JP6299809B2 - Illumination device, projection device, and projection-type image display device - Google Patents

Description

  The present invention relates to an illumination device that illuminates an illuminated area with coherent light, a projection device that projects coherent light, and a projection-type image display device that displays an image using coherent light, and in particular, generation of speckle is inconspicuous. The present invention relates to a lighting device, a projection device, and a projection-type image display device that can be made to operate.

  Projection-type image display devices having a screen and a projection device that projects image light on the screen are widely used. In a typical projection-type image display device, an original two-dimensional image is generated by using a spatial light modulator such as a liquid crystal micro display or a DMD (Digital Micromirror Device), and the two-dimensional image is projected into an optical system. An image is displayed on the screen by enlarging and projecting on the screen using the system.

  Various types of projectors have been proposed, including commercially available products called “optical projectors”. In general optical projectors, a spatial light modulator such as a liquid crystal display is illuminated using a lighting device consisting of a white light source such as a high-pressure mercury lamp, and the resulting modulated image is projected onto a screen using a lens. Adopted. For example, in Patent Document 1 below, white light generated by an ultra-high pressure mercury lamp is divided into three primary color components of R, G, and B by a dichroic mirror, and these lights are guided to a spatial light modulator for each primary color. A technique is disclosed in which a generated modulated image for each primary color is synthesized by a cross dichroic prism and projected onto a screen.

  However, high-intensity discharge lamps such as high-pressure mercury lamps have a relatively short life, and when used in optical projectors or the like, it is necessary to frequently replace the lamps. 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 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, in the following Non-Patent Document 1, detailed theoretical considerations regarding the generation of speckle are made.

  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, in Patent Document 2 below, the speckle is reduced by irradiating a scattering plate with laser light, guiding the scattered light obtained therefrom to a spatial light modulator, and rotating the scattering plate by a motor. Technology is disclosed.

JP 2004-264512 A Japanese Patent Laid-Open No. 6-208089

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

  As described above, technologies for reducing speckles have been proposed in projection devices and projection-type video display devices using a coherent light source. However, the methods proposed so far effectively and sufficiently suppress speckles. I can't do it. For example, in the method disclosed in the above-mentioned Patent Document 2, laser light is irradiated on the scattering plate and scattered, and therefore, part of the laser light is wasted without contributing to video display at all. Moreover, although it is necessary to rotate a scattering plate for speckle reduction, such a mechanical rotation mechanism becomes a comparatively large apparatus, and also power consumption becomes large. Furthermore, even if the scattering plate is rotated, the position of the optical axis of the illumination light does not change, so that speckles visually recognized on the screen cannot be sufficiently suppressed.

  Speckle is not a problem specific to a projection device or a projection type image display device, but is a problem in various devices in which an illumination device that illuminates coherent light in an illuminated area. For example, a scanner that reads image information incorporates an illumination device that illuminates an object to be read. When speckle is generated by the light that illuminates the object to be read, the image information cannot be read accurately. In order to avoid such an inconvenience, a scanner using coherent light needs to perform special processing such as image correction.

  Incidentally, coherent light generated from a single light source is typically monochromatic light, as represented by laser light. Further, coherent light generated from a practical light source is limited to light of a specific wavelength (range). 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. Therefore, the illumination device, the projection device, and the projection type image display device that are actually developed can illuminate the illuminated region with a plurality of coherent lights having different wavelength ranges in order to correspond to various applications today, or It is preferable that the present invention can be suitably applied to displaying an image using a plurality of coherent lights having different wavelength ranges.

  The present invention has been made in consideration of the above points, and is an illuminating apparatus that illuminates an illuminated area with a plurality of coherent lights having different wavelength ranges, and can make speckles inconspicuous It is another object of the present invention to provide a projection apparatus and a projection-type image display apparatus including the illumination apparatus.

A first lighting device according to the present invention comprises:
An optical element including a first hologram element and a second hologram element;
The first coherent light in the first wavelength region scans on the first hologram element, and the second coherent light in the second wavelength region on the longer wavelength side than the first wavelength region scans on the second hologram element. And an irradiation device that irradiates the optical element with a plurality of coherent lights having different wavelength ranges, and
The first coherent light incident on each position of the first hologram element from the irradiation device illuminates a region that is diffracted by the first hologram element and overlaps each other at least in part, and the second from the irradiation device. The second coherent light incident on each position of the hologram element illuminates a region that is diffracted by the hologram element and at least partially overlaps each other, and is illuminated so as to overlap with the first coherent light; The at least a portion illuminated in an overlapping manner by the second coherent light overlaps at least in part.
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb Then,
The maximum absolute value of ψa is smaller than the maximum absolute value of ψb.

A second lighting device according to the present invention comprises:
An optical element including a first hologram element, a second hologram element, and a third hologram element;
The first coherent light in the first wavelength region scans on the first hologram element, and the second coherent light in the second wavelength region on the longer wavelength side than the first wavelength region scans on the second hologram element. In addition, the optical element is irradiated with a plurality of coherent lights having different wavelength ranges so that the third coherent light in the third wavelength range that is longer than the second wavelength range scans the third hologram element. An irradiating device,
The first coherent light incident on each position of the first hologram element from the irradiation device illuminates a region that is diffracted by the first hologram element and overlaps each other at least in part, and the second from the irradiation device. The second coherent light incident on each position of the hologram element illuminates a region that is diffracted by the hologram element and overlaps at least partially, and is incident on each position of the third hologram element from the irradiation device Each of the third coherent lights is diffracted by the hologram element and illuminates a region that overlaps at least a part of the third coherent light, and overlaps with the at least a part of the third coherent light that is illuminated so as to overlap with the first coherent light. Illuminated Wherein at least a portion, at least a portion is illuminated to overlap by the third coherent light overlaps at least part of the range,
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb And an angle formed by the traveling direction of the third coherent light that is diffracted by the third hologram element and travels to the partial range with respect to the traveling direction of the third coherent light incident on the third hologram element. If ψc,
the maximum absolute value of ψa is smaller than the maximum absolute value of ψb, and
The maximum absolute value of ψa is smaller than the maximum absolute value of ψc.

  In the second illumination device according to the present invention, the first wavelength range corresponds to a first primary color component, the second wavelength range corresponds to a second primary color component, and the third wavelength range corresponds to a third primary color. It may correspond to an ingredient.

  In the second lighting device according to the present invention, the maximum absolute value of ψb may be smaller than the maximum absolute value of ψc. In this case, the first hologram element, the second hologram element, and the third hologram element may be arranged on one plane in this order.

  In the second lighting device according to the present invention, the maximum absolute value of ψb may be the same as the maximum absolute value of ψc. In this case, the second hologram element and the third hologram element may be arranged symmetrically about the first hologram element.

  In the first or second illumination device according to the present invention, each hologram element may be a relief type computer-generated hologram.

The projection apparatus according to the present invention
Either the first or second lighting device according to the invention as described above;
A spatial light modulator illuminated by each coherent light from the illumination device.

  The projection device according to the present invention may further include an integrator rod disposed between the illumination device and the spatial light modulator.

  The projection apparatus according to the present invention may further include a relay optical system disposed between the integrator rod and the spatial light modulator.

A first projection display apparatus according to the present invention is:
Any of the projection devices according to the invention described above;
And a screen on which the modulated image obtained on the spatial light modulator is projected.

A second projection type video display device according to the present invention is:
Any of the lighting devices according to the invention described above;
And a screen arranged at a position illuminated by each coherent light from the illumination device.

The first optical element according to the present invention comprises:
The first hologram element includes a transmission-type first hologram element and a transmission-type second hologram element, and the first hologram element receives first coherent light in a first wavelength region that is incident on each position of the first hologram element, respectively. It is configured to illuminate areas that are diffracted by the first hologram element and at least partially overlap each other,
In the second hologram element, second coherent light in a second wavelength range that is incident on each position of the second hologram element and is on a longer wavelength side than the first wavelength range is respectively the second hologram element. Configured to illuminate areas that are diffracted and at least partially overlap each other;
The at least a portion illuminated to overlap by the first coherent light and the at least a portion illuminated to overlap by the second coherent light overlap at least in a range;
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb Then,
The maximum absolute value of ψa is smaller than the maximum absolute value of ψb.

  ADVANTAGE OF THE INVENTION According to this invention, the speckle on the to-be-illuminated area | region or the surface which projects an image | video can be made effectively inconspicuous.

FIG. 1 is a diagram for explaining an embodiment according to the present invention, and is a diagram showing a schematic configuration of an illumination device, a projection device, and a projection type video display device as an embodiment. FIG. 2 is a diagram illustrating the illumination device illustrated in FIG. 1. FIG. 3 is a diagram illustrating a state in which a part illuminated by each coherent light overlaps at least in a part of the range. FIG. 4 is a diagram illustrating a state in which light that has passed through the spatial light modulator arranged so as to overlap the illuminated area reaches the screen. FIG. 5A is a diagram for explaining the arrangement of optical elements of the illumination device shown in FIG. 2. FIG. 5B is a perspective view for explaining the relationship between light incident on the hologram element and light diffracted by the hologram element. 5C (a), (b), and (c) are cross-sectional views for explaining the relationship between light incident on the hologram element and light diffracted by the hologram element. FIG. 6 is a perspective view for explaining the operation of the lighting device shown in FIG. FIG. 7 is a diagram corresponding to FIG. 1 and is a diagram for explaining a modification of the illumination device, the projection device, and the projection type video display device. FIG. 8 is a view for explaining the arrangement of the optical elements of the illumination device shown in FIG. FIG. 9 is a view corresponding to FIG. 8 and showing a modification of the optical element. FIG. 10 is a diagram corresponding to FIG. 1 and is a diagram for explaining a modification of the illumination device, the projection device, and the projection type video display device. FIG. 11 is a diagram corresponding to FIG. 6, and is a perspective view for explaining a modification of the irradiation apparatus and its operation.

  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. 1-11 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. 1-6, 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. 7 to 11 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 image light, which is a modulated image obtained in this way, is projected onto the screen 15 by the projection optical system 25 at the same magnification or scaled.
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.

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 FIG. 1 diffracts incident coherent light and directs the traveling direction of the coherent light toward the illuminated region LZ, an irradiation device 60 that irradiates the optical element 50 with coherent light, have. The optical element 50 is an element having a function of diffusing or expanding coherent light from the irradiation device 60. Such an optical element 50 can be formed from a hologram element 55, for example. Various known holographic optical elements can be used as the hologram element 55. As a specific example, the hologram element 55 can be formed of a transmission type volume hologram or a relief type computer-generated hologram.

  In the illustrated example, the hologram element 55 constituting the optical element 50 includes a first hologram element 55a, a second hologram element 55b, and a third hologram element 55c arranged adjacent to each other on one plane. Of these, the first hologram element 55a is provided corresponding to the first coherent light La in the first wavelength range, and the second hologram element 55b is the second wavelength range in the second wavelength range that is longer than the first wavelength range. The third hologram element 55c is provided so as to correspond to the third coherent light Lc in the third wavelength region that is longer than the second wavelength region.

  Specifically, the first hologram element 55a can receive the first coherent light La emitted from the irradiation device 60 as reproduction illumination light, and can diffract the first coherent light La with high efficiency. In particular, the first hologram element 55a is diffracted by the first hologram element 55a so that the first coherent light La incident on each position, in other words, each minute region that should also be called each point, is at least partially diffracted from each other. Illuminate the overlapping areas. In particular, in the embodiment described here, the first coherent light La incident on each position of the first hologram element 55a from the irradiation device 60 is diffracted by the first hologram element 55a, and is denoted by reference numeral LZa in FIG. At least the portion shown is illuminated.

  The first hologram element 55a will be described in detail with reference to FIG. In FIG. 2, for convenience, only the first hologram element 55a is shown among the hologram elements 55a, 55b, and 55c. As shown in FIG. 2, the first hologram element 55a has at least the sign that the coherent light La incident on each position of the first hologram element 55a from the irradiation device 60 is diffused (expanded) by the first hologram element 55a. It is configured to be incident on a part indicated by LZa. For example, the coherent light La incident on the upper position indicated by reference numeral (1) in the first hologram element 55a is diffracted by the first hologram element 55a to illuminate the area indicated by reference sign LZa (1). To do. Further, the coherent light La incident on the lower position indicated by the reference numeral (2) in the first hologram element 55a is diffracted by the first hologram element 55a to illuminate the area indicated by the reference sign LZa (2). To do. Here, as shown in FIG. 2, the region LZa (1) and the region LZa (2) are overlapped at least in a part indicated by the reference symbol LZa. Although not shown, the coherent light La diffracted at other positions of the first hologram element 55a also illuminates a region including at least a portion indicated by the symbol LZa. In other words, the first hologram element 55a can reproduce the image of the scattering plate that scatters the first coherent light in a part indicated by the symbol LZa.

  Similarly, the second hologram element 55b can receive the second coherent light Lb irradiated from the irradiation device 60 as reproduction illumination light, and can diffract the second coherent light Lb with high efficiency. In particular, the second hologram element 55b is diffracted by the second hologram element 55b and is at least partially at LZb. The second coherent light Lb incident on each position, in other words, each minute region that should be called each point, is diffracted by the second hologram element 55b. Areas that overlap each other are illuminated. In other words, the second hologram element 55b can reproduce the image of the scattering plate that scatters the second coherent light in part LZb.

  Further, the third hologram element 55c can receive the third coherent light Lc irradiated from the irradiation device 60 as reproduction illumination light, and can diffract the third coherent light Lc with high efficiency. In particular, the third hologram element 55c is diffracted by the third hologram element 55c and is at least partially in the LZc. The third coherent light Lc incident on each position, in other words, each minute region that should be called each point, is diffracted by the third hologram element 55c. Areas that overlap each other are illuminated. In other words, the third hologram element 55c can reproduce an image of the scattering plate that scatters the third coherent light in part LZc.

  Further, as shown in FIG. 3, each hologram element 55a, 55b, 55c includes a portion LZa where the first coherent light La diffracted at each position of the first hologram element 55a overlaps each other, and each position of the second hologram element 55b. At least one portion LZb in which the second coherent light Lb diffracted in step S1 overlaps with each other, and a portion LZc in which the third coherent light Lc diffracted in each position of the third hologram element 55c overlaps with each other, as indicated by reference numeral LZ. It is comprised so that it may overlap in the range of a part. In other words, each hologram element 55a, 55b, 55c can reproduce the image 5 of the scattering plate that scatters each coherent light La, Lb, Lc in the range indicated by the symbol LZ in FIGS. It has become.

  In the following description, a range in which the coherent lights La, Lb, and Lc diffracted at the respective positions of the hologram elements 55a, 55b, and 55c overlap is also referred to as an illuminated area LZ. And as FIG. 1 shows, the above-mentioned spatial light modulator 30 is arrange | positioned so that it may overlap with the to-be-illuminated area | region LZ. FIG. 4 is a diagram showing how each coherent light diffracted at each position of the hologram element 55 of the optical element 50 is modulated by the spatial light modulator 30 and reaches the screen 15. In FIG. 4, for the sake of simplicity, only the first hologram element 55a and the first coherent light La among the hologram elements 55a, 55b, and 55c and the coherent lights La, Lb, and Lc are shown.

  As each of the hologram elements 55a, 55b, and 55c enabling the diffraction action of such coherent light, for example, when receiving specific reproduction illumination light, the image of the scattering plate can be reproduced in the illuminated region LZ. A relief hologram as a computer-generated hologram (CGH) having a concavo-convex shape designed using a computer can be used.

  On the other hand, the irradiation device 60 that irradiates the optical element 50 including the hologram element 55 including the hologram elements 55a, 55b, and 55c with the coherent light can be configured as follows.

  The irradiation device 60 is configured to irradiate the optical element 50 with a combined light SL obtained by combining a plurality of coherent lights having different wavelength ranges. In the example shown in FIG. 1, the irradiation device 60 includes a first light source 61a that oscillates the first coherent light La in the first wavelength range, and a second wavelength range that is longer than the first wavelength range. A second light source 61b that oscillates the two coherent light Lb, a third light source 61c that oscillates the third coherent light Lc in the third wavelength region that is longer than the second wavelength region, and each of the coherent lights La, Lb, And a synthesis device 62 that synthesizes Lc. For example, the first wavelength region corresponds to the first primary color component (blue component), the second wavelength region corresponds to the second primary color component (green component) on the longer wavelength side than the first wavelength region, and The third wavelength region corresponds to the third primary color component (red component) on the longer wavelength side than the second wavelength region. In this case, the irradiation device 60 can irradiate white light by additive color mixing of the first to third primary color components. The “second wavelength region on the longer wavelength side than the first wavelength region” means that the peak wavelength of the second coherent light Lb in the second wavelength region is greater than the peak wavelength of the first coherent light La in the first wavelength region. Also means big. Similarly, “the third wavelength region that is longer than the second wavelength region” means that the peak wavelength of the third coherent light Lc in the third wavelength region is the peak of the second coherent light Lb in the second wavelength region. It means that it is larger than the wavelength.

  As the synthesizing device 62, various members, components, apparatuses, and the like that synthesize two lights can be used. In the illustrated example, a dichroic mirror having the advantage of being inexpensive and small compared with a cross dichroic prism or the like is used as the combining device 62.

  The irradiation device 60 further includes a scanning device 65 that changes the traveling directions of the coherent lights La, Lb, and Lc from the light sources 61a, 61b, and 61c. The scanning device 65 changes the traveling directions of the coherent lights La, Lb, and Lc with time, and directs the traveling directions of the coherent lights La, Lb, and Lc in various directions so that the traveling directions are not constant. As a result, each coherent light La, Lb, Lc whose traveling direction is changed by the scanning device 65 scans on the incident surface of each hologram element 55a, 55b, 55c of the hologram element 55 of the optical element 50. As shown in FIG. 1, a lens 64 that reflects the coherent light La, Lb, and Lc toward the scanning device 65 may be disposed between the light sources 61 a, 61 b, and 61 c and the scanning device 65. .

In particular, 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 6, the mirror device 66 changes the traveling direction of the first coherent light La from the 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 the first light source 61a at the reference point SP. For this reason, the first coherent light La whose traveling direction is finally adjusted by the mirror device 66 is used as the reproduction illumination light La (see FIG. 6) that can form one light beam diverging from the reference point SP. The light can enter the first hologram element 55 a of the element 55. As a result, the first coherent light La from the irradiation device 60 scans on the first hologram element 55a, and the first coherent light La incident on each position on the first hologram element 55a has the same contour. Is reproduced at least in 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. 6 shows the configuration of the illumination device 40 shown in FIG. 2 as a perspective view. In the example shown in FIG. 6, the rotation axis RA1 of the mirror 66a has an XY coordinate system defined on the plate surface of the first hologram element 55a, that is, the XY plane is parallel to the plate surface of the first hologram element 55a. It extends in parallel with the Y axis of the XY coordinate system. Then, since the mirror 66a rotates about the axis line RA1 parallel to the Y axis of the XY coordinate system defined on the plate surface of the first hologram element 55a, the optical of the first coherent light La from the irradiation device 60 is obtained. The incident point IP to the element 50 reciprocates in a direction parallel to the X axis of the XY coordinate system defined on the plate surface of the first hologram element 55a. That is, in the example shown in FIG. 6, the irradiation device 60 irradiates the optical element 50 with the first coherent light La so that the first coherent light La scans the first hologram element 55a along a linear path. To do.

  The form in which the second coherent light Lb scans on the second hologram element 55b and the form in which the third coherent light Lc scans on the third hologram element 55c differ only in the arrangement of the hologram elements and the coherent light used. In other respects, the first coherent light La scans the first hologram element 55a as shown in FIG. 2 and FIG.

  By the way, the transmission type volume hologram and the relief type computer-generated hologram have a feature that the wavelength selectivity is lower than that of the reflection type volume hologram. For this reason, only light in the design wavelength range is incident on a plurality of transmission-type volume holograms and relief-type computer-generated holograms that are intended to exert a predetermined diffraction action on light in different wavelength ranges. It has become. Specifically, as described with reference to FIG. 1, the hologram elements 55a, 55b, and 55c are not stacked, but are spatially shifted. The irradiation device 60 is configured such that the corresponding coherent light is incident on the hologram elements 55a, 55b, and 55c.

Specifically, the irradiation device 60 scans the incident surface of the first hologram element 55a using the first coherent light La, and scans the incident surface of the second hologram element 55b using the second coherent light Lb. The incident surface of the third hologram element 55c is scanned using the third coherent light Lc. For example, the irradiation device 60 may be operated in a time division manner.
Specifically, when the scanning device 65 directs the traveling direction of the coherent light toward the first hologram element 55a, only the first light source 61a generates the coherent light, and the scanning device 65 changes the traveling direction of the coherent light to the second direction. When directed to the hologram element 55b, only the second light source 61b generates coherent light, and when the scanning device 65 directs the traveling direction of the coherent light to the third hologram element 55c, only the third light source 61c is coherent light. May be generated. Thus, instantaneously, only one of the coherent lights La, Lb, and Lc can illuminate the illuminated region LZ or the spatial light modulator 30. .

  When the irradiation device 60 is operated in a time division manner as described above, the spatial light modulator 30 includes a color filter and always forms a modulated image for each of the coherent lights La, Lb, and Lc in each wavelength region. It may be actuated to obtain. Alternatively, 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 of each wavelength region irradiated on the spatial light modulator 30. As already described, the frequency of scanning devices 65 such as MEMS mirrors and polygon mirrors that are actually commercially available is usually several hundred Hz or higher, and scanning devices 65 that reach several tens of thousands of Hz are not uncommon. If the scanning of the scanning device 65 is extremely high in this way, the human eye cannot recognize the color transition of the light that illuminates the illuminated area LZ or the spatial light modulator 30, and is combined. It is recognized that the illuminated area LZ or the spatial light modulator 30 is illuminated with light, and an image is displayed with the combined light.

  By the way, in the relief type computer-generated hologram, the wavelength and the deflection angle are selected depending on the pitch and depth of the concavo-convex shape. For example, the pitch of the concavo-convex shape of the hologram element 55 is d, the wavelength of light incident on the hologram element 55 is λ, the incident angle to the hologram element 55 is θ, and the emission angle from the hologram element 55 is φ. In this case, in order to generate the first-order diffracted light, the pitch of the concavo-convex shape, the wavelength of the light, and the deflection angle are selected so that the condition of sin θ + sin φ = λ / d is satisfied. As is clear from this condition, in general, the pitch is small for short wavelengths and the pitch is large for long wavelengths. The deflection angle is an angle formed by the traveling direction of light diffracted by the hologram and emitted from the hologram with respect to the traveling direction of light incident on the hologram.

  On the other hand, when the deflection angle is set to be large, the ratio of the depth to the pitch of the concavo-convex shape is set to be large. By the way, in designing relief-type computer-generated holograms, Fresnel Kirchhoff approximation that ignores the influence of the thickness of the relief structure is generally used when determining the uneven shape. In this case, there is a concern that the larger the ratio of the depth to the pitch of the concavo-convex shape in order to increase the deflection angle, the closer to the approximation. Deviating from the approximation means that the diffraction efficiency and the light utilization efficiency are lowered.

  Here, as described above, the pitch of the concavo-convex shape is smaller in the case of the short wavelength than in the case of the long wavelength. Therefore, the decrease in diffraction efficiency and light utilization efficiency caused by setting the depth with respect to the pitch of the concavo-convex shape in order to set a large deflection angle is more remarkable in the case of a short wavelength than in the case of a long wavelength. It is thought to appear. Hereinafter, the structure of the optical element 50 employed in the present embodiment to solve such a problem will be described in detail with reference to FIG.

  As described above, the relief-type computer-generated hologram has a feature that its wavelength selectivity is lower than that of the reflection-type volume hologram. For this reason, when each hologram element 55a, 55b, 55c is configured as a relief type computer-generated hologram, it is difficult to use the hologram elements 55a, 55b, 55c in a stacked manner. In this case, the hologram elements 55a, 55b, and 55c are arranged so as to be spatially shifted so that only light in the design wavelength region can enter. In the example shown in FIG. 5, a preferable form when the hologram elements 55a, 55b, and 55c are spatially shifted in this way will be particularly described.

  In the example shown in FIG. 5A, the incident angle of the first coherent light La to the first hologram element 55a is indicated by the symbol θa, and the first coherent light La is diffracted by the first hologram element 55a to be illuminated region LZ. The exit angle from the first hologram element 55a when proceeding to is indicated by the symbol φa. Similarly, the incident angle of the second coherent light Lb to the second hologram element 55b is indicated by reference sign θb, and the second coherent light Lb is diffracted by the second hologram element 55b and travels to the illuminated region LZ. An exit angle from the second hologram element 55b is indicated by a symbol φb. Further, the incident angle of the third coherent light Lc to the third hologram element 55c is indicated by reference sign θc, and the third coherent light Lc is diffracted by the third hologram element 55c and travels to the illuminated region LZ. The exit angle from the three hologram elements 55c is indicated by the symbol φc. As described above, the coherent lights La, Lb, and Lc are changed in the traveling direction by the scanning device 65 and are incident on the respective positions on the hologram elements 55a, 55b, and 55c. Therefore, in the present embodiment, the incident angles θa, θb, and θc of the coherent lights La, Lb, and Lc to the hologram elements 55a, 55b, and 55c vary depending on the traveling directions of the coherent lights La, Lb, and Lc. Can take any value. However, in FIG. 5A, for the sake of simplicity, only the coherent lights La, Lb, and Lc incident on the center positions of the hologram elements 55a, 55b, and 55c and the incident angles θa, θb, and θc corresponding thereto are shown. Yes. For simplicity, in FIG. 5A, coherent lights La, Lb, and Lc that are diffracted by the hologram elements 55a, 55b, and 55c and travel to the illuminated region LZ are all incident on the hologram elements 55a, 55b, and 55c. The example which exists in the same plane as the plane where coherent light La, Lb, Lc exists, ie, the xz plane shown in FIG. The incident angles θa, θb, θc and the outgoing angles φa, φb, φc are all between the normals na, nb, nc of the hologram elements 55a, 55b, 55c and the coherent lights La, Lb, Lc. The case where the angle increases in one direction, for example, upward in FIG. 5A, is a positive value, and the opposite case is a negative value.

  As shown in FIG. 5A, the first coherent light La incident on the center position of the first hologram element 55a is emitted at various emission angles φa so as to illuminate a region including at least the illuminated region LZ. In FIG. 5A, the emission angles of the first coherent light La emitted to illuminate the upper end position, the center position, and the lower end position of the illuminated region LZ are denoted by φa (1), φa (2), and φa (3), respectively. It is shown. As described above, the emission angle φa of the first coherent light La incident on the center position of the first hologram element 55a from the first hologram element 55a can take various values according to the configuration of the first hologram element 55a. . Similarly, although not shown, the emission angle φa of the first coherent light La incident on a position other than the center position of the first hologram element 55a from the first hologram element 55a also depends on the configuration of the first hologram element 55a. It can take various values. Similarly, although not shown, the second coherent light Lb and the third coherent light Lc incident on the respective positions of the second hologram element 55b and the third hologram element 55c from the second hologram element 55b and the third hologram element 55c. The emission angle φb and the emission angle φc can take various values according to the configurations of the second hologram element 55b and the third hologram element 55c.

  Here, in each hologram element 55a, 55b, 55c, the maximum absolute value of “sin (θa) + sin (φa)” is smaller than the maximum absolute value of “sin (θb) + sin (φb)”. And the maximum absolute value of “sin (θa) + sin (φa)” is smaller than the maximum absolute value of “sin (θc) + sin (φc)”. Approximately, the maximum value of the absolute value of “θa + φa” is smaller than the maximum value of the absolute value of “θb + φb”, and the maximum value of the absolute value of “θa + φa” is “θc + φc”. It can be replaced with the condition that the hologram elements 55a, 55b, and 55c are arranged so as to be smaller than the maximum absolute value. In the following description, the conditions after approximation will be mainly described.

  The above-described condition is that the traveling direction of the first coherent light La diffracted by the first hologram element 55a and emitted from the first hologram element 55a with respect to the traveling direction of the first coherent light La incident on the first hologram element 55a. Is diffracted by the second hologram element 55b with respect to the traveling direction of the second coherent light Lb incident on the second hologram element 55b and is diffracted by the second hologram element 55b. The traveling direction of the third coherent light Lc that is smaller than the angle ψb formed by the traveling direction of the second coherent light Lb emitted from 55b, that is, the maximum absolute value of the deflection angle ψb, and is incident on the third hologram element 55c. In contrast, the light is diffracted by the third hologram element 55c and emitted from the third hologram element 55c. 3 the angle advancing direction forms a coherent light Lc Pusaishi, i.e. so as to be smaller than the maximum value of the absolute values of the deflection angles Pusaishi, each hologram element 55a, 55b, 55c are arranged, and can be rephrased. This is compared with the case where the hologram elements 55a, 55b, and 55c are arranged so that the deflection angles ψa, ψb, and ψc of the coherent lights La, Lb, and Lc in the hologram elements 55a, 55b, and 55c are equal. This means that a deviation from the Fresnel Kirchhoff approximation in the first hologram element 55a is reduced. For this reason, according to this Embodiment, it can suppress that diffraction efficiency and light utilization efficiency fall in the 1st hologram element 55a corresponding to a short wavelength range. The deflection angles ψa, ψb, and ψc described above will be described in detail later with reference to FIG. 5C.

  Preferably, the second hologram element 55b and the third hologram element 55c are arranged such that the maximum absolute value of “θb + φb” is smaller than the maximum absolute value of “θc + φc”. In other words, the second hologram element 55b and the third hologram element 55c are arranged so that the maximum absolute value of the deflection angle ψb is smaller than the maximum absolute value of the deflection angle ψc. Thus, as in the case of the first hologram element 55a, when the hologram elements 55b and 55c are arranged so that the deflection angles ψb and ψc of the coherent lights Lb and Lc in the hologram elements 55b and 55c are equal. In comparison, this means that the deviation from the Fresnel Kirchhoff approximation in the second hologram element 55b is reduced. For this reason, it can suppress that diffraction efficiency and light utilization efficiency fall not only about the 1st hologram element 55a but the 2nd hologram element 55b.

  Specifics of the hologram elements 55a, 55b, 55c for satisfying the above-mentioned conditions regarding the respective incident angles θa, θb, θc and the respective outgoing angles φa, φb, φc, or the above-mentioned conditions regarding the respective deflection angles ψa, ψb, ψc The specific configuration is not particularly limited. For example, as shown in FIGS. 1 and 5A, each of the hologram elements 55a, 55b, and 55c has a distance 55a, 55b, and 55c that increases in the order of 55a, 55b, and 55c. Are arranged on one plane in the order of.

  In FIG. 5A, the plane in which the normal lines of the coherent lights La, Lb, and Lc incident on the hologram elements 55a, 55b, and 55c and the hologram elements 55a, 55b, and 55c exist is an xz plane, and The example in which the plane where the coherent light La, Lb, Lc emitted from each hologram element 55a, 55b, 55c and the normal line of each hologram element 55a, 55b, 55c exist is also the xz plane is shown. However, the coherent light La, Lb, Lc incident on each hologram element 55a, 55b, 55c and the plane on which the normal line of each hologram element 55a, 55b, 55c exists coherent emitted from each hologram element 55a, 55b, 55c. It may be considered that the plane is different from the plane in which the normal lines of the light La, Lb, Lc and the hologram elements 55a, 55b, 55c exist. Even in such a case, the above-described conditions represented by the incident angles θa, θb, and θc and the outgoing angles φa, φb, and φc, or the above-described deflection angles ψa, ψb, and ψc are expressed in other words. By disposing the hologram elements 55a, 55b, and 55c so as to satisfy the above-described conditions, it is possible to prevent the diffraction efficiency and the light utilization efficiency from decreasing in the first hologram element 55a. Such an example will be described below with reference to FIGS. 5B and 5C. 5B and 5C, only the first hologram element 55a and the first coherent light La will be described for the sake of simplicity.

  In the example shown in FIG. 5B, the plane including the first coherent light La incident on the first hologram element 55a and the normal line of the first hologram element 55a is an xz plane. On the other hand, the first coherent light La (1), La (2), La (3) diffracted by the first hologram element 55a and emitted from the first hologram element 55a and the normal line of the first hologram element 55a are included. The plane is an xy plane. In this case, the incident angle θa and the emission angle φa or the deflection angle ψa of the first coherent light La can be individually considered in the plane including the first coherent light La.

  For example, FIG. 5C (a) shows the positional relationship shown in FIG. 5B with the first coherent light La incident on the first hologram element 55a and the first coherent light La (1) emitted from the first hologram element 55a. It is expressed on the plane that contains it. Similarly, FIG. 5C (b) shows the positional relationship shown in FIG. 5B according to the first coherent light La incident on the first hologram element 55a and the first coherent light La (2) emitted from the first hologram element 55a. It is expressed on a plane including FIG. 5C (c) shows the positional relationship shown in FIG. 5C with the first coherent light La incident on the first hologram element 55a and the first coherent light La (3) emitted from the first hologram element 55a. It is expressed on the plane that contains it. As shown in FIGS. 5C (a), (b), and (c), the coherent light La (1), La (2), La (3) emitted from the first hologram element 55a and the normal lines of the first hologram element 55a are Even if the existing plane is different from the plane where the coherent light La incident on the first hologram element 55a and the normal line of the first hologram element 55a exist, the incident light and the emitted light are made to correspond one-to-one. When considering the relationship between one incident light and one outgoing light, the incident angle θa and the outgoing angles φa (1), φa (2), φa (3) with respect to the first hologram element 55a are used. Can be expressed by The same applies to the other hologram elements 55b and 55c. Accordingly, the coherent light La, Lb, Lc emitted from each hologram element 55a, 55b, 55c and the plane on which the normal line of each hologram element 55a, 55b, 55c is present is coherent incident on each hologram element 55a, 55b, 55c. Even if the light La, Lb, Lc and the planes where the normal lines of the hologram elements 55a, 55b, 55c exist are different from each other, the above-mentioned incident angles θa, θb, θc and the emission angles φa, φb, φc are described above. Or the above-described conditions regarding the deflection angles ψa, ψb, and ψc, the first hologram element 55a can be prevented from being deteriorated in diffraction efficiency and light utilization efficiency.

As is clear from FIG. 5C (a), the first diffracted light emitted from the first hologram element 55a is diffracted by the first hologram element 55a with respect to the traveling direction of the first coherent light La incident on the first hologram element 55a. The angle ψa (1) formed by the traveling direction of one coherent light La (1), that is, the deflection angle ψa (1) is equal to “θa + φa (1)”.
Similarly, the deflection angle ψa (2) is equal to “θa + φa (2)”, and the deflection angle ψa (3) is equal to “θa + φa (3)”. Therefore, regardless of the plane on which the first coherent light La emitted from the first hologram element 55a exists, the maximum absolute value of “θa + φa” is the maximum absolute value of the deflection angle ψa. Matches. Accordingly, the coherent light La, Lb, Lc emitted from each hologram element 55a, 55b, 55c and the plane on which the normal line of each hologram element 55a, 55b, 55c is present is coherent incident on each hologram element 55a, 55b, 55c. Even if the light La, Lb, Lc and the planes where the normal lines of the hologram elements 55a, 55b, 55c exist are different from each other, the above-mentioned incident angles θa, θb, θc and the emission angles φa, φb, φc are described above. Can be rephrased as the above-described conditions regarding the deflection angles ψa, ψb, and ψc.

  Next, the operation of the illumination device 40, the projection device 20, and the projection display device 10 having the above-described configuration will be described. First, referring to FIG. 6, an operation capable of making speckles inconspicuous very effectively will be described. Note that the principle of making the speckle inconspicuous is the same for each hologram element 55a, 55b, 55c and each coherent light La, Lb, Lc, and here, only the first hologram element 55a and the first coherent light La are mainly described here. explain.

  First, the irradiation device 60 irradiates the optical element 50 with the first coherent light La such that the first coherent light La scans the first hologram element 55a of the optical element 50. Specifically, first coherent light La having a specific wavelength traveling along a certain direction is generated by the first light source 61 a, and the traveling direction of the first coherent light La is changed by the scanning device 65. The scanning device 65 causes the first coherent light La having a specific wavelength to enter each position on the first hologram element 55a at an incident angle that satisfies the Bragg condition at the position. As a result, the first coherent light La incident on each position reproduces the image 5 of the scattering plate at least on the illuminated area LZ by diffraction at the first hologram element 55a. That is, the first coherent light La that has entered the first hologram element 55a from the irradiation device 60 is diffused (expanded) by the first hologram element 55a and is incident on the entire illuminated area LZ. It becomes like this. Similarly, the second coherent light Lb and the third coherent light Lc incident on the respective positions of the second hologram element 55b and the third hologram element 55c from the irradiation device 60 are the second hologram element 55b and the third hologram element 55c, respectively. Is diffused (expanded) by the light and enters the entire illuminated area LZ. In this way, the irradiation device 60 illuminates the illuminated area LZ with the respective coherent lights La, Lb, and Lc. Therefore, the illuminated area LZ is illuminated with a color obtained by additive color mixing of the coherent lights La, Lb, and Lc. That is, in this example, the illumination device 60 illuminates the illuminated area LZ with white light.

  As shown in FIG. 1, in the projection device 20, the spatial light modulator 30 is arranged at a position overlapping the illuminated area LZ of the illumination device 40. For this reason, the spatial light modulator 30 is illuminated in a planar shape by the illumination device 40, and forms an image by selecting and transmitting the respective coherent lights La, Lb, and Lc for each pixel. This image is projected onto the screen 15 by the projection optical system 25. Each of the coherent lights La, Lb, and Lc projected on the screen 15 is diffused and recognized by the observer as a multi-color image, preferably as a full-color image. However, at this time, the coherent lights La, Lb, and Lc projected on the screen interfere with each other by diffusion and cause speckle.

  However, according to the lighting device 40 described here, speckles can be made extremely inconspicuous as described below.

According to the aforementioned Non-Patent Document 1, it is effective to multiplex parameters such as polarization, phase, angle, and time and increase the mode in order to make speckle inconspicuous.
The mode here refers to speckle patterns that are uncorrelated with each other. For example, when coherent light is projected from different directions onto the same screen from a plurality of laser light sources, there are as many modes as the number of laser light sources. In addition, when coherent light from the same laser light source is projected onto the screen from different directions by dividing the time, the mode is the same as the number of times the incident direction of the coherent light has changed during the time that cannot be resolved by the human eye. Will exist. When there are a large number of these modes, it is considered that the interference patterns of light are overlapped uncorrelatedly and averaged, and as a result, speckles observed by the observer's eyes become inconspicuous.

  In the present embodiment, as shown in FIG. 6, the first coherent light La is irradiated onto the optical element 50 so as to scan the first hologram element 55a. Further, the first coherent light La incident on each position of the first hologram element 55a from the irradiation device 60 illuminates the entire illuminated area LZ, but the first coherent light La that illuminates the illuminated area LZ. The illumination directions are different from each other. Since the position on the first hologram element 55a where the coherent light is incident changes with time, the incident direction of the first coherent light La to the illuminated region LZ also changes with time.

  Considering the illuminated area LZ as a reference, the first coherent light La is constantly incident on each position in the illuminated area LZ, but the incident direction is always as shown by the arrow A1 in FIG. Will continue to change. As a result, 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.

  The first coherent light La continuously scans on the first hologram element 55a. Therefore, the incident direction of the first coherent light La from the irradiation device 60 to the illuminated region LZ continuously changes, and accordingly, the incident direction of the first coherent light La from the projection device 20 to the screen 15 is also continuous. Changes. Here, the incident direction of the first coherent light La from the projection device 20 to the screen 15 is slightly, for example, 0. If it changes by a few degrees, the speckle pattern generated on the screen 15 also changes greatly, and an uncorrelated speckle pattern is sufficiently superimposed. In addition, although the reflection device 66 of the scanning device 65 is configured by a MEMS mirror, a polygon mirror, or the like, the frequency of the reflection device 66 such as a MEMS mirror or a polygon mirror that is actually commercially available is usually several hundred Hz or more. A reflection device 66 reaching tens of thousands of Hz is not uncommon.

  Similarly, the second coherent light Lb and the third coherent light Lc continuously scan on the second hologram element 55b and the third hologram element 55c. Therefore, the incident directions of the second coherent light Lb and the third coherent light Lc from the irradiation device 60 to the illuminated region LZ are continuously changed, and accordingly, the second coherent light from the projection device 20 to the screen 15 is changed. The incident directions of Lb and the third coherent light Lc also change continuously. For this reason, as in the case of the first coherent light La, uncorrelated speckle patterns are superimposed and averaged, and as a result, speckles observed by the observer's eyes can be made inconspicuous.

  From the above, according to the present embodiment described above, the incident directions of the coherent lights La, Lb, and Lc change temporally at each position on the screen 15 displaying an image, and This change is at a rate that cannot be resolved by the human eye, and as a result, the scattering pattern of each non-correlated coherent light La, Lb, Lc is multiplexed and observed by the human eye. become. 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.

  Note that conventional speckles observed by humans include not only speckles on the screen side caused by scattering of each coherent light La, Lb, Lc on the screen 15 but also before being projected on the screen. Speckle on the projection apparatus side caused by scattering of each coherent light La, Lb, Lc may also occur. The speckle pattern generated on the projection device side is projected onto the screen 15 via the spatial light modulator 30 so that it can be recognized by the observer. However, according to the present embodiment described above, each coherent light La, Lb, Lc continuously scans on each hologram element 55a, 55b, 55c, and each position of each hologram element 55a, 55b, 55c. Each of the coherent lights La, Lb, and Lc incident on the light illuminates the entire illuminated area LZ on which the spatial light modulator 30 is superimposed. That is, each of the hologram elements 55a, 55b, and 55c forms a new wavefront separate from the previous wavefront that had formed the speckle pattern, and the illumination area LZ and further the spatial light The screen 15 is illuminated via the modulator 30. Due to the formation of a new wavefront in each of the hologram elements 55a, 55b, and 55c, the speckle pattern generated on the projection apparatus side becomes invisible.

  In addition, in this embodiment, each coherent light La, Lb, Lc illuminates the illuminated area LZ and is projected onto the screen 15. The coherent lights La, Lb, and Lc are generated by different light sources 61a, 61b, and 61c, and therefore have no coherence. 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 this Embodiment, a speckle pattern can be made not more conspicuous.

  By the way, Non-Patent Document 1 described above proposes a method using a numerical value called speckle contrast (unit%) as a parameter indicating the degree of speckle generated on the screen. This speckle contrast is defined as a value obtained by dividing the standard deviation of the actual luminance variation on the screen divided by the average luminance value when displaying a test pattern image that should have a uniform luminance distribution. Amount. The larger the speckle contrast value is, the larger the speckle occurrence level on the screen is, which indicates that the spot-like luminance unevenness pattern is more prominently presented to the observer.

  When the speckle contrast was measured for the projection display apparatus 10 of the present embodiment described with reference to FIGS. 1 to 6, it was 3.7% (Condition 1). Further, as the optical element 50, instead of a relief hologram as a computer-generated hologram, a reflective type produced by an interference exposure method so that the image 5 of the scattering plate can be reproduced when receiving specific reproduction illumination light. The speckle contrast was measured for the projection type image display apparatus configured in the same manner as in Condition 1 except that the volume hologram was used, and the result was 3.0% (Condition 2). In HDTV (high-definition television) video display applications, a speckle contrast of 6.0% or less is a standard (for example, WO / 2001/081996) as a level at which an uneven brightness pattern is hardly recognized when an observer observes with the naked eye. However, the present embodiment described above sufficiently satisfies this criterion. Further, when actually observing with the naked eye, no brightness unevenness, which is a brightness unevenness that can be visually recognized, has occurred.

  On the other hand, when the spatial light modulator 30 is illuminated with the laser light from the laser light source as a mere parallel light beam, that is, the scanning device 65 or the optical device is added to the spatial light modulator 30 of the projection display apparatus 10 shown in FIG. When the coherent light from the first light source 61a was incident on the parallel light beam without passing through the element 50, the speckle contrast was 20.7% (Condition 3). Under these conditions, a spot-like luminance unevenness pattern was observed quite noticeably by visual observation.

  Further, when the light source mechanism 61 is replaced with a green LED (non-coherent light source) and light from the LED light source is incident on the spatial light modulator 30, that is, the projection-type image display device 10 shown in FIG. When the non-coherent light from the LED light source is incident as a parallel light beam on the spatial light modulator 30 without using the scanning device 65 or the optical element 50, the speckle contrast is 4.0% (condition 4). . Under these conditions, no brightness unevenness, which is a brightness unevenness that can be visually recognized by naked eye observation, has occurred.

  The results of Condition 1 and Condition 2 were much better than the results of Condition 3, and were also better than the measurement results of Condition 4. As already mentioned, the problem of speckle generation is a problem inherent in the case of using a coherent light source such as a laser beam in practice, and it is necessary to consider in an apparatus using a non-coherent light source such as an LED. There is no problem. In addition, in condition 1 and condition 2, as compared with condition 4, an optical element 50 that can cause speckles is added. From these points, it can be said that Condition 1 and Condition 2 were sufficient to cope with speckle defects.

  In addition, according to the above-described embodiment, the following advantages can be obtained.

  As described above, in each of the hologram elements 55a, 55b, and 55c of the optical element 50, the maximum absolute value of “θa + φa” related to the incident angle and the outgoing angle is smaller than the maximum absolute value of “θb + φb”. In addition, the arrangement is such that the condition that the maximum value of the absolute value of “θa + φa” is smaller than the maximum value of the absolute value of “θc + φc” is satisfied. In other words, in each hologram element 55a, 55b, 55c of the optical element 50, the maximum absolute value of the deflection angle ψa is smaller than the maximum absolute value of the deflection angle ψb, and the absolute value of the deflection angle ψa. Are arranged so that the condition that the maximum value of the angle becomes smaller than the maximum value of the absolute value of the deflection angle ψc is satisfied. As a result, it is possible to prevent the diffraction efficiency and light utilization efficiency of the first hologram element 55a from being lowered. As a result, the diffraction efficiency and light utilization efficiency of the entire hologram element 55 can be improved.

  Further, according to the present embodiment described above, the optical element 50 for making speckles inconspicuous also functions as an optical member for shaping and adjusting the beam form of coherent light emitted from the irradiation device 60. obtain. Therefore, the optical system can be reduced in size and simplified.

[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)
In the embodiment described above, an example has been shown in which the irradiation device 60 causes each coherent light La, Lb, and Lc to be incident on the optical element 50 so as to follow the optical path of one light beam included in the divergent light beam. Absent. For example, in the above-described embodiment, the scanning device 65 may further include a condensing lens 67 disposed on the downstream side of the mirror device 66 along the optical path of each of the coherent lights La, Lb, and Lc. In this case, as shown in FIG. 7, the light from the mirror device 66 traveling along the optical path of the light beam constituting the divergent light beam becomes light traveling in a certain direction by the condenser lens 67. That is, the irradiation device 60 causes the coherent lights La, Lb, and Lc to enter the hologram elements 55 a, 55 b, and 55 c of the optical element 50 so as to follow the optical path of the light beam that forms the parallel light flux. Since the combined light SL including a plurality of coherent lights La, Lb, and Lc having different wavelength ranges is incident on the lens 67, an achromatic lens is used as the lens 67 from the viewpoint of preventing problems such as chromatic dispersion. Is preferably used.

  FIG. 8 is an enlarged view of the optical element 50 of FIG. 7 and corresponds to FIG. 5 in the above-described embodiment. In this modification, the incident angles of the coherent lights La, Lb, and Lc incident on the respective positions of the hologram elements 55a, 55b, and 55c are substantially the same. In this case, the above-described conditions for increasing the diffraction efficiency and the light utilization efficiency in the first hologram element 55a corresponding to the first coherent light La in the short wavelength region can be read as follows. That is, in this modification, each of the hologram elements 55a, 55b, 55c has a maximum absolute value of the emission angle φa that is smaller than a maximum value of the absolute value of the emission angle φb and the absolute value of the emission angle φa. The maximum value is arranged to be smaller than the maximum absolute value of the emission angle φc. In other words, in each hologram element 55a, 55b, 55c, the maximum absolute value of the deflection angle ψa is smaller than the maximum absolute value of the deflection angle ψb, and the maximum absolute value of the deflection angle ψa is The deflection angle ψc is arranged so as to be smaller than the maximum absolute value. Also in this modification, preferably, the second hologram element 55b and the third hologram element 55c are arranged so that the maximum value of the emission angle φb is smaller than the maximum value of the emission angle φc. In other words, the second hologram element 55b and the third hologram element 55c are arranged such that the maximum value of the deflection angle ψb is smaller than the maximum value of the deflection angle ψc.

Moreover, in the form and the modification mentioned above, the example to which the to-be-illuminated area | region LZ was produced | generated in the position shifted | deviated from the front of the optical element 50 was shown. However, the present invention is not limited to this, and as shown in FIG. 9, the optical element 50 is configured so that the illuminated region LZ is generated in the front direction of the optical element 50, particularly in the front direction of the first hologram element 55a. May be. Here, when the hologram elements 55a, 55b, and 55c are arranged on one plane as shown in FIG. 9, the optical element 50 is arranged to face the illuminated area LZ at the shortest distance. 55a, and a second hologram element 55b and a third hologram element 55c arranged on both sides of the first hologram element 55a. As a result, also in this modification, the maximum absolute value of “θa + φa” is smaller than the maximum absolute value of “θb + φb”, and the maximum absolute value of “θa + φa” is the absolute value of “θc + φc”. The condition that the value is smaller than the maximum value can be established. In other words, the maximum absolute value of the deflection angle ψa is smaller than the maximum absolute value of the deflection angle ψb, and the maximum absolute value of the deflection angle ψa is smaller than the maximum absolute value of the deflection angle ψc. The condition of becoming smaller can be established.
As a result, it is possible to prevent the diffraction efficiency and light utilization efficiency of the first hologram element 55a from being lowered.

In the form shown in FIG. 9, the second hologram element 55b and the third hologram element 55c may be arranged symmetrically about the first hologram element 55a.
In this case, the maximum absolute value of “θb + φb” may be the same as the maximum absolute value of “θc + φc”. In other words, the maximum absolute value of the deflection angle ψb may be the same as the maximum absolute value of the deflection angle ψc.

  In the embodiment and the modification described above, the maximum absolute value of “θa + φa” is “θb + φb” for each of the coherent lights La, Lb, Lc diffracted by the hologram elements 55a, 55b, 55c and proceeding to the illuminated region LZ. In this example, the absolute value of “θa + φa” is smaller than the maximum absolute value of “θa + φa” and the maximum value of “θc + φc” is smaller than the maximum absolute value of “θc + φc”. However, the maximum absolute value of “θa + φa” is smaller than the maximum absolute value of “θb + φb” for all the coherent lights La, Lb, Lc diffracted by the hologram elements 55a, 55b, 55c, In addition, a condition that the maximum absolute value of “θa + φa” is smaller than the maximum absolute value of “θc + φc” may be imposed. In other words, for all the coherent lights La, Lb, Lc diffracted by the hologram elements 55a, 55b, 55c, the maximum absolute value of the deflection angle ψa is smaller than the maximum absolute value of the deflection angle ψb. In addition, a condition that the maximum absolute value of the deflection angle ψa is smaller than the maximum absolute value of the deflection angle ψc may be imposed. By imposing stricter conditions on the hologram elements 55a, 55b, and 55c in this manner, the diffraction efficiency and light utilization efficiency in the first hologram element 55a can be further increased. As a result, the diffraction efficiency and light utilization efficiency of the hologram element 55 as a whole can be further improved.

  In the embodiment and the modification described above, the optical element 50 includes a first hologram element 55a that diffracts the first coherent light La in the first wavelength range, and a second wavelength range that is longer than the first wavelength range. The example which has the 2nd hologram element 55b which Lb diffracts the 2nd coherent light, and the 3rd hologram element 55c which diffracts the 3rd coherent light Lc of the 3rd wavelength range which is longer wavelength side than the 2nd wavelength range Indicated. That is, the example is shown in which the optical element 50 is configured to be able to cope with coherent light in three wavelength regions. However, the present invention is not limited to this, and the optical element 50 may be configured to support coherent light in two wavelength regions, or configured to support coherent light in four or more wavelength regions. It may be. When the optical element 50 is configured to support coherent light in two wavelength ranges, the first hologram element 55a and the second hologram element 55b have a maximum value of “θa + φa” and a maximum value of “θb + φb”. It arrange | positions so that it may become smaller. In other words, the first hologram element 55a and the second hologram element 55b are arranged such that the maximum value of the deflection angle ψa is smaller than the maximum value of the deflection angle ψb. In addition, in the case where the optical element 50 is configured to support coherent light in four or more wavelength ranges, for example, although not shown, the fourth hologram in which the optical element 50 diffracts the fourth coherent light in the fourth wavelength range is used. When it further has an element, arrangement | positioning of a 4th hologram element is determined according to a 4th wavelength range. For example, when the fourth wavelength region corresponds to the yellow component, the fourth hologram element can be disposed between the second hologram element 55b and the third hologram element 55c of the optical element 50 shown in FIG. That is, each hologram element can be arranged so that the deflection angle becomes smaller as the hologram element corresponds to the short wavelength region.

  Moreover, according to the form mentioned above, a speckle can be made inconspicuous effectively. However, this effect is mainly due to the lighting device 40. Therefore, the lighting device 40 can be usefully used in various aspects. For example, the illumination device 40 can be used as simple illumination, and in this case, luminance unevenness and flicker that are unevenness in brightness can be made inconspicuous.

  Moreover, you may use the illuminating device 40 mentioned above as illumination for scanners (an image reading apparatus as an example). In such an example, the speckle generated on the target object can be made inconspicuous by arranging the target object to be scanned on the illuminated region LZ of the lighting device 40. As a result, it is possible to eliminate image correction means and the like that are conventionally required.

  When the illuminating device 40 is incorporated in a scanner, the illuminated area LZ by the illuminating device 40 may be a surface as in the above-described form. Alternatively, the illuminated region LZ by the illumination device 40 may be an elongated region (region also called a linear shape) extending in one direction. In this case, two-dimensional image information can be read by the illuminating device 40 incorporated in the scanner moving relative to the object along a direction orthogonal to the one direction.

(Spatial light modulator, projection optical system, screen)
According to the embodiment described above, speckle can be effectively made inconspicuous. However, this effect is mainly due to the lighting device 40. Even if this lighting device 40 is combined with various known spatial light modulators, projection optical systems, screens, etc., speckles can be effectively made inconspicuous. From this point, the spatial light modulator, the projection optical system, and the screen are not limited to those illustrated, and various known members, components, devices, and the like can be used.

(Projection-type image display device)
Moreover, although each hologram element 55a, 55b, 55c has been shown as an example configured to reproduce an image of a planar scattering plate having a shape corresponding to the incident surface of the spatial light modulator 30, the present invention is not limited thereto. Instead, each hologram element 55a, 55b, 55c may be manufactured by an interference exposure method using a scattering plate having some pattern. In this case, an image of the scattering plate having a certain pattern is reproduced by each hologram element 55a, 55b, 55c.
In other words, the optical element 50 having the hologram elements 55a, 55b and 55c 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 each hologram element 55a, 55b, 55c on the screen 15. Also in this display device, the irradiation device 60 irradiates the optical element 50 with the coherent lights La, Lb, and Lc so that the coherent lights La, Lb, and Lc scan the hologram elements 55a, 55b, and 55c. Therefore, speckles on the screen 15 can be made inconspicuous.

  In the embodiment described above, the illumination device 40 includes the optical element 50 including the hologram element 55, and the example in which the coherent light whose profile is shaped by the hologram element 55 is directly incident on the spatial light modulator 30 has been shown. However, the configuration of the projection device 20 including the illumination device 40 and the spatial light modulator 30 can be appropriately changed without being limited to such a configuration. As an example, in the example shown in FIG. 10, the integrator rod 22 and the relay optical system 23 are arranged in this order between the illumination device 40 and the spatial light modulator 30 in the optical path of the coherent light.

  In many conventional projection devices and projection-type video display devices, typically large conventional projection devices and projection-type video display devices, an integrator for making the illuminance distribution uniform upstream of the spatial light modulator A rod and a relay optical system capable of transmitting cross-sectional information of light traveling in a certain position to another position are provided. The illumination device 40 described in the above-described form can also be applied to such a conventional projection device and projection type image display device. As an example, as shown in FIG. 10, the integrator rod 22 and the relay optical system 23. Can be used as is.

  Moreover, with the form mentioned above, the irradiation apparatus 60 showed the example which has the light source mechanism 61 containing each light source 61a, 61b, 61c, and the scanning device 65. FIG. Although the scanning device 65 is an example of the uniaxial rotation type mirror device 66 that changes the traveling direction of each of the coherent lights La, Lb, and Lc by reflection, the scanning device 65 is not limited thereto. As shown in FIG. 11, the scanning device 65 has a second rotation in which the mirror (reflection surface 66a) of the mirror device 66 intersects not only the first rotation axis RA1 but also the first rotation axis RA1. It may be rotatable about the axis RA2. In the example shown in FIG. 11, the second rotation axis RA2 of the mirror 66a is a first rotation axis RA1 extending parallel to the Y axis of the XY coordinate system defined on the plate surface of the first hologram element 55a. And they are orthogonal. Since the mirror 66a is rotatable about both the first axis RA1 and the second axis RA2, the incident point IP of the first coherent light La from the irradiation device 60 to the optical element 50 is the hologram element 55. It is possible to move in a two-dimensional direction on the plate surface. For this reason, as shown in FIG. 11 as an example, the incident point IP of the first coherent light La to the optical element 50 can be moved on the circumference.

  Further, the scanning device 65 may include two or more mirror devices 66. In this case, even if the mirror 66a of the mirror device 66 can be rotated only about a single axis, the incident point IP of each coherent light La, Lb, Lc from the irradiation device 60 to the optical element 50 is determined. The hologram element 55 can be moved in a two-dimensional direction on the plate surface.

  Specific examples of the mirror device 66a included in the scanning device 65 include a MEMS mirror and a polygon mirror.

  The scanning device 65 may include a device other than a reflection device (for example, the mirror device 66 described above) that changes the traveling direction of coherent light by reflection. For example, the scanning device 65 may include a refractive prism, a lens, and the like.

  In the first place, the scanning device 65 is not essential, and each light source 61a, 61b, 61c of the irradiation device 60 is configured to be displaceable (moving, swinging, rotating) with respect to the optical element 50, and each light source 61a, 61b, 61c. Each of the coherent lights La, Lb, and Lc emitted from the light sources 61a, 61b, and 61c may scan the hologram elements 55a, 55b, and 55c by the displacement of the optical element 50.

  Furthermore, although each light source 61a, 61b, 61c of the irradiation apparatus 60 has been described on the assumption that it oscillates a laser beam shaped as a linear light beam, the present invention is not limited to this. In particular, in the above-described embodiment, each coherent light La, Lb, Lc irradiated to each position of the optical element 50 is shaped by the optical element 50 into a light beam that enters the entire illuminated area LZ. Therefore, there is no inconvenience even if the coherent lights La, Lb, and Lc emitted from the light sources 61a, 61b, and 61c of the irradiation device 60 to the optical element 50 are not accurately shaped. For this reason, each coherent light La, Lb, Lc generated from each light source 61a, 61b, 61c may be diverging light. The cross-sectional shape of each of the coherent lights La, Lb, and Lc generated from each of the light sources 61a, 61b, and 61c may be an ellipse or the like instead of a circle. Furthermore, the transverse mode of each coherent light La, Lb, Lc generated from each light source 61a, 61b, 61c may be a multimode.

  In addition, when each light source 61a, 61b, 61c generates a divergent light beam, each coherent light La, Lb, Lc is not a point but a certain amount when entering each hologram element 55a, 55b, 55c of the optical element 50. The light enters a region having an area. In this case, the light diffracted by the hologram elements 55a, 55b, and 55c and incident on each position of the illuminated region LZ is multiplexed in angle. In other words, at each moment, each coherent light La, Lb, Lc is incident on each position of the illuminated area LZ from a certain angle range. Speckle can be made more inconspicuous by such multiplexing of angles.

In the embodiment described above, an example in which each of the light sources 61a, 61b, and 61c of the irradiation device 60 has only a single laser light source has been described, but the present invention is not limited thereto. For example, each of the light sources 61a, 61b, and 61c may include a plurality of laser light sources that oscillate light in the same wavelength region.
In this case, the illumination device 40 can illuminate the illuminated area LZ more brightly. Further, coherent lights from different solid laser light sources do not have coherence with each other. Therefore, the multiplexing of the scattering pattern further proceeds and the speckle can be made less noticeable.

(Hologram element of optical element)
In the embodiment described above, the hologram element 55 of the optical element 50 is an example of a relief hologram as a computer-generated hologram (CGH). However, the present invention is not limited to this, and various types of hologram elements are used. obtain. For example, in the embodiment described above, an example in which a so-called Fresnel type hologram element is used has been described. However, the present invention is not limited to this, and a so-called Fourier transform type hologram element may be used. As described above, when a hologram element with weak wavelength selectivity is used as a plurality of hologram elements each having a predetermined diffraction action with respect to light in different wavelength ranges, the hologram elements are stacked. Instead, they are arranged spatially shifted. In this case, as described above, the hologram corresponding to the coherent light in the lowest wavelength region is obtained by appropriately arranging each hologram element so that the deflection angle in the hologram element that diffracts the coherent light in the lowest wavelength region is reduced. The diffraction efficiency of the element and the light utilization efficiency can be increased.

  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.

5 Image 10 Projection-type image display device 15 Screen 20 Projection device 22 Integrator rod 23 Relay optical system 25 Projection optical system 30 Spatial light modulator 40 Illumination device 50 Optical element 55 Hologram element 55a First hologram element 55b Second hologram element 55c Second 3 hologram element 60 irradiation device 61 light source mechanism 61a first light source 61b second light source 61c third light source 62 synthesis device 64 lens 65 scanning device 66 mirror device (reflection device)
66a Mirror (reflective surface)
67 Condensing lens LZ Illuminated area La First coherent light Lb Second coherent light Lc Third coherent light

Claims (14)

An optical element including a first hologram element and a second hologram element;
A first light source that oscillates with respect to the optical element and that oscillates a first coherent light in a first wavelength range;
A second light source that oscillates with respect to the optical element, oscillates a second coherent light in a second wavelength region that is longer than the first wavelength region,
The first hologram element includes the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element, respectively. And illuminating areas that are diffracted by one hologram element and at least partially overlap each other,
The second hologram element includes the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, respectively. It is configured to illuminate areas that are diffracted by the two hologram elements and overlap at least in part,
The at least a portion illuminated so as to overlap with the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element; The at least a portion illuminated so as to overlap with the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, Overlap at least in some areas,
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb Then,
A lighting device in which the maximum absolute value of ψa is smaller than the maximum absolute value of ψb. An optical element including a first hologram element, a second hologram element, and a third hologram element;
A first light source that oscillates with respect to the optical element and that oscillates a first coherent light in a first wavelength range;
A second light source that oscillates with respect to the optical element, oscillates a second coherent light in a second wavelength region that is longer than the first wavelength region;
A third light source that oscillates with respect to the optical element and that oscillates third coherent light in a third wavelength region that is longer than the second wavelength region;
The first hologram element includes the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element, respectively. And illuminating areas that are diffracted by one hologram element and at least partially overlap each other,
The second hologram element includes the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, respectively. It is configured to illuminate areas that are diffracted by the two hologram elements and overlap at least in part,
The third hologram element includes the third coherent light incident on the first position of the third hologram element and the third coherent light incident on the second position of the third hologram element, respectively. 3 is configured to illuminate areas that are diffracted by the three hologram elements and at least partially overlap each other;
The at least a portion illuminated so as to overlap with the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element; The at least part illuminated so as to overlap with the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element; The at least part illuminated so as to overlap with the third coherent light incident on the first position of the third hologram element and the third coherent light incident on the second position of the third hologram element. , At least partly overlapping,
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb And an angle formed by the traveling direction of the third coherent light that is diffracted by the third hologram element and travels to the partial range with respect to the traveling direction of the third coherent light incident on the third hologram element. If ψc,
the maximum absolute value of ψa is smaller than the maximum absolute value of ψb, and
The lighting device in which the maximum absolute value of ψa is smaller than the maximum absolute value of ψc.   The first wavelength range corresponds to a first primary color component, the second wavelength range corresponds to a second primary color component, and the third wavelength range corresponds to a third primary color component. Lighting equipment.   The lighting device according to claim 2, wherein the maximum absolute value of ψb is smaller than the maximum absolute value of ψc.   The illumination device according to any one of claims 2 to 4, wherein the first hologram element, the second hologram element, and the third hologram element are arranged on a plane in this order.   The lighting device according to claim 2 or 3, wherein the maximum absolute value of ψb is the same as the maximum absolute value of ψc.   The illumination device according to any one of claims 2, 3, and 6, wherein the second hologram element and the third hologram element are arranged symmetrically with respect to the first hologram element.   The illumination device according to claim 1, wherein each hologram element is a relief-type computer-generated hologram. An illumination device that emits a plurality of coherent lights having different wavelength ranges;
A spatial light modulator illuminated by each coherent light from the illumination device,
The lighting device includes:
An optical element including a first hologram element and a second hologram element;
A first light source that oscillates with respect to the optical element and that oscillates a first coherent light in a first wavelength range;
A second light source that oscillates with respect to the optical element, oscillates a second coherent light in a second wavelength region that is longer than the first wavelength region,
The first hologram element includes the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element, respectively. And illuminating areas that are diffracted by one hologram element and at least partially overlap each other,
The second hologram element includes the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, respectively. It is configured to illuminate areas that are diffracted by the two hologram elements and overlap at least in part,
The at least a portion illuminated so as to overlap with the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element; The at least a portion illuminated so as to overlap with the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, Overlap at least in some areas,
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb Then,
A projection apparatus in which the maximum absolute value of ψa is smaller than the maximum absolute value of ψb.   The projection device according to claim 9, further comprising an integrator rod disposed between the illumination device and the spatial light modulator.   The projection apparatus according to claim 10, further comprising a relay optical system disposed between the integrator rod and the spatial light modulator. A projection device comprising: an illumination device that emits a plurality of coherent lights having different wavelength ranges; and a spatial light modulator disposed at a position illuminated by each 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:
An optical element including a first hologram element and a second hologram element;
A first light source that oscillates with respect to the optical element and that oscillates a first coherent light in a first wavelength range;
A second light source that oscillates with respect to the optical element, oscillates a second coherent light in a second wavelength region that is longer than the first wavelength region,
The first hologram element includes the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element, respectively. And illuminating areas that are diffracted by one hologram element and at least partially overlap each other,
The second hologram element includes the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, respectively. It is configured to illuminate areas that are diffracted by the two hologram elements and overlap at least in part,
The at least a portion illuminated so as to overlap with the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element; The at least a portion illuminated so as to overlap with the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, Overlap at least in some areas,
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb Then,
A projection display apparatus in which the maximum absolute value of ψa is smaller than the maximum absolute value of ψb. An illumination device that emits a plurality of coherent lights having different wavelength ranges;
A screen disposed at a position illuminated by each coherent light from the illumination device,
The lighting device includes:
An optical element including a first hologram element and a second hologram element;
A first light source that oscillates with respect to the optical element and that oscillates a first coherent light in a first wavelength range;
A second light source that oscillates with respect to the optical element, oscillates a second coherent light in a second wavelength region that is longer than the first wavelength region,
The first hologram element includes the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element, respectively. And illuminating areas that are diffracted by one hologram element and at least partially overlap each other,
The second hologram element includes the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, respectively. It is configured to illuminate areas that are diffracted by the two hologram elements and overlap at least in part,
The at least a portion illuminated so as to overlap with the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element; The at least a portion illuminated so as to overlap with the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, Overlap at least in some areas,
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb Then,
A projection display apparatus in which the maximum absolute value of ψa is smaller than the maximum absolute value of ψb. An optical element that includes a first hologram element and a second hologram element and scatters coherent light,
The first hologram element is incident on the first position of the first hologram element, the first coherent light in the first wavelength region, and the incident angle different from the case of the first position of the first hologram element. The first coherent light incident on the second position of the first hologram element is configured to illuminate regions that are diffracted by the first hologram element and overlap each other at least in part,
The second hologram element is incident on a first position of the second hologram element , the second coherent light in a second wavelength region on the longer wavelength side than the first wavelength region, and the second hologram element The second coherent light incident on the second position of the second hologram element at an incident angle different from that in the case of the first position is diffracted by the second hologram element and illuminates a region that overlaps at least partially. Configured to
The at least a portion illuminated so as to overlap with the first coherent light incident on the first position of the first hologram element and the first coherent light incident on the second position of the first hologram element; The at least a portion illuminated so as to overlap with the second coherent light incident on the first position of the second hologram element and the second coherent light incident on the second position of the second hologram element, Overlap at least in some areas,
An angle formed by the traveling direction of the first coherent light that is diffracted by the first hologram element and travels to the partial range with respect to the traveling direction of the first coherent light incident on the first hologram element is denoted by ψa. The angle formed by the traveling direction of the second coherent light that is diffracted by the second hologram element and travels to the partial range with respect to the traveling direction of the second coherent light incident on the second hologram element is ψb Then,
An optical element in which the maximum absolute value of ψa is smaller than the maximum absolute value of ψb.

Images