JP2010062250A - Laser light source device, projector and monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser light source device of low cost and high power. <P>SOLUTION: The laser light source device 1 includes: a light emitting part 11 having a first reflecting part 111 on the opposite side of a light emitting end surface; a second reflecting part 15 reflecting the light of fundamental wavelength emitted from the light emitting part 11 to turn back; a wavelength converting element 14 which is arranged between the light emitting part 11 and the second reflecting part 15 and converts at least part of the incident light of the fundamental wavelength into the light of converting wavelength, and a wavelength selecting element 13 arranged between the wavelength converting element 14 and the light emitting part 11. A resonator is configured by including the first reflecting part 111 and the second reflecting part 15. The wavelength element 13 has a band narrowing surface 13a selectively transmitting the light of fundamental wavelength out of inside the resonator and a wavelength selecting surface 13b transmitting the light of fundamental wavelength and reflecting the light of converting wavelength. A normal line direction of the wavelength selecting surface 13b is inclined against an optical axis of the light incident from the light emitting part 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser light source device, a projector, and a monitor device.

  Conventionally, in the field of optical devices such as projectors, high-pressure mercury lamps are frequently used as illumination light sources. The high-pressure mercury lamp has the advantage that high-power light can be obtained, but there are also problems such as limited color reproducibility, difficulty in instantaneous lighting and extinguishing, and short life. Under such circumstances, a laser light source device using a solid light source such as a semiconductor laser instead of a high-pressure mercury lamp is expected.

  As said semiconductor laser, what is disclosed by patent document 1 is mentioned, for example. The semiconductor laser disclosed in Patent Document 1 includes a light emitting unit and an external resonator. The light emitting unit includes a 100% reflective abutting Bragg mirror, a partially reflective intermediate Bragg mirror, and an active layer provided between the Bragg mirrors. The light emitted from the active layer resonates to the extent that laser oscillation does not occur in the light emitting portion. The light passing through the intermediate Bragg mirror is resonated by an external resonator to generate laser oscillation.

Further, since the output is improved when laser oscillation is performed at a narrow band wavelength, a laser light source device such as an external resonance laser disclosed in Patent Document 2 has also been proposed. The external resonance laser disclosed in Patent Document 2 resonates laser light emitted from a laser oscillator (light emitting unit) with an external resonator, and a photopolymer volume hologram is disposed in the external resonator. The laser beam incident on the photopolymer volume hologram emitted from the laser oscillator is transmitted to the outside through the photopolymer volume hologram with a component having a predetermined wavelength. Components other than the predetermined wavelength are diffracted by the photopolymer volume hologram and incident on the mirror. The laser beam reflected by the mirror is folded back 180 ° and incident again on the photopolymer volume hologram, and then diffracted and returned to the laser oscillator. Laser light resonates and is amplified between the laser oscillator and the mirror via the photopolymer volume hologram. Further, a laser beam having a narrow band wavelength can be obtained by selectively transmitting a laser beam having a predetermined wavelength through the photopolymer volume hologram.
Special Table 2003-526930 JP 2001-284718 A

  According to the external resonance laser of Patent Document 2, it is considered that high-power laser light can be obtained. However, since the volume hologram element is generally expensive and the cost increases, it is difficult to construct the laser light source device itself. Further, when trying to further increase the output of the laser light source device, the external resonance laser of Patent Document 2 may not be able to cope with for the following reason.

  There is a limit to the output of laser light emitted from one light emitting unit, and it is conceivable to configure a laser light source device using a plurality of light emitting units as a method for achieving high output. However, if a volume hologram element is disposed in each of the plurality of light emitting units, the number of parts increases, resulting in an increase in manufacturing cost. In addition, when a volume hologram element common to a plurality of light emitting units is arranged, the volume hologram does not function between the light emitting units, so that the use efficiency of the volume hologram is lowered. This increases the cost of the laser light source device, making it difficult to cope with higher output.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser light source device that can cope with an increase in output without causing an increase in cost. Another object is to provide a projector including a high-power laser light source device. Another object is to provide a monitor device including a high-power laser light source device.

  The laser light source device of the present invention includes a light emitting portion having a first reflecting portion on the opposite side of the light emitting end surface, a second reflecting portion that reflects and reflects the light having the fundamental wavelength emitted from the light emitting portion, and the light emitting device. Between the wavelength converting element and the light emitting unit, the wavelength converting element being disposed between the wavelength converting element and the second reflecting unit, wherein the wavelength converting element converts at least part of the incident light having the fundamental wavelength into light having the converted wavelength. A wavelength selecting element, a resonator including the first reflecting part and the second reflecting part, wherein the wavelength selecting element is the fundamental wavelength of the light in the resonator. A band-narrowing surface that selectively transmits the light, and a wavelength selection surface that transmits the light of the fundamental wavelength and reflects the light of the conversion wavelength, and the normal direction of the wavelength selection surface is Inclined with respect to the optical axis of the light incident from the light emitting part That.

  If it does in this way, the light of a fundamental wavelength among the lights inject | emitted from the light emission part will enter into a 2nd reflection part through a wavelength conversion element through the narrow-band surface of a wavelength selection element. The light having the fundamental wavelength incident on the second reflecting portion is reflected and folded by the second reflecting portion, and enters (feeds back) the light emitting portion through the wavelength converting element and the wavelength selecting element. The light having the fundamental wavelength incident on the light emitting unit is emitted together with the light generated in the light emitting unit after being reflected by the first reflecting unit.

  The light emitted from the light emitting part resonates by reciprocating between the first reflecting part and the second reflecting part. The narrow-band surface of the wavelength selection element selectively transmits light of the fundamental wavelength, so that laser oscillation can be performed in a narrow band between the wavelength selection element and the second reflecting portion, and a high-output fundamental wavelength laser Light can be generated.

  The fundamental wavelength laser light passes through the narrow-band surface and the wavelength selection surface, and reciprocates between the first reflection unit and the second reflection unit. Each time the fundamental wavelength laser beam passes through the wavelength conversion element, at least a part of the fundamental wavelength laser beam is converted into a laser beam having a conversion wavelength. The laser beam having the converted wavelength is reflected by the wavelength selection surface of the wavelength selection element. Since the normal direction of the wavelength selection surface is tilted with respect to the optical axis of the light incident from the light emitting portion, the laser light having the converted wavelength reflected by the wavelength selection surface travels in a different direction from the light emitting portion, It is taken out.

Thus, according to the above-described configuration, a laser light source apparatus that can oscillate a laser in a narrow band and obtain a high-power laser beam is obtained. Further, since the laser light having the fundamental wavelength is converted into the laser light having the conversion wavelength by the wavelength conversion element, it becomes possible to extract the laser light having a wavelength that cannot be obtained directly from the light emitting unit, and the laser light having a desired wavelength can be obtained. It becomes a laser light source device.
Further, the band-narrowed surface can be formed of a dielectric multilayer film or the like, and it is not necessary to use a hologram element, so that an increase in cost is avoided.
In addition, since the wavelength selection element has the function of narrowing the fundamental wavelength light and the function of separating the conversion wavelength light, the number of components is smaller than when these functions are shared by independent optical elements. Less. Therefore, the cost can be reduced and the size can be reduced, and the number of interfaces through which light of the fundamental wavelength passes can be reduced, so that the loss of light can be reduced.
In addition, since laser light having a narrow band conversion wavelength can be obtained, if the device is configured using the laser light source device of the present invention as a light source, the device has good color reproducibility.
As described above, according to the present invention, it is possible to provide a laser light source device that can obtain a good laser beam without causing an increase in cost.

Further, the wavelength selection surface has a reflectance of P-polarized light with respect to the wavelength selection surface of incident light lower than a reflectance of S-polarization with respect to the wavelength selection surface of incident light, and the wavelength conversion It is preferable that the element selectively converts P-polarized light with respect to the wavelength selection surface of incident light to light having the conversion wavelength.
In this way, the polarization state of the light incident on the wavelength conversion element matches the polarization dependency of the wavelength selection element, so that laser light with a conversion wavelength can be generated efficiently. In general, at the interface where light enters, it is easy to make the reflectance of P-polarized light with respect to the interface lower than that of S-polarized light, so that laser light with a converted wavelength can be generated efficiently without complicating the configuration. Can be made. In addition, the number of components can be reduced as compared with the case where polarizing means such as a Brewster plate is used, and the use efficiency of light can be increased by reducing the number of interfaces through which light passes.

Further, the second reflection unit may reflect the light having the fundamental wavelength and transmit the light having the conversion wavelength.
If it does in this way, the laser beam of conversion wavelength will be taken out from the 2nd reflection part. Further, the laser light having the conversion wavelength is not folded back by the second reflecting portion and is not incident on the wavelength conversion element again, and the wavelength conversion element can be stably functioned.

Further, the wavelength conversion element may be configured such that the opposite side of the incident end surface on which light is incident from the light emitting portion is the second reflecting portion.
In this way, the number of interfaces through which the light passes can be reduced and the light utilization efficiency can be increased as compared with the case where the wavelength conversion element and the second reflecting portion are separated from each other.

The wavelength selection element is preferably formed by bonding a plurality of columnar prisms, and one of the surfaces where the plurality of columnar prisms are bonded together is the wavelength selection surface.
If the wavelength selection surface is given to the surface of any one of the plurality of columnar prisms and the wavelength selection element is formed by bonding the plurality of columnar prisms, the wavelength selection surface may be disposed inside the wavelength selection element. it can. Thereby, the refractive index can be made the same on both sides of the wavelength selection surface in the optical path in the wavelength selection element, and the refraction and reflection of the fundamental wavelength light on the wavelength selection surface can be prevented. Therefore, the light utilization efficiency is increased, and a highly efficient laser light source device is obtained.

In the wavelength selection element, a normal direction of one of a surface on which light is incident from the light emitting portion and a surface on which light is incident from the wavelength conversion element is not parallel to the optical axis of the incident light. The other surface may be substantially orthogonal to the optical axis of the incident light, and the one surface may be the band-narrowing surface.
In this way, the normal direction of the narrowband surface is not parallel to the optical axis of the light incident on the wavelength selecting element, so the optical axis of the light reflected by the narrowband surface is not incident. Become non-parallel. Therefore, the light reflected by the band narrowing surface does not resonate with the light before entering the band narrowing surface. In addition, since the other surface is orthogonal to the optical axis of the light incident on the wavelength conversion element, the light reflectance on the other surface is minimized, so that the light loss due to reflection is minimized.

In the wavelength selection element, a surface on which light is incident from the light emitting portion is substantially orthogonal to the optical axis of the light, and a surface on which light is incident from the wavelength conversion element is approximately orthogonal to the optical axis of the light. In addition, at least one of a surface on which light is incident from the light emitting unit and a surface on which light is incident from the wavelength conversion element may be the band narrowing surface.
In the wavelength selection element, if the surface on which light is incident from the light emitting section is substantially orthogonal to the optical axis of the light, the reflectance of the fundamental wavelength light incident from the light emitting section on the surface of the wavelength selection element is minimized. Light loss due to is minimized. For the same reason, if the surface on which light is incident from the wavelength conversion element is substantially orthogonal to the optical axis of the light, the loss of light incident on the wavelength selection element from the wavelength conversion element is minimized. Therefore, according to the above configuration, the light utilization efficiency is increased, and a highly efficient laser light source device is obtained.

  In the wavelength selection element, a surface on which light is incident from the light emitting portion is substantially orthogonal to the optical axis of the light, and a surface on which light is incident from the wavelength conversion element is approximately orthogonal to the optical axis of the light. In addition, it is preferable that at least one of a surface on which light is incident from the light emitting unit and a surface on which light is incident from the wavelength conversion element is the band narrowing surface.

  A plurality of the light emitting units; and a plurality of the light emitting units along a direction orthogonal to a traveling direction of light emitted from each of the plurality of light emitting units and orthogonal to a vibration direction of P-polarized light with respect to the wavelength selection surface. It is preferable that the light emitting portions are arranged.

  In general, the wavelength conversion element is made of a nonlinear optical crystal having a periodic polarization inversion structure, and the efficiency of wavelength conversion is high for polarized light that vibrates in the axial direction of polarization inversion. The domain-inverted structure is formed by selectively applying an electric field in the domain-inverted axis direction in the surface direction of the base material. Therefore, it is difficult to increase the size of the wavelength conversion element in the direction of the polarization inversion axis, but it is easy to increase the size of the wavelength conversion element in the direction orthogonal to the direction of the axis of polarization inversion.

  According to the above configuration, since the polarization dependency of the wavelength conversion element matches the polarization state of the light incident on the wavelength conversion element, the wavelength conversion efficiency in the wavelength conversion element is increased. Further, the plurality of light emitting units are arranged along the direction orthogonal to the vibration direction of the P-polarized light with respect to the wavelength selection plane, and it is easy to increase the size of the wavelength conversion element in the arrangement direction of the plurality of light emitting units. Therefore, it is easy to increase the number of light emitting units arranged, and it becomes easy to increase the output of the laser light source device. Further, it is easy to increase the optical path length in the wavelength conversion element, and it becomes easy to increase the efficiency of wavelength conversion by the wavelength conversion element.

The projector according to the present invention includes the laser light source device according to the present invention, an image forming device that forms image light indicating an image with the laser light emitted from the laser light source device, and the image light formed by the image forming device. And a projection device for projecting.
According to the laser light source device of the present invention, high output laser light can be obtained, and thus the high output laser light is projected by the projection device after becoming image light indicating an image by the image forming apparatus. Therefore, the projector can obtain a high-luminance projection image, and can obtain a high-quality projection image with a wide dynamic range. In addition, since a narrow-band laser beam can be obtained by the laser light source device, the projector has good color reproducibility.

A monitor device according to the present invention includes the laser light source device according to the present invention and an imaging device that captures an image of a subject illuminated by the laser light source device.
According to the laser light source device of the present invention, high-power laser light can be obtained, so that the subject can be illuminated with the high-power laser light. Therefore, the amount of light reflected by the subject is secured, and a good monitor device can be obtained in which a clear captured image can be obtained by capturing the light.

  Hereinafter, although embodiment of this invention is described, the technical scope of this invention is not limited to the following embodiment. In the following description, various structures are illustrated using drawings, but in order to show the characteristic parts of the structures in an easy-to-understand manner, the structures in the drawings are shown in different sizes and scales from the actual structures. There is.

[First Embodiment]
FIG. 1 is a plan view showing a schematic configuration of the laser light source device of the first embodiment. As shown in FIG. 1, the laser light source device 1 uses a base substrate 10 as a base. On the base substrate 10, a light emitting element 12 having a plurality of light emitting parts 11, a wavelength selecting element 13, a wavelength converting element 14, and a second reflecting part 15 are arranged.

  Each of the plurality of light emitting portions 11 emits light having a fundamental wavelength (here, infrared light IR), and has a first reflecting portion (described later) on the side opposite to the light emission end face. Yes. The infrared light IR emitted from the light emitting unit 11 enters the second reflecting unit 15 through the wavelength selection element 13 and the wavelength conversion element 14. The infrared light IR incident on the second reflecting portion 15 is reflected and folded by the second reflecting portion 15, enters the light emitting portion 11 through the wavelength conversion element 14 and the wavelength selection element 13. The infrared light IR incident on the light emitting unit 11 is reflected by the first reflecting unit and folded back, and then emitted from the light emitting unit 11 again. The infrared light IR reciprocates many times between the first reflecting portion and the second reflecting portion 15 and resonates, thereby causing laser oscillation. As described above, the resonator includes the first reflecting portion and the second reflecting portion 15.

FIG. 2 is a side view schematically showing a schematic configuration of the laser light source device 1. FIG. 2 schematically shows a cross-sectional structure of the light emitting unit 11 for convenience of explanation.
As shown in FIG. 2, the light emitting unit 11 includes a first electrode 111 formed on the substrate 12 </ b> A and an active layer 112 formed on the first electrode 111. An insulating film 113 is provided so as to cover the first electrode 111 and the active layer 112. The insulating film 113 is provided with an opening that exposes a part of the active layer 112, and a second electrode 114 that is in conductive contact with the active layer 112 is provided in the opening. The second electrode 114 is provided with an opening exposing a part of the active layer 112, and a DBR layer 115 is provided in the opening. The first electrode 111 is configured to reflect and refract incident light, and functions as a first reflecting portion. Further, the DBR layer 115 transmits light having a fundamental wavelength of incident light and reflects light other than the fundamental wavelength so as to be folded.

  In the light emitting unit 11 as described above, when a voltage is applied between the first electrode 111 and the second electrode 114, light is generated in the active layer 112. This light reciprocates between the first electrode 111 and the DBR layer 115 and resonates. Of the light resonated in the light emitting unit 11, light having a fundamental wavelength is emitted from the light emitting unit 11 in the normal direction of the substrate 12A through the DBR layer 115. Here, infrared light IR having a wavelength of 1064 nm is emitted as the fundamental wavelength light.

  On the substrate 12A, a plurality of light emitting portions 11 are collectively formed, and the light emitting element 12 is constituted by the substrate 12A and the plurality of light emitting portions 11. The light emitting element 12 is bonded to the base substrate 10 such that the light emission direction is the normal direction of the substrate 12 </ b> A, and the light emission direction is parallel to the surface direction of the base substrate 10.

  The wavelength selection element 13 of the present embodiment is configured by a prismatic prism, and is arranged so that the major axis direction is parallel to the arrangement direction of the plurality of light emitting units 11 shown in FIG. Here, the cross-sectional shape orthogonal to the major axis direction of the wavelength selection element 13 is a square. In the wavelength selection element 13, light is incident from one of the four side surfaces with respect to the major axis direction from the light emitting unit 11. A surface on which light is incident from the light emitting unit 11 is a narrow band surface 13a. The band-narrowing surface 13 a is orthogonal to the optical axis of the light incident from the light emitting unit 11. The narrow-band surface 13a is composed of a dielectric multilayer film and has a characteristic of transmitting light in a wavelength band centered on the fundamental wavelength. The width of the wavelength band can be appropriately selected according to the degree of narrowing the band.

  The normal direction of the band-narrowed surface may be non-parallel to the optical axis of light incident on the band-narrowed surface. For example, a configuration in which the wavelength selection element 13 is rotated around the major axis with respect to the arrangement of the present embodiment or a configuration in which the shape of the wavelength conversion element is changed can be given. With this configuration, the optical axis of the light reflected by the narrow band surface does not overlap with the optical axis of the light incident on the narrow band surface, so that the reflected light does not resonate with the incident light. Most of the reflected light on the narrow-band surface is a component that does not belong to the desired wavelength band, and by doing so, it is possible to prevent light having a wavelength other than the desired wavelength from resonating. Moreover, it is preferable that the surface other than the narrow-band surface in the wavelength selection element on which light is incident is substantially orthogonal to the optical axis of the incident light. This is because the reflectance of incident light is minimized on the light incident surface, and the light use efficiency is increased.

  The wavelength selection element 13 has a structure in which two triangular prisms 131 and 132 having substantially the same shape are bonded together. In the triangular prisms 131 and 132, the cross-sectional shape orthogonal to the long axis direction is a right-angled isosceles triangle. The triangular prisms 131 and 132 are bonded to each other with two surfaces orthogonal to each other among the three side surfaces in the major axis direction as outer surfaces and the remaining one surface (hereinafter referred to as a slope) as an inner surface. . The bonded inner surface is a wavelength selection surface 13b. The wavelength selection surface 13b has a characteristic of transmitting light having a fundamental wavelength and reflecting light having a conversion wavelength described later.

In this embodiment, an antireflection film is formed on one of the triangular prisms 131 and 132 on the slope. Thereby, in the wavelength selection surface 13b, the reflectance of the P-polarized light with respect to the wavelength selection surface 13b of the incident light is lower than the reflectance of the P-polarized light with respect to the wavelength selection surface 13b of the incident light. Instead of the antireflection film, a polarization separation means such as a wire grid or a polarization beam splitter film (PBS film) is formed so as to selectively transmit the P-polarized light to the wavelength selection surface 13b in the incident light. It may be.
In the following description, the P-polarized light for the wavelength selection surface 13b may be simply referred to as P-polarization, and the S-polarization for the wavelength selection surface 13b may be simply referred to as S-polarization.

  The infrared light incident on the wavelength selection element 13 from the light emitting unit 11 has a narrower spectral width than before the incidence by passing through the band narrowing surface 13a. Further, by passing through the wavelength selection surface 13b, the P-polarized component becomes larger than the S-polarized component. Infrared light emitted from the wavelength selection element 13 enters the wavelength conversion element 14.

  The wavelength conversion element 14 converts at least a part of incident light into light having a substantially half wavelength to generate a second harmonic. At least a part of light having a fundamental wavelength (for example, infrared light having a wavelength of 1064 nm) incident on the wavelength conversion element 14 is converted into light having a conversion wavelength (for example, green light having a wavelength of 532 nm). The wavelength conversion element 14 is made of a nonlinear optical crystal such as PPLN (periodically poled lithium niobate), for example. The nonlinear optical crystal is manufactured, for example, by the following method.

  In order to manufacture the nonlinear optical crystal, first, a wafer formed by a pulling method or the like and having a uniform crystal direction is prepared, and the wafer is thinned to a thickness capable of applying a uniform electric field in the thickness direction. Then, a striped resist pattern is formed on the wafer. Then, after forming electrode films on both surfaces of the wafer, a predetermined voltage is applied between the electrode films. As a result, an electric field is applied to the portion of the wafer that is not covered with the resist pattern to change the crystal structure to become an inversion portion, and the portion of the wafer that is covered with the resist pattern becomes a polarization portion. In this way, a nonlinear optical crystal is obtained in which the inversion part and the polarization part are periodically arranged in the plane direction of the wafer. The polarization inversion axis direction of the nonlinear optical crystal is the applied electric field direction, that is, the thickness direction of the wafer. In order to apply the electric field to the wafer satisfactorily, it is necessary to make the wafer thin to some extent. Therefore, it is generally difficult to increase the thickness of the nonlinear optical crystal in the direction of the polarization inversion axis.

  The wavelength conversion element 14 of this embodiment is disposed so that the polarization inversion axis direction is parallel to the vibration direction of the P-polarized light with respect to the wavelength selection surface 13b. Thereby, the polarization dependence of the wavelength conversion element 14 matches the polarization state of the incident light, and the conversion efficiency from the fundamental wavelength light to the converted wavelength light is increased. As described above, in the nonlinear optical crystal, it is difficult to increase the dimension in the polarization inversion axis direction, but it is easy to increase the dimension in two directions orthogonal to the polarization inversion axis direction. In the wavelength conversion element 14, two directions orthogonal to the polarization inversion direction are the arrangement direction of the light emitting units 11 and the traveling direction of light passing through the wavelength conversion element 14. If the size of the wavelength conversion element 14 in the arrangement direction is increased, it becomes possible to arrange a large number of light emitting portions 11 with respect to one wavelength conversion element 14, and it becomes easy to increase the output. Further, if the size of the wavelength conversion element 14 in the light traveling direction is increased, the wavelength conversion efficiency of the wavelength conversion element 14 can be improved. As described above, since the wavelength selection surface 13b selectively transmits the P-polarized light, high output and high efficiency are easily achieved.

  The second reflection unit 15 reflects and returns the light having the fundamental wavelength of the incident light, and transmits the light having the converted wavelength of the incident light. In the present embodiment, the wavelength selection element 13, the wavelength conversion element 14, and the second reflection unit 15 are disposed on the base 16. The green light wavelength-converted by the wavelength conversion element 14 is taken out through the second reflecting portion 15. Infrared light that has not been wavelength-converted by the wavelength conversion element 14 is reflected by the second reflecting portion 15 and is incident on the wavelength conversion element 14 again.

  A part of the infrared light incident again on the wavelength conversion element 14 is converted into green light. Both the green light and the infrared light that has not been wavelength-converted are emitted from the wavelength conversion element 14 and enter the wavelength selection element 13. The green light incident on the wavelength selection element 13 is reflected by the wavelength selection surface 13b, travels in a different direction from the light emitting unit 11, and is extracted outside. Further, the infrared light that has entered the wavelength selection element 13 enters the light emitting unit 11 through the wavelength selection surface 13b. Infrared light incident on the light emitting unit 11 is reflected by the first electrode (first reflecting unit) 111 and folded, and is emitted from the light emitting unit 11 together with infrared light generated in the light emitting unit 11.

  As described above, the infrared light emitted from the light emitting unit 11 reciprocates many times in the resonator formed between the first electrode 111 and the second reflecting unit 15. Since the optical axes of the forward path and the return path in the resonator coincide with each other, the infrared light resonates to cause laser oscillation. The infrared laser light generated thereby reciprocates in the resonator, and a part of the infrared laser light is converted into green laser light G every time it passes through the wavelength conversion element 14. The green laser light G passes through the second reflector 15 or is reflected by the wavelength selection surface 13b and is taken out of the resonator and taken out of the laser light source device 1.

  In the laser light source device 1 of the first embodiment, since the spectral width of the light that has passed through the narrow band surface 13a is narrowed, laser oscillation is performed in a narrow band between the wavelength selection element 13 and the second reflection unit 15. And a high-power laser beam having a fundamental wavelength can be obtained. Since the fundamental wavelength laser beam is converted into the converted wavelength laser beam by the wavelength conversion element 14 and extracted outside, the desired wavelength laser beam can be obtained.

  Further, since the band narrowing surface 13a can be formed of a dielectric multilayer film or the like, an increase in cost can be avoided as compared with a case where laser oscillation is performed in a narrow band by a hologram element or the like. In particular, when a plurality of light emitting units are arranged and a hologram element is provided in common for the plurality of light emitting units, the hologram element does not function between the light emitting units, so the use efficiency of the hologram element is reduced. Therefore, the increase in cost becomes remarkable and it becomes difficult to construct the laser light source device itself. In other words, it is difficult to increase the number of light emitting units in the configuration using the hologram element, whereas according to the configuration of the present embodiment, it is easy to increase the number of light emitting units. Thereby, it becomes easy to make the laser light source device 1 high output.

  Further, the wavelength selection element 13 is a single element having a function of narrowing the light in the resonator, a function of separating the P-polarized light and the S-polarized light, and a function of separating the laser light having the converted wavelength. Therefore, the number of interfaces through which light passes can be reduced as compared with the case where these functions are shared by a plurality of independent elements. Thereby, the loss of light can be reduced and the efficiency can be increased. As described above, the laser light source device 1 is a laser light source device that can obtain high-power laser light having a desired wavelength without causing an increase in cost.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The second embodiment is different from the first embodiment in that a part of the wavelength conversion element functions as a second reflection unit.

  FIG. 3 is a cross-sectional view showing a schematic configuration of the laser light source device 2 of the second embodiment. In FIG. 2, the same code | symbol is attached | subjected to the same component as 1st Embodiment. In addition, detailed description of components common to the first embodiment may be omitted.

As shown in FIG. 3, the laser light source device 2 includes a light emitting element 12, a wavelength selection element 13, and a wavelength conversion element 24. The light emitting element 12 and the wavelength selection element 13 are the same as those in the first embodiment. The wavelength conversion element 24 has the same function as the wavelength conversion element 14 of the first embodiment, and the end face 24a opposite to the incident end face on which light is incident from the wavelength selection element 13 functions as a second reflecting portion. It is like that. Specifically, the end face 24a is formed of a dielectric multilayer film, and the end face 24a reflects light having a fundamental wavelength and transmits light having a converted wavelength.
In the laser light source device 2 of the second embodiment, the number of interfaces through which light passes is reduced as compared with the case where the wavelength conversion element 24 and the second reflection unit are elements independent of each other. Accordingly, the probability that a part of light incident on the interface is reflected or refracted in an unexpected direction due to the minute unevenness of the interface is reduced, and the loss of light is reduced, so that a highly efficient laser light source device is obtained.

  In the first and second embodiments, the surface on which light is incident from the light emitting unit 11 in the wavelength selection element 13 is the band narrowing surface 13a, but the light from the wavelength selection element 13 to the wavelength conversion elements 14 and 24 is light. The emission end face from which the light is emitted may be a band narrowing surface. In this case, it is only necessary that the narrow band surface has a characteristic of transmitting light in a wavelength band centered on the fundamental wavelength and light in a wavelength band centered on the conversion wavelength. In addition, as described above, by configuring the normal direction of the narrowband surface to be non-parallel to the optical axis of the light incident on the narrowband surface, light having a wavelength other than desired may resonate. Can be avoided.

  In the first and second embodiments, a configuration including a plurality of light emitting units is employed, but a configuration including only one light emitting unit may be employed. In addition, components such as a wavelength selection element, a wavelength conversion element, and a second reflection unit are all provided in common in the plurality of light emitting units, but the plurality of light emitting units are divided into two or more groups. In addition, the above-described components may be provided for each group. Further, an optical element such as a lens or a mirror may be disposed between the first reflection unit and the wavelength selection element or between the second reflection unit and the wavelength conversion element. For example, the light emitting element may be disposed on the base substrate, and light emitted from the light emitting element may be reflected by a mirror and incident on the wavelength selection element. The second reflecting portion may be a part of an element other than the wavelength conversion element.

  Next, an embodiment of the projector of the present invention will be described. FIG. 4 is a schematic configuration diagram showing the projector 400 of the present embodiment. As shown in FIG. 4, the projector 400 includes laser light source devices (light source devices) 410R, 410G, and 410B, transmissive liquid crystal light valves (image forming devices) 430R, 430G, and 430B, a cross dichroic prism 440, and a projection device. 450. Laser light source devices 410R, 410G, and 410B emit red light, green light, and blue light, respectively, and the emitted color lights are modulated into liquid crystal light valves 430R, 430G, and 430B, respectively. The modulated color lights are combined by the dichroic prism 440, and the combined light is projected by the projection device 450.

  In addition, the projector 400 according to this embodiment includes uniformizing optical systems 420R, 420G, and 420B that uniformize the illuminance distribution of the laser light emitted from the laser light source devices 410R, 410G, and 410B. Accordingly, the liquid crystal light valves 430R, 430G, and 430B are illuminated with light having a uniform illuminance distribution. Here, the homogenizing optical system 420R includes a hologram 421R, a field lens 422R, and the like, and the homogenizing optical systems 420G and 420B have the same configuration.

  The color light modulated by each of the liquid crystal light valves 430R, 430G, and 430B enters the cross dichroic prism 440. The cross dichroic prism 440 is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. The three color lights are synthesized by these dielectric multilayer films and become light representing a color image. The combined light is enlarged and projected on the screen 460 by the projection device 450, whereby a projected image is displayed.

  In the projector 400 of the present embodiment, since the laser light source devices 410R, 410G, and 410B are configured by the light source device of the present invention, the projector has a wide dynamic range and a high-quality projection image can be obtained. In addition, since narrow-band laser light is emitted from each of the laser light source devices 410R, 410G, and 410B, the projector has good color reproducibility.

  Although the transmissive liquid crystal light valve is used as the image forming apparatus, a reflective light valve may be used, or an image forming apparatus other than the liquid crystal may be used. Examples of such an image forming apparatus include a reflective liquid crystal light valve and DMD (registered trademark). What is necessary is just to change suitably the structure of a projection optical system according to the kind of image forming apparatus used. Further, although the cross dichroic prism is used as the color light combining means, the present invention is not limited to this. As the color light synthesizing means, for example, a dichroic mirror having a cross arrangement to synthesize color light, or a dichroic mirror arranged in parallel to synthesize color light can be used.

Next, another embodiment of the projector according to the present invention will be described. This embodiment is different from the above embodiment in that it is a scanning projector. FIG. 5 is a schematic configuration diagram illustrating the scanning projector according to the present embodiment.
The scanning projector 500 of this embodiment includes a laser light source device 510, a condenser lens 520, and a MEMS mirror (image forming device) 530. The laser light emitted from the laser light source device 510 is condensed on the MEMS mirror 530 by the condenser lens 520. The condensed laser light is scanned in the horizontal direction and the vertical direction on the screen 540 by driving the MEMS mirror 520. As a result, an image is drawn (formed) on the screen 540.

  Next, an embodiment of a monitor device according to the present invention will be described. FIG. 6 is a schematic configuration diagram showing the monitor device of the present embodiment. The monitor apparatus 600 of this embodiment includes an apparatus main body 610 and an optical transmission unit 620, and the apparatus main body 610 is provided with a camera (imaging device) 611 and the laser light source device 612 of the present invention. The light transmission unit 620 is provided with a light guide 621 for illumination and a light guide 622 for light reception. The light guides 621 and 622 are a bundle of a large number of optical fibers, and can send laser light to a distant place. In the illumination light guide 621, a diffusion plate 623 is provided at one end (tip) on the emission side, and the other end is connected to the laser light source device 612. The laser light emitted from the laser light source device 612 is sent to the diffusion plate 623 through the light guide 621 and is diffused by the diffusion plate 623 to irradiate the subject.

  An imaging lens 624 is provided at the tip of the light transmission unit 620, and light reflected by the surface of the subject enters the imaging lens 624. The light incident on the imaging lens 624 is sent to a camera 611 provided in the apparatus main body 610 through a light guide 622 for receiving light. As described above, the laser light emitted from the laser light source device 612 irradiates the subject, and the light reflected by the subject surface can be captured by the camera 611.

    In the monitor device 600 of the present embodiment, the light source device of the present invention is used for the laser light source device 612, so that the subject can be illuminated with high-power laser light. Therefore, the amount of light reflected from the surface of the subject is secured, and the monitor device is a good monitor that can obtain a clear captured image.

It is a top view which shows schematic structure of the laser light source apparatus of 1st Embodiment. It is a side view which shows schematic structure of the laser light source apparatus of 1st Embodiment. It is sectional drawing which shows schematic structure of the laser light source apparatus of 1st Embodiment. It is a schematic block diagram which shows a projector. It is a schematic block diagram which shows a scanning projector. It is a schematic block diagram which shows a monitor apparatus.

Explanation of symbols

1, 2, 410R, 410G, 410B, 510, 612 ... laser light source device, 10 ... base substrate (substrate), 11 ... light emitting unit, 111 ... first electrode (first reflecting unit) , 12 ... Light emitting element, 13 ... Wavelength selection element, 13a ... Band narrowing surface, 13b ... Wavelength selection surface, 14, 24 ... Wavelength conversion element, 15 ... Second reflection , 400... Projector, 500... Scanning type projector (projector), 600.

Claims (10)

A light emitting part having a first reflecting part on the opposite side of the light emission end face;
A second reflecting portion that reflects and returns the light of the fundamental wavelength emitted from the light emitting portion;
A wavelength conversion element that is disposed between the light emitting unit and the second reflection unit and converts at least part of the incident light having the fundamental wavelength into light having a conversion wavelength;
A wavelength selection element disposed between the wavelength conversion element and the light emitting unit,
A resonator is configured including the first reflecting portion and the second reflecting portion,
The wavelength selecting element narrows the band of the fundamental wavelength light among the light in the resonator, and the wavelength selection for transmitting the fundamental wavelength light and reflecting the converted wavelength light. And having a surface,
The laser light source device, wherein a normal direction of the wavelength selection surface is inclined with respect to an optical axis of light incident from the light emitting unit. In the wavelength selection surface, the reflectance of P-polarized light with respect to the wavelength selection surface of incident light is lower than the reflectance of S-polarized light with respect to the wavelength selection surface of incident light,
2. The laser light source device according to claim 1, wherein the wavelength conversion element selectively converts P-polarized light with respect to the wavelength selection surface of incident light into light having the conversion wavelength.   3. The laser light source device according to claim 1, wherein the second reflection unit reflects light having the fundamental wavelength and transmits light having the converted wavelength. 4.   4. The laser light source device according to claim 1, wherein, in the wavelength conversion element, the second reflecting portion is an opposite side of an incident end surface on which light is incident from the light emitting portion.   5. The wavelength selection element according to claim 1, wherein the wavelength selection element is formed by bonding a plurality of prisms, and one of the surfaces where the plurality of prisms are bonded together is the wavelength selection surface. The laser light source device according to any one of the above.   In the wavelength selection element, a normal direction of one surface of a surface on which light is incident from the light emitting unit and a surface on which light is incident from the wavelength conversion element is not parallel to the optical axis of the incident light. The laser light source device according to claim 5, wherein the other surface is substantially orthogonal to the optical axis of incident light, and the one surface is the narrow-band surface.   In the wavelength selection element, a surface on which light is incident from the light emitting unit is substantially orthogonal to the optical axis of the light, and a surface on which light is incident from the wavelength conversion element is approximately orthogonal to the optical axis of the light. 6. The laser light source device according to claim 5, wherein at least one of a surface on which light is incident from the light emitting unit and a surface on which light is incident from the wavelength conversion element is the narrow band surface. . A plurality of the light emitting units,
The plurality of light emitting units are arranged along a direction orthogonal to a traveling direction of light emitted from each of the plurality of light emitting units and orthogonal to a vibration direction of P-polarized light with respect to the wavelength selection plane. The laser light source device according to any one of claims 1 to 7. The laser light source device according to any one of claims 1 to 8,
An image forming apparatus for forming image light indicating an image by laser light emitted from the laser light source device;
A projector that projects image light formed by the image forming apparatus. The laser light source device according to any one of claims 1 to 8,
An image pickup device for picking up an image of a subject illuminated by the laser light source device.

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