JP2006201366A - Device and method for producing hologram element and video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposing device and an exposing method which improve the optical performance of a hologram element in the production of the hologram element, and also to provide a video display device. <P>SOLUTION: The device is provided with: a regulating means (controlling part 74) of regulating the wavelength of the laser beam to be emitted; and a memorizing means (memorizing part 73) of beforehand memorizing the data on the percentage of the shrinkage in a hologram photosensitive material generated by exposure and heat treatment. The regulating means regulates the wavelength of the laser beam to be emitted according to the shrinkage percentage of the hologram photosensitive material memorized in the memorizing means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hologram element manufacturing apparatus and manufacturing method, and an image display apparatus.

  2. Description of the Related Art Conventionally, eyeglass-type wearable displays (WD), head-mounted displays (HMD), and the like have been developed for the purpose of improving workability by hands-free and visual assistance for low-sighted persons. The WD and HMD lenses are provided with an optical base material for optically guiding the image light from the display unit to the eyes. In recent years, a hologram element has been used on this optical substrate as a reflective film for displaying an image superimposed on the foreground in front of the eyes (see, for example, Patent Document 1).

By the way, in the manufacture of the hologram element described above, an exposure apparatus capable of irradiating laser light is used, and in general, laser light having three wavelengths in a narrow wavelength range corresponding to each color of R, G, and B is used. ing. Interference fringes generated when reference light and object light are incident on the hologram photosensitive material that is the basis of the hologram element from the exposure apparatus are recorded on the hologram photosensitive material. Furthermore, in order to stabilize the recorded interference fringes, a manufacturing process is performed in which the hologram photosensitive material is subjected to a heat treatment (baking process) at a predetermined temperature to form a hologram element. The hologram element manufactured in this way has excellent wavelength selectivity and can selectively diffract and reflect only light in a specific wavelength region, so that the color gamut of each color corresponding to three wavelengths can be accurately reproduced. can do.
JP 2000-214408 A

However, when the hologram photosensitive material is subjected to laser exposure and heat treatment, shrinkage occurs in the hologram photosensitive material, so that the interval between recorded interference fringes fluctuates, and the color gamut reproduction rate and diffraction efficiency decrease. There is a problem that the optical performance deteriorates. In the following, with reference to FIG. 5, the factors that cause the optical performance of the hologram element to deteriorate due to the shrinkage of the hologram photosensitive material will be described.
FIG. 5 is a schematic diagram showing a CIE 1931XYZ color system chromaticity diagram, and an area indicated by a triangle surrounded by a broken line is a display color gamut of a target color image (hereinafter referred to as a target display color gamut). The point P shows the white point. In the conventional exposure apparatus, since the interference fringe is not recorded at the laser wavelength considering the interval variation of the interference fringe due to the laser exposure process and the bake process, a deviation from the target display color gamut occurs, and FIG. ), The display color gamut that can be displayed (hereinafter referred to as the displayable color gamut) is an area indicated by a triangle surrounded by a solid line, and the hologram element cannot accurately display each color of RGB, The color gamut recall will be reduced. Similarly, since the diffraction efficiency of the hologram element is reduced due to the fluctuation of the interference fringe spacing due to the laser exposure process and the bake process, the color gamut is compared with the target display color gamut as shown in FIG. The displayable color gamut is suppressed, and the hologram element cannot accurately display RGB colors, and the color gamut reproducibility decreases.

  Moreover, in the apparatus of Patent Document 1, image light emitted from a display device is configured to be guided to the observer's eye using a hologram combiner. However, the contraction at the time of manufacturing the hologram combiner is not described. Can not solve the problem.

  An object of the present invention is to provide an exposure apparatus, an exposure method, and an image display apparatus capable of improving the optical performance of the hologram element in the manufacture of the hologram element.

In order to solve the above-mentioned problem, the invention described in claim 1
Exposure means for exposing laser light to record interference fringes on the hologram photosensitive material;
A heat treatment means for performing a heat treatment on the exposed hologram photosensitive material;
Storage means for preliminarily storing shrinkage rate data generated in the hologram photosensitive material by the exposure and heat treatment;
Adjusting means for adjusting the wavelength of the laser beam based on the stored shrinkage rate data;
It is characterized by having.

Furthermore, the invention according to claim 2 is the invention according to claim 1,
An input unit capable of inputting an instruction signal designating the wavelength of the laser beam;
The adjusting means adjusts the wavelength of the laser beam based on the input instruction signal.

Furthermore, the invention according to claim 3 is the invention according to claim 1 or 2,
The laser beam has at least three wavelengths corresponding to each color of R, G, and B.

Moreover, in order to solve the said subject, invention of Claim 4 is the following.
An exposure step of exposing a laser beam to record interference fringes on the hologram photosensitive material;
A heat treatment step for heat-treating the exposed hologram photosensitive material;
An adjustment step of adjusting the wavelength of the laser beam based on shrinkage rate data generated in the hologram photosensitive material by the exposure and heat treatment;
It is characterized by including.

Furthermore, the invention according to claim 5 is the invention according to claim 4,
An input step of inputting an instruction signal designating the wavelength of the laser beam;
The adjusting step is characterized in that the wavelength of the laser beam is adjusted based on the input instruction signal.

Furthermore, the invention according to claim 6 is the invention according to claim 4,
The shrinkage rate data is prestored in a storage means.

Furthermore, the invention according to claim 7 is the invention according to claim 4 or 5,
The laser beam has at least three wavelengths corresponding to each color of R, G, and B.

In order to solve the above problem, the invention according to claim 8 provides:
An image display device having an image projection unit that projects an optical image and an eyepiece optical system that guides an optical image projected from the image projection unit to an eye,
The eyepiece optical system includes a hologram element manufactured by the manufacturing method according to any one of claims 4 to 7.

  According to the first aspect of the present invention, the wavelength of the irradiated laser beam is adjusted based on the shrinkage rate data of the hologram photosensitive material. As a result, it is possible to perform exposure recording of interference fringes at the wavelength of the laser light in consideration of the interval of the interference fringes after shrinkage, so that the optical performance of the manufactured hologram element can be improved and the diffraction efficiency is lowered. And a reduction in the reproduction rate of the color gamut can be suppressed.

  According to a second aspect of the present invention, the apparatus further comprises input means capable of inputting an instruction signal for designating the wavelength of the laser light, and the adjusting means determines the wavelength of the laser light based on the inputted instruction signal. adjust. Thereby, exposure recording of interference fringes can be performed at a desired wavelength of laser light.

  According to the third aspect of the present invention, the laser light has at least three wavelengths corresponding to each color of R, G, and B. Thereby, since interference fringes can be recorded on the hologram photosensitive material with laser beams having wavelengths corresponding to the respective colors R, G, and B, a hologram element capable of displaying a color image can be manufactured.

  According to the fourth aspect of the present invention, the wavelength of the irradiated laser beam is adjusted based on the shrinkage rate data of the hologram photosensitive material. As a result, it is possible to perform exposure recording of interference fringes at the wavelength of the laser light in consideration of the interval of the interference fringes after shrinkage, so that the optical performance of the manufactured hologram element can be improved and the diffraction efficiency is lowered. And a reduction in the reproduction rate of the color gamut can be suppressed.

  According to the fifth aspect of the present invention, the method further includes an input step of inputting an instruction signal for designating the wavelength of the laser light, and the adjusting step adjusts the wavelength of the laser light based on the input instruction signal. To do. Thereby, exposure recording of interference fringes can be performed at a desired wavelength of laser light.

  According to the sixth aspect of the present invention, the shrinkage rate data is stored in advance in the storage means. Thereby, the wavelength of the laser beam irradiated can be adjusted based on the shrinkage | contraction rate data memorize | stored in the memory | storage means.

  According to the invention described in claim 7, the laser light has at least three wavelengths corresponding to the respective colors of R, G, and B. Thereby, since interference fringes can be recorded on the hologram photosensitive material with laser beams having wavelengths corresponding to the respective colors R, G, and B, a hologram element capable of displaying a color image can be manufactured.

  According to the invention described in claim 8, the eyepiece optical system of the video display device has the hologram element manufactured by the manufacturing method according to any one of claims 4-7. As a result, an image display device with improved diffraction efficiency and color gamut reproduction rate can be realized. In addition, a video display device capable of displaying a color image can be realized.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the scope of the present invention is not limited to the illustrated examples.

FIG. 1 is a schematic diagram of a main part of the exposure apparatus 100.
As shown in FIG. 1, the exposure apparatus 100 includes laser light sources 11, 21, and 31 that emit laser beams having predetermined wavelengths corresponding to red (R), green (G), and blue (B) colors, The variable beam splitters 13, 23, 33 disposed on the optical axis of the laser light from the laser light sources 11, 21, 31 and the reference light L1 and object light irradiated to the hologram photosensitive material 50 that is an exposure target And shutters 61 and 62 for blocking L2 respectively. The variable beam splitters 13, 23, and 33 separate the laser light emitted from the laser light sources 11, 21, and 31 into reference light and object light, respectively.

Here, the hologram photosensitive material 50 that is an exposure object and the optical substrate 51 that holds the hologram photosensitive material 50 will be described with reference to FIGS.
As shown in FIG. 2A, the hologram photosensitive material 50 is affixed to the optical substrate 51 and held in a state. After the interference fringes are recorded on the hologram photosensitive material 50 by the laser exposure by the exposure apparatus 100, The hologram element 52 is obtained by performing a baking process for stabilizing the recorded interference fringes by a temperature control device (not shown) such as a thermostat. As shown in FIG. 2B, the hologram element 52 manufactured in this way is integrated by adhering the optical base material 51 with the hologram element 52 attached thereto to another optical base material 53. By using the built-in lens 54, it can be used as a lens for WD or HMD.

FIG. 3 is a diagram illustrating an example of diffraction reflection of light incident on the hologram element built-in lens 54.
The optical base 51 has a plate-like shape opened obliquely upward to the right in the figure, and its upper end surface is a light incident surface, and the hologram element 52 is held on the lower end surface.
The light incident from the upper end surface is reflected in the optical base 51 and then diffracted and reflected by the hologram element 52 to a position E located in the left direction in the drawing as viewed from the lower end of the optical base 51. Here, the position E corresponds to the position of the user's eye when the hologram element built-in lens 54 is used in the eyeglass-type display device. In addition, although the upper end surface of the optical base material 51 was made into wedge shape in cross section, it shall not be restricted to this.

  In the case of a reflection type hologram such as the hologram element 52 described above, the wavelength selection characteristic for diffracting and reflecting only light having a specific wavelength is very high. Therefore, since it only affects a part of the wavelength of the external light and most of the external light does not need to be diffracted and reflected by the hologram element 52, the user can display the display image and the external image projected on the hologram element 52. So-called see-through function can be realized.

  Returning to FIG. 1, the laser light source 11 can use, for example, a Kr laser as a red laser light source. The laser light source 21 can use, for example, a YAG laser as a green laser light source. The laser light source 31 may be an Ar laser or the like as a blue laser light source. Laser light sources 11, 21, and 31 are not limited to the light sources described above.

  The red laser R emitted from the laser light source 11 is totally reflected by the total reflection mirror 12 and enters the variable beam splitter 13. Here, the light transmitted through the variable beam splitter 13 becomes the reference light R1, and the light reflected by the variable beam splitter 13 becomes the object light R2.

  The green laser G emitted from the laser light source 21 is totally reflected by the total reflection mirror 22 and enters the variable beam splitter 23. Here, the light transmitted through the variable beam splitter 23 becomes the reference light G1, and the light reflected by the variable beam splitter 23 becomes the object light G2.

  Further, the blue laser B emitted from the laser light source 31 is totally reflected by the total reflection mirror 32 and enters the variable beam splitter 33. Here, the light transmitted through the variable beam splitter 33 becomes the reference light B1, and the light reflected by the variable beam splitter 33 becomes the object light B2.

  The reference lights R1, G1, and B1 for each color separated by the variable beam splitters 13, 23, and 33 are color-combined by dichroic mirrors 41 and. Then, the color-combined reference light L1 enters the hologram photosensitive material 50 disposed on the optical substrate 51. Note that total reflection mirrors 43, 44, and 45 for changing the traveling direction of the reference light are disposed in the optical paths of the reference lights R1, G1, and B1.

  On the other hand, the object lights R2, G2, and B2 for each color separated by the variable beam splitters 13, 23, and 33 are color-combined by dichroic mirrors 46 and 47, respectively. Then, the color-combined object light L <b> 2 enters the hologram photosensitive material 50 disposed on the optical base 51. Note that total reflection mirrors 48 and 49 for changing the traveling direction of the object light are disposed in the optical paths of the object lights R2, G2, and B2.

  Here, the reference light L1 is incident on one main surface of the hologram photosensitive material 50, and the object light L2 is incident on the other main surface of the hologram photosensitive material 50. Thereby, the reference light L1 and the object light L2 interfere with each other on the photosensitive layer of the hologram photosensitive material 50, and interference fringes caused by the interference between the reference light l1 and the object light L2 have a refractive index on the photosensitive layer of the hologram photosensitive material 50. Is recorded as a change.

The exposure apparatus 100 includes a wavelength controller 70 that adjusts the wavelength of each color laser beam emitted from the laser light sources 11, 21, and 31 in addition to the above-described units.
The wavelength controller 70 includes a display unit 71, an operation unit 72, a storage unit 73, a control unit 74, and the like.

  The display unit 71 is configured by an LCD (Liquid Crystal Display) or the like, and displays various types of information according to control signals from the control unit 74.

  The operation unit 72 includes a keyboard, a mouse, and the like for inputting operation instructions, and outputs an operation signal corresponding to the operated key to the control unit 74. A user of the exposure apparatus 100 can designate a desired laser wavelength via the operation unit 72, and an instruction signal for designating the laser wavelength is input as an operation signal.

  The storage unit 73 includes a recording medium (not shown) in which programs, data, and the like are stored in advance, and stores various applications executed by the control unit 74 and data related to these programs in the recording medium. To do. Specifically, shrinkage rate data indicating the shrinkage rate of the hologram photosensitive material is stored in advance. Here, the shrinkage rate is the shrinkage rate of the hologram photosensitive material in the laser exposure process and the bake process, and the shrinkage rate is measured in advance for each type of the hologram photosensitive material, and the shrinkage rate data indicating the shrinkage rate is stored. Stored in the unit 73.

The control unit 74 performs overall control of each unit described above. Specifically, when the hologram photosensitive material 50 is exposed, each color laser beam emitted from the laser light sources 11, 21, and 31 is based on the shrinkage rate data of the hologram photosensitive material 50 stored in the storage unit 73. Adjust the wavelength.
Note that the control unit 74 adjusts the wavelength of the laser light emitted by changing the laser output voltage of the laser light sources 11, 21, and 31, but is not limited thereto. For example, adjustment using a filter such as an interference filter or adjustment using a waveguide using a nonlinear material may be performed.

  When the control unit 74 receives an instruction signal specifying the laser wavelength input from the operation unit 72, the control unit 74 adjusts the wavelength of each color laser beam based on the instruction signal and the contraction rate data.

  For example, when the hologram photosensitive material 50 is made to reproduce light having a maximum wavelength of 634 nm for red display, if the shrinkage rate of the hologram photosensitive material 50 is α, the control unit 74 is based on the following formula (1). The laser light source 11 is irradiated with laser light at a wavelength λ. It goes without saying that the same control is performed for the laser light source 21 and the laser light source 31. Further, it is preferable to derive the wavelength λ based on the wavelength of the light incident on the hologram element built-in lens 54 shown in FIG.

A region within a triangle indicated by a solid line in the chromaticity diagram of FIG. 4 indicates a displayable color gamut of the hologram element 52 recorded by exposure by the exposure apparatus 100.
As shown in FIG. 6A, the displayable color gamut of the hologram element 52 has the same shape as the target display color gamut, so that the hologram element 52 can accurately display each color of RGB. .

  Further, by making the half-value width of the emission wavelength spectrum emitted from the laser light sources 11, 21, and 31 minute, the displayable color gamut of the hologram element 52 is the target display color gamut, as shown in FIG. It becomes possible to make it a substantially similar shape exceeding. Therefore, the displayable color gamut of the hologram element 52 can be expanded.

  As described above, according to the embodiment of the present invention, since the wavelength of the irradiated laser beam is adjusted based on the shrinkage rate of the hologram photosensitive material, the laser beam considering the interval of the interference fringes after the shrinkage It is possible to perform exposure recording of interference fringes at a wavelength of 1, and to improve the optical performance of the hologram element. Accordingly, it is possible to suppress a decrease in diffraction efficiency, a decrease in color gamut reproduction rate, and the like.

  The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

It is a figure which shows the block structure of exposure apparatus. (A), (b) is a perspective view which shows a lens with a built-in hologram element. It is a figure for demonstrating the diffraction reflection of a hologram element built-in lens. (A), (b) It is a schematic diagram of a chromaticity diagram showing a target display color gamut and a displayable color gamut. (A), (b) It is a schematic diagram of a chromaticity diagram showing a target display color gamut and a displayable color gamut.

Explanation of symbols

100 Laser exposure apparatus 11 Laser apparatus (R)
12 Total Reflection Mirror 13 Variable Beam Splitter 21 Laser Device (G)
22 Total Reflection Mirror 23 Variable Beam Splitter 31 Laser Device (B)
32 Total reflection mirror 33 Variable beam splitter 41 Dichroic mirror 42 Dichroic mirror 43 Total reflection mirror 44 Total reflection mirror 45 Total reflection mirror 46 Dichroic mirror 47 Dichroic mirror 48 Total reflection mirror 49 Total reflection mirror 50 Hologram photoreceptor 51 Optical base material 52 Hologram Element 53 Optical base 54 Hologram element built-in lens 61 Shutter 62 Shutter 70 Wavelength controller 71 Display unit 72 Operation unit 73 Storage unit 74 Control unit

Claims (8)

Exposure means for exposing laser light to record interference fringes on the hologram photosensitive material;
A heat treatment means for performing a heat treatment on the exposed hologram photosensitive material;
Storage means for preliminarily storing shrinkage rate data generated in the hologram photosensitive material by the exposure and heat treatment;
Adjusting means for adjusting the wavelength of the laser beam based on the stored shrinkage rate data;
An apparatus for manufacturing a hologram element, comprising: An input unit capable of inputting an instruction signal designating the wavelength of the laser beam;
2. The hologram element manufacturing apparatus according to claim 1, wherein the adjusting unit adjusts the wavelength of the laser beam based on the input instruction signal. 3.   3. The hologram element manufacturing apparatus according to claim 1, wherein the laser light has at least three wavelengths corresponding to colors of R, G, and B. 4. An exposure step of exposing a laser beam to record interference fringes on the hologram photosensitive material;
A heat treatment step for heat-treating the exposed hologram photosensitive material;
An adjustment step of adjusting the wavelength of the laser beam based on shrinkage rate data generated in the hologram photosensitive material by the exposure and heat treatment;
A method for manufacturing a hologram element, comprising: An input step of inputting an instruction signal designating the wavelength of the laser beam;
The hologram element manufacturing method according to claim 4, wherein the adjusting step adjusts the wavelength of the laser beam based on the input instruction signal.   The hologram element manufacturing method according to claim 4, wherein the shrinkage rate data is stored in a storage unit in advance.   6. The method of manufacturing a hologram element according to claim 4, wherein the laser beam has at least three wavelengths corresponding to each of R, G, and B colors. An image display device having an image projection unit that projects an optical image and an eyepiece optical system that guides an optical image projected from the image projection unit to an eye,
The image display apparatus, wherein the eyepiece optical system includes a hologram element manufactured by the manufacturing method according to any one of claims 4 to 7.

Images