JP5534056B2 - Lighting device, image display device, and projector - Google Patents

Description

  The present invention relates to a lighting device, an image display device, and a projector, and more particularly to a technology of a lighting device using a laser light source.

  In recent years, a technique using a laser light source for a projector illumination device has been proposed. For example, a diffractive optical element can be used as the superimposing means for superimposing the laser light on the irradiated surface. The diffractive optical element diffracts the laser beam, which is coherent light, to shape and enlarge the irradiation region and to uniformize the light amount distribution in the irradiation region. By fulfilling a plurality of functions by the diffractive optical element, the lighting device can have a small number of parts, and can be easily reduced in size and saved in space. When the zero-order light and the diffracted light from the diffractive optical element are incident on the irradiated surface, the zero-order light and the diffracted light may overlap so that only a part of the irradiation region becomes bright. Since only a part of the irradiation area becomes bright, it becomes difficult to obtain a good light quantity distribution. On the other hand, by making the zero-order light travel to a position other than the irradiated surface, the light quantity distribution in the irradiation region can be made uniform easily. For example, Patent Document 1 proposes a technique of providing an irradiated surface at a position other than the position on the extension line of the laser beam emitted from the light source unit. The zero-order light emitted from the diffractive optical element travels on an extension line of the laser beam emitted from the light source unit, and travels to a position other than the irradiated surface.

JP 2007-58148 A

  In the technique proposed in Patent Document 1, the principal ray of the diffracted light emitted from the diffractive optical element is greatly inclined with respect to the normal of the reference plane on which the diffractive optical element is arranged. The diffractive optical element requires advanced design technology in order to realize shaping of an irradiation area and uniform light quantity distribution of diffracted light whose chief ray is greatly inclined with respect to the normal of the reference plane. For this reason, according to the conventional technique, there arises a problem that it may be difficult to shape the irradiation area and make the light amount distribution uniform. The present invention has been made in view of the above-described problems, and provides an illuminating device capable of easily shaping an irradiation area and uniforming a light amount distribution, an image display device using the illuminating device, and a projector. With the goal.

In order to solve the above-described problems and achieve the object, an illumination device according to the present invention diffracts a plurality of light source units and a plurality of coherent lights emitted from the plurality of light source units, and diffracts the light onto an irradiated surface. A diffractive optical element for propagating the diffractive optical element, wherein the diffractive optical element is arranged such that the plurality of coherent lights are incident obliquely with respect to a normal of a reference plane on which the diffractive optical element is arranged, The coherent light includes a first coherent light and a second coherent light, and the first coherent light and the second coherent light are an optical axis of an illumination optical system constituting the illumination device, or the Zero-order light, which is light other than the diffracted light, is incident on the diffractive optical element so as to be substantially symmetrical with respect to the plane including the optical axis and away from each other , and is emitted from the diffractive optical element. Covered Characterized by proceeding to a position other than the morphism surface.

  Zero-order light emitted from the diffractive optical element travels in an oblique direction with respect to the normal of the reference plane. By making the zero-order light travel in an oblique direction with respect to the normal of the reference surface, the angle formed by the normal of the reference surface and the principal ray of the diffracted light can be reduced. As the inclination of the principal ray of diffracted light with respect to the normal to the reference plane can be reduced, it is possible to design a diffractive optical element that can easily shape the irradiation area and make the light amount distribution uniform. Thereby, it is possible to obtain an illuminating device that can easily shape the irradiation area and make the light amount distribution uniform.

  Moreover, as a preferable aspect of the present invention, when the irradiated surface is moved in a direction parallel to the optical axis of the illumination optical system constituting the illumination device, a spatial region formed by the locus of the irradiated surface is predetermined. As a region, it is desirable that at least a part of the diffractive optical element is included in the predetermined region. When a part of the diffractive optical element is included in the predetermined region, the apparatus using the illumination device can be made compact as compared with the case where the diffractive optical element is arranged at a position away from the predetermined region. In addition, the principal ray of diffracted light emitted from the diffractive optical element can be made as close to the irradiated surface as possible.

  Moreover, as a preferable aspect of the present invention, it is desirable that the reference plane is substantially orthogonal to the optical axis. As a result, the angle formed by the perpendicular of the reference plane and the principal ray of the diffracted light can be minimized, and the irradiation area can be shaped and the light quantity distribution can be made uniform most easily. In addition, the chief ray of the diffracted light can be made most perpendicular to the irradiated surface.

  Further, as a preferred embodiment of the present invention, it is desirable to have a collimating lens that collimates the light beam of diffracted light from the diffractive optical element and advances it to the irradiated surface. The smaller the inclination of the chief ray of the diffracted light with respect to the normal of the reference surface, the more it becomes possible to use the central portion of the spherical lens having substantially the same shape as a portion of the spherical surface. Since the central portion of the spherical lens can be used, the influence of the aberration of the spherical lens can be reduced as compared with the case where the portion near the outer edge of the spherical lens is used. By making it possible to reduce the influence of aberrations, it is possible to reduce a decrease in light utilization efficiency due to uneven brightness in the irradiated area and distortion of the irradiated area. Thereby, using a spherical lens that can be easily manufactured with respect to an aspheric lens, it is possible to reduce luminance unevenness and light utilization efficiency reduction.

  Moreover, as a preferable aspect of the present invention, when the specific direction along the irradiated surface is the first direction, and the direction along the irradiated surface and substantially perpendicular to the first direction is the second direction, Among them, the irradiation region, which is the region where the diffracted light is incident, has a shape that is long in the second direction with respect to the first direction, and the chief ray of the coherent light incident on the diffractive optical element is tilted in the first direction with respect to the perpendicular. It is desirable that As a result, the angle formed by the zero-order light beam and the principal light beam of the diffracted beam can be made as small as possible. The smaller the angle formed between the zero-order light beam and the principal beam of diffracted light, the higher the diffraction efficiency of the diffractive optical element, and the higher the light utilization efficiency.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a plurality of light source units. Bright light can be supplied by using a plurality of light source units.

  Further, as a preferred aspect of the present invention, it is desirable that the plurality of light source units advance the coherent light substantially symmetrically with respect to the optical axis of the illumination optical system constituting the illumination device or a plane including the optical axis. Thereby, each zero-order light can be advanced to a position other than the irradiated surface, and the angle formed between the zero-order light beam and the principal light beam of diffracted light can be reduced.

  Moreover, as a preferable aspect of the present invention, it is desirable that the chief rays of the coherent light emitted from the light source unit are closest to each other in the optical path between the light source unit and the diffractive optical element. Small incident surface compared to the case where the coherent light diverged from each light source unit is incident on the diffractive optical element by making each coherent light converged between the light source unit and the diffractive optical element enter the diffractive optical element. The diffractive optical element can be used. Thereby, a diffractive optical element can be reduced in size and the manufacturing time and cost of a diffractive optical element can be reduced.

  As a preferred embodiment of the present invention, it is desirable that the chief rays of zero-order light emitted from the diffractive optical element are closest to each other in the optical path between the diffractive optical element and the irradiated surface. Also in this case, since the diffractive optical element can be made small, the manufacturing time and cost of the diffractive optical element can be reduced. Furthermore, since the space | interval of a light source part and a diffractive optical element can be shortened, size reduction of an illuminating device is also attained.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a deflecting element that deflects coherent light emitted from the light source unit and enters the diffractive optical element. Thereby, coherent light traveling obliquely with respect to the normal of the reference plane can be incident on the diffractive optical element. By appropriately deflecting the laser beam using the deflecting element, the light source unit can be arranged with a high degree of freedom.

  As a preferred embodiment of the present invention, it is desirable that the deflecting element refracts coherent light. Thereby, coherent light can be deflected.

  As a preferred embodiment of the present invention, it is desirable that the deflecting element diffracts coherent light. Thereby, coherent light can be deflected.

  Moreover, as a preferable aspect of the present invention, it is desirable that the deflection element and the diffractive optical element are integrally formed. Thereby, the number of parts of an illuminating device can be reduced and an illuminating device can be made simple and compact.

  Furthermore, an image display device according to the present invention displays an image using light supplied from the illumination device. By using the above illumination device, it is possible to obtain a good light amount distribution and high light utilization efficiency with a compact configuration. Thereby, an image display device capable of displaying a bright image with a good light quantity distribution can be obtained with a compact configuration.

  Furthermore, a projector according to the present invention includes the above illumination device, a spatial light modulation device that modulates light supplied from the illumination device according to an image signal, and a projection optical system that projects light emitted from the spatial light modulation device. It is characterized by having. By using the above illumination device, it is possible to obtain a good light amount distribution and high light utilization efficiency with a compact configuration. Thereby, a projector capable of displaying a bright image with a good light amount distribution can be obtained with a compact configuration. Since the angle formed by the light beam incident on the spatial light modulator can be suppressed, a high-contrast image can be displayed.

1 is a diagram illustrating a schematic top configuration of a projector according to a first embodiment of the invention. The figure which represented typically the diffraction grating formed in the diffractive optical element. The figure which shows the cross-sectional structure of a part of diffraction grating. The figure which shows the side surface schematic structure of a 1st illuminating device. The figure which shows side surface schematic structure, such as the conventional illuminating device. The figure explaining the irradiation area | region in the case of using the conventional illuminating device. The figure explaining the irradiation area | region in the case of using a 1st illuminating device. The figure showing the relationship between the angle which the extended line of incident light and the light beam of diffracted light make, and diffraction efficiency. The figure in case the chief ray of a laser beam is inclined to the X-axis direction with respect to a perpendicular. The figure in case the chief ray of a laser beam is inclined to the Y-axis direction with respect to a perpendicular. The figure in the case of arrange | positioning a diffractive optical element inclining the perpendicular of an entrance plane with respect to an optical axis. The figure which shows the side surface schematic structure of the illuminating device which concerns on Example 2 of this invention. The figure which shows the side surface schematic structure of the illuminating device which concerns on Example 3 of this invention. The figure explaining the advantage which advances a laser beam substantially symmetrically. FIG. 10 is a diagram for explaining a first modification of the third embodiment. FIG. 10 is a diagram illustrating a second modification of the third embodiment. The figure which shows the side surface schematic structure of the illuminating device which concerns on Example 4 of this invention. The figure which shows the side surface schematic structure of the illuminating device which concerns on the modification 1 of Example 4. FIG. The figure which shows the diffraction grating used as a deflection | deviation element. The figure which shows the blaze | braze grating | lattice used as a deflection | deviation element. The figure which shows the side surface schematic structure of the illuminating device which concerns on the modification 2 of Example 4. FIG. The figure which shows the side surface schematic structure of the illuminating device which concerns on Example 5 of this invention. The figure which shows the side surface schematic structure of the illuminating device which concerns on the modification of Example 5. FIG.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows a schematic top configuration of a projector 10 according to a first embodiment of the invention. The projector 10 is a front projection type projector that appreciates an image by projecting light onto a screen (not shown) and observing the light reflected by the screen. The projector 10 includes a first lighting device 11R, a second lighting device 11G, and a third lighting device 11B. The first lighting device 11R is a lighting device that supplies red (R) light that is first color light. The second illumination device 11G is an illumination device that supplies green (G) light that is second color light. The 3rd lighting device 11B is a lighting device which supplies blue (B) light which is the 3rd color light. The projector 10 is an image display device that displays an image using the R light supplied by the first lighting device 11R, the G light supplied by the second lighting device 11G, and the B light supplied by the third lighting device 11B. is there.

  The first illumination device 11R includes a laser light source 12R that emits R light. The laser light source 12R is a light source unit that emits laser light that is coherent light, and includes, for example, a semiconductor laser. The diffractive optical element 13R diffracts the R light from the laser light source 12R and advances the diffracted light to the irradiated surface of the first spatial light modulator 15R. The diffractive optical element 13R forms an irradiation region of a rectangular shape and a uniform light amount distribution on the irradiated surface of the first spatial light modulator 15R. The diffractive optical element 13R performs shaping and enlargement of the irradiation area, and uniformizing the light amount distribution in the irradiation area. The collimating lens 14 collimates the light beam of the diffracted light from the diffractive optical element 13R and advances it to the irradiated surface. The first spatial light modulation device 15R is a spatial light modulation device that modulates the R light supplied from the first illumination device 11R according to an image signal, and is a transmissive liquid crystal display device. The R light from the first spatial light modulator 15R enters the cross dichroic prism 16.

  The second illumination device 11G includes a laser light source 12G that emits G light. The laser light source 12G is a light source unit that emits laser light that is coherent light, and includes, for example, a semiconductor laser. The diffractive optical element 13G diffracts the G light from the laser light source 12G and advances the diffracted light to the irradiated surface of the second spatial light modulator 15G. The diffractive optical element 13G forms an irradiation region of a rectangular shape and a uniform light amount distribution on the irradiated surface on the second spatial light modulator 15G. The diffractive optical element 13G performs shaping and enlargement of the irradiation area, and uniformizing the light amount distribution in the irradiation area. The collimating lens 14 collimates the diffracted light beam from the diffractive optical element 13G and advances it to the irradiated surface. The second spatial light modulation device 15G is a spatial light modulation device that modulates the G light supplied from the second illumination device 11G according to an image signal, and is a transmissive liquid crystal display device. The G light from the second spatial light modulator 15G is incident on a surface of the cross dichroic prism 16 that is different from the surface on which the R light is incident.

  The 3rd illuminating device 11B has the laser light source 12B which inject | emits B light. The laser light source 12B is a light source unit that emits laser light that is coherent light, and includes, for example, a semiconductor laser. The diffractive optical element 13B diffracts the B light from the laser light source 12B and advances the diffracted light to the irradiated surface of the third spatial light modulator 15B. The diffractive optical element 13B forms an irradiation region of a rectangular shape and a uniform light amount distribution on the irradiated surface of the third spatial light modulator 15B. The diffractive optical element 13B performs shaping and enlargement of the irradiation area and uniformizing the light amount distribution in the irradiation area. The collimating lens 14 collimates the light beam of the diffracted light from the diffractive optical element 13B and advances it to the irradiated surface. The third spatial light modulator 15B is a spatial light modulator that modulates the B light supplied from the third illumination device 11B in accordance with an image signal, and is a transmissive liquid crystal display device. The B light from the third spatial light modulator 15B is incident on a surface of the cross dichroic prism 16 that is different from the surface on which the R light is incident and the surface on which the G light is incident.

  As the diffractive optical elements 13R, 13G, and 13B, for example, a computer generated hologram (CGH) can be used. As the transmissive liquid crystal display device, for example, a high-temperature polysilicon TFT liquid crystal panel (HTPS) can be used.

  The cross dichroic prism 16 has two dichroic films 17 and 18 arranged substantially orthogonal to each other. The first dichroic film 17 reflects R light and transmits G light and B light. The second dichroic film 18 reflects B light and transmits R light and G light. The cross dichroic prism 16 combines R light, G light, and B light incident from different directions, and emits the light toward the projection lens 19. The projection lens 19 functions as a projection optical system that projects light emitted from the spatial light modulators 15R, 15G, and 15B.

  FIG. 2 schematically shows the diffraction grating 20 formed on the diffractive optical elements 13R, 13G, and 13B. FIG. 3 shows an AA cross-sectional configuration of FIG. The diffraction grating 20 is formed at a position where the laser light is incident on the diffractive optical elements 13R, 13G, and 13B. The diffraction grating 20 is formed on the surface of the diffractive optical elements 13R, 13G, and 13B, for example, on the exit surface that emits light. The diffraction grating 20 includes a plurality of irregularities formed with the rectangular region 22 as a unit. Such irregularities are rectangular in the cross section shown in FIG. In FIG. 2, each rectangular region 22 is filled or hatched to indicate that a height difference in a direction perpendicular to the paper surface is provided.

  The diffraction grating 20 changes the phase of the laser beam for each rectangular region 22. The diffractive optical elements 13R, 13G, and 13B generate diffracted light by spatially changing the phase of the laser light in the diffraction grating 20. By optimizing the surface conditions including the pitch of the rectangular region 22 and the height of the irregularities, the diffractive optical elements 13R, 13G, and 13B can have predetermined functions. As a design method for optimizing the surface condition of the diffraction grating 20, a predetermined calculation method (simulation method) such as an iterative Fourier transform can be used. The diffractive optical elements 13R, 13G, and 13B may be provided with a diffraction grating 20 having irregularities having a rectangular shape in cross section, or a diffraction grating having irregularities having a triangular shape in cross section.

  For example, the diffractive optical elements 13R, 13G, and 13B can be manufactured using a so-called nanoimprint technique in which a mold having a desired shape is formed, and then the shape of the mold is thermally transferred to a substrate. In addition, the diffractive optical elements 13R, 13G, and 13B may be manufactured by other conventional methods as long as a desired shape can be formed.

  FIG. 4 shows a schematic side configuration of the first lighting device 11R. The first illuminating device 11R, the second illuminating device 11G, and the third illuminating device 11B have the same configuration except that the wavelength of the light to be supplied and the arrangement direction are different. Hereinafter, the configuration of the first lighting device 11R will be described as a representative example. The diffractive optical element 13R, the collimating lens 14, and the first spatial light modulation device 15R are provided on the optical axis AX of the illumination optical system that constitutes the first illumination device 11R. The optical axis AX is a line that passes through the center of the irradiation area of the first spatial light modulator 11R and is perpendicular to the irradiated surface. The main axis of the collimating lens 14 coincides with the optical axis AX. An axis parallel to the optical axis AX is taken as a Z axis. The X axis is an axis orthogonal to the Z axis. The Y axis is an axis orthogonal to the Z axis and the X axis.

  The incident surface S1 of the diffractive optical element 13R and the irradiated surface S2 of the first spatial light modulator 15R are both substantially orthogonal to the optical axis AX. The incident surface S1 and the irradiated surface S2 are both substantially parallel to the X axis and the Y axis. It is assumed that the incident surface S1 of the diffractive optical element 13R is a reference surface on which the diffractive optical element 13R is disposed. The perpendicular line N of the incident surface S1, which is the reference surface of the diffractive optical element 13R, is substantially parallel to the optical axis AX. The laser light source 12R advances the laser light obliquely with respect to the perpendicular N so that the principal ray of the laser light is inclined in the Y-axis direction with respect to the perpendicular N. The diffractive optical element 13R is arranged so that the laser beam is incident on the perpendicular N obliquely.

  The diffractive optical element 13R diffracts the laser light emitted from the laser light source 12R and advances the first-order diffracted light L1 to the irradiated surface S2. The diffractive optical element 13R uses the first-order diffracted light L1 to form an irradiation region with a rectangular shape and a uniform light amount distribution. The irradiation region is a region where the first-order diffracted light L1 is incident on the irradiated surface S2. The diffractive optical element 13R emits zero-order light L0 that is light other than the first-order diffracted light L1. The zero-order light L0 is light that is not diffracted by the diffractive optical element 13R but passes through the diffractive optical element 13R as it is.

  The first-order diffracted light L1 emitted from the diffractive optical element 13R expands about the optical axis AX. The principal ray of the first-order diffracted light L1 emitted from the diffractive optical element 13R substantially coincides with the optical axis AX. The zero-order light L0 emitted from the diffractive optical element 13R travels on an extension line of the laser beam emitted from the laser light source 12R, and travels to a position other than the irradiated surface S2. By causing the zero-order light L0 to travel to a position other than the irradiated surface S2, it is possible to reduce the occurrence of unevenness in which a part of the irradiation region becomes brighter, and to easily make the light amount distribution uniform in the irradiation region.

  A light absorbing portion 21 is provided at a position where the zero-order light L0 emitted from the diffractive optical element 13R is incident. The zero-order light L0 emitted from the diffractive optical element 13R is absorbed by the light absorbing unit 21. The light absorption part 21 is comprised using the light absorptive resin member, for example. By using the light absorbing portion 21, the generation of stray light can be reduced.

  FIG. 5 shows a schematic side view of a conventional illumination device 23 according to a comparative example of the present embodiment and each part from the illumination device 23 to the projection lens 19. The illumination device 23 includes a laser light source 12R, a diffractive optical element 24, and a collimating lens 25 provided on the same optical axis AX. The first spatial light modulator 15R, the cross dichroic prism 16, and the projection lens 19 are provided at positions moved from the optical axis AX in a specific direction, for example, the Y-axis direction. The laser light source 12R advances the laser light substantially parallel to the perpendicular line N. The diffractive optical element 24 is arranged so that the laser beam is incident substantially parallel to the perpendicular N.

  Zero-order light L0 emitted from the diffractive optical element 24 travels substantially parallel to the optical axis AX and travels to a position other than the irradiated surface S2. The first-order diffracted light L1 emitted from the diffractive optical element 24 travels to the irradiated surface S2. The principal ray of the first-order diffracted light L1 emitted from the diffractive optical element 24 is inclined with respect to the optical axis AX. The diffractive optical element 24 requires high-level design technology in order to realize shaping of the irradiation region and uniformity of the light amount distribution of the diffracted light whose principal ray is greatly inclined with respect to the normal N. For this reason, in the illumination device 23 according to this comparative example, it may be difficult to shape the irradiation area and make the light amount distribution uniform.

  Further, the first spatial light modulator 15R is arranged on the optical axis AX by adopting a configuration in which the first-order diffracted light L1 whose principal ray is inclined with respect to the optical axis AX is incident on the first spatial light modulator 15R. Compared to the case where the projector 10 is used, the projector 10 is also increased in size. The collimating lens 25 collimates the light beam of the first-order diffracted light L1 using a portion near the outer edge.

  FIG. 6 illustrates the irradiation area LA when the conventional illumination device 23 is used. For example, it is assumed that the parallelizing lens 25 is a spherical lens having a spherical shape. As the spherical lens is closer to the outer edge, the influence of the aberration of the spherical lens becomes more prominent. For example, if the influence of distortion that shrinks the image becomes more conspicuous as the portion closer to the outer edge of the spherical lens is used, the irradiation area LA is distorted with respect to the rectangular pixel area PA as shown in the figure. The more the irradiation area LA is deformed from the rectangular shape, the more light that is lost due to incidence to a position other than the pixel area PA, and the lower the light utilization efficiency. In addition, the luminance unevenness of the irradiation area LA may occur due to the influence of aberration. If luminance unevenness that becomes brighter with increasing distance from the optical axis AX occurs on the irradiated surface S2, light that is lost due to incidence on a position other than the pixel area PA further increases. In order to reduce the influence of such aberrations, when an aspheric lens is used as the collimating lens 25, it is necessary to design the aspheric lens with a high degree of difficulty.

  Returning to FIG. 4, by causing the zero-order light L0 to travel obliquely with respect to the perpendicular N, the angle formed between the perpendicular N and the principal ray of the first-order diffracted light L1 can be reduced. The diffractive optical element 13R that can easily shape the irradiation region and make the light quantity distribution easier can be designed as the inclination of the principal ray of the first-order diffracted light L1 with respect to the normal line N can be reduced. In the first illumination device 11R of the present embodiment, the perpendicular line N of the diffractive optical element 13R and the principal ray of the first-order diffracted light L1 are substantially matched, so that the irradiation area can be shaped and the light quantity distribution can be made uniform most easily. Become. As described above, each of the lighting devices 11R, 11G, and 11B has an effect that the irradiation area can be easily shaped and the light amount distribution can be made uniform.

  By allowing the first spatial light modulator 15R to be disposed on the optical axis AX, the projector 10 can be configured in a compact manner. The projector 10 can display a bright image with a good light amount distribution by a compact configuration. In addition, the first-order diffracted light L1 can be advanced so as to be as perpendicular as possible to the irradiated surface S2. Since the angle formed by the light beam of the first-order diffracted light L1 incident on the first spatial light modulator 15R can be suppressed, a high-contrast image can be displayed. By making the perpendicular line N and the principal ray of the first-order diffracted light L1 substantially coincide with each other, the collimating lens 14 collimates the light beam of the first-order diffracted light L1 using a central portion centered on the optical axis AX.

  FIG. 7 illustrates an irradiation area LA when the first illumination device 11R according to the present embodiment is used. For example, it is assumed that the collimating lens 14 is a spherical lens having a spherical shape. Since the central portion of the spherical lens can be used, the influence of the aberration of the spherical lens can be reduced as compared with the case where the portion near the outer edge of the spherical lens is used. By making it possible to reduce the influence of aberration, it is possible to reduce luminance unevenness in the irradiation area LA and a decrease in light utilization efficiency due to distortion. Thereby, using a spherical lens that can be easily manufactured with respect to an aspheric lens, it is possible to reduce luminance unevenness and light utilization efficiency reduction.

  FIG. 8 shows the relationship between the extension line of incident light incident on the diffractive optical element 13R, the angle formed by the light beam of diffracted light, and the diffraction efficiency of the diffractive optical element 13R. The vertical axis of the graph represents the diffraction efficiency in arbitrary units, and the horizontal axis represents the angle formed by the extension line of the incident light beam and the luminous flux of the diffracted light beam. The diffraction efficiency is a value indicating the intensity of diffracted light emitted from the diffractive optical element 13R with respect to the intensity of incident light incident on the diffractive optical element 13R. The first illumination device 11R can achieve higher light utilization efficiency as the diffraction efficiency of the diffractive optical element 13R is higher. The diffractive optical element 13R can appropriately determine the angle formed by the extended line of incident light and the light beam of diffracted light according to the design. The diffraction efficiency of the diffractive optical element 13R decreases as the angle formed between the extended line of incident light and the light beam of diffracted light increases from about 5 degrees to about 7.5 degrees. Therefore, in order for the diffractive optical element 13R to cause the primary diffracted light L1 to efficiently enter the irradiated surface S2, the angle formed by the extended line of the incident light beam and the light beam of the primary diffracted light L1 should be set as small as possible. This is desirable.

  FIG. 9 and FIG. 10 explain a desirable configuration for obtaining high diffraction efficiency in this embodiment. In FIG. 9 and FIG. 10, illustrations of components other than the laser light source 12R, the diffractive optical element 13R, and the first spatial light modulator 15R are omitted. The irradiation area LA formed on the irradiated surface S2 has a rectangular shape having a short side substantially parallel to the Y axis and a long side substantially parallel to the X axis. The Y-axis direction is a specific direction along the irradiated surface S2, and is the first direction. The X-axis direction is a direction along the irradiated surface S2 and substantially perpendicular to the Y-axis direction, which is the first direction, and is defined as the second direction. The irradiation area LA has a shape that is longer in the X-axis direction, which is the second direction, than the Y-axis direction, which is the first direction.

  FIG. 9 illustrates a case where the chief ray of the laser light incident on the diffractive optical element 13R is tilted in the X-axis direction with respect to the perpendicular N. The left side of FIG. 9 represents the behavior of the zero-order light L0 and the first-order diffracted light L1 in the XZ plane. The zero-order light beam L0 emitted from the diffractive optical element 13R coincides with the extension line of the incident light beam from the laser light source 12R to the diffractive optical element 13R. The principal ray L1C of the first-order diffracted light L1 and the ray of zero-order light L0 form an angle θ ′. The right side of FIG. 9 represents the behavior of the zero-order light L0 in the XY plane.

  FIG. 10 illustrates a case where the chief ray of the laser light incident on the diffractive optical element 13R is tilted in the Y-axis direction with respect to the normal N. The left side of FIG. 10 represents the behavior of the zero-order light L0 and the first-order diffracted light L1 in the YZ plane. The principal ray L1C of the first-order diffracted light L1 and the light ray of the zero-order light L0 form an angle θ. The right side of FIG. 10 represents the behavior of the zero-order light L0 in the XY plane. When the angle θ ′ in the case of FIG. 9 and the angle θ in the case of FIG. 10 are compared, the relationship θ ′> θ is established.

  Therefore, in order for the diffractive optical element 13R to obtain high diffraction efficiency, it is desirable that the chief ray of the laser light incident on the diffractive optical element 13R is tilted with respect to the perpendicular N in the Y-axis direction rather than in the X-axis direction. It can be said. As described above, the diffraction efficiency in the diffractive optical element 13R is increased by reducing as much as possible the angle formed between the zero-order light L0 and the primary light L1C according to the shape of the irradiation area LA. Can do. By increasing the diffraction efficiency in the diffractive optical element 13R, the projector 10 can realize high light utilization efficiency.

  The diffractive optical element 13R is not limited to the case where the incident surface S1 is disposed so as to be orthogonal to the optical axis AX. As shown in FIG. 11, the diffractive optical element 13R may be arranged so that the incident surface S1 is inclined with respect to the XY plane orthogonal to the optical axis AX. In this case, the perpendicular N of the incident surface S1 is inclined with respect to the optical axis AX. By making the angle formed by the perpendicular line N of the incident surface S1 and the optical axis AX as small as possible, it is possible to easily shape the irradiation area and make the light quantity distribution uniform.

  Further, the diffractive optical element 13R is not limited to being provided on the optical axis AX. In the diffractive optical element 13R, at least a part of the diffractive optical element 13R may be included in the predetermined region 27 indicated by a broken line in the drawing. Furthermore, it is desirable that the position where the laser beam is incident on the incident surface S1 of the diffractive optical element 13R is included in the predetermined region 27. The predetermined area 27 is assumed to be a spatial area formed by the locus of the irradiated surface S2 when the irradiated surface S2 is moved in a direction parallel to the optical axis AX. When a part of the diffractive optical element 13R is included in the predetermined region 27, the projector 10 can be made more compact than when the diffractive optical element 13R is arranged at a position away from the predetermined region 27. In addition, the principal ray of the first diffracted light L1 emitted from the diffractive optical element 13R can be made as close as possible to the irradiated surface S2. The laser light source 12R may be disposed at any position where the laser light travels obliquely with respect to the perpendicular N of the incident surface S1 of the diffractive optical element 13R. By arranging the laser light source 12R so that at least a part of the laser light source 12R is included in the predetermined area 27, the projector 10 can be made compact as compared with the case where the laser light source 12R is arranged at a position away from the predetermined area 27. Is possible.

  FIG. 12 shows a schematic side configuration of the illumination device 30 according to the second embodiment of the present invention. The illumination device 30 according to the present embodiment can be applied to the projector 10 according to the first embodiment. The same parts as those in the above embodiment are denoted by the same reference numerals, and redundant description is omitted. The illumination device 30 according to the present embodiment has three laser light sources 12. The laser light source 12 is a light source unit that emits laser light that is coherent light. The three laser light sources 12 are arranged in parallel in the Y-axis direction. Each of the laser light sources 12 causes the laser light to travel obliquely with respect to the normal N of the incident surface S1, which is a reference surface on which the diffractive optical element 31 is disposed. Laser light emitted from each laser light source 12 travels substantially in parallel.

  The diffractive optical element 31 diffracts each laser beam from the laser light source 12, and advances the first diffracted light L1 to the irradiated surface S2 of the spatial light modulator 15. The diffractive optical element 31 diffracts each laser beam using the diffraction grating 20 (see FIG. 2) provided at a position where each laser beam is incident. The spatial light modulator 15 is a spatial light modulator that modulates the laser light supplied from the illumination device 30 in accordance with an image signal.

  The diffractive optical element 31 is designed so that each primary diffracted light L1 generated by the laser light from each laser light source 12 is superimposed on the irradiated region of the irradiated surface S2. The illuminating device 30 of the present embodiment can supply bright light by using a plurality of laser light sources 12 as compared with the case of using one laser light source 12. The diffractive optical element 31 emits zero-order light L0 that is light other than the first-order diffracted light L1. Each zero-order light L0 generated by causing the laser light from each laser light source 12 to enter the diffractive optical element 31 travels substantially in parallel and enters the light absorption unit 21.

  In the configuration in which a plurality of laser beams arranged in parallel in the Y-axis direction are incident on the diffractive optical element 13R, for example, as shown in FIG. 11, the perpendicular N is inclined in the Y-axis direction with respect to the optical axis AX, and the diffractive optical element 13R. When the is arranged, a difference occurs in the focal length of each primary diffraction light L1. When a difference occurs in the focal length of each primary diffracted light L1, it becomes difficult to collimate the light beam of the primary diffracted light L1 by the collimating lens 14. Therefore, in the illumination device 30 of the present embodiment, it is desirable to arrange the diffractive optical element 13R so that the perpendicular N is substantially parallel to the optical axis AX.

  The number and arrangement of the laser light sources 12 are not limited to those described in the present embodiment. The illuminating device 30 should just be the structure which has the some laser light source 12 paralleled in at least one of the X-axis direction and the Y-axis direction.

  FIG. 13 shows a schematic side configuration of the illumination device 33 according to the third embodiment of the present invention. The illumination device 33 according to the present embodiment can be applied to the projector 10 according to the first embodiment. In the second embodiment, the laser light travels substantially parallel from the plurality of laser light sources, whereas in the present embodiment, the laser light travels in different directions from the plurality of laser light sources. The same parts as those in the above embodiment are denoted by the same reference numerals, and redundant description is omitted. The illumination device 33 according to the present embodiment includes a first laser light source 12a and a second laser light source 12b. The first laser light source 12a and the second laser light source 12b are light source units that emit laser light that is coherent light. The first laser light source 12a and the second laser light source 12b are arranged in parallel in the Y-axis direction.

  The first laser light source 12a and the second laser light source 12b advance the laser light substantially symmetrically with respect to the XZ plane including the optical axis AX. The laser light from the first laser light source 12a and the laser light from the second laser light source 12b diverge so as to be separated from each other in the Y-axis direction. In the diffractive optical element 34, the first-order diffracted light L1a generated by the first laser light source 12a and the first-order diffracted light L1b generated by the laser light from the second laser light source 12b overlap in the irradiation region of the irradiated surface S2. Designed to be The zero order light L0a generated by the laser light from the first laser light source 12a and the zero order light L0b generated by the laser light from the second laser light source 12b travel substantially symmetrically with respect to the XZ plane including the optical axis AX. . The light absorbing unit 21 has a position where the zero-order light L0a generated by the laser light from the first laser light source 12a is incident and a position where the zero-order light L0b generated by the laser light from the second laser light source 12b is incident, respectively. Is provided.

  FIG. 14 illustrates the advantage of causing the laser light to travel approximately symmetrically with respect to the XZ plane including the optical axis AX. As shown by a broken line, it is assumed that the laser light from the second laser light source 12b travels in substantially the same direction as the laser light from the first laser light source 12a. At this time, it is assumed that the angle formed between the principal ray L1C of the first-order diffracted light L1b generated by the laser beam from the second laser light source 12b and the ray of the zero-order light L0b ′ is θ1 ′. Zero-order light L0b 'generated by the laser light from the second laser light source 12b intersects with the first-order diffracted light L1a generated by the laser light from the first laser light source 12a. The angle θ1 ′ is set so that the zero-order light L0b ′ completely penetrates the light beam of the first-order diffracted light L1a before the collimating lens 14.

  In the case of the configuration of the present embodiment indicated by the solid line, the angle formed between the principal ray L1C of the first-order diffracted light L1b generated by the laser light from the second laser light source 12b and the light beam of the zero-order light L0b is θ1. . In this case, the zero-order light L0b generated by the laser light from the second laser light source 12b does not intersect the first-order diffracted light L1a generated by the laser light from the first laser light source 12a. The angle θ1 can be set smaller than when the zero-order light L0b penetrates the light beam of the first-order diffracted light L1a. Therefore, when the angle θ1 ′ and the angle θ1 are compared, the relationship θ1 ′> θ1 is established.

  As described above, the illuminating device 33 of the present embodiment advances the zero-order lights L0a and L0b to positions other than the irradiated surface S2, and the light beams of the zero-order lights L0a and L0b and the first-order diffracted lights L1a and L1b are formed. The angle can be reduced. As described above with reference to FIG. 8, the diffractive optical element 34 can obtain high diffraction efficiency by setting the angle formed by the extension line of the incident light beam and the light beam of the diffracted light as small as possible. The diffraction efficiency in the diffractive optical element 34 can be increased by reducing the angle formed between the zero-order light beams L0a and L0b and the first-order diffracted light beams L1a and L1b. Therefore, the illumination device 33 can realize high light use efficiency.

  FIG. 15 illustrates a first modification of the present embodiment. The irradiation area LA formed on the irradiated surface S2 has a rectangular shape having a short side substantially parallel to the Y axis and a long side substantially parallel to the X axis. The irradiation area LA has a shape that is longer in the X-axis direction, which is the second direction, than the Y-axis direction, which is the first direction.

  The upper part of FIG. 15 shows the behavior of the zero-order lights L0a and L0b in the XY plane when the first laser light source 12a and the second laser light source 12b cause the laser light to travel substantially symmetrically with respect to the XZ plane S3 including the optical axis AX. Represents. Such a configuration is applied to the illumination device 33 according to the present embodiment. The lower part of FIG. 15 shows the configuration of the illumination device according to this modification. In the illumination device according to this modification, the first laser light source 12a and the second laser light source 12b cause the laser light to travel substantially symmetrically with respect to the YZ plane S4 including the optical axis AX. The illumination device may have any configuration shown in the figure.

  As in the case of the first embodiment described with reference to FIGS. 9 and 10, the diffractive optical element 34 has a chief ray of laser light incident on the diffractive optical element 34 in the X-axis direction with respect to the perpendicular N. Higher diffraction efficiency can be obtained by tilting in the Y-axis direction. Therefore, also in the case of the present embodiment, when the configuration shown in the upper part of FIG. 15 is used, it is possible to obtain higher diffraction efficiency than in the case of the configuration shown in the lower part of FIG.

  FIG. 16 illustrates a second modification of the present embodiment. The illumination device according to this modification has four laser light sources. The four laser light sources are arranged in parallel, two in the X-axis direction and two in the Y-axis direction. The diffractive optical element 36 is designed so that the first-order diffracted light generated by the laser light from each laser light source is superimposed on the irradiation area LA of the irradiated surface S2.

  The upper part of FIG. 16 represents the behavior of the zero-order light L0 in the XY plane when the laser light is caused to travel approximately symmetrically with respect to the XZ plane S3 including the optical axis AX by each laser light source. The middle part of FIG. 16 represents the behavior of the zero-order light L0 in the XY plane when the laser light is caused to travel approximately symmetrically with respect to the YZ plane S4 including the optical axis AX by each laser light source. The lower part of FIG. 16 represents the behavior of the zero-order light L0 in the XY plane when the laser light is caused to travel approximately symmetrically with respect to the optical axis AX by each laser light source. The illumination device according to this modification may have any configuration illustrated.

  The angle formed by the zero-order light beam L0 and the principal light beam of the first-order diffracted light beam L1 is the smallest in the upper part of FIG. 16 and the largest in the lower part. In the case of this modification, it is possible to obtain high diffraction efficiency in the order of the configuration shown in the upper part of FIG. 16, the configuration shown in the middle part, and the configuration shown in the lower part. It should be noted that the level of diffraction efficiency of the diffractive optical elements 34 and 36 described in the present embodiment may change depending on the shape of the reproduced image by the diffractive optical elements 34 and 36. The illuminating device of the present embodiment may be configured so that the laser light travels substantially symmetrically with respect to the optical axis AX or the plane including the optical axis AX, and the number and arrangement of the laser light sources may be appropriately changed.

  FIG. 17 shows a schematic side configuration of the illumination device 40 according to the fourth embodiment of the present invention. The illumination device 40 according to the present embodiment can be applied to the projector 10 according to the first embodiment. The same parts as those in the above embodiment are denoted by the same reference numerals, and redundant description is omitted. The illumination device 40 according to the present embodiment includes a prism 41. The prism 41 functions as a deflecting element that deflects the laser light emitted from the first laser light source 12 a and the second laser light source 12 b and enters the diffractive optical element 34.

  Each of the first laser light source 12a and the second laser light source 12b advances the laser light substantially parallel to the perpendicular N of the incident surface S1, which is a reference surface on which the diffractive optical element 34 is disposed. The prism 41 is disposed on the incident surface S <b> 1 of the diffractive optical element 34. The prism 41 is configured using a transparent member. The prism 41 has an interface 42 provided to be inclined with respect to the incident surface S1. The prism 41 deflects the laser light by refracting the laser light at the interface 42. Laser light from the first laser light source 12a and the second laser light source 12b travels substantially symmetrically with respect to the XZ plane including the optical axis AX by deflection using the prism 41. The laser light transmitted through the prism 41 enters the diffractive optical element 34.

  By advancing the laser light substantially symmetrically with respect to the XZ plane including the optical axis AX, high diffraction efficiency can be obtained in the present embodiment as well as the illumination device according to the third embodiment. The illuminating device 40 of the present embodiment can cause the laser light traveling obliquely with respect to the normal N of the incident surface S1 to enter the diffractive optical element 34 by appropriately deflecting the laser light by the prism 41. The illumination device 40 can arrange the laser light sources 12a and 12b with a high degree of freedom by using the prism 41. The prism 41 may be any shape as long as the laser light can be appropriately deflected. The prism 41 is not limited to the case where the prism 41 is disposed on the incident surface S1 of the diffractive optical element 34, and may be disposed at a distance from the incident surface S1 of the diffractive optical element 34.

  FIG. 18 illustrates a schematic side configuration of the illumination device 44 according to the first modification of the present embodiment. The illumination device 44 of this modification has a concave lens 45 that functions as a deflection element. The concave lens 45 is provided in the optical path between the first laser light source 12 a and the second laser light source 12 b and the diffractive optical element 34. The concave lens 45 has a concave surface 46 having a concave shape. The concave lens 45 deflects the laser light by refracting the laser light on the concave surface 46. Also in this modification, the laser light sources 12a and 12b can be arranged with a high degree of freedom. The concave lens 45 may be provided on the incident surface S1 of the diffractive optical element 34.

  As the deflecting element that refracts the laser light, in addition to the prism 41 and the concave lens 45, a refractive index distribution type lens having a refractive index gradient, an electro-optical element that changes the refractive index distribution according to the electric field, and the like may be used. The deflecting element is not limited to the case that refracts the laser beam. The deflection element may diffract the laser light. For example, a diffraction grating 47 shown in FIG. 19 may be used as a deflection element that diffracts laser light. The diffraction grating 47 only needs to be able to deflect light by diffraction, and has, for example, a fine binary structure. The fine binary structure is a fine structure in which convex portions formed at a substantially constant height and concave portions formed at a substantially constant height are alternately formed. A blazed grating 48 shown in FIG. 20 may be used as a deflecting element that diffracts laser light. A Fresnel lens may be used as the deflection element.

  FIG. 21 shows a schematic side configuration of the illumination device 50 according to the second modification of the present embodiment. The illumination device 50 according to the present embodiment includes an optical element 51 in which a blaze grating 52 and a diffraction grating 53 are integrally formed. The optical element 51 is provided at a position where the laser light emitted from the laser light source 12 enters. The optical element 51 is configured using a transparent member. The blazed grating 52 is formed on the incident surface of the optical element 51 where the laser light from the laser light source 12 is incident. The blaze grating 52 functions as a deflection element that diffracts the laser light.

  The diffraction grating 53 is formed on the emission surface of the optical element 51 that emits light from the blazed grating 52. The diffraction grating 53 functions as a diffractive optical element that diffracts the laser light from the blazed grating 52 and advances the first-order diffracted light L1 to the irradiated surface S2. The diffraction grating 53 is designed so that the first-order diffracted light L1 generated by the incidence of the laser light from the blazed grating 52 is superimposed on the irradiated area of the irradiated surface S2. Further, the zero-order light L0 generated by making the laser light from the blazed grating 52 incident on the diffraction grating 53 travels substantially in parallel and enters the light absorbing portion 21.

  By using the optical element 51 in which the blazed grating 52 and the diffraction grating 53 are integrally formed, the number of parts of the lighting device 50 can be reduced, and the lighting device 50 can be simplified and made compact. In the case of the illuminating device 40 shown in FIG. 17 as well, the illuminating device 40 can be made simple and compact by providing the prism 41 on the incident surface S1 of the diffractive optical element 34, as in this modification. The optical element 51 may be provided with a diffraction grating having a fine binary structure, a prism that refracts light, a concave lens, or the like instead of the blaze grating 52.

  The optical element 51 is not limited to the case where the structure functioning as the deflecting element is formed on the incident surface and the structure functioning as the diffractive optical element is formed on the exit surface, and may be appropriately modified. For example, a structure that functions as a deflection element may be formed inside the optical element 51. Each illumination device of the present embodiment may be configured to deflect the laser light from one or a plurality of laser light sources by a deflecting element, and the number and arrangement of the laser light sources may be appropriately changed.

  FIG. 22 shows a schematic side configuration of the illumination device 60 according to the fifth embodiment of the present invention. The illumination device 60 according to the present embodiment can be applied to the projector 10 according to the first embodiment. The illumination device 60 according to the present embodiment is characterized in that chief rays of laser light emitted from the laser light source 12 are closest to each other in an optical path between the laser light source 12 and the diffractive optical element 61. The same parts as those in the above embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The illumination device 60 has two laser light sources 12. Each laser light source 12 advances the laser light substantially symmetrically with respect to the XZ plane including the optical axis AX. The laser light from each laser light source 12 converges so as to approach each other in the Y-axis direction, and intersects in an optical path between the laser light source 12 and the diffractive optical element 61. The laser beams diverge so as to be separated from each other in the Y-axis direction after intersecting in the optical path between the laser light source 12 and the diffractive optical element 61. The respective laser beams are incident on different positions on the incident surface S1 of the diffractive optical element 61 in the Y-axis direction.

  The diffractive optical element 61 is designed so that the first-order diffracted light L1 generated by the incidence of the laser light from each laser light source 12 is superimposed on the irradiated region of the irradiated surface S2. Zero-order light L0 generated by the laser light from each laser light source 12 is incident on the light absorber 21. Also in the case of the present embodiment, the angle formed by the zero-order light L0 and the first-order diffracted light L1 can be reduced similarly to the case of the illumination device 33 (see FIG. 13) according to the above-described third embodiment. The diffraction efficiency in the element 61 can be increased, and high light utilization efficiency can be realized.

  Compared to the case where the laser light converged between the laser light source 12 and the diffractive optical element 61 is incident on the diffractive optical element 61 so that the laser light diverged from each laser light source 12 is incident on the diffractive optical element 61. Thus, the diffractive optical element 61 having a small incident surface S1 can be used. Thereby, the diffractive optical element 61 can be reduced in size, and the manufacturing time and cost of the diffractive optical element 61 can be reduced. For example, if the laser light source 12 is large and the emission positions of the laser light sources 12 cannot be made dense, the diffraction optical element 61 must be made large if each laser beam travels or diverges in parallel. Cases arise. The illumination device 60 according to the present embodiment is useful when the laser light source 12 is large because the diffractive optical element 61 can be made small by converging each laser beam. The illumination device 60 may be configured so that the principal rays of the laser beams are closest to each other in the optical path between the laser light source 12 and the diffractive optical element 61, and the laser is transmitted in the optical path between the laser light source 12 and the diffractive optical element 61. It is not limited to a configuration in which light intersects.

  FIG. 23 shows a schematic side configuration of a lighting device 65 according to a modification of the present embodiment. The illumination device 65 according to this modification is characterized in that the principal rays of the zero-order light L0 emitted from the diffractive optical element 66 are closest to each other in the optical path between the diffractive optical element 66 and the irradiated surface S2. Laser beams from the respective laser light sources 12 converge so as to approach each other in the Y-axis direction. The laser beams are incident on different positions in the Y-axis direction on the incident surface S1 of the diffractive optical element 66. The diffractive optical element 66 is designed so that the first-order diffracted light L1 generated by the incidence of the laser light from each laser light source 12 is superimposed on the irradiated region of the irradiated surface S2.

  The zero-order light L0 generated by the laser light from each laser light source 12 travels on the extended line of the laser light incident on the diffractive optical element 66, and intersects in the optical path between the diffractive optical element 66 and the irradiated surface S2. . Each zero-order light L0 diverges away from each other in the Y-axis direction after intersecting the optical path between the diffractive optical element 66 and the irradiated surface S2, and enters the light absorbing unit 21, respectively. Also in the case of this modification, the diffractive optical element 66 can be reduced in size by making each laser beam converged between the laser light source 12 and the diffractive optical element 66 enter the diffractive optical element 66, and the diffractive optical element 66 is manufactured. Time and cost can be reduced. Furthermore, since the distance between the laser light source 12 and the diffractive optical element 66 can be shortened as compared with the illumination device 60 (see FIG. 22), the illumination device 65 can be downsized. The illumination device 65 only needs to have a configuration in which chief rays of the zero-order light are closest to each other in the optical path between the diffractive optical element 66 and the irradiated surface S2, and between the diffractive optical element 66 and the irradiated surface S2. It is not limited to the configuration in which the zero-order lights intersect in the optical path.

  The illumination devices 60 and 65 according to the present embodiment require that the laser beams be incident on different positions on the incident surface S1 of the diffractive optical elements 61 and 66. By adopting a configuration in which each laser beam is incident as close as possible on the incident surface S1, the diffractive optical elements 61 and 66 can be made as small as possible.

  In addition, the illuminating device of each said Example is not restricted to the case where a laser light source provided with a semiconductor laser is used, You may use the laser light source provided with a solid laser, a liquid laser, a gas laser etc. An illuminating device is not restricted to using a laser light source for a light source part. The illumination device may be configured to use a solid light source such as a light emitting diode (LED) or a super luminescence diode (SLD) as the light source unit. The projector according to the present invention is not limited to the case where a transmissive liquid crystal display device is used as the spatial light modulation device. As the spatial light modulator, a reflective liquid crystal display (Liquid Crystal On Silicon; LCOS), DMD (Digital Micromirror Device), GLV (Grating Light Valve), or the like may be used. The projector is not limited to a configuration including a spatial light modulator for each color light. The projector may be configured to modulate two or three or more color lights with one spatial light modulator. The projector is not limited to the case where the spatial light modulator is used. The projector may be a slide projector that uses a slide having image information. The projector may be a so-called rear projector that supplies light to one surface of the screen and observes an image by observing light emitted from the other surface of the screen.

  The illumination device according to the present invention may be applied to electronic equipment other than the image display device, for example, a monitor device that captures an image of a subject illuminated with light from the illumination device. Moreover, you may use the illuminating device concerning this invention for optical systems, such as an exposure apparatus for exposure using a laser beam, and a laser processing apparatus, for example.

  As described above, the illumination device according to the present invention is suitable for use in an image display device such as a projector.

  DESCRIPTION OF SYMBOLS 10 Projector, 11R 1st illuminating device, 11G 2nd illuminating device, 11B 3rd illuminating device, 12R, 12G, 12B Laser light source, 13R, 13G, 13B Diffraction optical element, 14 Parallelizing lens, 15R 1st spatial light modulator , 15G second spatial light modulator, 15B third spatial light modulator, 16 cross dichroic prism, 17 first dichroic film, 18 second dichroic film, 19 projection lens, 20 diffraction grating, 22 rectangular region, 21 light absorption part , AX optical axis, L0 zero order light, L1 first order diffracted light, N perpendicular, S1 incident surface, S2 irradiated surface, 23 illumination device, 24 diffractive optical element, 25 collimating lens, LA irradiation region, PA pixel region, L1C Chief ray, 27 predetermined region, 12 laser light source, 15 spatial light modulator, 30 illumination device, 31 Diffractive optical element, 12a, 12b Laser light source, 33 illumination device, 34 Diffractive optical element, L0a, L0b Zero order light, L1a, L1b First order diffracted light, S3 XZ plane, S4 YZ plane, 36 Diffractive optical element, 40 Illumination device, 41 prism, 42 interface, 44 illumination device, 45 concave lens, 46 concave surface, 47 diffraction grating, 48 blazed grating, 50 illumination device, 51 optical element, 52 blazed grating, 53 diffraction grating, 60 illumination device, 61 diffractive optical element, 65 Illumination device, 66 diffractive optical element.

Claims (11)

A plurality of light source units;
A diffractive optical element that diffracts a plurality of coherent lights emitted from the plurality of light source units and advances the diffracted light to an irradiated surface;
The diffractive optical element is disposed such that the plurality of coherent lights are incident obliquely with respect to a normal line of a reference surface on which the diffractive optical element is disposed.
The plurality of coherent lights includes a first coherent light and a second coherent light,
The first coherent light and the second coherent light are substantially symmetric with respect to an optical axis of an illumination optical system constituting the illumination device or a plane including the optical axis, and are diffracted so as to be separated from each other. Incident on the optical element,
Of the light emitted from the diffractive optical element, zero-order light that is light other than the diffracted light travels to a position other than the irradiated surface. Wherein the plurality of light source sections, the optical axis, or substantially symmetrically with respect to a plane including the optical axis, according to claim 1, characterized in that to proceed with the first coherent light and said second coherent light Lighting equipment. The principal rays of the first coherent light and the second coherent light emitted from the light source unit are closest to each other in an optical path between the light source unit and the diffractive optical element. Or the illuminating device of 2. The light source unit is deflected the injected between the first coherent light and said second coherent light from any one of claims 1 to 3, wherein a deflecting element is incident to the diffractive optical element The lighting device described in 1. The illumination device according to claim 4 , wherein the deflecting element and the diffractive optical element are integrally formed. When the illuminated surface is moved in a direction parallel to the optical axis of the illumination optical system that constitutes the illumination device, and the spatial region formed by the locus of the illuminated surface is a predetermined region,
At least a portion of the diffractive optical element, the illumination device according to any one of claims 1 to 5, characterized in that included in the predetermined region. The lighting device according to claim 6 , wherein the reference plane is substantially orthogonal to the optical axis. The illuminating device according to claim 1 , further comprising: a collimating lens that collimates the light beam of the diffracted light from the diffractive optical element and advances the light beam to the irradiated surface. When a specific direction along the irradiated surface is a first direction, a direction along the irradiated surface and substantially perpendicular to the first direction is a second direction,
An irradiation area that is an area where the diffracted light is incident on the irradiated surface has a shape that is long in the second direction with respect to the first direction,
The principal rays of the coherent light incident on the diffractive optical element, the illumination device according to any one of claims 1-8, characterized in that it is inclined to the first direction with respect to the vertical. Image display device and displaying an image using light provided by the lighting device according to any one of claims 1 to 9. The illumination device according to any one of claims 1 to 9 ,
A spatial light modulation device that modulates light supplied by the illumination device in accordance with an image signal;
And a projection optical system that projects light emitted from the spatial light modulator.

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