JP2009054672A - Light source device, illumination device, monitor device, and image display device - Google Patents

Abstract

A light source device capable of efficiently emitting light using an external resonator and capable of reducing the generation of speckle noise, an illumination device using the light source device, a monitor device, and an image display device.
A semiconductor element is a light source unit in which a plurality of light emitting units that emit light are arranged in parallel, a volume hologram is an external resonator that resonates light emitted from the light source unit, a light source unit and an external An SHG element 14 that is provided in the optical path between the resonators and converts the wavelength of light emitted from the light source unit, a fluid flow unit 13 that adjusts the temperature of the light source unit, and an external resonator It has a heat supply unit for external resonator 18 for adjusting the temperature and a heat supply unit for wavelength conversion element 15 for adjusting the temperature of the wavelength conversion element, and has a fluid flow unit 13, a heat supply unit for external resonator 18 and a wavelength conversion. The element heat supply unit 15 applies a temperature gradient in a specific direction that is a direction substantially parallel to the direction in which the light emitting units 12 are arranged in parallel.
[Selection] Figure 1

Description

  The present invention relates to a light source device, an illumination device, a monitor device, and an image display device, and more particularly to a technology of a light source device using an external resonator.

  In recent years, a technique using a laser light source as a light source device of an image display device has been proposed. Compared with a UHP lamp conventionally used as a light source device for an image display device, a laser light source has advantages such as high color reproducibility, instant lighting, and long life. When a laser beam, which is coherent light, is irradiated onto a diffusion surface, an interference pattern called a speckle pattern in which bright spots and dark spots are randomly distributed may appear. The speckle pattern is generated when light diffused at each point on the diffusion surface interferes randomly. When a speckle pattern is recognized when an image is displayed, a glimmering flickering feeling is given to the observer, which adversely affects image viewing. For this reason, when using a laser light source, it is desired to reduce the generation of speckle noise. In order to reduce the generation of speckle noise, for example, Patent Document 1 proposes a technique in which a plurality of light emitting elements that emit laser beams having different wavelengths are arranged in an array. In the technique of Patent Document 1, the wavelength of the laser light emitted from each light emitting element is made different by changing the temperature of each light emitting element. Since the coherence length of the laser beam is approximately inversely proportional to the wavelength width of the laser beam, it is possible to shorten the coherence length and reduce the generation of speckle noise by increasing the wavelength width.

JP 2004-144794 A

  As a laser light source, one that emits harmonic light whose wavelength is converted by a wavelength conversion element is known. By using the wavelength conversion element, it is possible to supply laser light having a desired wavelength and a sufficient amount of light using a general-purpose light-emitting element that can be easily obtained. Further, the laser light source uses an external resonator that resonates light, so that the wavelength of the laser light can be narrowed and the output of the laser light can be increased. In the case of using an external resonator and a wavelength conversion element, even if a wide wavelength range is secured at the stage of emitting light from the light emitting element, the laser beam is narrowed in the external resonator. When the laser beam is narrowed by an external resonator, it becomes difficult to reduce the generation of speckle noise. On the other hand, if the selected wavelength width is widened for the entire external resonator corresponding to the wavelength width of the laser light, it becomes difficult to resonate the light, and it is difficult to efficiently emit the laser light. As described above, according to the conventional technique, there is a problem that it is difficult to reduce the generation of speckle noise in a configuration using an external resonator. The present invention has been made in view of the above-described problems. A light source device that can efficiently emit light using an external resonator and can reduce generation of speckle noise, an illumination device using the light source device, An object is to provide a monitor device and an image display device.

  In order to solve the above-described problems and achieve the object, the light source device according to the present invention includes a light source unit in which a plurality of light emitting units emitting light are arranged in parallel and an external resonance that resonates light emitted from the light source unit. A wavelength conversion element that converts the wavelength of light emitted from the light source unit, and a temperature adjustment unit for the light source unit that adjusts the temperature of the light source unit, provided in the optical path between the light source unit and the external resonator, A temperature adjusting unit for the external resonator that adjusts the temperature of the external resonator, and a temperature adjusting unit for the wavelength conversion element that adjusts the temperature of the wavelength conversion element, the temperature adjusting unit for the light source unit, and the temperature adjusting unit for the external resonator The wavelength conversion element temperature adjusting unit applies a temperature gradient in a specific direction that is a direction substantially parallel to a direction in which the plurality of light emitting units are arranged in parallel.

  By applying a temperature gradient to the light source unit by the temperature control unit for the light source unit, it is possible to emit fundamental light in a wide wavelength range using each light emitting unit. By applying a temperature gradient to the external resonator by the external resonator temperature control unit, it is possible to resonate the fundamental wave light in a wide wavelength region and emit harmonic light in a wide wavelength region. By applying a temperature gradient to the wavelength conversion element by the wavelength conversion element temperature control unit, it is possible to convert the wavelength of fundamental light in a wide wavelength range. By appropriately adjusting the temperature gradient of the light source unit, external resonator, and wavelength conversion element, the fundamental wave light in a wide wavelength range from the light source unit is resonated and the wavelength converted harmonic light in a wide wavelength range is efficiently emitted. it can. By making it possible to emit harmonic light in a wide wavelength range, the light source device can reduce the generation of speckle noise. Thereby, it is possible to obtain a light source device that can emit light efficiently using an external resonator and can reduce generation of speckle noise.

  Moreover, as a preferable aspect of the present invention, the external resonator temperature adjustment unit includes an external resonator heat supply unit that supplies heat to the external resonator, and the external resonator heat supply unit is specified among the external resonators. It is desirable to be provided in the vicinity of the outer edge which is one end in the direction. By supplying heat using the external resonator heat supply unit, the temperature in the vicinity of the outer edge, which is one end in a specific direction, of the external resonator is increased. Thereby, a temperature gradient can be given to a specific direction in an external resonator.

  Further, as a preferred aspect of the present invention, the external resonator temperature adjustment unit includes an external resonator heat dissipation unit that dissipates heat from the external resonator, and the external resonator heat supply unit is the first of the external resonators. Preferably, the external resonator heat dissipating portion is provided in the vicinity of one outer edge portion, and is provided in the vicinity of the second outer edge portion on one side of the external resonator in a specific direction and opposite to the first outer edge portion. Due to the heat radiation using the heat radiation portion for the external resonator, the temperature in the vicinity of the second outer edge portion of the external resonator is lowered. Thereby, a temperature gradient can be efficiently given to a specific direction in an external resonator.

  Further, as a preferred aspect of the present invention, there is a heat insulating portion for an external resonator that blocks heat transfer from the external resonator, and a direction substantially parallel to the traveling direction of the light emitted from the light source portion is specified as the first direction. Assuming that the direction is the second direction, and the direction substantially orthogonal to the first direction and the second direction is the third direction, the external resonator heat insulating portion is preferably provided in parallel with the external resonator in the third direction. Thereby, the propagation of heat in the third direction can be reduced, and a temperature gradient can be efficiently applied in the second direction.

  Moreover, as a preferable aspect of the present invention, the light source temperature control unit includes a fluid flow part through which a fluid flows, and the fluid may flow in a direction substantially parallel to a specific direction inside the fluid flow part. desirable. The fluid flows in a direction substantially parallel to the specific direction, and the temperature rises by receiving heat from the light source unit. A temperature gradient is generated in the light source unit such that the temperature increases as the fluid flows. Thereby, a temperature gradient can be given to a specific direction in a light source part.

  Moreover, as a preferable aspect of the present invention, the light source unit temperature control unit includes a light source unit heat supply unit that supplies heat to the light source unit, and the light source unit heat supply unit is arranged in a specific direction in the light source unit. It is desirable to be provided in the vicinity of the outer edge which is one end. Thereby, a temperature gradient can be easily given in a light source part.

  Moreover, as a preferable aspect of the present invention, it is desirable that the wavelength conversion element temperature adjusting unit includes a plurality of wavelength conversion element heat supply units for supplying heat to the wavelength conversion element. Thereby, normal temperature adjustment of the wavelength conversion element and application of a temperature gradient can be easily performed.

  As a preferred embodiment of the present invention, it is desirable that the plurality of wavelength conversion element heat supply units be provided in parallel in a specific direction. Thereby, a temperature gradient can be provided in a specific direction in the wavelength conversion element.

  Moreover, as a preferable aspect of the present invention, the wavelength conversion element heat supply unit includes a wavelength conversion element first heat supply unit arranged in accordance with a center in a specific direction of the wavelength conversion element, and a wavelength conversion element specified. It is desirable to have the 2nd heat supply part for wavelength conversion elements arrange | positioned in the vicinity of the outer edge part which is the end of a direction. Thereby, normal temperature adjustment can be performed mainly using the first heat supply unit for wavelength conversion elements, and a temperature gradient can be applied mainly using the second heat supply unit for wavelength conversion elements.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a wavelength conversion element thermal diffusion section that diffuses the heat supplied by the wavelength conversion element first heat supply section. Thereby, the heat from the 1st heat supply part for wavelength conversion elements can be uniformly propagated to a wavelength conversion element.

  As a preferred aspect of the present invention, when the direction substantially parallel to the traveling direction of the light emitted from the light source unit is the first direction and the specific direction is the second direction, the heat supply unit for the wavelength conversion element is It is desirable to make the shape longer in the first direction than in the two directions. Thereby, the temperature of the wavelength conversion element is made uniform in the first direction, and high wavelength conversion efficiency can be realized.

  Moreover, as a preferable aspect of the present invention, at least one of the temperature gradient of the light source unit provided by the temperature control unit for light source unit and the temperature gradient of the wavelength conversion device provided by the temperature control unit for wavelength conversion element is an external It is desirable to determine the temperature based on the temperature gradient of the external resonator provided by the resonator temperature adjustment unit. The wavelength range of light reflected by the external resonator is determined by the temperature gradient of the external resonator. By determining the temperature gradient of the light source unit and the temperature gradient of the wavelength conversion element according to the reflection characteristics of the external resonator, adjustment for efficiently emitting the harmonic light after wavelength conversion can be facilitated.

  Furthermore, an illumination device according to the present invention includes the light source device described above, and illuminates an object to be irradiated using light from the light source device. By using the above light source device, light can be emitted efficiently and speckle noise can be reduced. As a result, it is possible to obtain a lighting device that can supply light with high efficiency and can reduce the generation of speckle noise.

  Furthermore, a monitor device according to the present invention includes the above-described illumination device and an imaging unit that captures an image of a subject illuminated by the illumination device. By using the above illumination device, light can be supplied with high efficiency and generation of speckle noise can be reduced. As a result, a monitor device capable of monitoring a bright and high-quality image can be obtained.

  Furthermore, an image display device according to the present invention includes the light source device described above, and displays an image using light from the light source device. By using the above light source device, light can be emitted efficiently and speckle noise can be reduced. Thereby, an image display device capable of displaying a bright and high-quality image can be obtained.

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

  FIG. 1 shows a schematic configuration of a light source device 10 according to Embodiment 1 of the present invention. The light source device 10 is an array laser having a semiconductor element 11, a second-harmonic generation (SHG) element 14, and a volume hologram 17. The semiconductor element 11 is a light source unit in which a plurality of light emitting units 12 that emit fundamental light are arranged in parallel, and is, for example, a surface-emitting type semiconductor element. The fundamental light is, for example, infrared light.

  The semiconductor element 11 has a mirror layer (not shown) that reflects the fundamental wave light. The semiconductor element 11 is mounted on the fluid flow part 13. The semiconductor element 11 only needs to be able to supply a plurality of lights by the plurality of light emitting units 12, and is not limited to the configuration including the seven light emitting units 12. Here, the Z-axis direction is a first direction substantially parallel to the traveling direction of the light emitted from the semiconductor element 11. The semiconductor element 11, the SHG element 14, and the volume hologram 17 are arranged in parallel in the Z-axis direction. The X-axis direction is a direction substantially orthogonal to the Z-axis direction and is a second direction substantially parallel to the direction in which the plurality of light emitting units 12 are arranged in parallel. The Y-axis direction is a direction substantially orthogonal to the Z-axis direction and the X-axis direction.

The SHG element 14 emits harmonic light when the fundamental light is incident. The harmonic light is light having a wavelength that is half the wavelength of the fundamental light, and is, for example, visible light. The SHG element 14 is a wavelength conversion element that converts the wavelength of light emitted from the semiconductor element 11. The SHG element 14 is provided in the optical path between the semiconductor element 11 and the volume hologram 17. The SHG element 14 is, for example, a polarization inversion crystal (Periodically Poled Lithium Niobate; PPLN) of lithium niobate (LiNbO ₃ ) which is a nonlinear optical crystal. The SHG element 14 has a rectangular parallelepiped shape.

  The polarization inversion structure is configured by inverting the sign of the nonlinear optical constant for each coherent length. The SHG element 14 converts the wavelength of light corresponding to the pitch of the domain-inverted structure. For the formation of the domain-inverted structure, a method of applying a voltage to a nonlinear optical crystal having spontaneous polarization is often used. The domain-inverted structure can be obtained, for example, by forming a fine pattern of an insulating layer on a lithium niobate (LN) substrate and applying a voltage through a metal film or an electrolytic solution. A wavelength conversion element second heat supply unit 15 and a wavelength conversion element heat diffusion unit 16 are provided around the SHG element 14.

The volume hologram 17 is an external resonator that resonates the fundamental wave light emitted from the semiconductor element 11 between the mirror layer of the semiconductor element 11. The volume hologram 17 selectively reflects the fundamental wave light and transmits light having a wavelength different from the wavelength of the fundamental wave light (including harmonic light). As the volume hologram 17, for example, VHG (Volume Holographic Grating) can be used. VHG can be formed using a photorefractive crystal such as LiNbO ₃ or BGO, a polymer, or the like. An external resonator heat supply unit 18 is provided around the volume hologram 17.

  Interference fringes generated by incident light incident from two directions are recorded on the VHG. The interference fringes are recorded as a periodic structure in which a high refractive index portion and a low refractive index portion are periodically arranged. The VHG selectively reflects only light that satisfies the interference fringes and the Bragg condition by diffraction. The volume hologram 17 has a rectangular parallelepiped shape. The volume hologram 17 is obtained by cutting a material formed in a plate shape. The volume hologram 17 can be set to a desired size by appropriately changing the thickness of the material before cutting and the size cut out from the material.

  FIG. 2 illustrates a configuration for adjusting the temperature of the volume hologram 17. The external resonator heat supply unit 18 is a heater that supplies heat to the volume hologram 17. For example, an electric heater can be used as the heater. The external resonator heat supply unit 18 is provided in contact with the first outer edge 24 which is one end of the volume hologram 17 in the X-axis direction. The external resonator heat dissipation portion 21 dissipates heat from the volume hologram 17. The external resonator heat dissipation portion 21 is provided in contact with the second outer edge portion 25 of the volume hologram 17. The second outer edge portion 25 is one end in the X-axis direction of the volume hologram 17 and is opposite to the first outer edge portion 24.

  The external resonator heat insulating portion 22 blocks heat transfer from the volume hologram 17. The two external resonator heat insulating portions 22 sandwich the volume hologram 17, the external resonator heat supply portion 18, and the external resonator heat dissipation portion 21 in the Y-axis direction that is the third direction. The external resonator heat insulating portion 22 is provided in parallel with the volume hologram 17 in the Y-axis direction. The external resonator heat insulating portion 22 is configured using a heat insulating member, for example, a resin member. The volume hologram 17 is surrounded by an external resonator heat supply unit 18, an external resonator heat dissipation unit 21, and an external resonator heat insulation unit 22.

  By supplying heat using the external resonator heat supply section 18, the temperature of the volume hologram 17 in the vicinity of the first outer edge section 24 is raised. Further, the temperature of the portion near the second outer edge portion 25 of the volume hologram 17 is reduced by heat radiation using the heat radiation portion 21 for the external resonator. The external resonator heat supply unit 18 and the external resonator heat radiation unit 21 function as an external resonator temperature adjustment unit that adjusts the temperature of the volume hologram 17. Further, heat insulation in the Y-axis direction is reduced by heat insulation using the external resonator heat insulation portion 22. The heat from the external resonator heat supply unit 18 propagates in the volume hologram 17 toward the external resonator heat dissipation unit 21. The temperature T1 of the volume hologram 17 is distributed so as to increase from t1 to t1 'as it proceeds in the arrow direction of the X axis in the figure. As described above, the external resonator heat supply unit 18 and the external resonator heat dissipation unit 21 impart a temperature gradient in the X-axis direction, which is a specific direction, in the volume hologram 17.

  The volume hologram 17 expands as the temperature rises. The interval between the interference fringes becomes wider as the volume hologram 17 expands. As the interval between the interference fringes becomes wider, the wavelength of the reflected light and the wavelength of the transmitted light both change to the longer wavelength side. The volume hologram 17 shifts the wavelength of the reflected fundamental light and the wavelength of the transmitted harmonic light to the longer wavelength side from the second outer edge 25 to the first outer edge 24 (from B to A in the figure). it can. Accordingly, the volume hologram 17 can resonate fundamental wave light in a wide wavelength region and emit harmonic light in a wide wavelength region. Usually, the members constituting the volume hologram 17 exhibit a relatively low thermal conductivity. The thermal conductivity of the volume hologram 17 is, for example, about 0.1 W / mK. Since it exhibits low thermal conductivity, a temperature gradient can be easily applied to the volume hologram 17.

  FIG. 3 illustrates a configuration for adjusting the temperature of the semiconductor element 11. A refrigerant that is a fluid, for example, water, flows inside the fluid flow portion 13. The fluid flow unit 13 functions as a temperature adjusting unit for the light source unit that adjusts the temperature of the semiconductor element 11. The fluid flow part 13 is connected to a circulation part (not shown). The circulation part forms a flow path through which the refrigerant flows. A circulation pump (not shown) is used for the flow of the refrigerant. The heat generated in the semiconductor element 11 is transmitted to the refrigerant flowing inside the fluid flow part 13. By disposing the fluid flow portion 13 immediately below the semiconductor element 11, the semiconductor element 11 can be efficiently cooled. The heat transferred to the refrigerant is released to the ambient air in the process of circulating the refrigerant in the circulation section. For example, a heat exchanger can be used for heat radiation from the refrigerant to the ambient air.

  As indicated by the arrows, the refrigerant flows through the fluid flowing portion 13 in a direction substantially parallel to the X-axis direction that is the specific direction. As the refrigerant flows in the direction of the arrow and receives heat from the semiconductor element 11, the temperature rises. As the refrigerant flows in the direction of the arrow directly below the semiconductor element 11, the heat taken away from the semiconductor element 11 by the refrigerant decreases. For this reason, the temperature T2 of the semiconductor element 11 is distributed so as to increase from t2 to t2 'as it proceeds in the arrow direction of the X axis in the figure. The wavelength of the light emitted from the semiconductor element 11 changes to the longer wavelength side as the semiconductor element 11 has a higher temperature. The semiconductor element 11 can shift the wavelength of the fundamental wave light to be emitted toward the longer wavelength side from the upstream side to the downstream side of the refrigerant in the fluid flow part 13 (from B to A in the figure). Therefore, the semiconductor element 11 can emit fundamental light in a wide wavelength range using each light emitting unit 12.

  FIG. 4 illustrates a configuration for adjusting the temperature of the SHG element 14. The wavelength conversion element first heat supply unit 27 and the wavelength conversion element second heat supply unit 15 are heaters that supply heat to the SHG element 14 and adjust the temperature of the SHG element 14. It functions as a part. For example, an electric heater can be used as the heater. The SHG element 14 is mounted on the thermal diffusion part 16 for wavelength conversion element. The wavelength conversion element heat diffusion unit 16 diffuses the heat supplied by the wavelength conversion element first heat supply unit 27. The wavelength conversion element thermal diffusion section 16 is configured using a member having high thermal conductivity, for example, copper which is a metal member.

  The wavelength conversion element first heat supply unit 27 is provided on the surface of the wavelength conversion element heat diffusion unit 16 opposite to the surface on which the SHG element 14 is mounted. The first heat supply unit 27 for wavelength conversion element is arranged in alignment with the center of the SHG element 14 in the X-axis direction. The wavelength conversion element second heat supply unit 15 is provided on the surface of the wavelength conversion element thermal diffusion unit 16 on which the SHG element 14 is mounted. The second heat supply unit 15 for wavelength conversion element is disposed in the vicinity of the first outer edge portion 28 that is one end in the X-axis direction of the SHG element 14.

  FIG. 5 shows a planar configuration of the configuration shown in FIG. 4 as viewed from the side where the SHG element 14 is provided. Each of the first heat supply unit for wavelength conversion element 27 and the second heat supply unit for wavelength conversion element 15 has a strip shape that is longer in the Z-axis direction that is the first direction than the X-axis direction that is the second direction. . Both the first heat supply unit for wavelength conversion element 27 and the second heat supply unit for wavelength conversion element 15 are formed with substantially the same length as the SHG element 14 in the Z-axis direction.

  FIG. 6 shows the relationship between the position in the X-axis direction and the temperature T3 of the SHG element 14. The heat supplied by the first wavelength conversion element heat supply unit 27 is made uniform by the wavelength conversion element heat diffusion unit 16 and then propagates to the SHG element 14. Moreover, the temperature of the part of the SHG element 14 in the vicinity of the first outer edge 28 is raised by supplying heat using the second heat supply unit 15 for wavelength conversion element. The temperature T3 of the SHG element 14 is distributed so as to increase from t3 to t3 'as it proceeds in the arrow direction of the X axis in FIG.

  Thus, the wavelength conversion element first heat supply unit 27 and the wavelength conversion element second heat supply unit 15 provide a temperature gradient in the X-axis direction, which is a specific direction, in the SHG element 14. The first heat supply unit 27 for wavelength conversion element performs normal temperature adjustment in which the temperature T3 of the SHG element 14 is t3. The second heat supply unit 15 for wavelength conversion element performs temperature adjustment to give a temperature gradient to the SHG element 14 from t3 to t3 '. By using the wavelength conversion element first heat supply unit 27 and the wavelength conversion element second heat supply unit 15, normal temperature adjustment of the SHG element 14 and provision of a temperature gradient can be easily performed.

  The SHG element 14 expands as the temperature rises. The pitch of the domain-inverted structure becomes wider as the SHG element 14 expands. As the pitch of the domain-inverted structure becomes wider, the wavelength of light that can be wavelength-converted changes to the longer wavelength side. The SHG element 14 can shift the wavelength of wavelength-convertible fundamental wave light to the longer wavelength side from the second outer edge portion 29 toward the first outer edge portion 28 (from B to A in the figure). Therefore, the SHG element 14 can convert the wavelength of fundamental light in a wide wavelength range. In response to wavelength conversion of fundamental wave light in a wide wavelength range, harmonic light in a wide wavelength range can be emitted. By using the first heat supply unit for wavelength conversion element 27 and the second heat supply unit for wavelength conversion element 15 formed with substantially the same length as the SHG element 14 in the Z-axis direction, the SHG element 14 in the Z-axis direction is used. The temperature can be made even. Thereby, high wavelength conversion efficiency is realizable.

  As described above, the semiconductor element 11, the SHG element 14, and the volume hologram 17 are all given a temperature gradient in the same X-axis direction. The temperature gradient of the volume hologram 17 can be adjusted by changing the amount of heat supplied by the external resonator heat supply unit 18. The temperature gradient of the SHG element 14 can be adjusted by changing the amount of heat supplied by the wavelength conversion element second heat supply unit 15. The temperature gradient of the semiconductor element 11 can be adjusted by changing at least one of the temperature and the flow rate of the refrigerant.

  By appropriately adjusting the temperature gradients of the semiconductor element 11, the SHG element 14, and the volume hologram 17, the fundamental wave light in a wide wavelength range from the semiconductor element 11 is resonated and the wavelength converted harmonic light in the wide wavelength range is efficiently used. We can inject well. By making it possible to emit harmonic light in a wide wavelength range, the light source device 10 can reduce the generation of speckle noise. Thereby, there is an effect that light can be efficiently emitted using an external resonator and generation of speckle noise can be reduced.

  When a temperature gradient is applied to the semiconductor element 11, the SHG element 14, and the volume hologram 17, the width of the wavelength range of light that can be resonated by the volume hologram 17 is the width of the wavelength range of light emitted from the semiconductor element 11, and It becomes small with respect to any width of the wavelength range of light that can be converted by the SHG element 14. The temperature gradient of the semiconductor element 11 provided by the light source temperature adjustment unit and the temperature gradient of the SHG element 14 provided by the wavelength conversion element temperature adjustment unit are the volume hologram 17 provided by the external resonator temperature adjustment unit. It is desirable to be determined based on the temperature gradient. Thereby, the adjustment for efficiently emitting the harmonic light after wavelength conversion can be facilitated.

  The configuration of the external resonator temperature adjustment unit is not limited to that described in the present embodiment, and may be modified as appropriate. For example, the positions of the external resonator heat supply unit 18 and the external resonator heat radiation unit 21 may be appropriately changed. Further, as long as a sufficient temperature gradient can be applied to the volume hologram 17, at least one of the external resonator heat dissipating part 21 and the external resonator heat insulating part 22 may be omitted. The configuration of the light source temperature adjustment unit and the wavelength conversion element temperature adjustment unit may be modified as appropriate. For example, a heat radiating unit may be applied to the light source unit temperature control unit and the wavelength conversion element temperature control unit. Other elements such as a Peltier element or a thin film resistor may be used for each heat supply unit instead of the heater.

  FIG. 7A shows a modification of the configuration for adjusting the temperature of the semiconductor element 11. The light source heat supply unit 31 is a heater that supplies heat to the semiconductor element 11. The fluid flow section 13 and the light source section heat supply section 31 function as a light source section temperature adjusting section that adjusts the temperature of the semiconductor element 11. The heat supply unit 31 for the light source unit is provided on the surface of the fluid flow unit 13 on which the semiconductor element 11 is mounted. The light source part heat supply part 31 is disposed in the vicinity of the outer edge part 32 on the downstream side of the refrigerant, which is one end of the semiconductor element 11 in the X-axis direction.

  The heat supplied by the light source unit heat supply unit 31 propagates to the semiconductor element 11 through the fluid flow unit 13. By supplying heat using the heat supply unit 31 for the light source unit, the temperature in the vicinity of the outer edge portion 32 of the semiconductor element 11 is increased. By using the light source unit heat supply unit 31 in addition to the fluid flow unit 13, a temperature gradient can be easily applied to the semiconductor element 11. The position of the heat supply unit 31 for the light source unit is not limited to the case described in the present embodiment, and may be any position where a temperature gradient can be easily applied in the semiconductor element 11. Moreover, as the temperature control part for light sources, it is good also as using only the heat supply part 31 for light sources without using the fluid flow part 13. FIG.

  FIG. 7-2 shows another modification of the configuration for adjusting the temperature of the semiconductor element 11. The semiconductor element 11 is mounted on the substrate 35. The light source unit heat supply unit 31, which is a light source unit temperature control unit, is provided on the surface of the substrate 35 on which the semiconductor element 11 is mounted. A heat sink 36 is provided on the surface of the substrate 35 opposite to the surface on which the semiconductor element 11 and the light source unit heat supply unit 31 are provided.

  Heat generated in the semiconductor element 11 is released to the surrounding air through the substrate 35 and the heat sink 36. The heat supplied by the light source unit heat supply unit 31 propagates to the semiconductor element 11 through the substrate 35. By supplying heat using the heat supply unit 31 for the light source unit, the temperature in the vicinity of the outer edge portion 32 of the semiconductor element 11 is increased. Also in this case, a temperature gradient can be easily applied to the semiconductor element 11. In addition, the heat sink 36 is good also as giving a high thermal radiation efficiency as it leaves | separates from the heat supply part 31 for light sources in the X-axis direction. In this case, the heat sink 36 functions as a light source temperature adjusting unit that applies a temperature gradient in the X-axis direction. Thereby, a temperature gradient can be further provided in the semiconductor element 11.

  FIG. 8 shows a modification of the configuration for adjusting the temperature of the SHG element 14. The wavelength conversion element first heat supply unit 33 and the wavelength conversion element second heat supply unit 34 are heaters that supply heat to the SHG element 14, and adjust the temperature of the SHG element 14. It functions as a part. For example, an electric heater can be used as the heater. The wavelength conversion element first heat supply unit 33 and the wavelength conversion element second heat supply unit 34 are provided on the surface of the wavelength conversion element heat diffusion unit 16 opposite to the surface on which the SHG element 14 is mounted. ing.

  The first heat supply unit 33 for wavelength conversion element is arranged in accordance with the position of the second outer edge part 29 in the SHG element 14. The second heat supply unit 34 for wavelength conversion element is arranged in accordance with the position of the first outer edge 28 in the SHG element 14. The wavelength conversion element first heat supply unit 33 and the wavelength conversion element second heat supply unit 34 are provided in parallel in the X-axis direction, which is a specific direction.

  FIG. 9 shows a planar configuration when the configuration shown in FIG. 8 is viewed from the side where the SHG element 14 is provided. Both the first heat supply unit for wavelength conversion element 33 and the second heat supply unit for wavelength conversion element have a strip shape that is longer in the Z-axis direction, which is the first direction, than in the X-axis direction, which is the second direction. . The wavelength conversion element first heat supply unit 33 and the wavelength conversion element second heat supply unit 34 are formed to have substantially the same length as the SHG element 14 in the Z-axis direction. Thereby, the temperature of the SHG element 14 can be made uniform in the Z-axis direction.

  Both the heat supplied by the first wavelength conversion element heat supply unit 33 and the heat supplied by the second wavelength conversion element heat supply unit 34 propagate to the SHG element 14 via the wavelength conversion element heat diffusion unit 16. To do. In this modification, normal temperature adjustment of the SHG element 14 and temperature adjustment that imparts a temperature gradient by temperature adjustment by both the first heat supply unit 33 for wavelength conversion element and the second heat supply unit 34 for wavelength conversion element. And do. By increasing the amount of heat supplied from the second heat supply unit for wavelength conversion element 34 with respect to the amount of heat supplied from the first heat supply unit for wavelength conversion element 33, the process proceeds in the direction of the arrow on the X axis in the figure. A temperature gradient that is high in temperature can be applied. Also in this case, high wavelength conversion efficiency can be realized.

  The number of wavelength conversion element heat supply units is not limited to two, and may be one or more. The shape and position of the wavelength conversion element heat supply unit are not limited to those described in the present embodiment, and any shape can be used as long as normal temperature adjustment of the SHG element 14 and temperature adjustment that provides a temperature gradient are possible. It may be a position. The external resonator is not limited to the volume hologram 17 as long as it has wavelength selectivity. As the external resonator, for example, a bandpass filter or a dichroic mirror may be used. The light source device 10 may be, for example, a semiconductor laser pumped solid state (DPSS) laser. The light source device 10 may be provided with optical elements such as a polarization selection filter and a wavelength selection filter as necessary.

  FIG. 10 shows a schematic configuration of a monitor device 40 according to the second embodiment of the present invention. The monitor device 40 includes a device main body 41 and an optical transmission unit 42. The device main body 41 includes the light source device 10 (see FIG. 1) of the first embodiment. The light transmission unit 42 includes two light guides 44 and 45. A diffusion plate 46 and an imaging lens 47 are provided at the end of the optical transmission unit 42 on the subject (not shown) side. The first light guide 44 transmits light from the light source device 10 to the subject. The diffusion plate 46 is provided on the emission side of the first light guide 44. The light propagating through the first light guide 44 is diffused on the subject side by passing through the diffusion plate 46. Each part in the optical path from the light source device 10 to the diffusion plate 46 constitutes an illumination device that illuminates the subject.

  The second light guide 45 transmits light from the subject to the camera 43. The imaging lens 47 is provided on the incident side of the second light guide 45. The imaging lens 47 condenses light from the subject onto the incident surface of the second light guide 45. Light from the subject enters the second light guide 45 by the imaging lens 47, then propagates through the second light guide 45 and enters the camera 43.

  As the first light guide 44 and the second light guide 45, a bundle of a large number of optical fibers can be used. By using an optical fiber, light can be transmitted far away. The camera 43 is provided in the apparatus main body 41. The camera 43 is an imaging unit that captures an image of a subject illuminated by light from the light source device 10. By making the light incident from the second light guide 45 enter the camera 43, the camera 43 can image the subject. By using the light source device 10 of the first embodiment, light with high efficiency and reduced speckle noise can be supplied. This produces an effect that a bright and high-quality image can be monitored.

  FIG. 11 shows a schematic configuration of a projector 50 according to the third embodiment of the invention. The projector 50 is a front projection type projector that views light by supplying light to the screen 59 and observing light reflected by the screen 59. The projector 50 includes a red (R) light source device 51R, a green (G) light source device 51G, and a blue (B) light source device 51B. Each of the color light source devices 51R, 51G, and 51B has the same configuration as the light source device 10 (see FIG. 1) of the first embodiment. The projector 50 is an image display device that displays an image using light from each color light source device 51R, 51G, 51B.

  The R light source device 51R is a light source device that supplies R light. The diffusing element 52 performs shaping and enlargement of the illumination area and uniformizing the light amount distribution in the illumination area. As the diffusing element 52, for example, a computer generated hologram (CGH) which is a diffractive optical element can be used. The field lens 53 collimates the light from the R light source device 51R and makes it incident on the R light spatial light modulator 54R. The R light source device 51R, the diffusing element 52, and the field lens 53 constitute an illumination device that illuminates the R light spatial light modulation device 54R. The R light spatial light modulation device 54R is a spatial light modulation device that modulates R light from the illumination device in accordance with an image signal, and is a transmissive liquid crystal display device. The R light modulated by the R light spatial light modulator 54R is incident on a cross dichroic prism 55 which is a color synthesis optical system.

  The light source device 51G for G light is a light source device that supplies G light. The light that has passed through the diffusing element 52 and the field lens 53 enters the G spatial light modulator 54G. The light source device 51G for G light, the diffusing element 52, and the field lens 53 constitute an illumination device that illuminates the spatial light modulation device 54G for G light. The G light spatial light modulation device 54G is a spatial light modulation device that modulates the G light from the illumination device in accordance with an image signal, and is a transmissive liquid crystal display device. The G light modulated by the G light spatial light modulator 54G is incident on a different surface of the cross dichroic prism 55 from the surface on which the R light is incident.

  The light source device 51B for B light is a light source device that supplies B light. The light that has passed through the diffusing element 52 and the field lens 53 enters the spatial light modulator 54B for B light. The light source device 51B for B light, the diffusing element 52, and the field lens 53 constitute an illumination device that illuminates the spatial light modulation device 54B for B light. The B light spatial light modulation device 54B is a spatial light modulation device that modulates B light from the illumination device in accordance with an image signal, and is a transmissive liquid crystal display device. The B light modulated by the B light spatial light modulator 54B is incident on a surface of the cross dichroic prism 55 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 transmissive liquid crystal display device, for example, a high temperature polysilicon TFT liquid crystal panel (HTPS) can be used.

  The cross dichroic prism 55 has two dichroic films 56 and 57 arranged substantially orthogonal to each other. The first dichroic film 56 reflects R light and transmits G light and B light. The second dichroic film 57 reflects B light and transmits R light and G light. The cross dichroic prism 55 combines R light, G light, and B light incident from different directions, and emits the light toward the projection lens 58. The projection lens 58 projects the light combined by the cross dichroic prism 55 toward the screen 59.

  By using each color light source device 51R, 51G, 51B having the same configuration as the light source device 10 described above, light can be emitted efficiently and generation of speckle noise can be reduced. This produces an effect that a bright and high-quality image can be displayed. 2. Description of the Related Art Conventionally, in a projector, a technique for reducing the generation of speckle noise using an element or a screen in an optical path has been proposed. In order to make it difficult to recognize a specific speckle pattern, a mechanical drive of a screen or an element may be used, or light scattering may be used. The present invention does not require a separate mechanism for driving, and therefore has an advantage over these conventional techniques in that measures for increasing the size of the device, lowering reliability due to vibration, and lowering quietness are unnecessary. . The present invention has an advantage that a decrease in light utilization efficiency can be reduced over a technique using light scattering. The present invention has an advantage that a general-purpose screen can be used as opposed to the technique of reducing the generation of speckle noise by using the screen configuration.

  The projector 50 is not limited to the case where each of the R light source device 51R, the G light source device 51G, and the B light source device 51B has the same configuration as the light source device 10 of the above embodiment. For example, the R light source device 51R may emit the fundamental light from the light source unit without using the SHG element.

  The projector 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 laser scanning projector that scans the laser light from the light source device by scanning means such as a galvanometer mirror and displays an image on the irradiated surface. 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 light source device of the present invention may be applied to a liquid crystal display that is an image display device. By combining the light source device of the present invention and the light guide plate, it can be used as an illumination device for illuminating the liquid crystal panel. Also in this case, a bright and high-quality image can be displayed. The light source device of the present invention is not limited to being applied to a monitor device or an image display device. The light source device of the present invention may be used, for example, in an optical system such as an exposure device for laser beam exposure or a laser processing device.

  As described above, the light source device according to the present invention is suitable for use in a monitor device or an image display device.

The figure which shows schematic structure of the light source device which concerns on Example 1 of this invention. The figure explaining the structure for adjusting the temperature of a volume hologram. 3A and 3B illustrate a structure for adjusting the temperature of a semiconductor element. The figure explaining the structure for adjusting the temperature of a SHG element. The figure which shows the planar structure which looked at the structure shown in FIG. 4 from the side in which the SHG element was provided. The figure which shows the relationship between the position of a X-axis direction, and the temperature of a SHG element. The figure which shows the modification of the structure for adjusting the temperature of a semiconductor element. The figure which shows the other modification of the structure for adjusting the temperature of a semiconductor element. The figure which shows the modification of the structure for adjusting the temperature of a SHG element. The figure which shows the planar structure which looked at the structure shown in FIG. 8 from the side in which the SHG element was provided. The figure which shows schematic structure of the monitor apparatus which concerns on Example 2 of this invention. FIG. 6 is a diagram illustrating a schematic configuration of a projector according to a third embodiment of the invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Light source device, 11 Semiconductor element, 12 Light emission part, 13 Fluid flow part, 14 SHG element, 15 2nd heat supply part for wavelength conversion elements, 16 Thermal diffusion part for wavelength conversion elements, 17 Volume hologram, 18 Heat for external resonators Supply part, 21 External resonator heat radiation part, 22 External resonator heat insulation part, 24 First outer edge part, 25 Second outer edge part, 27 Wavelength conversion element first heat supply part, 28 First outer edge part, 29 Second outer edge Part, 31 heat supply part for light source part, 32 outer edge part, 33 first heat supply part for wavelength conversion element, 34 second heat supply part for wavelength conversion element, 35 substrate, 36 heat sink, 40 monitor device, 41 apparatus main body, 42 light transmission unit, 43 camera, 44 first light guide, 45 second light guide, 46 diffuser plate, 47 imaging lens, 50 projector, light source device for 51R R light, 51G Light source device for G light, light source device for 51B B light, 52 diffuser element, 53 field lens, spatial light modulation device for 54R R light, spatial light modulation device for 54G G light, spatial light modulation device for 54B B light, 55 cross Dichroic prism, 56 1st dichroic film, 57 2nd dichroic film, 58 projection lens, 59 screen

Claims (15)

A light source unit in which a plurality of light emitting units emitting light are arranged in parallel;
An external resonator for resonating light emitted from the light source unit;
A wavelength conversion element that is provided in an optical path between the light source unit and the external resonator and converts a wavelength of light emitted from the light source unit;
A light source temperature control unit for adjusting the temperature of the light source unit;
An external resonator temperature adjusting unit for adjusting the temperature of the external resonator;
A wavelength conversion element temperature adjustment unit for adjusting the temperature of the wavelength conversion element;
The temperature adjusting unit for the light source unit, the temperature adjusting unit for the external resonator, and the temperature adjusting unit for the wavelength conversion element provide a temperature gradient in a specific direction that is substantially parallel to the direction in which the plurality of light emitting units are arranged in parallel. And a light source device. The external resonator temperature control unit includes an external resonator heat supply unit that supplies heat to the external resonator,
The light source device according to claim 1, wherein the external resonator heat supply unit is provided in the vicinity of an outer edge that is one end in the specific direction of the external resonator. The external resonator temperature control unit includes an external resonator heat dissipation unit that dissipates heat from the external resonator,
The external resonator heat supply unit is provided in the vicinity of the first outer edge of the external resonator,
The heat radiation portion for the external resonator is provided at one end in the specific direction of the external resonator and in the vicinity of the second outer edge portion on the side opposite to the first outer edge portion. The light source device described. Having an external resonator heat insulating portion that blocks heat transfer from the external resonator;
When the direction substantially parallel to the traveling direction of the light emitted from the light source unit is a first direction, the specific direction is a second direction, and the direction substantially orthogonal to the first direction and the second direction is a third direction. ,
The light source device according to claim 2, wherein the heat insulating portion for the external resonator is provided in parallel with the external resonator in the third direction. The light source temperature control unit has a fluid flow part through which a fluid flows,
5. The light source device according to claim 1, wherein the fluid flows in the fluid flow portion in a direction substantially parallel to the specific direction. The light source unit temperature control unit includes a light source unit heat supply unit that supplies heat to the light source unit,
The light source device according to claim 5, wherein the heat supply unit for the light source unit is provided in the vicinity of an outer edge portion that is one end in the specific direction of the light source unit.   The light source device according to claim 1, wherein the wavelength conversion element temperature adjusting unit includes a plurality of wavelength conversion element heat supply units that supply heat to the wavelength conversion element. .   The light source device according to claim 7, wherein the plurality of wavelength conversion element heat supply units are provided in parallel in the specific direction. The wavelength converter heat supply unit is
A first heat supply unit for a wavelength conversion element arranged in alignment with the center of the wavelength conversion element in the specific direction;
The light source device according to claim 7, further comprising: a second heat supply unit for a wavelength conversion element disposed in the vicinity of an outer edge that is one end in the specific direction among the wavelength conversion elements.   10. The light source device according to claim 9, further comprising a wavelength conversion element thermal diffusion unit that diffuses heat supplied by the first wavelength conversion element heat supply unit. When the direction substantially parallel to the traveling direction of the light emitted from the light source unit is a first direction and the specific direction is a second direction,
The light source device according to claim 6, wherein the wavelength conversion element heat supply unit has a shape that is longer in the first direction than in the second direction.   At least one of the temperature gradient of the light source unit provided by the temperature adjustment unit for the light source unit and the temperature gradient of the wavelength conversion element provided by the temperature adjustment unit for the wavelength conversion element is the temperature adjustment unit for the external resonator. The light source device according to claim 1, wherein the light source device is determined based on a temperature gradient of the external resonator applied by the step.   An illumination device comprising the light source device according to any one of claims 1 to 12 and illuminating an object to be irradiated using light from the light source device. A lighting device according to claim 13;
An image pickup unit for picking up an image of a subject illuminated by the illumination device.   An image display device comprising the light source device according to claim 1 and displaying an image using light from the light source device.

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