JP4930036B2 - External resonant laser light source device, monitor device using the same, and image display device - Google Patents

Description

  The present invention relates to an external resonance type laser light source device.

  In recent years, a highly efficient laser light source is sometimes used as a light source of an image display device such as a projector. Laser light is likely to interfere because of its relatively high coherence compared to a light source such as a discharge lamp. Therefore, in an image display apparatus that projects an image with laser light, interference fringes appear as speckle noise on the projection surface, and the image deteriorates. Therefore, a light source device that reduces such speckle noise has been proposed (see Patent Document 1 below).

Japanese Patent Laid-Open No. 4-69987

  The light source device described in Patent Document 1 continuously changes the inclination of the bandpass filter with respect to the optical axis by rotating a flat plate-shaped bandpass filter that selectively transmits light of a predetermined wavelength. By doing in this way, the wavelength of the light which permeate | transmits a band pass filter changes continuously, and it can reduce coherence as the whole light source device. However, when such a light source device is used as an external resonance type laser light source device, a drive unit for rotating the band-pass filter is required, and the mounting size as the light source device is increased, The problem that a typical operation cannot be expected may occur.

  The above-described problems may occur in various devices that require a light source device, such as a lighting device, as well as a light source device used in an image display device.

  An object of the present invention is to provide a technique capable of stably emitting low-coherence light in an external resonance type laser light source device.

In order to achieve the above object, an external resonance light source device of the present invention transmits a part of laser light obtained by resonating a first mirror for resonance and fundamental light to be subjected to external resonance. A second mirror for resonance that reflects the remaining light toward the first mirror, a laser medium disposed between the first mirror and the second mirror, and the first mirror A wavelength that is disposed between a mirror and the second mirror, and enters a plurality of fundamental light beams respectively passing through a plurality of different optical paths, and selectively transmits light of a predetermined wavelength included in each fundamental wave light A domain structure in which spontaneous polarization and inversion polarization are alternately stacked in a direction along the plurality of optical paths, the selective element, and disposed between the wavelength selection element and the second mirror; Wavelength change to convert wavelength by incident fundamental light The wavelength conversion element by applying a voltage to each of the element, a plurality of electrodes disposed in contact with positions corresponding to each of the plurality of optical paths, of the surface of the wavelength conversion element, and the plurality of electrodes A voltage control unit that adjusts a polarization reversal period between the spontaneous polarization and the reversal polarization in a portion corresponding to each of the plurality of optical paths, and the wavelength selection element is selected according to an incident position of the fundamental light The wavelength control light is different, and the voltage control unit is arranged in contact with the position corresponding to each optical path according to the center wavelength of the light incident on the part corresponding to each optical path in the wavelength conversion element The gist is to apply different voltages to each electrode .

  In the external resonance type laser light source device of the present invention, when a plurality of fundamental light beams passing through a plurality of different optical paths are incident on the wavelength selection element, the incident positions are different, and therefore the wavelengths of selectively transmitted light are different from each other. Low coherence light can be emitted. Further, since the wavelength of the light to be selected differs depending on the incident position, the wavelength selection element itself does not have to be rotated or rotated in order to selectively transmit light of different wavelengths. Can be stably injected.

  In the external resonance light source device, the wavelength selection element has a configuration that selectively transmits light of the same wavelength as long as the incident angle of the fundamental wave light is the same. Of the incident positions, at least two incident positions may have different incident angles of the fundamental light.

  In this way, in the wavelength selection element, the incident angles at at least two incident positions of the fundamental wave light are different from each other. Therefore, the wavelengths of light selectively transmitted from these two fundamental wave lights are mutually different. Can be different.

  In the external resonance type laser light source device, the wavelength selection element may be configured such that an incident surface of the fundamental light is bent.

  By doing in this way, in the wavelength selection element, the incident angles at at least two incident positions can be made different from each other.

  The external resonance type laser light source device further includes a wavelength conversion element that receives the fundamental wave light and converts the wavelength, and the wavelength conversion element corresponds to the incident position for each incident position of the fundamental wave light. Wavelength conversion may be performed in accordance with the wavelength of light that is selectively transmitted at the incident position of the wavelength selection element.

  In this way, when the wavelengths of the plurality of light selectively transmitted by the wavelength selection element are different from each other, the wavelength conversion element appropriately converts the wavelength of each of the plurality of transmitted lights. be able to. Therefore, for example, it is possible to reduce the coherence of the light after wavelength conversion while converting the fundamental wave light, which is infrared light, into light having a half wavelength (green light or the like).

  The present invention can be configured as a monitor device or an image display device including the external resonance laser light source device in addition to the configuration as the external resonance laser light source device described above.

Hereinafter, the best mode for carrying out the present invention will be described in the following order based on examples.
A. First embodiment:
B. Second embodiment:
C. Third embodiment:
D. Fourth embodiment:
E. Fifth embodiment:
F. Sixth embodiment:
G. Seventh embodiment:
H. Eighth embodiment:
I. Ninth embodiment:
J. et al. Tenth embodiment:
K. Eleventh embodiment:
L. Twelfth embodiment:
M.M. Variations:

A. First embodiment:
FIG. 1 is an explanatory diagram showing a schematic configuration of a laser light source device as one embodiment of the present invention. The laser light source device 100 is an external resonance type laser light source device, and includes a semiconductor laser array 20, a band pass filter 30, and an output mirror 50. The semiconductor laser array 20 has a one-dimensional array structure in which the laser elements 21 to 24 are arranged in a line in the X-axis direction. Each of the laser elements 21 to 24 is a surface emitting laser element, and includes a resonance mirror 25, an internal resonance mirror 26, and a laser medium 27 including a clad layer and an active layer. Each of the laser elements 21 to 24 is referred to as laser light (hereinafter referred to as “basic laser light”) obtained by resonance (hereinafter referred to as “internal resonance”) between the resonance mirror 25 and the internal resonance mirror 26. However, light close to spontaneous emission obtained not by perfect resonance but by very weak resonance is also emitted in the Y-axis direction. The resonance mirror 25 is a total reflection mirror. The internal resonance mirror 26 transmits a part of the internally resonated light and serves as an output window for basic laser light. The basic laser light is red light having a center wavelength of 635 nm and a predetermined bandwidth. Note that the number of laser elements included in the semiconductor laser array 20 is not limited to four, and may be any number. The output mirror 50 is paired with the resonance mirror 25 included in each of the laser elements 21 to 24 to constitute an external resonator.

  Here, the “external resonance type” in the external resonance laser light source device 100 is a method of amplifying light emitted from the semiconductor laser array 20 by resonating with a resonator provided outside the semiconductor laser array 20. It shows that. That is, the laser light source device 100 further resonates and amplifies the basic laser light emitted from each of the surface emitting laser elements 21 to 24 using an external resonator composed of the output mirror 50 and the resonance mirror 25. The laser beam is emitted as a higher output laser beam. Specifically, among the basic laser beams W11 to W14 emitted from the laser elements 21 to 24, light W21 to W41 having a predetermined wavelength is selectively transmitted through the bandpass filter 30. Most of the light W21 to W24 is reflected by the output mirror 50, becomes reflected light R21 to R24, and enters the laser elements 21 to 24 again via the bandpass filter 30. The laser light returned to the laser elements 21 to 24 is reflected by the resonance mirror 25 and is emitted from the semiconductor laser array 20 together with the basic laser lights W11 to W14 as light R11 to R14.

The bandpass filter 30 is a multilayer filter in which a plurality of dielectric thin films (TiO ₂ layer, SiO ₂ layer, etc.) are stacked on a glass substrate. For example, like a etalon plate, a multilayer filter generally has a flat plate shape, but the band pass filter 30 has a shape in which the flat plate is curved in the Y-axis direction. The band-pass filter 30 having such a shape can be generated, for example, by depositing a dielectric thin film on a previously curved glass substrate. The band pass filter 30 selectively transmits light having a predetermined wavelength among light included in incident light W11 to W14 (red light having a predetermined bandwidth with a center wavelength of 635 nm).

  FIG. 2A is an explanatory diagram schematically showing the transmission characteristics of the bandpass filter 30 shown in FIG. The bandpass filter 30 has a characteristic that the center wavelength of the transmitted light is different depending on the incident angle of the incident light, similarly to a general bandpass filter. Specifically, when the incident angle is 0 ° (when the light is incident perpendicular to the incident surface), the transmitted light has a center wavelength of 635 nm and transmits 100% of light having a wavelength of 635 nm. In the example of FIG. 2A, the central wavelengths of the transmitted light are shortened to 634.8 nm, 634 nm, 633.5 nm, and 630 nm as the incident angles increase to θ1, θ2, θ3, and θ4.

  FIG. 2B is an explanatory diagram schematically showing the reflection characteristics of the output mirror 50 shown in FIG. The output mirror 50 reflects light having a wavelength of 630 nm to 640 nm with a reflectance of 98% or more. In particular, light with a wavelength of 635 nm reflects 99%.

  The basic laser beams W11 to W14 described above correspond to the fundamental wave light in the claims. The resonance mirror 25 in each laser element 21 to 24 corresponds to a first mirror in the claims, and the output mirror 50 corresponds to a second mirror in the claims.

  FIG. 3 is a cross-sectional view of the laser light source device 100 shown in FIG. 1 cut along a line L1 including four optical axes in the bandpass filter 30. The reflected lights R11 to R14 are omitted for convenience of illustration. The basic laser beam W11 emitted from the laser element 21 enters the bandpass filter 30 at an angle θ1. Further, the basic laser light W12 emitted from the laser element 22 has an angle θ2, the basic laser light W13 emitted from the laser element 23 has an angle θ3, and the basic laser light W14 emitted from the laser element 24 has an angle θ4. The light enters the pass filter 30. Note that the angles θ1 to θ4 are the same as θ1 to θ4 shown in FIG.

  Since the basic laser light W11 is incident on the bandpass filter 30 at an angle θ1, most of the light W21 that is selectively transmitted through the bandpass filter 30 is light having a wavelength of 634.8 nm as shown in FIG. It becomes. Then, as shown in FIG. 2B, the light W21 is reflected by 98% or more on the output mirror 50 (light R21) and used for amplification of the laser light. On the other hand, in the output mirror 50, 1% to 2% of the light W 21 is transmitted and emitted from the laser light source device 100. In this way, part of the light amplified by external resonance is emitted from the laser light source device 100 as the laser light W41. Therefore, the wavelength (center wavelength) of the laser beam W41 is 634.8 nm.

  Similarly, since the basic laser light W12 is incident on the bandpass filter 30 at an angle θ2, most of the light W22 is light having a wavelength of 634 nm (see FIG. 2A). Then, a laser beam W42 having a center wavelength of 634 nm is emitted from the laser light source device 100. Since the basic laser light W13 is incident on the bandpass filter 30 at an angle θ3, most of the light W23 is light having a wavelength of 633.5 nm (see FIG. 2A). Then, a laser beam W43 having a center wavelength of 633.5 nm is emitted from the laser light source device 100. Since the basic laser light W14 is incident on the bandpass filter 30 at an angle θ4, most of the light W24 is light having a wavelength of 630 nm (see FIG. 2A). Then, a laser beam W44 having a center wavelength of 630 nm is emitted from the laser light source device 100.

  Thus, in the laser light source device 100, the basic laser beams W11 to W14 emitted from the laser elements 21 to 24 resonate and are amplified, and are emitted from the laser light source device 100 as laser beams W41 to W44. At this time, the central wavelengths of the laser beams W41 to W44 are different from 634.8 nm, 634 nm, 633.5 nm, and 630 nm, respectively. Therefore, the coherence of the laser beams W41 to W44 can be reduced, and the generation of speckle noise can be suppressed when the laser beams W41 to W44 are irradiated.

B. Second embodiment:
FIG. 4 is an explanatory diagram showing a schematic configuration of the laser light source device in the second embodiment. The laser light source device 100a is different from the laser light source device 100 shown in FIG. 1 in that the shape of the bandpass filter 30a is different, and the other configuration is the same as that of the first embodiment. The bandpass filter 30 (FIG. 1) in the first embodiment has a shape in which the flat plate is curved in the Y-axis direction, whereas the bandpass filter 30a has a shape in which the flat plate is twisted. is doing.

  FIG. 5 is a cross-sectional view of the laser light source device 100a shown in FIG. 4 cut along a line L2 including four optical axes in the band-pass filter 30a. The reflected lights R11 to R14 and R21 to 24 are omitted for convenience of illustration. Since the bandpass filter 30a is twisted, the basic laser beams W11 to W14 do not enter the bandpass filter 30a perpendicularly. Specifically, the basic laser light W11 is incident on the bandpass filter 30a at an incident angle θ11. The basic laser beam W12 is incident on the bandpass filter 30a at an incident angle θ12, the basic laser beam W13 is incident at an incident angle θ13, and the basic laser beam W14 is incident at an incident angle θ14. Here, if the twist of the bandpass filter 30a is asymmetric in the X-axis direction, θ11 to θ14 can be different angles. In this case, since the incident angles are different from each other, the wavelengths of the lights W21 to W24 transmitted through the bandpass filter 30a are different wavelengths λ11 to λ14. Therefore, the laser beams W41 to W44 that are transmitted through the output mirror 50 and emitted from the laser light source device 100a become light having different center wavelengths (λ11 to λ14). Therefore, similarly to the first embodiment, the coherence of the laser beams W41 to W44 can be reduced, and the generation of speckle noise can be suppressed when the laser beams W41 to W44 are irradiated.

  Further, unlike the bandpass filter 30 (FIG. 1), the bandpass filter 30a does not have a curved shape in which one end of the flat plate is lifted in the Y-axis direction, and two corners of the flat plate are lifted in the Y-axis direction. It is a twisted shape. Accordingly, the thickness in the Y-axis direction of the entire band-pass filter 30a is smaller than the thickness in the Y-axis direction of the entire band-pass filter 30, and the overall size of the laser light source device is smaller than that of the first embodiment. Can be made smaller.

C. Third embodiment:
FIG. 6 is an explanatory diagram showing a schematic configuration of the laser light source device in the third embodiment. This laser light source device 100b differs from the laser light source device 100 shown in FIG. 1 in that the shape of the bandpass filter 30b is different, and the other configuration is the same as that of the first embodiment. The bandpass filter 30 (FIG. 1) in the first embodiment has a shape in which the flat plate is curved in the Y-axis direction, whereas the bandpass filter 30b has a shape bent in the Y-axis direction. Have. In addition, this band pass filter 30b can be produced | generated by vapor-depositing a dielectric film on the flat plate-shaped glass substrate bent beforehand, for example.

  FIG. 7 is a cross-sectional view of the laser light source device 100b shown in FIG. 6 cut along a line L3 including four optical axes in the bandpass filter 30b. The reflected lights R11 to R14 and R21 to 24 are omitted for convenience of illustration. Since the bandpass filter 30b is bent, the incident angles of the basic laser beams W11 to W14 are different (θ21 to θ24). Since the incident angles are different from each other, the wavelengths (center wavelengths) of the lights W21 to W24 transmitted through the bandpass filter 30a are different wavelengths λ21 to λ24. Accordingly, the laser beams W41 to W44 that are transmitted through the output mirror 50 and emitted from the laser light source device 100b become light having different center wavelengths (λ21 to λ24). Therefore, similarly to the above-described embodiments, the coherence of the laser beams W41 to W44 can be reduced, and the generation of speckle noise can be suppressed when the laser beams W41 to W44 are irradiated.

D. Fourth embodiment:
FIG. 8 is an explanatory diagram showing a schematic configuration of the laser light source device in the fourth embodiment. This laser light source device 100c is different from the laser light source device 100 shown in FIG. 1 in that the shape of the bandpass filter 30c is different, and the other configuration is the same as that of the first embodiment. The bandpass filter 30 (FIG. 1) in the first embodiment has a shape in which the flat plate is curved in the Y-axis direction, whereas the bandpass filter 30c has a stepped shape. Yes. Specifically, the bandpass filter 30c includes a glass substrate 39b and a dielectric thin film layer 39a formed on the glass substrate 39b, and includes four regions S1, T1, and D4 having different thicknesses. U1 and V1 are included. The thickness of the dielectric thin film layer 39a in each of the regions S1 to V1 increases in the order of the regions S1, T1, U1, and V1. Such a band-pass filter 30c can be generated by, for example, bonding four filters that have been generated in advance so that the thicknesses of the dielectric thin films are different in the X-axis direction. Or it can produce | generate by vapor-depositing so that the thickness of a dielectric thin film may differ for every area | region S1-V1 on the same glass substrate.

  In the laser light source device 100c, the basic laser beam W11 is incident on the region S1, the basic laser beam W12 is incident on the region T1, the basic laser beam W13 is incident on the region U1, and the basic laser beam W14 is incident on the region V1. In general, in a band-pass filter, the wavelength of light that is selectively transmitted increases as the thickness of the dielectric thin film increases, and the wavelength of light that transmits selectively decreases as the thickness of the film decreases. Therefore, in the laser light source device 100c, the center wavelengths λ31 to λ34 of the lights W21 to W24 transmitted through the regions S1 to V1 become longer in the order of the wavelengths λ31, λ32, λ33, and λ34. Accordingly, the laser beams W41 to W44 transmitted through the output mirror 50 and emitted from the laser light source device 100c are also light having different center wavelengths (λ31 to λ34). Therefore, the coherence of the laser beams W41 to W44 can be reduced, and the generation of speckle noise can be suppressed when the laser beams W41 to W44 are irradiated.

E. Fifth embodiment:
FIG. 9 is an explanatory diagram showing a schematic configuration of the laser light source device in the fifth embodiment. This laser light source device 100d differs from the laser light source device 100c shown in FIG. 8 in that the shape of the bandpass filter 30d is different, and the other configuration is the same as that of the fourth embodiment. The band-pass filter 30c (FIG. 8) in the fourth embodiment had a stepped shape due to four regions having different thicknesses of the dielectric thin film layer 39a. On the other hand, the band pass filter 30d is the same in that it has four regions (S2, T2, U2, V2) having different thicknesses of the dielectric thin film layer 39a. It differs from the band pass filter 30c in that the thickness of the body thin film layer 39a continuously changes in the X direction. Specifically, the thickness of the dielectric thin film layer 39a increases in the order of the regions S2, T2, U2, and V2, and the thickness of the dielectric thin film layer 39a gradually increases in the + X direction in each of the regions S2 to V2. It is getting bigger. Such a band pass filter 30d can be generated, for example, by depositing a dielectric thin film from an oblique direction with respect to the glass substrate 39b.

  In the laser light source device 100d, the basic laser light W11 enters the region S2, the basic laser light W12 enters the region T2, the basic laser light W13 enters the region U2, and the basic laser light W14 enters the region V2. Since the thickness of the dielectric thin film layer 39a is increased in the order of the regions S2, T2, U2, and V2, the center wavelengths λ41 to λ44 of the light W21 to W24 transmitted through the regions S2 to V2 are the wavelengths λ41 and λ42. , Λ43, λ44 in this order. As described above, also in the laser light source device 100d, the central wavelengths of the lights W41 to W44 transmitted through the laser light source device 100d are different from each other as in the third embodiment. Accordingly, the laser beams W41 to W44 transmitted through the output mirror 50 and emitted from the laser light source device 100d are also light having different center wavelengths (λ41 to λ44). Therefore, the coherence of the laser beams W41 to W44 can be reduced, and the generation of speckle noise can be suppressed when the laser beams W41 to W44 are irradiated.

F. Sixth embodiment:
FIG. 10 is an explanatory diagram showing a schematic configuration of the laser light source apparatus in the sixth embodiment. This laser light source device 100e is different from the laser light source device 100 shown in FIG. 1 in that it includes a wavelength conversion element 40, a Peltier element 61, temperature sensors 62a to 62d, and a temperature control unit 63. The wavelength conversion element 40 is a phenomenon of second harmonic generation (SHG), that is, two photons are converted into one photon having twice the frequency (light having a half wavelength). This is an element that causes a second-order nonlinear optical phenomenon, and has a polarization inversion structure formed in a ferroelectric material. For example, PPLN (Periodically Poled LiNb ₃ ) can be used as the wavelength conversion element 40. It is assumed that the polarization inversion period (domain pitch) between the spontaneous polarization and the inversion polarization in this polarization inversion structure is uniform in the wavelength conversion element 40 in the initial state. The wavelength conversion element 40 is disposed between the band pass filter 30e and the output mirror 50a. Then, the wavelength conversion element 40 receives the lights W21 to W24 selectively transmitted through the bandpass filter 30e, converts the lights W21 to W24 to ½ wavelengths, and emits the lights W31 to W34.

  The Peltier element 61 is bonded to one side surface of the wavelength conversion element 40. The temperature sensor 62a is installed in the vicinity of the optical axis of the light W31 on the wavelength conversion element 40. Similarly, the temperature sensor 62b is near the optical axis of the light W32 on the wavelength conversion element 40, the temperature sensor 62c is near the optical axis of the light W33 on the wavelength conversion element 40, and the temperature sensor 62d is on the wavelength conversion element 40. It is installed near the optical axis of the light W34.

  The temperature control unit 63 supplies power to the Peltier element 61 and controls the current flowing through the Peltier element 61. Since the Peltier element 61 cools the wavelength conversion element 40 bonded thereto, the temperature control unit 63 can control the temperature of the wavelength conversion element 40 by controlling the current flowing through the Peltier element 61. The temperature control unit 63 is connected to the temperature sensors 62a to 62d, and based on the temperature measurement values notified from these temperature sensors 62a to 62d, the wavelength conversion element 40 maintains a constant temperature distribution. The Peltier element 61 can be controlled. The wavelength conversion element 40 can be controlled to have a predetermined temperature distribution using a heater instead of the Peltier element 61 or together with the Peltier element 61.

  Here, in the laser light source device 100e, the output characteristics of the laser elements 21a to 24a included in the semiconductor laser array 20a are different from the output characteristics of the laser elements 21 to 24 in the laser light source device 100 (FIG. 1). In the laser light source device 100e, the transmission characteristics of the bandpass filter 30e are different from the transmission characteristics of the bandpass filter 30 (FIG. 1). In the laser light source device 100e, the reflection characteristic of the output mirror 50a is different from the reflection characteristic of the output mirror 50 (FIG. 1).

  Specifically, unlike the laser elements 21 to 24 (FIG. 1), the laser elements 21a to 24a emit infrared light having a predetermined bandwidth with a center wavelength of 1065 nm. Therefore, in the laser light source device 100e, the infrared light emitted from the laser elements 21a to 24a is converted into light having a half wavelength (green light of about 532.5 nm) by the wavelength conversion element 40 and emitted. The detailed configurations of the laser elements 21a to 24a are the same as the detailed configurations of the laser elements 21 to 24 shown in FIG.

  FIG. 11A is an explanatory diagram schematically showing the transmission characteristics of the bandpass filter 30e shown in FIG. Similar to the bandpass filter 30 (FIG. 1), the bandpass filter 30e has a characteristic that the center wavelength of the transmitted light is different depending on the incident angle. For example, when the incident angle is 0 °, the center wavelength of transmitted light is 1065 nm, and 100% of light having a wavelength of 1065 nm is transmitted. In the example of FIG. 11A, the center wavelengths of transmitted light are shortened to 1064 nm, 1063 nm, 1062 nm, and 1061 nm as the incident angles become larger as θ31, θ32, θ33, and θ34.

  FIG. 11B is an explanatory diagram schematically showing the reflection characteristics of the output mirror 50a shown in FIG. The output mirror 50a reflects 100% of light having a wavelength of 1061 nm to 1069 nm. Note that light having a wavelength shorter than 532.5 nm has a reflectance of 5% or less and transmits about 95%.

  FIG. 12 is a cross-sectional view of the laser light source device 100e shown in FIG. 10 cut along a line L4 including four optical axes in the bandpass filter 30e. The reflected lights R11 to R14 and R21 to 24 are omitted for convenience of illustration. The basic laser light W11 emitted from the laser element 21a is incident on the bandpass filter 30e at an angle θ31. The basic laser light W12 emitted from the laser element 22a has an angle θ32, the basic laser light W13 emitted from the laser element 23a has an angle θ33, and the basic laser light W14 emitted from the laser element 24a has an angle θ34. The light enters the pass filter 30e. The angles θ31 to θ34 are the same as θ31 to θ34 shown in FIG.

  Since the basic laser light W11 is incident on the bandpass filter 30e at an angle θ31, most of the light W21 selectively transmitted through the bandpass filter 30e is light having a wavelength of 1064 nm, as shown in FIG. . A part of the light W21 (FIG. 12) is converted into light having a wavelength of ½, that is, light having a wavelength of 532 nm, in the wavelength conversion element 40. In addition, since the conversion efficiency in the wavelength conversion element 40 is not 100%, the light before wavelength conversion (wavelength = 532 nm) and the original light before conversion (wavelength = 1064 nm) are also transmitted through the wavelength conversion element 40 to generate light. The light enters the output mirror 50a as W31.

  Similarly, since the basic laser light W12 is incident on the bandpass filter 30e at an angle θ32, most of the light W22 that is selectively transmitted through the bandpass filter 30e is light having a wavelength of 1063 nm (FIG. 11 ( A)). A part of the light W22 is converted into light having a wavelength of 531.5 nm in the wavelength conversion element 40. Since the basic laser light W13 (FIG. 12) is incident on the bandpass filter 30e at an angle θ33, most of the light W23 selectively transmitted through the bandpass filter 30e is light having a wavelength of 1062 nm (FIG. 12). 11 (A)). A part of the light W23 is converted into light having a wavelength of 531 nm in the wavelength conversion element 40. Further, since the basic laser light W14 (FIG. 12) is incident on the bandpass filter 30e at an angle θ34, most of the light W24 selectively transmitted through the bandpass filter 30e is light having a wavelength of 1061 nm. A part of the light W24 is converted into light having a wavelength of 530.5 nm in the wavelength conversion element 40 (see FIG. 11A).

  Here, in the wavelength conversion element 40, temperature dependency is recognized in the wavelength of the light to be subjected to wavelength conversion. That is, at a certain temperature, wavelength conversion is performed with high efficiency for light having a predetermined wavelength determined by the temperature. This is because, as a characteristic of the wavelength conversion element 40 (SHG), the refractive index changes due to thermal expansion, and the polarization inversion period (domain pitch) between spontaneous polarization and inversion polarization changes, so that wavelength conversion can be performed with high efficiency. This is because the wavelengths of light to be performed are different. As described above, the central wavelengths of the lights W21 to W24 incident on the wavelength conversion element 40 are slightly different from each other. Therefore, in order to perform wavelength conversion appropriately for each of the lights W21 to W24, the temperature control unit 63 controls the Peltier element 61 so that the temperature distribution in the wavelength conversion element 40 becomes as follows.

  That is, as shown in FIG. 12, the temperature is made highest in the region where the light W21 is incident (the light W31 is emitted). Then, a temperature gradient is provided so that the temperature decreases as it goes in the + X direction, so that the temperature becomes the lowest in the region where the light W24 is incident (the light W34 is emitted). By doing in this way, each light W21-W24 can be wavelength-converted with high efficiency in the position where each light W21-W24 injects. A specific temperature distribution in the wavelength conversion element 40 is obtained in advance by experiments or the like and set in the temperature control unit 63.

  Of the light W31 emitted from the wavelength conversion element 40 (FIG. 12), most of the light having a wavelength of 532 nm is transmitted through the output mirror 50a (95% or more) (see FIG. 11B) as laser light W41. The light is emitted to the outside of the laser light source device 100e. On the other hand, the light having a wavelength of 1064 nm included in the light W31 is reflected 100% by the output mirror 50a and used for amplification of the laser light. Similarly, most of the light W32 having a wavelength of 531.5 nm is transmitted through the output mirror 50a and emitted as laser light W42 to the outside of the laser light source device 100e. On the other hand, the light having a wavelength of 1063 nm included in the light W32 is reflected 100% by the output mirror 50a and used for amplification of the laser light. Of the light W33, most of the light having a wavelength of 531 nm is transmitted through the output mirror 50a and emitted as laser light W43 to the outside of the laser light source device 100e. On the other hand, the light with a wavelength of 1062 nm included in the light W33 is reflected 100% by the output mirror 50a and used for amplification of the laser light. Of the light W34, most of the light having a wavelength of 530.5 nm is transmitted through the output mirror 50a and emitted as laser light W44 to the outside of the laser light source device 100e. On the other hand, the light having a wavelength of 1061 nm included in the light W34 is reflected 100% by the output mirror 50a and used for amplification of the laser light.

  As described above, in the laser light source device 100e, the basic laser light, which is infrared light emitted from each of the laser elements 21a to 24a, resonates and is amplified, and the wavelength conversion is performed by the wavelength conversion element 40, thereby the green laser. Light is emitted as light W41 to W44. At this time, the wavelengths of the laser beams W41 to W44 are different from 532 nm, 531.5 nm, 531 nm, and 530.5 nm, respectively. Therefore, the coherence of the laser beams W41 to W44 can be reduced, and the generation of speckle noise can be suppressed when the laser beams W41 to W44 are irradiated. Further, in the laser light source device 100e, the wavelength conversion element 40 is cooled by the Peltier element 61 so that the temperature distribution of the wavelength conversion element 40 is kept constant, so that each of the incident lights W21 to W24 is controlled. Wavelength conversion can be performed with high efficiency according to the wavelength.

G. Seventh embodiment:
FIG. 13 is an explanatory diagram showing a schematic configuration of the laser light source device in the seventh embodiment. The laser light source device 100f does not include the Peltier element 61, the temperature sensors 62a to 62d, and the temperature controller 63, and the laser light source device 100e shown in FIG. 10 is different in the internal structure of the wavelength conversion element 40a. Unlike the sixth embodiment, the other configurations are the same as those of the sixth embodiment.

  The polarization inversion period (domain pitch) of the wavelength conversion element 40 in the sixth embodiment described above was uniform in the initial state. On the other hand, the domain pitch of the wavelength conversion element 40a is not uniform in the initial state. Specifically, the wavelength conversion element 40a has four regions S3, T3, U3, and V3 having different domain pitches, and the domain pitches of the regions S3, T3, U3, and V3 become shorter in this order. ing. The domain pitch in each area | region S3-V3 is defined according to the wavelength of the lights W21-W24 which inject into each area | region S3-V3. That is, the domain pitch in the region S3 is set so as to perform wavelength conversion with high efficiency for light having a wavelength of 1064 nm. Similarly, the domain pitch in the region T3 is light with a wavelength of 1063 nm, the domain pitch in the region U3 is light with a wavelength of 1062 nm, and the domain pitch in the region V3 is light with a wavelength of 1061 nm. Is set to In addition, the specific domain pitch in each area | region S3-V3 is determined by experiment.

  In this way, in the laser light source device 100f, the domain pitch in the wavelength conversion element 40a is formed to have a length corresponding to the wavelength of the incident light W21 to W24, so that the light W21 to W24 having different wavelengths can be obtained. Even if it enters, wavelength conversion of each light can be carried out with high efficiency. Further, since the Peltier element is not used to make the domain pitch non-uniform, the size of the laser light source device 100f can be made smaller than that of the laser light source device 100e.

H. Eighth embodiment:
FIG. 14 is an explanatory diagram showing a schematic configuration of a laser light source apparatus according to the eighth embodiment. The laser light source device 100g includes, in place of the Peltier element 61 and the temperature sensor 62a~62d and the temperature controller 63 shown in FIG. 10, in that it includes a voltage control unit 71 and the electrode 72, the laser light source device 100 e Unlike the above, the other configuration is the same as the laser light source device 100e in the sixth embodiment. In the sixth embodiment described above, the wavelength conversion element 40 is cooled using the Peltier element 61, thereby changing the refractive index of the wavelength conversion element 40 and changing the domain pitch according to the incident positions of the lights W21 to W24. It was changing. In contrast, in this embodiment, the refractive index and the domain pitch of the wavelength conversion element 40 are changed by applying a voltage to the wavelength conversion element 40.

  The wavelength conversion element 40 has a domain structure in which spontaneous polarization and inversion polarization are alternately stacked in the Y-axis direction. The electrode 72 is bonded to the inversion polarization portion on one side surface of the wavelength conversion element 40. A pair of electrodes (not shown) is bonded to the surface opposite to the surface to which the electrode 72 is bonded. The wavelength conversion element 40 is sandwiched between the pair of electrodes and applied to the inversion polarization portion, thereby causing thermal expansion in the wavelength conversion element 40. This thermal expansion changes the refractive index of the wavelength conversion element 40 and changes the domain pitch.

  Each electrode 72 is connected to a voltage control unit 71, and the voltage control unit 71 controls an applied voltage at each electrode 72. At this time, the voltage control unit 71 changes the applied voltage over time. Then, for example, at a certain time, the light W21 (center wavelength = 1064 nm) is wavelength-converted by the refractive index and the domain pitch determined by the voltage applied to the wavelength conversion element 40 at that time, and the other light W22˜ W24 is hardly wavelength-converted. Similarly, at other times, wavelength conversion is executed for any one of the lights W22 to W24, and wavelength conversion is hardly performed for the other lights. Therefore, even when four light beams W21 to W24 (wavelengths: 1064 nm to 1061 nm) having different center wavelengths are incident on the wavelength conversion element 40, it is possible to perform wavelength conversion on each light beam. Therefore, the four laser beams W41 to W44 having different center wavelengths can be emitted from the output mirror 50a, and the generation of speckle noise can be suppressed by reducing the coherence of the laser beams W41 to W44.

I. Ninth embodiment:
FIG. 15 is an explanatory diagram showing a schematic configuration of a laser light source device according to the ninth embodiment. This laser light source device 100h differs from the laser light source device 100g (FIG. 14) in the eighth embodiment in that the shapes of the electrodes 72a to 72d are different and the method of applying a voltage to the electrodes 72a to 72d is different. The configuration is the same as in the eighth embodiment.

  Specifically, in the laser light source device 100h, the electrode 72a is disposed at a distance from the adjacent electrode 72b in the reverse polarization portion of the region S4 where the light W21 is incident. Similarly, the electrode 72b is an inverted polarization portion of the region T4 where the light W22 is incident, the electrode 72c is an inverted polarization portion of the region U4 where the light W23 is incident, and the electrode 72d is an inverted polarization portion of the region V4 where the light W24 is incident. In FIG. 2, the electrodes are spaced apart from adjacent electrodes. Under such a configuration, the voltage control unit 71 applies different voltages to the electrodes 72a to 72d.

  Specifically, the voltage control unit 71 applies a voltage that realizes a refractive index and a domain pitch so that light with a wavelength of 1064 nm is wavelength-converted with high efficiency to the electrode 72a. Similarly, the electrode 72b has a refractive index and a domain pitch such that light having a wavelength of 1063 nm is converted into a wavelength, light having a wavelength of 1062 nm is applied to the electrode 72c, and light having a wavelength of 1061 nm is applied to the electrode 72d. Apply the voltage to be realized. Note that these voltages are previously measured by experiments and set in the voltage control unit 71. With the configuration as described above, even when four light beams W21 to W24 (wavelengths: 1064 nm to 1061 nm) having different center wavelengths are incident on the wavelength conversion element 40, wavelength conversion is performed for each light. Can be done. Therefore, the four laser beams W41 to W44 having different center wavelengths can be emitted from the output mirror 50a, and the generation of speckle noise can be suppressed by reducing the coherence of the laser beams W41 to W44.

J. et al. Tenth embodiment:
FIG. 16 is a cross-sectional view showing a schematic configuration of the laser light source apparatus in the tenth embodiment. This laser light source device 100i differs from the laser light source device 100e (FIG. 10) in the sixth embodiment described above in that the wavelength conversion element 40 is disposed between the semiconductor laser array 20a and the band pass filter 30f. Other configurations are the same as those of the sixth embodiment. Here, the transmission characteristics of the bandpass filter 30f are different from the transmission characteristics of the bandpass filter 30e (FIG. 10) in the sixth embodiment. The reflected lights R11 to R14 are omitted for convenience of illustration.

  FIG. 17 is an explanatory diagram schematically showing the transmission characteristics of the bandpass filter 30f. The band pass filter 30f has a transmission characteristic in which there exists a wavelength region (hereinafter referred to as “local transmission wavelength region”) in which the transmittance increases from the minimum value to 100% locally. The central wavelength of the local transmission wavelength region has different characteristics depending on the incident angle. For example, when the incident angle is 0 °, the central wavelength of the local transmission wavelength region is 1065 nm, whereas when the angle θ41 (> 0 °), the central wavelength of the local transmission wavelength region is 1064 nm. It is. In the example of FIG. 17, as the incident angle increases, the central wavelength of the local transmission wavelength region becomes shorter. When the angle is θ44 (> θ41), the central wavelength of the local transmission wavelength region is 1061 nm. ing. For convenience of illustration, when the incident angle is other than 0 °, only the local transmission wavelength region is indicated by a broken line, but the shape of the graph other than the local transmission wavelength region is the same as the case where the incident angle is 0 °. It is the same. Although not shown, the central wavelength of the local transmission wavelength region is 1063 nm when the incident angle is θ42 (θ44 <θ42 <θ41), and the local region when θ43 (θ44 <θ43 <θ42). The center wavelength of the transmission wavelength region is assumed to be 1062 nm. The bandpass filter 30f has a transmittance of almost 100% regardless of the incident angle at a wavelength sufficiently shorter than 1061 nm. In the example of FIG. 17, the transmittance is almost 100% at 532.5 nm, which is a half wavelength of 1061 nm.

A part of the light W 11 (center wavelength = 1064 nm) emitted from the laser element 21 a (FIG. 16) is wavelength-converted in the wavelength conversion element 40. Therefore, the light W21 includes the original light (wavelength = 1064 nm) before the conversion as well as the light after wavelength conversion (wavelength = 532 nm). This light W21 enters the bandpass filter 30f at an incident angle θ41. Therefore, as shown in FIG. 17 , the light having a wavelength of 1064 nm and the light having a wavelength of 532 nm included in the light W21 are both transmitted through the bandpass filter 30f and directed to the output mirror 50a as the light W21. As shown in FIG. 11B, the output mirror 50a has a reflectivity of 100% for light having a wavelength of 1064 nm and a reflectivity of less than 5% for light having a wavelength of 532 nm. . Therefore, of the light W21 emitted from the bandpass filter 30f, the light having a wavelength of 1064 nm is reflected by the output mirror 50a and travels toward the bandpass filter 30f as reflected light R21 to be used for amplification of the laser light. On the other hand, of the light 21 emitted from the band pass filter 30f, the light having a wavelength of 532 nm is transmitted through the output mirror 50a and emitted as laser light W41 to the outside of the laser light source device 100i.

  Similarly, part of the light W12 to W14 emitted from the laser elements 22a to 24a is also wavelength-converted by the wavelength conversion element 40, and is incident on the bandpass filter 30f as light W22 to W24. At the incident angles θ42 to θ44 of the light W22 to W24 with respect to the bandpass filter 30f, the light before wavelength conversion and the light after wavelength conversion (light of ½ wavelength) included in each light W22 to W24 are: , Most of the light passes through and enters the output mirror 50a as light W22 to W24. Most of the light before wavelength conversion is reflected by the output mirror 50a (lights R22 to R24) and used for amplification of the laser light. On the other hand, the wavelength-converted light passes through the output mirror 50a and is emitted to the outside of the laser light source device 100i as laser light W42 to W44.

  As described above, even if the wavelength conversion element 40 is arranged between the semiconductor laser array 20a and the bandpass filter 30f, the light (visible light) converted in wavelength by the wavelength conversion element 40 is output. The light passes through the mirror 50a and is emitted outside the laser light source device 100i as laser light W41 to W44. On the other hand, light (infrared light) before wavelength conversion can be used for amplification of laser light. Further, since the laser beams W41 to W44 emitted from the laser light source device 100i have different wavelengths, the coherence of the laser beams W41 to W44 can be reduced. Therefore, it is possible to suppress the generation of speckle noise when the laser beams W41 to W44 are irradiated.

  In the configurations of the laser light source devices 100f, 100g, and 100h in the seventh to ninth embodiments, the arrangement position of the wavelength conversion element 40 is also changed between the semiconductor laser array 20a and the bandpass filter 30f. Similarly to the present embodiment, the coherence of the laser beams W41 to W44 can be reduced, and the generation of speckle noise can be suppressed.

K. Eleventh embodiment:
FIG. 18 is a schematic configuration diagram of a monitor device to which the laser light source device of the present invention is applied. The monitor device 400 includes a device main body 410 and an optical transmission unit 420. The apparatus main body 410 includes the laser light source apparatus 100 (FIG. 1) in the first embodiment described above. In addition, the apparatus main body 410 includes a condenser lens 150 and a camera 411.

  The light transmission unit 420 includes a light guide 421 that transmits light and a light guide 422 that receives light. Each of the ride guides 421 and 422 is a bundle of a large number of optical fibers, and can send laser light to a distant place. The laser light source device 100 is disposed on the incident side of the light guide 421 that transmits light, and the diffusion plate 423 is disposed on the other emission side. An imaging lens 424 is disposed on the incident side of the light guide 422 on the light receiving side.

  The laser light emitted from the laser light source device 100 is collected by the condenser lens 150, is diffused by the diffusion plate 423 through the light guide 421, and irradiates the subject. Then, the reflected light from the subject enters the imaging lens 424, travels through the light guide 422, and is sent to the camera 411. In this manner, an image based on the reflected light obtained by irradiating the subject with the laser light emitted from the laser light source device 100 can be captured by the camera 411. The monitor device 400 may include any of the laser light source devices 100a to 100i described above instead of the laser light source device 100.

L. Twelfth embodiment:
FIG. 19 is a schematic configuration diagram of a projector to which the laser light source device of the present invention is applied. The projector 500 includes the laser light source device 100 (FIG. 1) that emits red light, the laser light source device 100f (FIG. 13) that emits green light, a laser light source device 100j that emits blue light, It has. The laser light source device 100j has substantially the same configuration as the laser light source device 100f. Specifically, the laser light source device 100j includes a semiconductor laser array 20b, a band pass filter 30g, a wavelength conversion element 40a, and an output mirror 50b. The semiconductor laser array 20b includes a laser element (not shown) that emits near infrared light having a center wavelength of about 900 nm. The bandpass filter 30g transmits near infrared rays having a center wavelength of about 900 nm. The wavelength conversion element 40a performs wavelength conversion of near infrared rays with high efficiency and emits blue light having a center wavelength of about 450 nm. The output mirror 50b has a reflection characteristic that transmits blue light after wavelength conversion and substantially reflects light before wavelength conversion (infrared light having a center wavelength of about 900 nm). The laser beams emitted from the laser light source device 100j have different wavelengths and low coherence, like the laser light source device 100f.

  The projector 500 also outputs the laser beams LBr, LBg, and LBb of the respective colors emitted from the laser light source devices 100, 100f, and 100j that emit the respective color lights in accordance with image signals sent from a personal computer (not shown) or the like. Liquid crystal light valves 504R, 504G, and 504B for modulation are provided. The projector 500 also includes a cross dichroic prism 506 that synthesizes light emitted from the liquid crystal light valves 504R, 504G, and 504B, and a projection lens 507.

  Further, the projector 500 makes the illuminance distribution of the laser light emitted from each laser light source device 100, 100f, 100j uniform, so that the homogenizing optical system is located downstream of the laser light source devices 100, 100f, 100j in the optical path. 502R, 502G, and 502B are arranged. The projector 500 irradiates the liquid crystal light valves 504R, 504G, and 504B with light whose illuminance distribution is made uniform by these uniformizing optical systems 502R, 502G, and 502B. The uniformizing optical systems 502R, 502G, and 502B can be configured by a combination of a hologram and a field lens, for example.

  The three color lights modulated by the liquid crystal light valves 504R, 504G, and 504B are incident on the cross dichroic prism 506. This prism 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 combined light is projected onto the screen 510 by the projection lens 507, and an enlarged image is displayed.

  As described above, the laser light emitted from each of the laser light source devices 100, 100f, and 100j has low coherence. Therefore, speckle noise can be reduced on the screen 510 on which the combined light is projected.

M.M. Variations:
In addition, elements other than the elements claimed in the independent claims among the constituent elements in the above embodiments are additional elements and can be omitted as appropriate. The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

M1. Modification 1:
In each of the embodiments described above, the laser elements 21 to 24 and 21a to 24a included in the laser light source devices 100 to 100j have a one-dimensional array structure, but may have a two-dimensional array structure. Good. The laser elements 21 to 24 and 21a to 24a are surface-emitting laser elements. However, instead of the surface-emitting laser elements, the light resonating direction is parallel to the substrate surface. An edge-emitting laser element may be used. The light source may not be composed of a semiconductor laser element that performs internal resonance, but may be composed of a laser device that emits a solid-state laser, a gas laser, or the like that does not perform internal resonance. For example, when the light source is composed of a YAG (Yttrium Aluminum Garnet) laser device, light obtained by irradiating a laser rod of a YAG crystal with light from an excitation light source (for example, a semiconductor laser) (the fundamental wave light in the claims) Equivalent) is resonated with an external resonator, amplified, and emitted. Even in such a configuration, it is possible to reduce the coherence of the plurality of laser beams by setting the wavelengths of the laser beams emitted from the plurality of YAG laser devices to be different from each other, and it is possible to suppress the generation of speckle noise.

M2. Modification 2:
In each of the above-described embodiments, the configuration is such that the light passing through the plurality of optical paths is emitted by the laser array including a plurality of laser elements, but the configuration may be such that the laser array is not used. For example, the laser light emitted from one laser element may be divided into a plurality of optical paths and emitted by a splitter or the like. In such a configuration, the plurality of laser beams have substantially the same wavelength and phase, and have high coherence. However, as described above, each of the laser light source devices 100 to 100j emits the plurality of laser beams as laser beams having different center wavelengths, thereby reducing the coherence and suppressing the generation of speckle noise. Can do.

M3. Modification 3:
In each of the above-described embodiments, each of the laser light source devices 100 to 100j is an external resonance type laser light source device, but may be a laser light source device that does not perform external resonance. For example, in the laser light source device 100 (FIG. 1) in the first embodiment, when the output of each laser element 21 to 24 is sufficiently large without external resonance, the output mirror 50 is not provided as an external configuration. The laser beam may be emitted outside without resonating. In this case, the lights W21 to W24 transmitted through the bandpass filter 30 are emitted from the laser light source device 100. As described above, since the center wavelengths of the lights W21 to W24 are different from each other, the coherence of the laser light emitted from the laser light source device is reduced and the generation of speckle noise is suppressed even in the above configuration. be able to.

M4. Modification 4:
In the twelfth embodiment described above, a liquid crystal light valve is used as the light modulation means in the projector 500, but is not limited to the liquid crystal light valve, but a DMD (digital micromirror device: trademark of Texas Instruments) or the like. A configuration using other arbitrary modulation means may be used. Further, the laser light source devices 100 to 100f in the first to tenth embodiments described above require a light source such as an illumination device in addition to the monitor device (the eleventh embodiment) and the projector (the twelfth embodiment). It can be used for any device.

M5. Modification 5:
In the first embodiment described above, the light W11 to W14 incident on the band-pass filters 30 to 30f are all different in incident angle, but the incident angles of at least two of these lights W11 to W14 are different. It may be different. Even if it does in this way, compared with the case where all the incident angles of light W11-W14 are the same, it becomes possible to reduce coherence. In addition to the first embodiment, in the second to third embodiments and the sixth to twelfth embodiments, the incident angles may be different for at least two lights. In the fourth to fifth embodiments, the thickness of the dielectric thin film layer 39a may be different in at least two of the regions S1 to V1.

It is explanatory drawing which shows schematic structure of the laser light source apparatus as one Example of this invention. It is explanatory drawing which shows typically the transmission characteristic of the band pass filter 30 shown in FIG. 1, and the reflective characteristic of the output mirror 50 shown in FIG. 2 is a cross-sectional view of the laser light source device 100 shown in FIG. 1 cut along a line L1 including four optical axes in a bandpass filter 30. FIG. It is explanatory drawing which shows schematic structure of the laser light source apparatus in a 2nd Example. FIG. 5 is a cross-sectional view of the laser light source device 100a shown in FIG. 4 cut along a line L2 including four optical axes in the bandpass filter 30a. It is explanatory drawing which shows schematic structure of the laser light source apparatus in a 3rd Example. It is sectional drawing which cut | disconnected the laser light source device 100b shown in FIG. 6 by the line L3 containing the four optical axes in the band pass filter 30b. It is explanatory drawing which shows schematic structure of the laser light source apparatus in a 4th Example. It is explanatory drawing which shows schematic structure of the laser light source apparatus in a 5th Example. It is explanatory drawing which shows schematic structure of the laser light source apparatus in a 6th Example. It is explanatory drawing which shows typically the transmission characteristic of the band pass filter 30e shown in FIG. 10, and the reflection characteristic of the output mirror 50a shown in FIG. It is sectional drawing which cut | disconnected the laser light source apparatus 100e shown in FIG. 10 by the line L4 containing the four optical axes in the band pass filter 30e. It is explanatory drawing which shows schematic structure of the laser light source apparatus in a 7th Example. It is explanatory drawing which shows schematic structure of the laser light source apparatus in an 8th Example. It is explanatory drawing which shows schematic structure of the laser light source apparatus in a 9th Example. It is sectional drawing which shows schematic structure of the laser light source apparatus in a 10th Example. It is explanatory drawing which shows typically the transmission characteristic of the band pass filter 30f. It is a schematic block diagram of the monitor apparatus to which the laser light source apparatus of this invention is applied. It is a schematic block diagram of the projector to which the laser light source apparatus of this invention is applied.

Explanation of symbols

20, 20a, 20b ... semiconductor laser array 21-24, 21a-24a ... laser element 25 ... resonance mirror 26 ... internal resonance mirror 30, 30a-30g ... band pass filter 39a ... Dielectric thin film layer 39b ... Glass substrate 40, 40a ... Wavelength conversion element 50, 50a, 50b ... Output mirror 61 ... Peltier element 62a-62d ... Temperature sensor 63 ... Temperature controller 71 ... Voltage controller 72, 72a to 72d ... Electrode 100, 100a to 100j ... Laser light source device 150 ... Condensing lens 400 ... Monitor device 410 ... Device main body 411 ... Camera 420 ... Light transmission unit 421,422 ... Light guide 423 ... Diffusion plate 424 ... Image forming lens 500 ... Projector 502R ... Uniform optical system 504R ... Liquid crystal Light valve 506 ... Cross dichroic prism 50 ... projection lens 510 ... screen

Claims (5)

An external resonant laser light source device,
A first mirror for resonance;
A second mirror for resonance that transmits part of the laser light obtained by resonating the fundamental wave light to be subjected to external resonance, and reflects the remaining light toward the first mirror;
A laser medium disposed between the first mirror and the second mirror;
A plurality of the fundamental light beams that are disposed between the first mirror and the second mirror and respectively pass through a plurality of optical paths different from each other are incident, and light having a predetermined wavelength included in each fundamental light beam is selectively selected. A wavelength selective element that transmits through
It is disposed between the wavelength selection element and the second mirror, and has a domain structure in which spontaneous polarization and inversion polarization are alternately stacked in a direction along the plurality of optical paths, and the fundamental light is incident And a wavelength conversion element for converting the wavelength,
A plurality of electrodes arranged in contact with positions corresponding to each of the plurality of optical paths, of the surface of the wavelength conversion element;
A voltage control unit that adjusts a polarization inversion period between the spontaneous polarization and the inversion polarization in a portion corresponding to each of the plurality of optical paths in the wavelength conversion element by applying a voltage to each of the plurality of electrodes;
With
The wavelength selection element has different wavelengths of light to be selected depending on the incident position of the fundamental light,
The voltage control unit is configured so that each electrode disposed in contact with a position corresponding to each optical path is in accordance with a center wavelength of light incident on a portion corresponding to each optical path in the wavelength conversion element. An external resonant laser light source device that applies different voltages . The external resonance type laser light source device according to claim 1,
The wavelength selection element is configured to selectively transmit light having the same wavelength as long as the incident angles of the fundamental light are the same, and at least two of the incident positions of the plurality of fundamental light At the incident position, the incident angles of the fundamental light are different from each other.
External resonant laser light source device. In the external resonance type laser light source device according to claim 2,
In the wavelength selection element, the incident surface of the fundamental light is bent.
External resonant laser light source device. An external resonant laser light source device according to any one of claims 1 to 3,
An imaging unit for imaging a subject irradiated by the external resonance type laser light source device;
A monitor device comprising: An external resonant laser light source device according to any one of claims 1 to 3,
A light modulation unit that modulates laser light emitted from the external resonance laser light source device according to an image signal;
A projection optical system for projecting an image formed by the light modulator;
An image display device comprising:

Images