding wavelength;

2. 2. The holographic optical element manufacturing apparatus according to claim 1, further comprising a recording medium position adjusting means for adjusting the position of the recording medium in accordance with the irradiation angle of the signal light adjusted by the signal light irradiation angle adjusting means.

3. The recording medium position adjusting means a linear moving means for moving the recording medium linearly in a predetermined direction; a recording medium height adjusting means for moving the recording medium in a height direction; Equipped with The signal light irradiation angle adjustment means 3. The holographic optical element manufacturing apparatus according to claim 2, wherein the position of the recording medium is adjusted in accordance with the irradiation angle of the signal light adjusted by changing the irradiation angle of the signal light with respect to the recording medium in three dimensions.

4. The recording medium position adjusting means a recording medium plane moving means for moving the recording medium two-dimensionally within a predetermined plane; a recording medium height adjusting means for moving the recording medium in a height direction; Equipped with The signal light irradiation angle adjustment means 3. The holographic optical element manufacturing apparatus according to claim 2, wherein the recording medium position adjustment means adjusts the position of the recording medium in accordance with the irradiation angle of the signal light adjusted by three-dimensionally changing the irradiation angle of the signal light with respect to the recording medium.

5. The recording medium position adjusting means a recording medium plane moving means for moving the recording medium two-dimensionally within a predetermined plane; a recording medium tilt angle changing means for changing the tilt of the recording medium; Equipped with The signal light irradiation angle adjustment means The irradiation angle of the signal light with respect to the recording medium is changed two-dimensionally, and The reference beam irradiation angle adjusting means adjusting an irradiation angle of the reference beam with respect to the recording medium in accordance with the adjusted irradiation angle of the signal beam; The recording medium tilt angle changing means 3. The holographic optical element manufacturing apparatus according to claim 2, wherein the tilt of the recording medium is changed in accordance with the irradiation angles of the signal light and the reference light, thereby changing the relative irradiation angles of the signal light and the reference light with respect to the recording medium in three dimensions.

6. The recording medium position adjusting means 6. The holographic optical element manufacturing apparatus according to claim 5, further comprising a recording medium height adjustment means for moving the recording medium in a height direction.

7. A method for manufacturing a holographic optical element, comprising: irradiating a recording medium made of a photosensitive material having sensitivity to a predetermined wavelength region with signal light and reference light, each of which is generated by splitting a source beam of a single wavelength, along different optical paths, thereby causing the signal light and the reference light to interfere with each other, and exposing the recording medium to interference fringes generated by the interference, thereby manufacturing a holographic optical element, the method comprising: The irradiation angle of the signal light with respect to the recording medium is changed three-dimensionally by a predetermined value increments according to the intervals of the generated interference fringes, and the reference light is line-focused by a cylindrical lens having a curvature on one axis. Then, the irradiation angle of the reference light spreading from the line focus with respect to the recording medium is adjusted in accordance with the change in the irradiation angle of the signal light with respect to the recording medium, and the reference light after the irradiation angle adjustment is irradiated onto the recording medium, thereby causing interference between the reference light and the signal light whose angle has been adjusted three-dimensionally, and a plurality of layered interference fringes each having a parabolic cylindrical shape with a different curvature are three-dimensionally stacked. a method for manufacturing a holographic optical element, the method comprising: generating a plurality of interference fringes exhibiting a layer structure while changing the spacing between the layers; multiplexing the plurality of interference fringes onto the recording medium to form a plurality of holographic diffraction gratings each having a different grating spacing and grating curved surface, the plurality of holographic diffraction gratings having a layer structure in which layers each having a different refractive index are stacked three-dimensionally; and having a different number of layers according to a corresponding wavelength, the method comprising manufacturing a holographic optical element that, when irradiated with parallel light of the corresponding wavelength, diffracts the parallel light and line-focuses the light.

8. 8. The method for producing a holographic optical element according to claim 7, further comprising three-dimensionally changing the irradiation angle of the signal light relative to the recording medium, thereby adjusting the irradiation angle of the signal light, and moving the recording medium three-dimensionally to irradiate the signal light at a desired position on the recording medium.

9. 9. The method for manufacturing a holographic optical element according to claim 8, wherein the relative irradiation angles of the signal beam and the reference beam with respect to the recording medium are changed three-dimensionally by changing the position and tilt of the recording medium according to the irradiation angle of the signal beam.

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