JP2010186111A - Laser light source device, monitoring device, and image display device - Google Patents

Abstract

The present invention provides a laser light source device that is small in size, reduces coherence between a plurality of laser beams, and suppresses speckle noise, and an image display device including the laser light source device.
A laser light source device according to the present invention comprises: a light source part that outputs fundamental light; and a wavelength selection element that receives the fundamental light and selectively transmits a predetermined wavelength included in the fundamental light. The wavelength selection element is characterized in that a selection wavelength is changed by incidence of the fundamental wave light.
[Selection] Figure 1

Description

  The present invention relates to a laser light source device, a monitor device using the laser light source device, and an image display device.

  In recent projection type image display apparatuses, a discharge lamp such as an ultrahigh pressure mercury lamp is generally used as a light source. However, such discharge lamps have problems such as a relatively short life, difficult to light instantaneously, a narrow color reproducibility range, and ultraviolet rays emitted from the lamp may deteriorate the liquid crystal light bulb. . Therefore, a projection type image display apparatus using a laser light source that emits monochromatic light instead of such a discharge lamp has been proposed. However, the laser light source does not have the above-described problem, but has a defect that it has coherence. Thereby, interference fringes appear as speckle noise from the projection surface on which the laser light is projected, and the image is deteriorated. In order to display a high-definition image, it is necessary to take measures against speckle noise.

Since speckle noise depends on the coherence length, it is possible to reduce the speckle noise by shortening the coherence length. As means for reducing speckle noise, there are means for arranging a scattering element in a projection surface or an optical system for projecting laser light onto the projection surface, or for vibrating the scattering element. An image display device having such means has been proposed (for example, see Patent Document 1).
The image display device described in Patent Document 1 includes a diffusing element in which irregularities of a predetermined shape are formed on the surface. The intensity distribution of the laser light incident on the diffusing element is changed by vibrating the diffusing element at a predetermined frequency by a vibrating means in a plane orthogonal to the optical axis. As a result, speckle noise can be suppressed.
Since the coherence length is inversely proportional to the spectral width, it is also known that speckle noise is reduced by means of widening the spectral width. Speckle noise can be reduced by using means for controlling the output wavelength width of the laser light source (see, for example, Patent Document 2).

  In addition, a high-power laser is required as a light source for a projector having high brightness, and an array light source is used for high output. As a countermeasure against speckle noise caused by the array light source, a method of controlling the temperature of the array light source has been proposed (see, for example, Patent Document 3). In the image display device described in Patent Document 3, each semiconductor laser of an array light source is maintained at a different temperature, and each semiconductor laser emits a light beam having a different wavelength according to the difference in temperature. ing. Thus, by making the output wavelengths different, coherence between the semiconductor lasers is reduced, and speckle noise is reduced as a whole of the output light.

JP 2004-144936 A Japanese Patent Laid-Open No. 4-69987 JP 2004-144794 A

However, since the image display device described in Patent Document 1 uses a vibration means to vibrate the diffusing element, the entire device is increased in size and noise due to vibration is generated.
The light source device described in Patent Document 2 continuously changes the tilt 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. Let 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 a laser light source device, a drive unit for rotating the band-pass filter is required, and the mounting size as a light source device increases, noise, and stable operation. The problem of not being expected can occur.
In addition, when a method other than providing a driving unit such as a rotation is used, it is necessary to perform precision processing or the like on the bandpass filter, which causes a problem of cost increase.

The image display device described in Patent Document 3 is premised on the use of a light source that does not require an external resonator structure, that is, a light source that directly outputs laser light. Certainly, in the case of a light source that does not require an external resonator structure, there is an effect of suppressing speckle noise.
Here, in the case of a light source including an external resonator, basic components are a light emitting element, a wavelength selection element, and a resonator mirror. Even when a plurality of light emitting elements are used, a wavelength selecting element that selects a single wavelength is generally used in consideration of cost and ease of assembly. As a result, as described in Patent Document 3, even if the wavelength of each light emitted from the array light source is varied, a single wavelength is selected by the wavelength selection element. The coherence of the entire light source including the element does not decrease.

  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.

  The present invention is realized as the following forms or application examples so as to solve at least a part of the problems described above.

  [Application Example 1] A laser light source device according to this application example includes a light source portion that outputs fundamental light, and a wavelength selection element that allows the fundamental light to enter and selectively transmits a predetermined wavelength included in the fundamental light. The wavelength selection element is characterized in that the selection wavelength is changed by the incidence of the fundamental light.

  [Application Example 2] A laser light source device according to this application example transmits a part of laser light obtained by resonating a fundamental mirror light to be resonated with a first mirror for resonance, and the rest. A second mirror for resonance that reflects light toward the first mirror, the first mirror and the second mirror, and the fundamental wave light incident on the second mirror; And a wavelength selection element that selectively transmits light of a predetermined wavelength included in the wavelength selection element, wherein the wavelength selection element has a selection wavelength that is changed by incidence of the fundamental light.

  According to the application example described above, the spectrum of light emitted from the laser light source device can be temporally changed without external control, and the spectrum width can be widened. In addition, when this emitted light is used, speckle noise can be reduced.

  Application Example 3 In the laser light source device according to the application example, the wavelength selection element may be made of a material whose absorption wavelength is changed by incidence of the fundamental wave light.

  In this application example, the wavelength selection element uses functional dye molecules whose absorption spectrum is changed by the incidence of light. By utilizing the fact that the wavelength absorbed by the dye molecule is changed by the excitation of the dye molecule by laser light, the selected wavelength can be changed without external control in space and time.

  Application Example 4 In the laser light source device according to the application example described above, the wavelength selection element is made of at least two kinds of mixed materials having different absorption wavelength bands.

  In this application example, the dye molecule used in the wavelength selection element can change the absorption spectrum depending on the molecular structure, pH, and the like. Depending on the selection of the absorption wavelength of the dye molecule, it is possible to select the transmission wavelength bandwidth and the center wavelength of the wavelength selection element. As a result, it is possible to improve the degree of freedom of the output wavelength of the laser beam that is finally output.

  Application Example 5 In the laser light source device according to the application example described above, the wavelength selection element has at least two divided regions made of materials having different absorption wavelength bands.

  As a result, in the wavelength selection element, the absorption spectra of at least two incident positions of the fundamental wave light are different from each other, and the wavelengths of light transmitted from the two fundamental wave lights can be different from each other.

  Application Example 6 In the laser light source device according to the application example described above, the wavelength selection element has a circulation mechanism for stirring the wavelength selection material.

  A mechanism that circulates the dye molecules in the cell may be used for the dye molecule cell by utilizing the fact that the dye molecules used in the wavelength selection element are liquid and can flow in the cell. As a result, in the wavelength selection element, the dye molecules in different excited states are always switched, so that the absorption spectrum can be changed with time depending on the incident position.

  Application Example 7 In the laser light source device according to the application example described above, an array light source is used as a light source for emitting the fundamental wave light.

  When a plurality of fundamental light beams passing through a plurality of different optical paths are made incident on the wavelength selection element using an array light source, the dye molecules are excited at each of the incident positions. Since the plurality of fundamental wave lights are lights outputted from different emitters, the wavelengths and the light intensities are different from each other. As a result, the excited state of the molecule varies depending on the incident position, and the change in the absorption spectrum also varies. Since the wavelengths of transmitted light are different from each other, a plurality of wavelengths can be obtained for the entire array beam, and low-coherence light can be emitted. Further, the wavelength selection element in this application example can be returned to the non-excited state without external control by light emission after the saturated state after excitation. By utilizing the reversible reaction of the absorption spectrum of the wavelength selection element, it is autonomous only by the incidence of excitation light without the need to drive the wavelength selection element itself or perform precision processing to vary the wavelength depending on the position. In addition, the absorption spectrum can be changed spatially and temporally, and the effect of low coherence can be obtained.

  Application Example 8 The laser light source device according to the application example described above, characterized in that it includes another wavelength selection element different from the wavelength selection element.

  When the output wavelength width of the light source that outputs the fundamental wave light is narrower than the absorption wavelength width of the dye molecule, a desired transmission wavelength can be obtained by controlling the absorption center wavelength of the dye molecule. On the other hand, when the output wavelength width of the light source that outputs the fundamental wave light is wider than the absorption wavelength width of the dye molecule, all wavelengths outside the absorption wavelength of the dye molecule are transmitted on both the long wavelength side and the short wavelength side. As a result, it becomes difficult to select a specific transmission wavelength with the wavelength selection element alone. Therefore, by using another wavelength selection element to limit the output wavelength of the fundamental wave light to about the absorption wavelength width of the dye molecule, the wavelength selection by the dye molecule can be performed effectively.

  Application Example 9 In the laser light source device according to the application example described above, the wavelength selection element has a fixed selection wavelength.

  This makes it possible to effectively perform wavelength selection by the dye molecules.

  [Application Example 10] The laser light source device according to the application example described above, further including a wavelength conversion element that receives the fundamental light and converts a wavelength, and the wavelength conversion element is selected by the wavelength selection element Wavelength conversion corresponding to the wavelength of the transmitted light is performed.

  Thereby, it is possible to reduce speckle noise even in a laser light source device with wavelength conversion.

  Application Example 11 A monitor comprising: the laser light source device according to any one of Application Example 1 to Application Example 10; and an imaging unit that images a subject irradiated by the laser light source device. apparatus.

  Application Example 12 The laser light source device according to any one of Application Examples 1 to 10, the light modulation unit that modulates the laser light emitted from the laser light source device according to an image signal, An image display apparatus comprising: a projection optical system that projects an image formed by the light modulation unit.

The top view which shows the light source device which concerns on 1st Embodiment of this invention. Absorption characteristics of the bandpass filter (Dye A, Dye B ground state). Transmission characteristics of the bandpass filter (Dye A, Dye B ground state). Schematic diagram of energy level diagram of laser dye. Absorption characteristics of the bandpass filter (Dye A ground state, Dye B saturated state). Transmission characteristics of the bandpass filter (Dye A ground state, Dye B saturated state). Absorption characteristics of the bandpass filter (Dye A saturated state, Dye B ground state). Transmission characteristics of the bandpass filter (Dye A saturated state, Dye B ground state). The top view which shows the light source device which concerns on 2nd Embodiment of this invention. The top view which shows the light source device which concerns on 3rd Embodiment of this invention. The top view which shows the light source device which concerns on 4th Embodiment of this invention. The top view which shows the light source device which concerns on 5th Embodiment of this invention. The top view which shows the light source device which concerns on 6th Embodiment of this invention. Schematic which shows the monitor apparatus which concerns on 7th Embodiment of this invention. Schematic which shows the projector which concerns on 8th Embodiment of this invention.

[First Embodiment]
Next, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an explanatory diagram showing a schematic configuration of a laser light source device as one embodiment of the present invention. This laser light source device 100 is an external resonance type laser light source device, and is provided between a semiconductor laser 20 as a light source, an output mirror 50 as a second mirror, and between the semiconductor laser 20 and the output mirror 50. And a band pass filter 30 as a wavelength selection element. The semiconductor laser 20 has an array structure in which laser elements 21 to 24 are arranged in the X-axis direction. Each of the laser elements 21 to 24 is a surface emitting laser element. Each of the laser elements 21 to 24 emits fundamental laser light as fundamental wave light in the Y-axis direction. The basic laser light is red light having a center wavelength of 635 nm and a predetermined bandwidth. The number of laser elements included in the semiconductor laser 20 may be a single element other than the array shown in the figure. Further, the number of laser elements in the array is not limited to four and may be any number. The output mirror 50 is paired with a resonance mirror (not shown) as a first mirror of each of the laser elements 21 to 24 to constitute an external resonator.

  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, and is higher. Emitted as output laser light. Specifically, among the basic laser beams W11 to W14 emitted from the laser elements 21 to 24, light W21 to W24 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 light that has not been reflected by the output mirror 50 is emitted from the laser light source device 100 as emitted light W41 to W44. The laser light returned to the laser elements 21 to 24 is emitted from the semiconductor laser 20 together with the basic laser lights W11 to W14 as light R11 to R14.

  The band pass filter 30 is composed of a cell in which two types of liquid dye molecules are mixed. For example, for a red light source, a dye having an absorption region at a wavelength of 600 to 700 nm (Rhodamine 700, Rhodamine 800, Oxazine 750, Nile Blue 690, etc.) is used, and one kind or two kinds of dyes having different absorption center wavelengths are mixed. To provide a function as a bandpass filter. The type of the dye is selected according to the wavelength of the desired light source, and for the green light source, a dye having an absorption region at a wavelength of 500 to 600 nm (Rhodamine 590, Rhodamine 610, Rhodamine 6G, etc.) is used. For a blue light source, a dye having an absorption region at a wavelength of 400 to 500 nm (Coumarin440, Coumarin460, Coumarin450, etc.) is used as a bandpass filter.

2 to 8 are explanatory diagrams schematically showing absorption / transmission characteristics and energy level diagrams of the bandpass filter 30 shown in FIG. The band pass filter 30 transmits the wavelength between two absorption peaks of two types of dyes (Dye A and Dye B). Due to the characteristics of the dye molecule, the dye molecule is excited when light is incident thereon and transitions from the ground state S0 to the excited state S1, and light is absorbed at that time. Since the excited dye molecules are in an unstable state, light is emitted according to the energy band of each dye molecule and returns to the ground state. When light is incident again, it is excited, absorbs light, transitions to an excited state, and repeats this process. All the dye molecules do not repeat the same process at the same time, and the molecules are in a state where the excited state is maintained and no absorption occurs, and different wavelengths are transmitted depending on the position of the dye cell. As a result, different wavelengths in time and space are selected by the wavelength selection element. Therefore, the emitted lights W41 to W44 emitted from the laser light source device 100 have different wavelengths in time, and the emitted lights W41 to W44 have different wavelengths. Specifically, when a mixed dye of Nile Blue 640 and Rhodamine 700 is used, absorption occurs in each dye by the incidence of laser in the ground state (Nile Blue 640 absorption maximum: 640 nm, Rhodamine 700 absorption maximum: 650 nm). When the output wavelength width of the fundamental wave light is substantially narrower than the absorption wavelength width of each dye, what is transmitted is a wavelength region sandwiched between the respective absorption center wavelengths. Therefore, the center wavelength of transmitted light is 645 nm. When Nile Blue 640 is saturated first after excitation by the light source, the absorption center wavelength shifts to a shorter wavelength side than 645 nm because there is no absorption at 640 nm. On the other hand, when Rhodamine 700 is saturated first, the transmission center wavelength moves to a longer wavelength side than 645 nm. Further, when both the dye molecules are saturated, the dye cell has no function as a bandpass filter and the wavelength of the light source is transmitted as it is. The saturation state of each dye changes depending on the oscillation wavelength and intensity of the array light source. Since the object of the present embodiment is to reduce speckle noise due to wavelength shift, it is not necessary to precisely control the transmission wavelength of the bandpass filter, and the phenomenon that the transmission wavelength changes occurs.
From the above, the spectrum of the emitted light emitted from the laser light source device 100 changes with time. Further, when the emission light emitted from the laser light source device 100 is viewed as a whole, that is, when the emission lights W41 to W44 are combined, the spectrum width is widened. Thereby, when this emitted light is used, speckle noise can be reduced.
Although the response time at which the absorption wavelength changes depends on the material of the dye molecule, it is a picosecond level for a material with a fast response speed, which is less than the accumulated time of the human eye. As a result, an absorption spectrum can be autonomously changed temporally only by the incidence of excitation light, and the same effect as that of low coherence can be obtained by visually integrating the wavelengths before and after the reaction.

[Second Embodiment]
FIG. 9 is an explanatory diagram illustrating a schematic configuration of a laser light source device according to 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 dye molecule in one cell, whereas the bandpass filter 30a has a cell shape divided into regions. .
Each divided cell uses a dye having a different absorption wavelength. In addition, since the dye molecules (cyanine dyes, etc.) have the property that the absorption wavelength varies depending on the pH concentration, the same dye molecules or dye molecules having different pH concentrations may be used.
The operation of the laser light source device 100a and the operation of changing the selected wavelength in the bandpass filter 30a are the same as in the first embodiment.
By using molecules having different absorption wavelengths depending on the region, a wider transmission spectrum width and a plurality of types of transmission spectra can be obtained. It is possible to increase the speckle noise reduction effect by changing the transmission spectrum depending on the region.

[Third Embodiment]
FIG. 10 is an explanatory diagram illustrating a schematic configuration of a laser light source device according to 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 band-pass filter 30 (FIG. 1) in the first embodiment has a dye molecule in one cell, whereas the band-pass filter 30b has an internal dye molecule in one cell. It differs in that it has a mechanism 60 that circulates. By circulating the molecules excited by the incident beam of the array laser light source in the cell, the dye molecules in different excited states are always exchanged, so that the absorption spectrum can be changed with time depending on the incident position. A small pump or the like is used for circulation of the cell.
Thereby, it is possible to obtain a wider transmission spectrum width and a plurality of types of transmission spectra. Therefore, the speckle noise reduction effect can be increased.

[Fourth Embodiment]
FIG. 11 is an explanatory diagram showing a schematic configuration of a laser light source device according to the fourth embodiment. This laser light source device 100c is different from the laser light source device 100 shown in FIG. 1 in that a band pass filter 31 as another wavelength selection element is added in addition to the band pass filter 30. The same as in the first embodiment. The bandpass filter 31 is a general bandpass filter, and the selected wavelength does not change unlike the bandpass filter 30. As the band-pass filter 31, a filter whose selection wavelength range is approximately equal to the band width of the absorption wavelength of the band-pass filter 30 is used. When the output wavelength width of the fundamental wave light emitted from the semiconductor laser 20 is wider than the change range of the absorption wavelength of the dye molecules of the bandpass filter 30, short-wavelength light and long-wavelength light outside the absorption wavelength are in the band. The light passes through the pass filter 30. Then, it becomes impossible to obtain laser resonance with a desired wavelength. Therefore, by using the bandpass filter 31, the spectrum width of the fundamental light is limited to be approximately equal to the bandwidth of the absorption wavelength of the bandpass filter 30. As a result, since a wavelength greatly deviating from a desired wavelength does not enter the bandpass filter 30, only a specific wavelength can be transmitted according to the absorption wavelength of the bandpass filter 30. A laser beam having a desired wavelength is obtained.
Thereby, stable resonance of the laser beam is possible.

[Fifth Embodiment]
FIG. 12 is an explanatory diagram illustrating a schematic configuration of a laser light source device according to the fifth embodiment. This laser light source device 100d is different from the laser light source device 100 shown in FIG. 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 wavelength of 1/2). 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 LiNb3) 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 semiconductor laser 20 and the bandpass filter 30. And the wavelength conversion element 40 inject | emits the fundamental laser beam (fundamental wave light source) W11-W14, and inject | emits the light converted into the wavelength of 1/2, respectively. In particular, the wavelength conversion of this method is most practical in the green wavelength region where direct oscillation is technically difficult at present. Further, the wavelength conversion element 40 may be disposed between the band pass filter 30 and the output mirror 50. In this embodiment, the output mirror 50 may have a characteristic of reflecting the fundamental light and transmitting the second harmonic.
As a result, even in a laser light source device that obtains the second harmonic using the wavelength conversion element, it is possible to obtain a wide spectrum width or a spectrum that changes with time. Therefore, speckle noise can be reduced.

[Sixth Embodiment]
FIG. 13 is an explanatory diagram showing a schematic configuration of a laser light source device according to the sixth embodiment. This laser light source device 100e is different from the laser light source device 100 shown in FIG. 1 in that the position where the band pass filter 30e is arranged, and the other configuration is the same as that of the first embodiment. The band-pass filter 30 (FIG. 1) in the first embodiment is disposed in the resonator. In the present embodiment, the band-pass filter 30e is disposed outside the resonator as the light source portion. Even in such a case, it is possible to select spatially and temporally different wavelengths for the beam after laser oscillation, and speckle noise can be reduced.

[Seventh Embodiment]
FIG. 14 is a schematic configuration diagram showing an embodiment (seventh embodiment) 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 arranged on the incident side of the light guide 421 on the light sending side, and the diffusion plate 423 is arranged 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 way, 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. Note that the monitor device 400 may include any of the laser light source devices 100a to 100e described above instead of the laser light source device 100.

[Eighth Embodiment]
FIG. 15 is a schematic configuration diagram showing an embodiment (eighth embodiment) of a projector to which the laser light source device of the 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 that emits green light, and the laser light source device 100j that emits blue light. The laser light source device 100f includes a semiconductor laser 20a, a band pass filter 30e, a wavelength conversion element 40, and an output mirror 50a. Laser light emitted from the laser light source device 100f has low coherence. The laser light source device 100j includes a semiconductor laser 20b, a bandpass filter 30g, a wavelength conversion element 40a, and an output mirror 50b. The laser light emitted from the laser light source device 100j has low coherence. The laser light source device 100f and the laser light source device 100j may have any of the above-described configurations of the laser light source device 100 and 100a to 100e.

  In addition, the projector 500 respectively outputs the laser beams LBr, LBg, and LBb of each color emitted from the laser light source devices 100, 100f, and 100j that emit each color light according to 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 combines light emitted from the liquid crystal light valves 504R, 504G, and 504B, and a projection lens 507.

  Further, the projector 500 makes the uniform optical system downstream of the laser light source devices 100, 100f, 100j in order to make the illuminance distribution of the laser light emitted from the laser light source devices 100, 100f, 100j uniform. 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. The prism 506 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. In the above-described eighth embodiment, the liquid crystal light valve is used as the light modulation means in the projector 500. However, the light modulation means is not limited to the liquid crystal light valve. A configuration using other arbitrary modulation means may be used. In addition, the laser light source devices 100 to 100e in the first to sixth embodiments described above require a light source such as a lighting device in addition to the monitor device (seventh embodiment) and the projector (eighth embodiment). It can be used for any device.

  20, 20a, 20b ... semiconductor laser, 21-24 ... laser element, 30, 31 ... band pass filter, 40, 40a ... wavelength conversion element, 50, 50a, 50b ... output mirror, 60 ... mechanism, 100, 100a-100j DESCRIPTION OF SYMBOLS ... Laser light source device, 150 ... Condensing lens, 400 ... Monitor apparatus, 410 ... Apparatus main body, 411 ... Camera, 420 ... Light transmission part, 421, 422 ... Light guide, 423 ... Diffusing plate, 424 ... Imaging lens, 500 ... Projector, 502R ... Uniform optical system, 504R ... Liquid crystal light valve, 506 ... Cross dichroic prism, 507 ... Projection lens, 510 ... Screen.

Claims (12)

A light source that outputs fundamental light; and
A wavelength selecting element that enters the fundamental light and selectively transmits a predetermined wavelength included in the fundamental light; and
The laser light source device according to claim 1, wherein the wavelength selection element changes a selection wavelength by the incidence of the fundamental wave light. 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 wavelength selection element that is disposed between the first mirror and the second mirror and that receives the fundamental light and selectively transmits light having a predetermined wavelength included in the fundamental light. ,
The laser light source device according to claim 1, wherein the wavelength selection element changes a selection wavelength by the incidence of the fundamental wave light. In the laser light source device according to claim 1 or 2,
The laser light source device, wherein the wavelength selection element is made of a material whose absorption wavelength is changed by incidence of the fundamental light. In the laser light source device according to claim 3,
The laser light source device, wherein the wavelength selection element is made of at least two kinds of mixed materials having different absorption wavelength bands. In the laser light source device according to claim 3,
The laser light source device, wherein the wavelength selection element has at least two divided regions made of materials having different absorption wavelength bands. In the laser light source device according to claim 3,
The laser light source device, wherein the wavelength selection element has a circulation mechanism for stirring the wavelength selection material. In the laser light source device according to any one of claims 1 to 6,
A laser light source device in which the light source emitting the fundamental wave light is an array light source. In the laser light source device according to any one of claims 1 to 7,
A laser light source device comprising another wavelength selection element different from the wavelength selection element. The laser light source device according to claim 8,
The laser light source device characterized in that the wavelength selection element has a fixed selection wavelength. The laser light source device according to any one of claims 1 to 9,
And a wavelength conversion element that converts the wavelength by entering the fundamental wave light,
The laser light source device according to claim 1, wherein the wavelength conversion element performs wavelength conversion corresponding to a wavelength of light selectively transmitted through the wavelength selection element. The laser light source device according to any one of claims 1 to 10,
And an imaging unit that images a subject irradiated by the laser light source device. The laser light source device according to any one of claims 1 to 10,
A light modulation unit that modulates laser light emitted from the laser light source device according to an image signal;
An image display apparatus comprising: a projection optical system that projects an image formed by the light modulation unit.

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