JP6322926B2 - Illumination device, projection device, and projection display device - Google Patents

Description

  The present invention relates to an illumination device having an irradiation device that emits first light and second light in different wavelength ranges, and a diffractive optical element that bends the optical paths of the first light and second light in a desired direction. The present invention also relates to a projection device and a projection display device including the illumination device.

  For example, as shown in Patent Document 1, illumination devices using light in a plurality of wavelength ranges are widely used. In such an illuminating device, the optical path of light in each wavelength region is adjusted using a diffractive optical element. However, the diffraction angle in a diffractive optical element typified by a hologram recording medium changes according to the wavelength. Therefore, light in different wavelength ranges incident on the diffractive optical element from the same direction is diffracted in different directions. That is, a shift occurs in the area illuminated by light in each wavelength range. As a result, the peripheral edge of the area illuminated by the illumination device may be tinted, and even the entire illuminated area may not be illuminated with light in a specific wavelength range.

  Moreover, as shown in Patent Document 1, the illumination device may be used as a device for illuminating the spatial light modulator. The spatial light modulator needs to be illuminated over the entire area by light in each wavelength range. For this reason, the spatial light modulator must be arranged in an overlapping region of regions illuminated by light in each wavelength region. Therefore, if there is a shift in the area illuminated with light in each wavelength range, the light utilization efficiency will be significantly reduced. That is, in the illuminating device that illuminates the spatial light modulator, a problem that a shift occurs in an area illuminated by light in each wavelength band becomes a more important problem.

  Furthermore, recently, as disclosed in Patent Document 1, by irradiating the hologram recording medium with coherent light so that the coherent light scans on the hologram recording medium, the area illuminated by the illumination light is detected. Research has been conducted to suppress the generation of speckles in the sea. In such an illuminating device, light incident on each position on the hologram recording medium illuminates a region where the light overlaps at least partially. In this apparatus, there is a possibility that a problem that a shift occurs in an area illuminated by light in each wavelength band is more prominent.

WO2012-033179A1

  The present invention has been made in consideration of the above points, and a deviation between a region to be illuminated by the first light and a region to be illuminated by the second light having a wavelength region different from that of the first light. It aims at providing the illuminating device which can relieve effectively.

The lighting device according to the present invention comprises:
An irradiation device that emits first light in a first wavelength region and second light in a second wavelength region different from the first wavelength region;
A diffractive optical element that diffracts the first light and the second light from the irradiation device;
A prism having a pair of main surfaces forming a top portion and a bottom portion facing the top portion and extending between the pair of main surfaces, wherein the first light and the second light pass through the pair of main surfaces. A prism arranged to pass through,
In observation from a direction orthogonal to both the direction connecting the top and bottom of the prism and the normal direction of the diffractive optical element, the first light and the second light incident on the diffractive optical element are: Proceeding in the direction normal to the diffractive optical element or in the direction inclined to one side with respect to the normal direction of the diffractive optical element so as to go from the top side to the bottom side of the prism, the diffraction The first light and the second light diffracted by the optical element travel in a direction inclined at a larger angle than before diffraction to the one side with respect to the normal direction of the diffractive optical element.

  In the illumination device according to the present invention, the prism may be positioned upstream of the diffractive optical element along the optical path of the first light and the second light emitted from the irradiation device.

  In the illumination device according to the present invention, the prism may be positioned downstream of the diffractive optical element along the optical path of the first light and the second light emitted from the irradiation device.

  In the illumination device according to the present invention, the irradiating device may emit a parallel light flux of the first light and a parallel light flux of the second light.

  In the illuminating device according to the present invention, the irradiating device scans the first one of the prism and the diffractive optical element that is located upstream in the optical path of the first light and the second light. You may irradiate light and said 2nd light.

  In the illuminating device according to the present invention, the first light and the second light are respectively on the one of the prism and the diffractive optical element that is located upstream in the optical path of the first light and the second light. You may make it inject into a position along a fixed direction.

  In the illuminating device according to the present invention, the first light incident on each position on the one of the prism and the diffractive optical element located on the upstream side in the optical path of the first light and the second light is respectively And then illuminating a region that is diffracted by the diffractive optical element and overlaps at least in part with each other, and the one of the prism and the diffractive optical element located on the upstream side in the optical path of the first light and the second light The second light incident on each of the upper positions may be diffracted by the diffractive optical element and then illuminate areas overlapping each other.

The illumination device according to the present invention is a second prism having a pair of main surfaces defining a top portion and a bottom portion facing the top portion and extending between the pair of main surfaces, wherein the first light and the A second prism disposed so that the second light passes through the pair of main surfaces;
The direction connecting the top and the bottom of the second prism intersects the direction connecting the top and the bottom of the prism,
The first light and the second light incident on the diffractive optical element in observation from a direction orthogonal to both the direction connecting the top and the bottom of the second prism and the normal direction of the diffractive optical element Is in a direction inclined to one side with respect to the normal direction of the diffractive optical element so as to proceed in the normal direction of the diffractive optical element or from the top side to the bottom side of the second prism. The first light and the second light diffracted by the diffractive optical element travel in a direction inclined at a larger angle than before diffraction to the one side with respect to the normal direction of the diffractive optical element. Also good.

The projection apparatus according to the present invention
Any of the lighting devices according to the invention described above;
A spatial light modulator disposed at a position illuminated by coherent light from the illumination device.

The projection display device 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.

  According to the present invention, the deviation between the traveling direction of the first light projected from the lighting device and the traveling direction of the second light in a wavelength region different from the first light projected from the lighting device is effectively reduced. can do. As a result, it is possible to effectively relieve the deviation between the region to be illuminated by the first light and the region to be illuminated by the second light.

FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a diagram for explaining an example of a lighting device. FIG. 2 is a side view of the lighting device of FIG. 1 and is a view for explaining the operation of the lighting device. FIG. 3 is a diagram for explaining the operation of the diffractive optical element included in the illumination device. FIG. 4 is a diagram for explaining the operation of the prism included in the illumination device. FIG. 5 is a diagram corresponding to FIG. 2 and is a diagram for explaining a modification of the lighting device. FIG. 6 is a diagram corresponding to FIG. 1 and is a diagram for explaining another modified example of the illumination device. FIG. 7 is a top view of the illuminating device of FIG. 6 for explaining the operation of the second prism included in the illuminating device of FIG. FIG. 8 is a diagram showing still another modification of the lighting device. FIG. 9 is a diagram showing a projection device and a projection display device including the illumination device of FIG.

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

  In addition, as used in this specification, the shape and geometric conditions and the degree thereof are specified, for example, terms such as “parallel”, “orthogonal”, “identical”, length and angle values, etc. are strictly Without being bound by meaning, it should be interpreted including the extent to which similar functions can be expected.

  1 to 9 are diagrams for explaining one embodiment of the present invention and its modification. Among these, FIGS. 1-4 is a figure for demonstrating one Embodiment of the illuminating device by this invention. FIG. 1 is a perspective view schematically showing the configuration of the lighting device, and FIG. 2 is a side view of the lighting device. 3 and 4 are side views showing a diffractive optical element and a prism included in the illumination device, respectively.

  As shown in FIGS. 1 to 4, the illumination device 11 includes an irradiation device 51 that emits light, a diffractive optical element 21 that diffracts light from the irradiation device 51, and a prism that bends the optical path of light from the irradiation device 51. 31. As illustrated in FIG. 2, the illumination device 11 is a device that illuminates an illuminated area LZ located on a virtual plane. As shown in FIG.1 and FIG.2, the irradiation apparatus 51 inject | emits at least 1st light L11, L21 and 2nd light L12, L22 of a mutually different wavelength range. The diffractive optical element 21 bends the traveling direction of the light from the irradiation device 51 by the diffractive action, and directs the light from the irradiation device 51 toward the illuminated region LZ. On the other hand, the prism 31 corrects the traveling direction of light for each wavelength in order to eliminate the difference in the degree of diffraction effect in the diffractive optical element 21 based on the wavelength. Due to the action of the prism 31, the illuminating device 11 described here uses a region to be illuminated by the first light L11, L21 and a second light L12, L22 in a wavelength region different from the first light L11, L21. Effectively mitigating the deviation from the area to be illuminated. A so-called apex angle prism can be used as the prism 31. Hereinafter, each component of the illumination device 11 will be described.

  As described above, the irradiation device 51 emits light in a plurality of different wavelength ranges. In the illustrated example, the irradiation device 51 emits the first light L11, L21 and the second light L12, L22, but is not limited thereto. For example, light in three types of wavelength bands of red light, green light, and blue light may be emitted. The irradiation device 51 includes a light source that emits light in a specific wavelength range, for example, a laser light source that emits coherent light.

  The diffractive optical element 21 is an optical element that changes the traveling direction of light by diffractive action. A typical example of the diffractive optical element 21 is a hologram recording medium. FIG. 3 shows an example of the diffractive optical element 21. The diffractive optical element 21 in FIG. 3 is formed as a diffraction grating having an uneven surface 21a, and corresponds to a relief-type transmission hologram recording medium. However, the invention is not limited to the example shown in FIG. 3, and a transmission type volume hologram can also be used as the diffractive optical element 21.

As shown in FIG. 3, the diffractive action of the diffractive optical element 21 is expressed by the following equation (a).
d × sin θ _x = λ Formula (a)
In the formula (a), d is the arrangement pitch of the unit structures forming the concavo-convex surface 21 a of the diffractive optical element 21, and θ _x is incident on the diffractive optical element 21 along the normal direction nd of the diffractive optical element 21. Λ is the wavelength of light diffracted by the diffractive optical element 21. The diffraction angle θ _x of the diffractive optical element 21 changes according to the wavelength of the diffracted light. That is, in the diffractive optical element 21, the path of the long wavelength light is greatly changed. Then, assuming that the wavelength of the first light is the first wavelength region λ ₁ and the wavelength of the second light is the second wavelength region λ ₂ , the first wavelength region λ ₁ incident on the diffractive optical element 21 from the same direction. The light and the second light in the second wavelength band λ ₂ are diffracted in a direction shifted by an angle Δθ _x expressed by the following equation (b).
Δθ _x = sin ⁻¹ (λ ₁ / d) −sin ⁻¹ (λ ₂ / d) Expression (b)

  The “normal direction” means a normal direction to the sheet surface (plate surface, film surface) of the target member. Further, the sheet surface (plate surface, film surface) of the target member refers to a surface that coincides with the planar direction of the target member when viewed as a whole and globally.

  The prism 31 has a pair of main surfaces 33 a and 33 b that define an apex angle 32. A top portion 35 is formed on one side of the pair of main surfaces 33a and 33b, and a bottom portion 34 is formed on the other side of the pair of main surfaces 33a and 33b. Between the pair of main surfaces 33a and 33b, the top portion 35 and the bottom portion 34 are arranged to face each other. In the illustrated example, the apex portion 32 is formed by the apex angle 32. The prism 31 is disposed so that the pair of main surfaces 33a and 33b cross the optical path of the light projected from the irradiation device 51 and directed to the illuminated region LZ via the diffractive optical element 21. That is, the first light and the second light projected from the irradiation device 51 pass through the prism 31. The pair of main surfaces 33a and 33b are nonparallel, that is, intersect. Therefore, as shown in FIG. 4, when the first light and the second light pass through the pair of main surfaces 33 a and 33 b and pass through the prism 31, the traveling directions thereof are bent by refraction.

When the apex angle 32 of the prism 31 is sufficiently small, specifically, when the angle of the apex angle 32 is θ, it is small enough to approximate sin θ = θ. The following equation (c) may be considered.
θ _y = (n−1) × θ _a Formula (c)
N is in the formula (c), the refractive index of the prism 31, the theta _a, is the angle value of the vertical angle 32 (i.e., a pair of main surfaces 33a, the relative angle of inclination of the value of 33b). On the other hand, θ _y is the value of the angle formed by the light path between the light incident on the prism 31 and the light emitted from the prism 31, and represents the magnitude of the deviation of the optical path before and after passing through the prism 31. However, the refractive index n of the prism 31 changes according to the wavelength. In general, the refractive index for short-wavelength light is increased. For this reason, in the prism 31, the path of the short wavelength light is greatly changed. Then, assuming that the wavelength of the first light is the first wavelength region λ ₁ and the wavelength of the second light is the second wavelength region λ ₂ , the first light and the second light incident on the prism 31 from the same direction are The light is emitted from the prism 31 in a direction shifted by the angle Δθ _y expressed by the equation (d).
Δθ _y = (n _λ2 −n _λ1 ) × θ _a (formula (d))

  In the illustrated example, the prism 31 is formed in a triangular prism shape. Therefore, the prism 31 actually has an apex angle 32, and the apex angle 32 forms the apex portion 35. The prism 31 has a ridge line 32a formed at a position where the pair of main surfaces 33a and 33b are connected. However, the present invention is not limited to this example, and the prism 31 may be formed, for example, in a trapezoidal column shape so as not to include the actual apex angle 32. Even if the prism 31 does not include the apex angle 32, the same effect as the prism 31 including the apex angle 32 can be exhibited as long as the relative inclination angles of the pair of main surfaces 33a and 33b are adjusted.

In the present embodiment, the wavelength dispersion phenomenon that has inevitably occurred in the diffractive optical element 21 that directs the optical path of the light from the irradiation device 51 toward the illuminated region LZ, that is, the traveling direction of the diffracted light is different for each wavelength. The phenomenon of becoming different at least is mitigated at least by the prism 31. Specifically, as shown in FIG. 2, the chromatic dispersion phenomenon in the diffractive optical element 21 is caused by the chromatic dispersion phenomenon in the prism 31, that is, the phenomenon in which the traveling direction of the light transmitted through the prism 31 varies for each wavelength. Has been countered. As a result, light of a plurality of different wavelength ranges emitted from the irradiation device 51 passes through the prism 31 and is diffracted by the diffractive optical element 21, and then travels in substantially the same direction. In particular, the diffractive optical element 21 and the prism 31 are designed so that Δθ _x in the above-described equation (c) and Δθ _y in the equation (d) are the same, so that the first direction toward the illuminated region LZ is reached. It is also possible to make the traveling directions of the one light and the second light parallel.

  In the example shown in FIG. 2, the irradiation device 51 emits a parallel light beam of the first light L21 and a parallel light beam of the second light L22. The parallel light flux of the first light L21 and the parallel light flux of the second light L22 travel in directions parallel to each other and travel toward the same region. The prism 31 is located upstream of the diffractive optical element 21 along the optical paths of the first light L21 and the second light L22 emitted from the irradiation device 51. FIG. 2 shows the illumination device 11 from the direction orthogonal to both the direction connecting the top portion 35 and the bottom portion 34 of the prism 31 and the normal direction nd of the diffractive optical element 21. The first light L21 and the second light L22 incident on the diffractive optical element 21 proceed in the normal direction nd of the diffractive optical element 21, or from the top 35 side (upper side of the drawing in FIG. 2) of the prism 31 to the bottom 34 side. It proceeds in a direction inclined to one side with respect to the normal direction nd of the diffractive optical element 21 so as to go to (the lower side of the paper surface in FIG. 2). The first light L21 and the second light L22 diffracted by the diffractive optical element 21 travel in a direction inclined at a larger angle than before diffraction to the one side with respect to the normal direction nd of the diffractive optical element 21. Become. According to such an arrangement of the diffractive optical element 21 and the prism 31, the shift in the diffraction direction corresponding to the wavelength generated in the diffractive optical element 21 is corrected by the shift in the transmission direction (refractive direction) corresponding to the wavelength generated in the prism 31. can do.

  According to the present embodiment as described above, the prism 31 is provided on the optical paths of the first light L11, L21 and the second light L21, L22. The first light beams L11, L21 and the first light beams L11 and L21 incident on the diffractive optical element 21 are observed in a direction orthogonal to both the direction connecting the top part 35 and the bottom part 34 of the prism 31 and the normal direction nd of the diffractive optical element 21. The two lights L12 and L22 travel in the normal direction nd of the diffractive optical element 21 or on one side with respect to the normal direction nd of the diffractive optical element 21 so as to go from the top 35 side to the bottom 34 side of the prism 31. The first light L11, L21 and the second light L12, L22 diffracted by the diffractive optical element 21 toward the one direction with respect to the normal direction nd of the diffractive optical element 21 than before diffracting. Proceed in a direction inclined at a large angle. In such an illuminating device 11, the diffraction directions of the first lights L11 and L21 and the diffraction directions of the second lights L12 and L22 at the diffractive optical element 21 that occur when the light enters the diffractive optical element 21 from the same direction. The prism 31 changes the traveling direction of the first lights L11 and L21 and the traveling direction of the second lights L12 and L22 so as to alleviate the deviation. As a result, it is possible to effectively align the traveling direction of the first light L11, L21 as the illumination light projected from the lighting device 11 and the traveling direction of the second light L12, L22. Therefore, it is possible to effectively align the area illuminated by the first lights L11 and L21 emitted from the illumination device 11 and the area illuminated by the second lights L12 and L22 emitted from the illumination device. Thereby, it is possible to illuminate the entire illuminated area LZ to be illuminated by the illumination device 11 with the first light L11, L21 and the second light L12, L22. In addition, it is possible to effectively prevent color unevenness from conspicuous in the outer edge portion of the illuminated area LZ to be illuminated by the illumination device 11.

  Moreover, in this Embodiment, the irradiation apparatus 51 inject | emits the parallel light beam of 1st light L11, L21, and inject | emits the parallel light beam of 2nd light L12, L22. According to the present embodiment, it is possible to align the incident directions of the first lights L11 and L21 to the respective positions of the diffractive optical element 21 and the first lights L11 and L21 to the respective positions of the prism 31. It is possible to align the incident direction. As a result, the traveling direction of the first lights L11 and L21 emitted from the illumination device 11 can be uniformly corrected by the prism 31. Similarly, the incident directions of the second lights L12 and L22 to the respective positions of the diffractive optical element 21 can be made uniform, and the incident directions of the second lights L12 and L22 to the respective positions of the prism 31 can be made uniform. Become. As a result, the traveling direction of the second lights L12 and L22 emitted from the illumination device 11 can be uniformly corrected by the prism 31. As a result, the traveling directions of the first light L11, L21 and the second light L12, L22 emitted from the illumination device 11 can be more effectively aligned.

  Various modifications can be made to the above-described embodiment. Hereinafter, an example of modification will be described with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted.

  First, in the above-described embodiment, the prism 31 is disposed upstream of the diffractive optical element 21 along the optical paths of the first light L11, L21 and the second light L12, L22 emitted from the irradiation device 51. It was. However, as in the illuminating device 12 shown in FIG. 5, the prism 31 is located downstream of the diffractive optical element 21 along the optical paths of the first light L51 and the second light L52 emitted from the irradiation device 51. It may be arranged. The lighting device 12 shown in FIG. 5 can also obtain the same effects as those of the above-described embodiment.

  Furthermore, in the embodiment described above, an example in which the illumination device 11 includes only one prism 31 has been shown. In the above-described embodiment, the chromatic dispersion caused by the diffractive optical element 21 is relaxed along one direction connecting the top 35 and the bottom 34 of the prism 31. However, the second prism 41 may be provided in addition to the prism 31 as in the illumination device 13 shown in FIGS. 6 and 7.

  In the example shown in FIGS. 6 and 7, the second prism 41 has a pair of main surfaces 43 a and 43 b that define an apex angle 42, similarly to the prism 31. A top portion 45 is formed on one side of the pair of main surfaces 43a and 43b, and a bottom portion 44 is formed on the other side of the pair of main surfaces 43a and 43b. Between the pair of main surfaces 43a and 43b, the top portion 45 and the bottom portion 44 are arranged to face each other. In the illustrated example, the apex 45 is formed by the apex angle 42. The second prism 41 is disposed so that the pair of main surfaces 43 a and 43 b cross the optical path of the light projected from the irradiation device 51 and directed to the illuminated region LZ via the diffractive optical element 21. The pair of main surfaces 43a and 43b are non-parallel. As a result, as shown in FIG. 7, when the first light L71 and the second light L72 pass through the pair of main surfaces 43a and 43b and pass through the second prism 41, their traveling directions are bent by refraction.

  That is, like the prism 31, the second prism 41 has a function of bending the light traveling direction by refraction. However, the direction connecting the top 45 and the bottom 44 of the second prism 41 is not parallel to the direction connecting the top 35 and the bottom 34 of the prism 31. Therefore, the direction in which the light from the irradiation device 51 is bent is different between the prism 31 and the second prism 41.

  FIG. 7 shows the illumination device 13 from a direction orthogonal to both the direction connecting the top 45 and the bottom 44 of the second prism 41 and the normal direction nd of the diffractive optical element 21. That is, FIG. 7 corresponds to a top view of the illumination device 13 of FIG. The first light L71 and the second light L72 incident on the diffractive optical element 21 travel in the normal direction nd of the diffractive optical element 21 or from the top 45 side (the lower side of the drawing in FIG. 7) of the second prism 41 to the bottom. It proceeds in a direction inclined to one side with respect to the normal direction nd of the diffractive optical element 21 so as to go to the side 34 (the upper side of the paper surface in FIG. 2). The first light L71 and the second light L72 diffracted by the diffractive optical element 21 travel in a direction inclined at a larger angle than before diffraction to one side with respect to the normal direction nd of the diffractive optical element 21. . According to such an illuminating device 13, in addition to the shift in the diffraction direction corresponding to the wavelength generated in the diffractive optical element 21, the shift in the transmission direction (refractive direction) corresponding to the wavelength generated in the prism 31 described above, the second Correction can also be made by a deviation in the transmission direction (refractive direction) according to the wavelength generated by the prism 41.

  That is, according to the example shown in FIGS. 6 and 7, the region illuminated by the first light L <b> 71 emitted from the illumination device 13 along the direction connecting the top portion 35 and the bottom portion 34 of the first prism 31. It is possible to effectively align the area illuminated by the second light L72 emitted from the illumination device 13. In addition, along the direction connecting the top portion 45 and the bottom portion 44 of the second prism 41, the region illuminated by the first light L71 emitted from the illumination device 13 and the second light L72 emitted from the illumination device 13 are illuminated. It is possible to effectively align the area with the area. In other words, the area illuminated by the first light L71 and the area illuminated by the second light L72 can be aligned along the first direction connecting the top 35 and the bottom 34 of the first prism 31. The region illuminated by the first light L71 and the second light L72 are illuminated along a second direction that is non-parallel to the first direction connecting the top 45 and the bottom 44 of the second prism 41. Can be aligned. As a result, the area illuminated by the first light L71 and the area illuminated by the second light L72 can be very effectively aligned.

  In the example shown in FIGS. 6 and 7, the second prism 41, the prism 31, and the diffractive optical element 21 are arranged in this order along the optical path of the light emitted from the irradiation device 51. However, the arrangement order of the second prism 41, the prism 31, and the diffractive optical element 21 is not particularly limited. In the example shown in FIGS. 6 and 7, the second prism 41 is formed in a triangular prism shape. Therefore, the apex second prism 41 actually has an apex angle 42, and the apex angle 42 forms the apex 45. The second prism 41 has a ridge line 42a formed at a position where the pair of main surfaces 43a and 43b are connected. However, the present invention is not limited to this example, and the second prism 41 may be formed, for example, in the shape of a trapezoidal column and does not actually include the apex angle 42, like the prism 31 described above. Even if the second prism 41 does not include the apex angle 42, the same function and effect as the prism 41 including the apex angle 42 can be exhibited as long as the relative inclination angles of the pair of main surfaces 43 a and 43 b are adjusted. it can.

  Furthermore, in the above-described embodiment, an example has been shown in which the irradiation device 51 irradiates light in a plurality of different wavelength ranges as parallel light fluxes. However, like the illumination device 14 shown in FIG. 8, the irradiation device 54 scans one of the prism 31 and the diffractive optical element 21 located on the upstream side in the optical path of light in a plurality of wavelength regions. In addition, light may be irradiated. In addition, although the irradiation apparatus 54 of the illuminating device 14 shown by FIG. 8 inject | emits the light of the several wavelength range containing at least 1st light and 2nd light, in order to make an understanding of the structure of the irradiation apparatus 54 easy. In FIG. 9, which will be described later in connection with FIGS. 8 and 8, the illustration of light for each wavelength is omitted, and the optical path as the combined light SL is shown.

  In the example shown in FIG. 8, the irradiation device 54 irradiates the prism 31 with synthetic light. The irradiation device 54 in the example shown in FIG. 8 is not particularly limited, but irradiates each position on the prism 31 with the combined light SL traveling in a certain direction ds. In other words, the irradiation device 54 irradiates each position of the prism 31 with the composite light SL along the optical path of one light beam forming a virtual parallel light beam.

  As a specific configuration, the irradiation device 54 includes a light source 61 that generates combined light and a scanning device 64 that changes the optical path of the combined light SL from the light source 61. The light source 61 includes a first light source 61a that generates the first light L81 in the first wavelength band, a second light source 61b that generates the second light L82 in the second wavelength band, the first light L81, and the second light L82. And a synthesis device 61c. The scanning device 64 changes the optical path of the combined light SL over time. Thus, the combined light SL enters the prism 31 so as to scan the main surface 33 a of the prism 31. In the example shown in FIG. 8, the scanning device 64 of the irradiation device 54 is a reflection device 66 a that reflects the combined light SL and has a reflection surface 66 a that can be rotated about at least one axis RA. 66 and a deflecting element 67 that deflects the optical path of the light reflected by the reflecting device 66 in a direction parallel to a certain direction ds.

  In the example shown in FIG. 8, 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. The mirror device 66 changes the traveling direction of light from the light source 61 by changing the direction of the mirror 66a. At this time, as shown in FIG. 8, the mirror device 66 receives the light SL from the light source 61 at a certain position (reference position) SP. Therefore, the combined light SL is changed in the traveling direction by the mirror device 66 that periodically rotates within a predetermined angle range, and then travels along the optical path of the light beam that forms the divergent light beam that diverges from the reference position SP. become. On the other hand, the deflecting element 67 is configured to collimate the divergent light beam that diverges from the reference position SP and convert it into a parallel light beam, corresponding to the configuration of the reflection device 66 described above. Specifically, the deflection element 67 is configured as a lens and is disposed at a position where a divergent light beam diverging from the reference position SP can be collimated. For this reason, the combined light SL whose optical path is adjusted by the deflecting element 67 can be incident on the prism 31 as light forming one light beam of the parallel light flux.

  In the example shown in FIG. 8, the light incident on the prism 31 changes the traveling direction by the prism 31 and then travels toward the diffractive optical element 24. The light incident on the diffractive optical element 24 is diffracted by the diffractive optical element 24 and travels toward the illuminated region LZ. The prism 31 and the diffractive optical element 24 in the illuminating device 14 shown in FIG. 8 can achieve the same functions and effects as those of the above-described embodiment.

  In the above-described embodiment, the example in which the light incident on each position of the diffractive optical element 21 simply changes the traveling direction by the diffractive action of the diffractive optical element 21 has been described. Even when such a diffractive optical element 21 is applied to the illuminating device 14 of FIG. 8, if the scanning speed of the scanning device 64 is high enough that it cannot be disassembled by human eyes, the illumination target is illuminated. It can be recognized that the region LZ is illuminated in a planar shape.

  On the other hand, like the illumination device 14 shown in FIG. 8, the diffractive optical element 24 may be formed as a diffusing element that diffuses light incident on each position into a divergent light beam. In the example shown in FIG. 8, the first light L81 incident on each position on the upstream side in the optical path of the first light and the second light of the prism 31 and the diffractive optical element 24, respectively, Thereafter, the regions that are diffracted by the diffractive optical element 24 and overlap each other at least partially are illuminated. Similarly, the second light L82 incident on each position on the upstream side in the optical path of the first light L81 and the second light L82 of the prism 31 and the diffractive optical element 24 is respectively diffracted optically thereafter. Illuminate areas that are diffracted by the element 24 and overlap at least in part with each other. In this example, the region illuminated by the first light L81 diffracted at each position of the diffractive optical element 24 and the region illuminated by the second light L82 diffracted at each position of the diffractive optical element 24 are at least By overlapping in a part, it becomes possible to illuminate the part with light in a plurality of wavelength regions. That is, the part becomes the illuminated area LZ. In the example shown in FIG. 8, the illuminating device 14 further includes an optical path correcting unit 19 disposed on the downstream side of the diffractive optical element 24. In the example shown in FIG. 8, the optical path is corrected by the optical path correction means 19 so that the diffused light diffracted at each position of the diffractive optical element 24 is directed to the entire illuminated area LZ. Is done. In the example shown in FIG. 8, the optical path correction means 19 is formed by a lens.

  By the way, in an illuminating device using a coherent light source such as a laser beam, there arises a problem of speckle generation. A speckle is a speckled pattern that appears when a scattering surface is irradiated with laser light or other coherent light. When it occurs on the illuminated area LZ, it is observed as speckled luminance irregularity (brightness irregularity). It becomes a factor that adversely affects the observer physiologically. On the other hand, in the illuminating device 14 shown in FIG. 8, the illuminating device 14 illuminates the illuminated region LZ with light that changes in angle with time. More specifically, the illumination device 14 illuminates the illuminated area LZ with diffused light, and the incident angle of the diffused light changes with time. As a result, the diffusion pattern of light generated on the illuminated region LZ also changes over time, and speckles generated by the diffusion of coherent light are averaged over time and become inconspicuous. That is, according to the illuminating device 14 shown in FIG. 8, it can respond also to a speckle.

  Furthermore, the illuminating devices 11, 12, 13, and 14 described above can more accurately guide light in a plurality of different wavelength ranges onto the same illuminated region LZ. Such illumination devices 11, 12, 13, and 14 can be suitably used as devices for illuminating the spatial light modulator 72. According to the combination of the illumination devices 11, 12, 13, 14 and the spatial light modulator 72, the illumination devices 11, 12, 13, 14 can illuminate the spatial light modulator 72 with high accuracy. It is preferable in terms of light utilization efficiency.

  FIG. 9 shows an example in which the projection device 70 and the projection display device 80 are formed using the illumination device 14 shown in FIG. 8 as an example. In the example shown in FIG. 9, the projection device 70 projects the illumination device 14, a spatial light modulator 72 illuminated by the illumination device 14, and a modulated optical system formed by the spatial light modulator 72. 74. The projection display device 80 includes a projection device 70 and a screen 82 onto which a modulated image is projected from the projection device 70.

  The spatial light modulator 72 is disposed on the illuminated area LZ illuminated by the illumination device 14. The spatial light modulator 72 is disposed in the illuminated area LZ. The spatial light modulator 72 is illuminated by the illumination device 14 and forms a modulated image. As described above, the light from the illumination device 14 illuminates only the entire illuminated area LZ with high accuracy. Therefore, it is preferable that the incident surface of the spatial light modulator 72 has the same shape and size as the illuminated region LZ irradiated with light by the illumination device 14. In this case, it is because the light from the illuminating device 14 can be utilized with high utilization efficiency for the formation of a modulated image. The spatial light modulator 72 is not particularly limited, and various known spatial light modulators can be used. As the spatial light modulator 72, for example, a transmissive liquid crystal microdisplay or a reflective microdisplay such as a MEMS element such as DMD (Digital Micromirror Device) can be used.

  The screen 82 may be configured as a transmissive screen, or may be configured as a reflective screen. The coherent light projected on the screen 82 is diffused and recognized as an image by the observer. When the illuminating device 14 uses coherent light, the coherent light projected on the screen interferes by diffusion and causes speckle. However, the illumination device 14 included in the projection display device 80 shown in FIG. 9 illuminates the illuminated region LZ on which the spatial light modulator 72 is superimposed with coherent light that changes in angle with time. More specifically, the illuminating device 14 illuminates the illuminated area 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 82 also changes with time, and speckles generated by the diffusion of the coherent light are temporally superimposed so as to be inconspicuous.

  In addition, although the some modification with respect to embodiment mentioned above was demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

DESCRIPTION OF SYMBOLS 11 Illuminating device 12 Illuminating device 13 Illuminating device 14 Illuminating device 19 Optical path correction means 21 Diffractive optical element 21a Irregular surface 31 Prism, 1st prism 32 Apex angle 32a Ridge line 33a Main surface 33b Main surface 34 Bottom part 35 Top part 41 Second prism 42 Top Corner 42a Ridge 43b Main surface 43c Main surface 44 Bottom 45 Top 51 Irradiation device 54 Irradiation device 61 Light source 61a Light source 61b Light source 61c Combining device 64 Scan device 66 Mirror device 66a Reflecting surface 67 Deflection element 70 Projection device 72 Spatial light modulator 74 Projection Optical system 80 Projection type display device 82 Screen

Claims (8)

An irradiation device that emits first light in a first wavelength region and second light in a second wavelength region different from the first wavelength region;
A diffractive optical element that diffracts the first light and the second light from the irradiation device;
A prism having a pair of main surfaces forming a top portion and a bottom portion facing the top portion and extending between the pair of main surfaces, wherein the first light and the second light pass through the pair of main surfaces. A prism arranged to pass through,
All of the first light and the second light incident on the diffractive optical element in observation from a direction orthogonal to both the direction connecting the top and bottom of the prism and the normal direction of the diffractive optical element All of the prism travels in a direction inclined to one side with respect to the normal direction of the diffractive optical element so as to go from the top side to the bottom side of the prism, and is diffracted by the diffractive optical element. The lighting device, wherein the first light and the second light travel in a direction inclined to the one side at a larger angle than before diffraction with respect to the normal direction of the diffractive optical element.   The illumination device according to claim 1, wherein the irradiation device emits a parallel light flux of the first light and emits a parallel light flux of the second light.   The irradiation device scans the first light and the second light so as to scan one of the prism and the diffractive optical element located on the upstream side in the optical path of the first light and the second light. The illumination device according to claim 1 irradiating.   The first light and the second light are in a predetermined direction at each position on the one of the prism and the diffractive optical element that is located upstream in the optical path of the first light and the second light. The illumination device according to claim 3, wherein the illumination device is incident along. The first light that has entered each position on the one of the prism and the diffractive optical element that is located on the upstream side in the optical path of the first light and the second light overlaps each other at least partially. Illuminate the
The second light that has entered each position on the one of the prism and the diffractive optical element that is located upstream in the optical path of the first light and the second light overlaps each other in the portion. The illumination device according to claim 3 or 4, wherein the illumination device is illuminated. A second prism having a pair of main surfaces defining a top portion and a bottom portion facing the top portion and extending between the pair of main surfaces, wherein the first light and the second light are the pair of A second prism arranged to pass through the main surface,
The direction connecting the top and the bottom of the second prism intersects the direction connecting the top and the bottom of the prism,
The first light and the second light incident on the diffractive optical element in observation from a direction orthogonal to both the direction connecting the top and the bottom of the second prism and the normal direction of the diffractive optical element Is in a direction inclined to one side with respect to the normal direction of the diffractive optical element so as to proceed in the normal direction of the diffractive optical element or from the top side to the bottom side of the second prism. The first light and the second light diffracted by the diffractive optical element travel in a direction inclined at a larger angle than before diffraction to the one side with respect to the normal direction of the diffractive optical element; The illumination device according to any one of claims 1 to 5. The lighting device according to any one of claims 1 to 6,
And a spatial light modulator disposed at a position illuminated by coherent light from the illumination device. A projection device according to claim 7;
And a screen on which a modulated image obtained on the spatial light modulator is projected.

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