JP5945932B2 - Optical module, illumination device, projection device, and projection-type image display device - Google Patents

Description

  The present invention relates to an optical module that includes an optical element that diffracts incident coherent light, and in particular, can suppress an increase in temperature of the optical element due to incident coherent light. The present invention also relates to an illuminating device, a projection device, and a projection-type image display device including an optical module.

  Various types of projection-type image display devices that display images by projecting light onto a screen have been proposed, including commercially available products called “optical projectors”. The basic principle of such a projection-type image display device is to use a spatial light modulator such as a liquid crystal micro display or DMD (Digital Micromirror Device) to generate an original two-dimensional image. A two-dimensional image is enlarged and projected on a screen using a projection optical system. For example, an optical projector is known in which a white light source such as a high-pressure mercury lamp is used to illuminate a spatial light modulator such as a liquid crystal display, and an obtained modulated image is enlarged and projected onto a screen by a lens.

  By the way, in a spatial light modulator such as a DMD, not all light is used, and a part of the light is absorbed as heat by the spatial light modulator and the optical element. Such heat generation becomes more prominent when light having a high luminous flux density is used.

  Various methods have been proposed to prevent deterioration of the characteristics and reliability of the spatial light modulator even when heat is generated due to light absorption. For example, in Patent Document 1, a spatial light modulator such as a DMD is provided on a surface opposite to a surface on which light is incident, and a heat receiving unit that absorbs heat generated in the spatial light modulator, and a cooling unit that cools the heat receiving unit And a metal fitting for holding the spatial light modulator, a heat conductive sheet attached to the spatial light modulator and the metal fitting, and a heat diffusing plate and a cooling unit for releasing the heat of the heat conductive sheet. Cooling devices have been proposed.

  By the way, a high-intensity discharge lamp such as a high-pressure mercury lamp has a relatively short life, and when used in an optical projector or the like, it is necessary to frequently replace the lamp. Further, since it is necessary to use a relatively large optical system such as a dichroic mirror in order to extract the light of each primary color component, there is a problem that the entire apparatus becomes large. In order to cope with such a problem, a method using a coherent light source such as a laser light source has been proposed. For example, a semiconductor laser widely used in the industry has a very long life compared to a high-intensity discharge lamp such as a high-pressure mercury lamp. In addition, since the light source can generate light having a single wavelength, a spectroscopic device such as a dichroic mirror is not necessary, and the entire device can be reduced in size.

  On the other hand, a method using a coherent light source such as a laser beam has a new problem such as generation of speckle. A speckle is a speckled pattern that appears when a scattering surface is irradiated with coherent light such as laser light. When speckle is generated on a screen, it is observed as a spotted brightness unevenness and observed. It becomes a factor having a physiological adverse effect on the person. The reason why speckles occur when coherent light is used is that coherent light reflected by each part of a scattering reflection surface such as a screen interferes with each other because of its extremely high coherence. . For example, the document “Speckle Phenomena in Optics, Joseph W. Goodman, Roberts & Co., 2006” provides a detailed theoretical discussion of speckle generation.

  As described above, in the system using the coherent light source, a problem inherent to the generation of speckles occurs, and thus a technique for suppressing the generation of speckles has been proposed. For example, Patent Literature 2 discloses an illumination device that illuminates a spatial light modulator and includes a hologram recording medium and an irradiation device that irradiates the hologram recording medium with coherent light so as to scan the hologram recording medium. A device has been proposed. In Patent Document 2, by illuminating the spatial light modulator using such an illuminating device, the incident angle of diffracted light that reaches each point on the spatial light modulator from the hologram recording medium is changed with time. be able to. As a result, speckle can be reduced.

  The recording layer on which the interference fringes of the hologram recording medium are recorded is generally formed by applying a photosensitive composition on a support such as glass. On the recording layer, as described in Patent Document 3, glass or a film is provided as a protective member.

JP 2011-170013 A Japanese Patent No. 4816819 JP-A-6-301322

Speckle Phenomena in Optics, Joseph W. Goodman, Roberts & Co., 2006

  Members such as glass for supporting the hologram recording medium and glass or film for protecting the hologram recording medium are usually not members having high heat dissipation characteristics. Therefore, when the hologram recording medium is irradiated with light having a high luminous flux density, the temperature of the irradiated area becomes high, and as a result, the light diffraction characteristics of the hologram recording medium are affected. Can be considered.

  An object of the present invention is to provide an optical module, an illumination device, a projection device, and a projection-type image display device that can effectively solve such problems.

The optical module according to the present invention comprises:
A transparent container in which the refrigerant flows;
A refrigerant circulation device for circulating the refrigerant through the transparent container and cooling the refrigerant;
An optical element having a hologram recording medium disposed in the refrigerant in the transparent container and diffracting coherent light incident from the outside of the transparent container.

In the optical module according to the present invention,
The optical element is
A first transparent substrate disposed on the side on which the coherent light of the hologram recording medium is incident;
A second transparent substrate disposed on the opposite side of the hologram recording medium from which the coherent light is incident;
You may have a sealing member which covers the edge part of the said hologram recording medium, a said 1st transparent substrate, and a said 2nd transparent substrate so that the said hologram recording medium may not contact the said refrigerant | coolant.

In the optical module according to the present invention,
The refrigerant may include any one of a fluorinated liquid, a fluorinated inert liquid, silicone oil, an organic solvent, a liquid fatty acid, alcohol and water.

The lighting device according to the present invention comprises:
A transparent container in which a refrigerant flows, a refrigerant circulation device that circulates the refrigerant through the transparent container and cools the refrigerant, and the refrigerant in the transparent container are disposed in the transparent container. An optical element having a hologram recording medium that diffracts coherent light incident from the outside, and an optical module,
An irradiation device for irradiating the optical element from the outside of the transparent container so that the coherent light scans the hologram recording medium of the optical element; and
A region on the hologram recording medium of the optical element that is irradiated with coherent light by the irradiation device at an arbitrary moment is a part of the hologram recording medium.

  In the illumination device according to the present invention, the coherent light incident on each position of the hologram recording medium of the optical element from the irradiation device is diffracted by the hologram recording medium and overlaps each other at least partially. A refractive index of the transparent container, the coolant, and the first and second transparent substrates may be set and the irradiation device and the optical module may be disposed so as to illuminate the region.

The projection apparatus according to the present invention
A lighting device;
A spatial light modulator disposed at a position illuminated by coherent light from the illumination device,
The lighting device includes:
A transparent container in which a refrigerant flows, a refrigerant circulation device that circulates the refrigerant through the transparent container and cools the refrigerant, and the refrigerant in the transparent container are disposed in the transparent container. An optical element having a hologram recording medium that diffracts coherent light incident from the outside, and an optical module,
An irradiation device for irradiating the optical element from the outside of the transparent container so that coherent light scans the hologram recording medium of the optical element;
A region on the hologram recording medium of the optical element that is irradiated with coherent light by the irradiation device at an arbitrary moment is a part of the hologram recording medium.

A first projection display apparatus according to the present invention is:
A projection device comprising: an illumination device; and a spatial light modulator disposed at a position illuminated by coherent light from the illumination device;
A screen on which a modulated image obtained on the spatial light modulator is projected,
The lighting device includes:
A transparent container in which a refrigerant flows, a refrigerant circulation device that circulates the refrigerant through the transparent container and cools the refrigerant, and the refrigerant in the transparent container are disposed in the transparent container. An optical element having a hologram recording medium that diffracts coherent light incident from the outside, and an optical module,
An irradiation device for irradiating the optical element from the outside of the transparent container so that coherent light scans the hologram recording medium of the optical element;
A region on the hologram recording medium of the optical element that is irradiated with coherent light by the irradiation device at an arbitrary moment is a part of the hologram recording medium.

A second projection type video display device according to the present invention is:
A lighting device;
A screen disposed at a position illuminated by coherent light from the illumination device,
The lighting device includes:
A transparent container in which a refrigerant flows, a refrigerant circulation device that circulates the refrigerant through the transparent container and cools the refrigerant, and the refrigerant in the transparent container are disposed in the transparent container. An optical element having a hologram recording medium that diffracts coherent light incident from the outside, and an optical module,
An irradiation device for irradiating the optical element from the outside of the transparent container so that coherent light scans the hologram recording medium of the optical element;
A region on the hologram recording medium of the optical element that is irradiated with coherent light by the irradiation device at an arbitrary moment is a part of the hologram recording medium.

  According to the present invention, heat generated in the hologram recording medium can be appropriately released.

FIG. 1 is a diagram for explaining a basic form of an embodiment according to the present invention, and shows a schematic configuration of a lighting device, a projection apparatus, and a projection type video display apparatus as one specific example of the basic form. FIG. FIG. 2 is a diagram illustrating the illumination device illustrated in FIG. 1. FIG. 3 is a diagram for explaining an exposure method for producing a hologram recording medium that forms an optical element of the illumination device of FIG. FIG. 4 is a diagram for explaining the operation of the hologram recording medium manufactured through the exposure method of FIG. FIG. 5 is a perspective view for explaining the operation of the lighting apparatus shown in FIG. FIG. 6 is a cross-sectional view of the optical element and a plan view of one side of the optical element. FIG. 7 is a perspective view showing the optical module. FIG. 8 is a diagram for explaining a modification of the optical element, and is a plan view showing the optical element together with a corresponding illuminated region. FIG. 9 is a diagram for explaining an application form to which the basic form of one embodiment according to the present invention is applied, and is a lighting device, a projection apparatus, and a projection type video display apparatus as specific examples of the application form It is a figure which shows schematic structure of these.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  FIGS. 1-9 is a figure for demonstrating the optical element which concerns on one embodiment of this invention, an illuminating device, a projection apparatus, a projection type video display apparatus, and its modification. Among these, with reference to FIGS. 1-7, the optical element which concerns on one Embodiment, an illuminating device, a projection apparatus, and a projection type video display apparatus are demonstrated. Thereafter, an example of a modification to the optical element, the illumination device, the projection device, and the projection type video display device according to the embodiment will be described with reference to FIGS. 8 and 9 as appropriate.

〔Constitution〕
First, the configuration of a projection-type image display device that includes an illumination device that projects coherent light and a projection device and can make speckles inconspicuous will be described mainly with reference to FIGS.

  A projection video display device 10 shown in FIG. 1 includes a screen 15 and a projection device 20 that projects video light including coherent light. The projection device 20 includes an illuminating device 40 that illuminates the illuminated region LZ located on the virtual plane with coherent light, and a spatial light modulator that is disposed at a position overlapping the illuminated region LZ and that is illuminated with the coherent light by the illuminating device 40. 30 and a projection optical system 25 that projects the coherent light from the spatial light modulator 30 onto the screen 15.

  As the spatial light modulator 30, for example, a transmissive liquid crystal microdisplay can be used. In this case, the spatial light modulator 30 illuminated in a planar shape by the illumination device 40 selects and transmits coherent light for each pixel, thereby forming a modulated image on the screen of the display that forms the spatial light modulator 30. Will come to be. The modulated image (video light) thus obtained is projected onto the screen 15 at the same magnification or scaled by the projection optical system 25. As a result, the modulated image is displayed on the screen 15 at the same magnification or scaled (usually enlarged), and the observer can observe the image.

  As the spatial light modulator 30, a reflective micro display can be used. In this case, a modulated image is formed by the reflected light from the spatial light modulator 30, the surface on which the spatial light modulator 30 is irradiated with coherent light from the illumination device 40, and the image light that forms the modulated image from the spatial light modulator 30. The surface where the lead is the same surface. When such reflected light is used, a MEMS element such as a DMD (Digital Micromirror Device) can be used as the spatial light modulator 30.

  Moreover, it is preferable that the incident surface of the spatial light modulator 30 has the same shape and size as the illuminated region LZ irradiated with the coherent light by the illumination device 40. In this case, it is because the coherent light from the illuminating device 40 can be used with high utilization efficiency for displaying the image on the screen 15.

  The screen 15 may be configured as a transmissive screen or may be configured as a reflective screen. When the screen 15 is configured as a reflective screen, the observer observes an image displayed by the coherent light reflected by the screen 15 from the same side as the projection device 20 with respect to the screen 15. On the other hand, when the screen 15 is configured as a transmission screen, the observer observes the image displayed by the coherent light transmitted through the screen 15 from the side opposite to the projection device 20 with respect to the screen 15. .

  By the way, the coherent light projected on the screen 15 is diffused and recognized as an image by the observer. At this time, the coherent light projected on the screen interferes by diffusion and causes speckle. However, in the projection display apparatus 10 described here, the illumination apparatus 40 described below illuminates the illuminated area LZ on which the spatial light modulator 30 is superimposed with coherent light that changes in angle with time. It is like that. More specifically, the illuminating device 40 described below illuminates the illuminated region LZ with diffused light composed of coherent light, and the incident angle of this diffused light changes over time. As a result, the diffusion pattern of the coherent light on the screen 15 also changes with time, and speckles generated by the diffusion of the coherent light are temporally superimposed and become inconspicuous. Hereinafter, such an illuminating device 40 will be described in more detail.

  The illumination device 40 shown in FIGS. 1 and 2 includes an optical module 70 including an optical element 50 that diffracts incident coherent light and directs the traveling direction of the coherent light toward the illuminated region LZ, and the coherent light to the optical element 50. And an irradiating device 60 for irradiating.

  The optical module 70 further includes a refrigerant circulation device (chiller) 71, refrigerant circulation tubes 72 and 73, and a transparent container 74. As will be described in detail later, the transparent container 74 is filled with a refrigerant 75 for cooling the hologram recording medium 55. The transparent container 74 is configured such that the refrigerant 75 flows inside. The refrigerant circulation device 71 passes the refrigerant 75 through the refrigerant circulation tube 72, the refrigerant inlet 74a of the transparent container 74, the transparent container 74, the refrigerant outlet 74b of the transparent container 74, and the refrigerant circulation tube 73 in this order. While circulating, the refrigerant 75 is cooled.

  In the following description of the optical element 50 and each component of the optical element 50, “one side” means a side on which coherent light from the irradiation device 60 is incident, and “other side” means one side. Means the other side. In FIG. 1, the surface on one side of the optical element 50 is indicated by reference numeral 50a, and the surface on the other side of the optical element 50 is indicated by reference numeral 50b.

  The optical element 50 includes a hologram recording medium 55 that functions as a light diffusing element or a light diffusing element, in particular, a hologram recording medium 55 that can reproduce the image 5 of the scattering plate 6. In the illustrated example, the optical element 50 is disposed in the refrigerant 75 in the transparent container 74. The optical element 50 includes a first transparent substrate 51 constituting one surface 50a of the optical element 50, a hologram recording medium 55 that diffracts coherent light incident from the outside of the transparent container 74, an adhesive layer 52, an optical layer A second transparent substrate 53 constituting the other surface 50 b of the element 50, a sealing member 56 covering the hologram recording medium 55, the adhesive layer 52, the first transparent substrate 51, and the second transparent substrate 53. Have. The first transparent substrate 51 is arranged on the side on which the coherent light of the hologram recording medium 55 is incident, that is, one side. The second transparent substrate 53 is disposed on the opposite side to the side on which the coherent light of the hologram recording medium 55 enters, that is, the other side, with the adhesive layer 52 interposed therebetween. The “hologram recording medium” is a medium on which a hologram is recorded.

  The transparent container 74, the refrigerant 75, and the first transparent substrate 51 are made of a material having sufficient translucency. For this reason, most of the light incident on the optical element 50 from the outside of the transparent container 74 passes through the transparent container 74, the refrigerant 75, and the first transparent substrate 51 and reaches the hologram recording medium 55.

  The hologram recording medium 55 of the optical element 50 can receive the coherent light emitted from the irradiation device 60 as the reproduction illumination light La, and can diffract the coherent light with high efficiency. In particular, the hologram recording medium 55 can reproduce the image 5 of the scattering plate 6 by diffracting coherent light incident on each position, in other words, each minute region that should be called each point. ing.

  On the other hand, the irradiation device 60 irradiates the optical element 50 with the coherent light so that the coherent light of the hologram recording medium 55 scans the hologram recording medium 55 of the optical element 50. Therefore, the region on the hologram recording medium 55 that is irradiated with the coherent light by the irradiation device 60 at an arbitrary moment is a part of the entire surface of the hologram recording medium 55, and in particular, in the illustrated example, is called a point. It is a very small area.

  Then, the coherent light irradiated from the irradiation device 60 and scanned on the hologram recording medium 55 is diffracted by the hologram recording medium 55 at each position (each point or each region (hereinafter the same)) on the hologram recording medium 55. Incidence is made at an incident angle that satisfies the conditions. The coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 illuminates a region outside the transparent container 74 that is diffracted by the hologram recording medium 55 and overlaps at least partially. In particular, in the embodiment described here, the coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 is diffracted by the hologram recording medium 55 to illuminate the same illuminated region LZ. . More specifically, as shown in FIG. 2, the coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 is superimposed on the illuminated region LZ to reproduce the image 5 of the scattering plate 6. It has become. That is, the coherent light that has entered the hologram recording medium 55 from the irradiation device 60 is diffused (expanded) by the optical element 50 and enters the same illuminated area LZ. 2 and FIGS. 4 and 5 to be described later, in order to clarify the function of the hologram recording medium 55, the components other than the hologram recording medium 55 among the components of the optical element 50 are described. Omitted.

  In the illustrated example, a reflection type volume hologram using a photopolymer is used as the hologram recording medium 55 that enables the diffraction action of such coherent light. As shown in FIG. 3, the hologram recording medium 55 is manufactured by using the scattered light from the actual scattering plate 6 as the object light Lo. FIG. 3 shows a state in which the hologram photosensitive material 58 having photosensitivity that forms the hologram recording medium 55 is exposed to the reference light Lr and the object light Lo, which are coherent light beams having coherence with each other. ,It is shown.

  As the reference light Lr, for example, laser light from a laser light source that oscillates laser light in a specific wavelength region is used, and passes through the condensing element 7 formed of a lens and enters the hologram photosensitive material 58. In the example shown in FIG. 3, the laser light that forms the reference light Lr is incident on the condensing element 7 as a parallel light beam parallel to the optical axis of the condensing element 7. The reference light Lr passes through the condensing element 7, so that it is shaped (converted) into a convergent light beam from the parallel light beam so far, and is incident on the hologram photosensitive material 58. At this time, the focal position FP of the convergent light beam Lr is at a position beyond the hologram photosensitive material 58. In other words, the hologram photosensitive material 58 is disposed between the condensing element 7 and the focal position FP of the convergent light beam Lr collected by the condensing element 7.

  Next, the object light Lo is incident on the hologram photosensitive material 58 as scattered light from a scattering plate 6 made of, for example, opal glass. Here, since the hologram recording medium 55 to be manufactured is a reflection type, the object light Lo is incident on the hologram photosensitive material 58 from the surface opposite to the reference light Lr. The object light Lo needs to have coherency with the reference light Lr. Therefore, for example, laser light oscillated from the same laser light source can be divided, and one of the divided lights can be used as the reference light Lr and the other can be used as the object light Lo.

  In the example shown in FIG. 3, a parallel light beam parallel to the normal direction to the plate surface of the scattering plate 6 is incident on and scattered by the scattering plate 6, and the scattered light transmitted through the scattering plate 6 is the object light Lo. The light enters the hologram photosensitive material 58. According to this method, when an isotropic scattering plate that is usually available at a low cost is used as the scattering plate 6, the object light Lo from the scattering plate 6 is incident on the hologram photosensitive material 58 with a substantially uniform light amount distribution. Is possible. Further, according to this method, although depending on the degree of scattering by the scattering plate 6, the reference light Lr is incident on each position of the hologram photosensitive material 58 with a substantially uniform light amount from the entire area of the exit surface 6 a of the scattering plate 6. It becomes easy. In such a case, the light incident on each position of the obtained hologram recording medium 55 reproduces the image 5 of the scattering plate 6 with the same brightness, and the reproduced scattering plate 6 It can be realized that the image 5 is observed with substantially uniform brightness.

  As described above, when the hologram recording material 58 is exposed to the reference light Lr and the object light Lo, an interference fringe formed by the interference of the reference light Lr and the object light Lo is generated. It is recorded on the hologram recording material 58 as a pattern (in the case of a volume hologram, for example, a refractive index modulation pattern). Thereafter, appropriate post-processing corresponding to the type of the hologram photosensitive material 58 is performed, and the hologram recording medium 55 is obtained.

  FIG. 4 shows the diffraction action (reproduction action) of the hologram recording medium 55 obtained through the exposure process of FIG. As shown in FIG. 4, the hologram recording medium 55 formed from the hologram photosensitive material 58 of FIG. 3 is light having the same wavelength as the laser beam used in the exposure process, and the optical path of the reference light Lr in the exposure process. The light traveling in the opposite direction satisfies the Bragg condition. That is, as shown in FIG. 4, the reference point SP positioned with respect to the hologram recording medium 55 in the same positional relationship as the relative position of the focal point FP (see FIG. 3) with respect to the hologram photosensitive material 58 during the exposure process. The divergent light beam that diverges from the light and has the same wavelength as the reference light Lr during the exposure process is diffracted as the reproduction illumination light La to the hologram recording medium 55, and the relative position of the scattering plate 6 with respect to the hologram photosensitive material 58 during the exposure process A reproduced image 5 of the scattering plate 6 is generated at a specific position with respect to the hologram recording medium 55 that has the same positional relationship as (see FIG. 3).

  At this time, the reproduction light (light obtained by diffracting the reproduction illumination light La by the hologram recording medium 55) Lb that generates the reproduction image 5 of the scattering plate 6 travels from the scattering plate 6 toward the hologram photosensitive material 58 during the exposure process. Each point of the image 5 of the scattering plate 6 is reproduced as light traveling in the opposite direction along the optical path of the object light Lo that has been emitted. As described above and as shown in FIG. 3, the scattered light Lo emitted from each position on the exit surface 6 a of the scattering plate 6 in the exposure process is incident on almost the entire region of the hologram photosensitive material 58. Is spreading (spreading). That is, the object light Lo from the entire area of the exit surface 6 a of the scattering plate 6 is incident on each position on the hologram photosensitive material 58, and as a result, information on the entire exit surface 6 a is placed on each position of the hologram recording medium 55. Each is recorded. For this reason, each light which forms the divergent light beam from the reference point SP functioning as the reproduction illumination light La shown in FIG. 4 is incident on each position of the hologram recording medium 55 independently and has the same contour. The image 5 of the scattering plate 6 can be reproduced at the same position (illuminated area LZ).

  On the other hand, the irradiation device 60 that irradiates the optical element 50 composed of the hologram recording medium 55 with the coherent light can be configured as follows. In the example shown in FIGS. 1 and 2, the irradiation apparatus 60 includes a laser light source 61a that generates coherent light in a specific wavelength region, and a scanning device 65 that changes the optical path of the coherent light from the laser light source 61a. doing. The scanning device 65 changes the optical path of the coherent light with time, and changes the incident position of the coherent light on the optical element 50. As a result, the coherent light whose traveling direction is changed by the scanning device 65 scans the incident surface of the hologram recording medium 55 of the optical element 50.

  In the example shown in FIG. 2, the scanning device 65 includes a reflective device 66 having a reflective surface 66a that can be rotated about one axis RA1. More specifically, the reflection device 66 is configured as a mirror device having a mirror as a reflection surface 66a that can be rotated about one axis RA1. As shown in FIGS. 2 and 5, the mirror device 66 changes the optical path of the coherent light from the laser light source 61a by changing the orientation of the mirror 66a. At this time, as shown in FIG. 2, the mirror device 66 generally receives coherent light from the laser light source 61a at the reference point SP. For this reason, the coherent light whose traveling direction is finally adjusted by the mirror device 66 is reproduced illumination light La (see FIG. 4) that can form one light beam diverging from the reference point SP, and the hologram recording medium 55 of the optical element 50. Can be incident. As a result, the coherent light from the irradiation device 60 scans on the hologram recording medium 55, and the image of the scattering plate 6 in which the coherent light incident on each position on the hologram recording medium 55 has the same contour. 5 is reproduced at the same position (illuminated area LZ).

  The mirror device 66 shown in FIG. 2 is configured to rotate the mirror 66a along one axis line RA1. FIG. 5 shows the configuration of the illumination device 40 shown in FIG. 2 as a perspective view. In the example shown in FIG. 5, the rotation axis RA <b> 1 of the mirror 66 a has an XY coordinate system defined on the plate surface of the hologram recording medium 55 (that is, the XY plane is parallel to the plate surface of the hologram recording medium 55. It extends parallel to the Y axis of the (XY coordinate system). Then, since the mirror 66a rotates around the axis line RA1 parallel to the Y axis of the XY coordinate system defined on the plate surface of the hologram recording medium 55, the coherent light from the irradiation device 60 is applied to the optical element 50. The incident point IP reciprocates in a direction parallel to the X axis of the XY coordinate system defined on the plate surface of the hologram recording medium 55. That is, in the example shown in FIG. 5, the irradiation device 60 irradiates the optical element 50 with coherent light so that the coherent light scans on the hologram recording medium 55 along a linear path.

  The coherent light incident on each position of the hologram recording medium 55 from the irradiation device 60 illuminates the entire illuminated area LZ with the coherent light, but the coherent light that illuminates the illuminated area LZ. The illumination directions are different from each other. Since the position on the hologram recording medium 55 on which the coherent light is incident changes with time, the incident direction of the coherent light to the illuminated region LZ also changes with time, as indicated by an arrow A1 in FIG. As a result, the light forming each pixel of the image formed by the light transmitted through the spatial light modulator 30 is projected to a specific position on the screen 15 while changing the optical path over time as indicated by an arrow A2 in FIG. Will come to be. For this reason, the coherent light scattering pattern having no correlation is multiplexed and observed by the human eye. Therefore, speckles generated corresponding to each scattering pattern are overlapped and averaged and observed by an observer. Thereby, speckles can be made very inconspicuous for an observer who observes the image displayed on the screen 15.

  By the way, the wavelength of the coherent light incident on the hologram recording medium 55 of the optical element 50 does not need to exactly match the wavelength of the light used in the exposure process (recording process) in FIG. Even if it is slightly deviated from the wavelength, the image 5 can be substantially reproduced in the illuminated area LZ. In the first place, as a practical problem, there is a case where the hologram photosensitive material 58 contracts when the hologram recording medium 55 is produced. In such a case, the hologram recording material 58 is considered in consideration of the contraction of the hologram photosensitive material 58. When the medium 55 is manufactured, it is preferable that the incident angle of the coherent light is adjusted. From this point, the wavelength of the coherent light generated by the coherent light source 61a does not need to be exactly the same as the wavelength of the light used in the exposure process (recording process) in FIG. .

  Similarly, the traveling direction of the coherent light incident on the hologram recording medium 55 of the optical element 50 is also in the illuminated region LZ even if it does not take exactly the same path as one light beam included in the divergent light beam from the reference point SP. The image 5 can be substantially reproduced. Actually, in the example shown in FIGS. 2 and 5, the mirror (reflecting surface) 66a of the mirror device 66 constituting the scanning device 65 is inevitably deviated from the rotation axis RA1. Therefore, when the mirror 66a is rotated around the rotation axis RA1 that does not pass through the reference point SP, the light incident on the hologram recording medium 55 may not be a single light beam that forms a divergent light beam from the reference point SP. is there. However, in practice, the image 5 can be substantially reproduced by being superimposed on the illuminated region LZ by coherent light from the irradiation device 60 having the illustrated configuration.

  Further, as described above, the coherent light passes through the transparent container 74, the coolant 75, and the first transparent substrate 51 and enters the hologram recording medium 55. Therefore, when the refractive indexes of the transparent container 74, the refrigerant 75, and the first transparent substrate 51 are different, the light incident on the hologram recording medium 55 does not become one light beam that forms a divergent light beam from the reference point SP. However, in practice, if the refractive indexes of the transparent container 74, the refrigerant 75, and the first transparent substrate 51 are equal, the image is superimposed on the illuminated region LZ by the coherent light from the irradiation device 60 having the illustrated configuration. 5 can be substantially reproduced. That is, the coherent light incident on each position of the hologram recording medium 55 is diffracted by the hologram recording medium 55 and illuminates a region outside the transparent container 74 that at least partially overlaps the transparent container 74 and the refrigerant 75. And the refractive index of the 1st transparent substrate 51 should just be set.

  As described above, in the present embodiment, the region (position) on the hologram recording medium 55 that is irradiated with the coherent light by the irradiation device 60 at an arbitrary moment is a part of the hologram recording medium 55. . Further, as described above, the image 5 of the scattering plate 6 having the same contour is reproduced at the same position (illuminated region LZ) by the coherent light incident on each position on the hologram recording medium 55 at each moment. . Accordingly, in the present embodiment, on average, the energy of light necessary for reproducing the entire image 5 of the scattering plate 6 at each moment is incident on each position on the hologram recording medium 55 at each moment. It is obtained by the energy of the coherent light. Therefore, in the present embodiment, the light flux density of the coherent light irradiated onto the hologram recording medium 55 is higher than that when the entire area of the hologram recording medium 55 is irradiated with the coherent light at each moment.

  Most of the coherent light incident on the hologram recording medium 55 is diffracted, and the other part is transmitted through the hologram recording medium 55 or absorbed as heat by the hologram recording medium 55. Here, when the luminous flux density of the coherent light irradiated to the hologram recording medium 55 is high, the energy of the coherent light absorbed as heat in each region of the hologram recording medium 55 also increases. Here, in the present embodiment, by arranging the optical element 50 including the hologram recording medium 55 in the refrigerant 75 in the transparent container 74, the temperature rise of the hologram recording medium 55 can be suppressed. Hereinafter, the configuration of the optical element 50 disposed in the refrigerant 75 and the configuration of the optical module 70 will be described in detail with reference to FIGS. 6 and 7.

  FIG. 6A is a cross-sectional view of the optical element 50, and FIG. 6B is a plan view of one side of the optical element 50. As shown in FIG. 6A, as described above, the first transparent substrate 51 is disposed on one side of the hologram recording medium 55, and on the other side of the hologram recording medium 55, A second transparent substrate 53 is disposed via the adhesive layer 52. The first transparent substrate 51a and the second transparent substrate 51b are made of, for example, glass or a resin material.

  In addition, the optical element 50 includes a sealing member 56 that covers the hologram recording medium 55, the adhesive layer 52, the first transparent substrate 51, and the ends of the second transparent substrate 53 so that the hologram recording medium 55 does not contact the coolant 75. Have As shown in FIG. 6B, the seal member 56 does not interfere with the coherent light incident on the surface 50a on one side of the first transparent substrate 51, so that the hologram recording medium 55, the adhesive layer 52, and the first The ends of the transparent substrate 51 and the second transparent substrate 53 are enclosed. The seal member 56 is made of, for example, silicon rubber. If the hologram recording medium 55 is in contact with the refrigerant 75 for a long time, the hologram recording medium 55 may be deteriorated. However, the presence of the seal member 56 can prevent the hologram recording medium 55 from being deteriorated.

  FIG. 7 is a perspective view showing the optical module 70. As shown in FIG. 7, an element installation member 76 is provided inside a cubic transparent container 74. The optical element 50 is installed on the element installation member 76. A refrigerant inlet 74a and a refrigerant outlet 74b are provided on opposite side surfaces different from the one side and the other side of the transparent container 74, respectively. The transparent container 74 is made of, for example, glass or a resin material.

  As described above, the refrigerant circulation device 71 circulates the refrigerant 75 through the refrigerant circulation tube 72, the refrigerant inlet 74a, the transparent container 74, the refrigerant outlet 74b, and the refrigerant circulation tube 73 in this order. 75 is cooled. Thereby, the heat generated in the hologram recording medium 55 moves to the cooled refrigerant 75 in the transparent container 74.

  The refrigerant 75 is made of a liquid that transmits coherent light. Further, as described above, the coolant 75 preferably has a refractive index equivalent to that of the transparent container 74 and the first transparent substrate 51. As an example, the refrigerant includes any one of a fluorinated liquid, a fluorinated inert liquid, a silicone oil such as methylphenyl silicone oil, an organic solvent, a Cargill standard refraction liquid, a liquid fatty acid, water, and alcohol. The organic solvent includes any one of isooctane, cyclohexane, toluene, 2.4-dichlorotoluene, dibenzyl ether, 1-bromonaphthalene and the like.

  Further, the flow rate of the refrigerant 75 is set as appropriate so that the temperature of the refrigerant 75 is stabilized while the hologram recording medium 55 is irradiated with the coherent light, that is, the temperature of the hologram recording medium 55 is not excessively increased. do it.

  The shape and structure of the transparent container 74 described above are not particularly limited as long as it has a shape that can accommodate the optical element 50 and the element installation member 76 and can circulate the refrigerant 75.

  According to the embodiment described above, the following advantages can be obtained.

  As described above, the coherent light is applied to the optical element 50 so as to scan the hologram recording medium 55. Accordingly, the hologram recording medium 55 generates heat due to the energy of the coherent light. In particular, since the screen 15 in the projection display apparatus 10, that is, the illuminated area LZ in the illumination device 40 is preferably sufficiently bright, coherent light having a high light flux density is used. As a result, the amount of heat generated by the hologram recording medium 55 increases. Here, according to the present embodiment, the hologram recording medium 55 is installed in the refrigerant 75 in the transparent container 74. For this reason, the heat generated in the hologram recording medium 55 can be appropriately released to the outside.

  On the other hand, when the transparent container 74 and the refrigerant 75 are not provided, the following problems may occur. That is, the hologram recording medium 55 gradually deteriorates due to continuous heat generation, and may eventually be damaged. Further, the hologram recording medium 55 may gradually expand or contract due to continuous heat generation, and the interference fringes may change, or molecular diffusion may occur and the contrast of the interference fringes may be lowered. As the light diffracted in (2) diffuses outside the illuminated area LZ, there is a possibility that the brightness and accuracy will decrease. Thus, the durability of the hologram recording medium 55 may be reduced by heat. According to the present embodiment, these problems can be effectively prevented, and the durability of the hologram recording medium 55 can be improved.

  Accordingly, the illumination device 40, the projection device 20, and the projection type image display device 10 also include the optical module 70 having such a transparent container 74 and the refrigerant 75, thereby preventing deterioration in luminance and accuracy in each device. In addition, the durability of each device can be improved.

[Modification]
Various modifications can be made to the present embodiment described based on one specific example illustrated in FIGS. Hereinafter, an example of modification will be described with reference to the drawings. In the drawings used in the following description, the same reference numerals as those used for the corresponding portions in the above-described embodiment are used, and redundant descriptions are omitted.

(Lighting device)
As shown in FIG. 8, the optical element 50 may include a plurality of hologram recording media 55-1, 55-2,. Each of the hologram recording media 55-1, 55-2,... Shown in FIG. 8 is formed in a strip shape, and is arranged side by side with no gap in a direction orthogonal to the longitudinal direction. Further, the hologram recording media 55-1, 55-2,... Are located on the same virtual plane. Each hologram recording medium 55-1, 55-2,... Has an image 5 of the scattering plate 6 in the illuminated areas LZ-1, LZ-2,. Generate, in other words, illuminate the illuminated areas LZ-1, LZ-2,... With coherent light. Each of the illuminated areas LZ-1, LZ-2,... Is formed as an elongated area extending in one direction (an area that is also referred to as a linear shape), and is arranged side by side in a direction orthogonal to the longitudinal direction. ing. In addition, each of the illuminated areas LZ-1, LZ-2,... Is located on the same virtual plane.

  In the example shown in FIG. 8, the illuminated areas LZ-1, LZ-2,... May be illuminated as follows. First, the irradiation device 60 repeatedly scans the path along the longitudinal direction (the one direction) of the first hologram recording medium 55-1 so that the coherent light repeatedly scans the first hologram recording medium 55-of the optical element 50. 1 is irradiated with the coherent light. The coherent light incident on each position of the first hologram recording medium 55-1 is superimposed on the first illumination area LZ-1 to reproduce the image 5 of the linear or elongated scattering plate 6, and the first One illumination area LZ-1 is illuminated with coherent light. When a predetermined time elapses, the irradiation device 60 irradiates the second hologram recording medium 55-2 adjacent to the first hologram recording medium 55-1 with the coherent light, and the first illuminated region LZ-1 Instead, the second illuminated area LZ-2 adjacent to the first illuminated area LZ-1 is illuminated with coherent light. Hereinafter, the hologram recording medium is sequentially irradiated with coherent light, and the illuminated area corresponding to the hologram recording medium is illuminated with the coherent light. According to such a method, it is possible to read two-dimensional image information without moving the illumination device. Also in this modification, the heat generated in each hologram recording medium 55-1, 55-2,... Is appropriately released to the outside by installing the optical element 50 in the refrigerant 75 in the transparent container 74. can do.

(Projection-type image display device)
Moreover, although the example in which the hologram recording medium 55 is manufactured by the interference exposure method using the planar scattering plate 6 having a shape corresponding to the incident surface of the spatial light modulator 30 is shown, the present invention is not limited thereto. The hologram recording medium 55 may be manufactured by an interference exposure method using a scattering plate having a certain pattern. In this case, the image of the scattering plate having a certain pattern is reproduced by the hologram recording medium 55. In other words, the optical element 50 having the hologram recording medium 55 illuminates the illuminated area LZ having a certain pattern. When this optical element 50 is used, the spatial light modulator 30 and the projection optical system 25 are also omitted from the projection type image display apparatus 10 in the above-described embodiment, and the screen 15 is positioned so as to overlap the illuminated area LZ. By disposing, it is possible to display some pattern recorded on the hologram recording medium 55 on the screen 15. Also in this display device, the speckles on the screen 15 can be made inconspicuous by the irradiation device 60 irradiating the optical element 50 with the coherent light so that the coherent light scans the hologram recording medium 55. .

(Optical element hologram recording medium)
In the embodiment described above, the reflection type hologram recording medium 55 of the optical element 50 is composed of the volume hologram 55 using a photopolymer. However, the present invention is not limited to this. As already described, the optical element 50 may include a plurality of hologram recording media 55. Further, the optical element 50 may include a volume hologram that is recorded using a photosensitive medium including a silver salt material. Further, the optical element 50 may include a transmission type volume hologram recording medium or a relief type (emboss type) hologram recording medium.

  However, in the relief (embossed) hologram, hologram interference fringes are recorded by the concavo-convex structure on the surface. However, in the case of this relief type hologram, scattering due to the uneven structure on the surface may become a new speckle generation factor. In this respect, the volume type hologram is preferable. In the volume hologram, since the hologram interference fringe is recorded as a refractive index modulation pattern (refractive index distribution) inside the medium, it is not affected by scattering due to the uneven structure on the surface.

  However, in the case of a volume hologram that is recorded using a photosensitive medium containing a silver salt material, scattering by silver salt particles may be a new speckle generation factor. In this respect, the hologram recording medium 55 is preferably a volume hologram using a photopolymer.

  In addition, in the exposure process shown in FIG. 3, a so-called Fresnel type hologram recording medium is produced. However, a Fourier transform type hologram recording medium obtained by performing recording using a lens may be produced. Absent. However, when a Fourier transform type hologram recording medium is used, a lens may also be used during image reproduction.

  Further, the striped pattern (refractive index modulation pattern or concave / convex pattern) to be formed on the hologram recording medium 55 does not use the actual object light Lo and reference light Lr, but the planned wavelength and incident direction of the reproduction illumination light La. In addition, it may be designed using a computer based on the shape and position of the image to be reproduced. The hologram recording medium 55 obtained in this way is also called a computer-generated hologram. When a plurality of coherent lights having different wavelength ranges are irradiated from the irradiation device 60 as in the above-described modification, the hologram recording medium 55 as a computer-generated hologram corresponds to each coherent light in each wavelength range. The coherent light in each wavelength region may be diffracted in the corresponding region to reproduce an image.

(Combination of modified examples)
In addition, although the some modification with respect to the basic form mentioned above has been demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

<Application form>
[Configuration of application form and operation of application form]
Next, an application form obtained by applying the basic form described above will be described with reference to the illumination device 40, the projection device 20, and the projection type video display device 10 illustrated in FIG. In the following description, only points that are added to the basic form described above will be described, and other parts that may be configured similarly to the basic form described above are denoted by the same reference numerals as in the basic form described above in FIG. The duplicated explanation is omitted.

  In the basic mode described above, the irradiation apparatus 60 has an example having only a single light source 61a that generates coherent light. The coherent light generated from the single light source 61a is typically light in a narrow wavelength band and is monochromatic light, as represented by laser light. Further, coherent light generated from a substantially usable light source, that is, a light source which can be obtained at a low cost and has a sufficient output is limited to light of a specific wavelength (range). That is, light of various colors cannot be displayed with light from a single light source. On the other hand, in many cases today, it is desirable to illuminate the illuminated area or display an image in a desired color that cannot be displayed with a single light source, or in multiple colors, typically full color. It is rare. The form shown in FIG. 9 is an application of the basic form described above in consideration of such points.

  In the applied form, the irradiation device 60 irradiates the optical element 50 with the synthesized light SL formed by synthesizing a plurality of coherent lights having different wavelength ranges. In the example shown in FIG. 9, the irradiation device 60 includes a first coherent light La in the first wavelength range, a second coherent light Lb in a second wavelength range different from the first wavelength range, a first wavelength range, and The synthetic light SL formed by synthesizing the third coherent light Lc in the third wavelength range different from both of the second wavelength ranges is irradiated. In particular, in the following, the first wavelength region corresponds to the first primary color component (for example, red component), the second wavelength region corresponds to the second primary color component (for example, green component), and the third wavelength. An example in which the irradiating device 60 emits white light by additive color mixing of the first to third primary color components corresponding to the third primary color component (for example, blue component) will be described.

  In the example illustrated in FIG. 9, the irradiation apparatus 60 includes the above-described scanning device 65 and a light source mechanism 61 that generates the combined light SL. The light source mechanism 61 includes a plurality of light sources 61a, 61b, and 61c that respectively oscillate coherent light in a wavelength region corresponding to the wavelength region of each coherent light, and a combining device that combines the coherent light from the plurality of light sources 61a, 61b, and 61c. 62. The light source mechanism 61 includes, as a plurality of light sources, a first light source 61a that oscillates the first coherent light La in the first wavelength region, a second light source 61b that oscillates the second coherent light Lb in the second wavelength region, And a third light source 61c that oscillates the third coherent light Lc in the three wavelength regions. On the other hand, as the synthesizing device 62, various members, components, apparatuses, and the like that synthesize two lights can be used. In the illustrated example, a half mirror having an advantage of being inexpensive and small compared with a cross dichroic prism or the like is used as the combining device 62.

  In the example shown in FIG. 9, the optical element 50 includes a hologram recording medium 55 made of a reflective volume hologram that diffracts the combined light and illuminates the illuminated area LZ. However, the reflective volume hologram has a strong wavelength selectivity. For this reason, the hologram recording medium 55 of the illustrated optical element 50 includes first to third hologram elements 55a, 55b, and 55c provided corresponding to coherent light in each wavelength region. The first hologram element 55a is provided corresponding to the first coherent light La in the first wavelength range, the second hologram element 55b is provided corresponding to the second coherent light Lb in the second wavelength range, and the third The hologram element 55c is provided corresponding to the third coherent light Lc in the third wavelength region.

  Each of the first to third hologram elements 55a, 55b, and 55c can reproduce the image 5 of the scattering plate 6. In particular, the first hologram element 55a diffracts the first coherent light La in the first wavelength region as the reproduction illumination light, and the second hologram element 55b diffracts the second coherent light Lb in the second wavelength region as the reproduction illumination light. As a result, the third hologram element 55c diffracts the third coherent light Lc in the third wavelength region as the reproduction illumination light, whereby the images 5 of the same scattering plate 6 can be reproduced. .

  Note that the hologram elements 55a, 55b, and 55c for coherent light in each wavelength region are used as exposure light (reference light Lr and object light Lo) in the method already described with reference to FIGS. 3 and 4, for example. , By using coherent light in the corresponding wavelength range.

  As shown in FIG. 9, the first to third hologram elements 55a, 55b, 55c of the hologram recording medium 55 are stacked on each other. Similarly to the basic form described above, when the irradiation device 60 irradiates the optical element 50 with the synthesized light SL, the synthesized light SL scans on the hologram recording medium 55. As a result, at least the first coherent light La of the combined light SL scans on the first hologram element 55a, and at least the second coherent light Lb of the combined light SL scans on the second hologram element 55b to combine the light. At least the third coherent light Lc of the light SL scans on the third hologram element 55c. Then, the first coherent light La of the combined light SL incident on each position of the hologram recording medium 55 from the irradiation device 60 reproduces the image 5 so as to overlap the illuminated region LZ, and from the irradiation device 60 to the hologram recording medium 55. The second coherent light Lb of the combined light SL incident on each of the positions of the combined light reproduces the image 5 superimposed on the illuminated region LZ, and is incident on each position of the hologram recording medium 55 from the irradiation device 60 The optical element 50 and the irradiation device 60 are positioned so that the third coherent light Lc of the light SL is superimposed on the illuminated area LZ to reproduce the image 5.

  In the application mode shown in FIG. 9, when the combined light SL from the irradiation device 60 enters the optical element 50, coherent light (first to third coherent light) La, Lb, and Lc in each wavelength region that forms the combined light. Thus, the image 5 of the scattering plate 6 is reproduced so as to overlap the illuminated area LZ. As a result, the illuminated area LZ is illuminated with a color obtained by additive color mixing of the first to third coherent lights La, Lb, and Lc. That is, in this example, the illumination device 60 illuminates the illuminated area LZ with white light.

  In the projection device 20 or the transmissive image display device 10, the spatial light modulator 30 includes, for example, a color filter, and a modulated image can be formed for each of the coherent lights La, Lb, and Lc in each wavelength region. In this case, it is possible to display a video in a plurality of colors, and further to display a video in full color. Even if the spatial light modulation area does not include a color filter, the irradiation device 60 time-divides the coherent light La, Lb, and Lc in each wavelength area, that is, the coherent light La, Lb, and Lc in fine time units. Irradiation may be performed sequentially, and the spatial light modulator 30 may be operated in a time division manner so as to form a modulated image corresponding to the coherent light in the irradiated wavelength region. Even in such an example, if the time-division operation is fast enough to be undetectable by the human eye, the image can be displayed in a plurality of colors when viewed by the human eye, and further, the image can be displayed in full color. Can be displayed.

  Further, according to the application form shown in FIG. 9, similarly to the basic form described above, the illuminated areas LZ of the respective coherent lights La, Lb, Lc diffracted by the hologram elements 55a, 55b, 55c of the optical element 50 are provided. The incident direction at each position of the lens changes continuously. Accordingly, the incident direction of the image light composed of the first to third coherent lights La, Lb, and Lc projected from the projection device 20 to each position on the screen 15 also changes continuously. For this reason, as already described in the basic embodiment, uncorrelated speckle patterns are superimposed and averaged, and as a result, speckles observed by the observer's eyes can be made inconspicuous.

  In addition, in the form shown in FIG. 9, the first to third coherent lights La, Lb, and Lc simultaneously illuminate the illuminated area LZ and are simultaneously projected onto the screen 15. The first to third coherent lights La, Lb, and Lc are generated by different light sources 61a, 61b, and 61c, and thus have no coherency. That is, the speckle pattern resulting from each of the coherent lights La, Lb, and Lc is uncorrelated, and the uncorrelated speckle pattern is superimposed on the screen 15 and averaged. For this reason, in the application form shown in FIG. 9, the speckle pattern can be made less noticeable.

  9 also, the hologram recording medium 55 including the first to third hologram elements 55a, 55b, and 55c is installed in the refrigerant 75 in the transparent container 74. The refrigerant circulation device 71 circulates the refrigerant 75 via the transparent container 74 and cools the refrigerant 75. For this reason, the heat generated in the first to third hologram elements 55a, 55b, and 55c of the hologram recording medium 55 can be appropriately released to the outside.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to this Example.

Example 1
A blue plate glass having a thickness of 1 mm and an area of 30 × 50 mm ² was prepared as the first transparent substrate 51. Next, a hologram photosensitive material 58 was provided on the other surface of the first transparent substrate 51. As the hologram photosensitive material 58, the photosensitive composition for volume hologram recording described in Patent Document 3 described above was used. Next, the hologram photosensitive material 58 was irradiated with object light and reference light, whereby the hologram recording medium 55 was formed on the first transparent substrate 51.

  Next, a blue plate glass having a thickness of 1 mm was prepared as the second transparent substrate 53. Next, the hologram recording medium 55 formed on the first transparent substrate 51 and the second transparent substrate 53 were bonded using an adhesive layer 52 made of NOA61.

  Then, the end portions of the hologram recording medium 55, the adhesive layer 52, the first transparent substrate 51, and the second transparent substrate 53 were sealed with a sealing member 56 made of silicon rubber. Thus, the optical element 50 was produced. NOA61 is an adhesive containing an acrylic UV curable resin, and has a refractive index of 1.56 and a glass transition point of 30 ° C. The thickness of the adhesive layer 52 was 50 μm.

The optical element 50 produced as described above was placed in the transparent container 74 having a volume of 100 × 100 × 100 mm ³ using the element placement member 76. Then, methylphenyl silicone oil (refractive index: 1.49) was circulated as the refrigerant 75 in the transparent container 74 using the refrigerant circulation device 71.

Next, a laser beam having a light flux density of 1.6 W / mm ² was irradiated to a region on the hologram recording medium 55 of the optical element 50 for 1 hour at room temperature. At this time, the beam diameter of the laser beam was about 1 mm.

  The optical element 50 after being irradiated with laser light for 1 hour was observed using thermography. As a result, the maximum temperature of each region on the optical element 50 was about 30 ° C. Further, in the optical element 50, a region where the temperature was significantly higher than the other regions, that is, a so-called heat spot was not observed. As an apparatus for thermography observation, Thermo Gear G100 manufactured by NEC AVIO Infrared Technology was used.

(Example 2)
Except for using a Cargill standard refraction liquid (refractive index: 1.52) instead of methylphenyl silicone oil as the refrigerant 75, the same as in the case of Example 1, one on the hologram recording medium 55 of the optical element 50 The region was irradiated with laser light. Then, the optical element 50 was observed using thermography. As a result, the maximum temperature of each region on the optical element 50 was about 30 ° C. Moreover, no heat spot was observed.

(Example 3)
A laser is applied to a region on the hologram recording medium 55 of the optical element 50 in the same manner as in Example 1 except that toluene (refractive index: 1.49) is used as the refrigerant 75 instead of methylphenyl silicone oil. Irradiated with light. Then, the optical element 50 was observed using thermography. As a result, the maximum temperature of each region on the optical element 50 was about 30 ° C. Moreover, no heat spot was observed.

(Comparative Example 1)
The same optical element 50 as in the first embodiment is not installed in the transparent container 74, but a laser beam is irradiated on a region of the optical element 50 on the hologram recording medium 55 in the same manner as in the first embodiment. did. Then, the optical element 50 was observed using thermography. As a result, a region where the temperature was significantly higher than the other regions, that is, a so-called heat spot was observed in the optical element 50. The temperature of the heat spot was about 50 ° C. That is, a significant heat distribution was generated on the surface of the hologram recording medium 55.

  As is clear from the comparison between Examples 1 to 3 and Comparative Example 1, the temperature rise of the hologram recording medium 55 could be suppressed by installing the optical element 50 in the refrigerant 75 in the transparent container 74. . Further, it was possible to prevent heat spots from being generated on the hologram recording medium 55.

5 Image 6 Scattering plate 10 Projection type image display device 15 Screen 20 Projection device 25 Projection optical system 30 Spatial light modulator 40 Illumination device 50 Optical element 50a One side surface 50b The other side surface 51 First transparent substrate 52 Adhesive layer 53 Second transparent substrate 55 Hologram recording medium 56 Seal member 58 Holographic photosensitive material 60 Irradiation device 61a Light source 65 Scan device 66 Mirror device (reflection device)
66a Mirror (reflective surface)
70 Optical module 71 Refrigerant circulation device 72, 73 Refrigerant circulation tube 74 Transparent container 74a Refrigerant inlet 74b Refrigerant outlet 75 Refrigerant 76 Element installation member LZ Illuminated area

Claims (5)

A transparent container in which a refrigerant flows, a refrigerant circulation device that circulates the refrigerant through the transparent container and cools the refrigerant, and the refrigerant in the transparent container are disposed in the transparent container. An optical element having a hologram recording medium that diffracts coherent light incident from the outside, and an optical module,
An irradiation device for irradiating the optical element from the outside of the transparent container so that the coherent light scans the hologram recording medium of the optical element; and
The area on the hologram recording medium of the optical element irradiated with coherent light by the irradiation apparatus at an arbitrary moment is a part of the hologram recording medium. The optical element includes a first transparent substrate disposed on a side on which the coherent light of the hologram recording medium is incident, and a second transparent substrate disposed on a side opposite to the side on which the coherent light of the hologram recording medium is incident. A substrate,
The coherent light incident on each position of the hologram recording medium of the optical element from the irradiation device illuminates a region outside the transparent container that is diffracted by the hologram recording medium and at least partially overlaps each other. , the irradiation device and the optical module with the refractive index of the transparent container and the refrigerant and the first and second transparent substrates are set is arranged, the lighting apparatus according to claim 1. A lighting device;
A spatial light modulator disposed at a position illuminated by coherent light from the illumination device,
The lighting device includes:
A transparent container in which a refrigerant flows, a refrigerant circulation device that circulates the refrigerant through the transparent container and cools the refrigerant, and the refrigerant in the transparent container are disposed in the transparent container. An optical element having a hologram recording medium that diffracts coherent light incident from the outside, and an optical module,
An irradiation device for irradiating the optical element from the outside of the transparent container so that coherent light scans the hologram recording medium of the optical element;
The area on the hologram recording medium of the optical element irradiated with coherent light by the irradiation apparatus at an arbitrary moment is a part of the hologram recording medium. A projection device comprising: an illumination device; and a spatial light modulator disposed at a position illuminated by coherent light from the illumination device;
A screen on which a modulated image obtained on the spatial light modulator is projected,
The lighting device includes:
A transparent container in which a refrigerant flows, a refrigerant circulation device that circulates the refrigerant through the transparent container and cools the refrigerant, and the refrigerant in the transparent container are disposed in the transparent container. An optical element having a hologram recording medium that diffracts coherent light incident from the outside, and an optical module,
An irradiation device for irradiating the optical element from the outside of the transparent container so that coherent light scans the hologram recording medium of the optical element;
The projection-type image display apparatus, wherein a region on the hologram recording medium of the optical element irradiated with coherent light by the irradiation apparatus at an arbitrary moment is a part of the hologram recording medium. A lighting device;
A screen disposed at a position illuminated by coherent light from the illumination device,
The lighting device includes:
A transparent container in which a refrigerant flows, a refrigerant circulation device that circulates the refrigerant through the transparent container and cools the refrigerant, and the refrigerant in the transparent container are disposed in the transparent container. An optical element having a hologram recording medium that diffracts coherent light incident from the outside, and an optical module,
An irradiation device for irradiating the optical element from the outside of the transparent container so that coherent light scans the hologram recording medium of the optical element;
The projection-type image display apparatus, wherein a region on the hologram recording medium of the optical element irradiated with coherent light by the irradiation apparatus at an arbitrary moment is a part of the hologram recording medium.

Images