JP2008268706A - Light source device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device having a wavelength converting element for efficiently emitting light with low coherence. <P>SOLUTION: The light source device (laser light source device 1) has a light source (semiconductor laser 2) having a plurality of light emission units (emitters 6) and a plurality of wavelength converting elements 9 composed of a plurality of optical crystals wavelength-converting a plurality of light beams emitted by the plurality of light emission units, where at least one or more light beams emitted from at least one or more light emission units among the plurality of light emission units are made incident on one of the plurality of wavelength converting element 9 and the wavelength of a light beam emitted by at least one light emission unit among wavelengths of the plurality of light beams emitted by the plurality of light emission units is different from wavelengths of light beams emitted from other light emission units. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  In recent years, as the demand for miniaturization of projectors has increased, projectors using laser light sources have been developed along with the increase in output of semiconductor lasers and the appearance of blue semiconductor lasers. This type of projector can be used as a next-generation display device because the wavelength range of the light source is narrow, so the color reproduction range can be sufficiently widened, and downsizing and reduction of components are possible. It has sex. In this case, laser light sources of three colors of red (R), green (G), and blue (B) are necessary as light sources. For example, the source light for the R light and the light source for the B light are present in the semiconductor laser, but the source light for the G light is not present, so the infrared light from the infrared laser is incident on the nonlinear optical element. It is considered to use a second harmonic generation (hereinafter abbreviated as SHG) generated when it is applied (see Patent Document 1).

In wavelength conversion of light using the nonlinear optical effect, a phase matching condition needs to be established between the fundamental wave before conversion and the harmonic wave after conversion, and a pseudo phase that periodically reverses the polarization direction in the crystal A matching method is used. In Patent Document 1, a structure in which the polarization direction is periodically reversed at a fine pitch (hereinafter referred to as a periodic polarization reversal structure in this specification) is formed in an MgO: LiNbO ₃ crystal, which is used as a wavelength conversion element. . However, the actual wavelength conversion element has an extremely narrow allowable wavelength range that satisfies the phase matching condition, and if the wavelength of the fundamental wave is slightly shifted, the output (conversion efficiency) is greatly reduced. On the other hand, it is known that the conversion efficiency strongly depends on the temperature of the wavelength conversion element. Utilizing this, a laser light source device comprising a plurality of wavelength conversion elements for wavelength-converting a plurality of laser beams and individually controlling the temperature of each wavelength conversion element to ensure the conversion efficiency of the entire wavelength conversion element It has been proposed (see Patent Document 2).
JP 2006-253406 A JP 2006-352009 A

  Conventional projectors often use a discharge lamp such as an ultra-high pressure mercury lamp as a light source. However, this type of discharge lamp has problems such as a relatively short life, difficulty in instantaneous lighting, and a narrow color reproducibility range. In that respect, according to the projector using the laser light source described in Patent Documents 1 and 2, the above problem can be solved. However, the light projected on the screen by the laser light source has very high coherence since the phases of the light beams in the adjacent regions are aligned. Since the coherent length of the laser light may reach several tens of meters, when a plurality of laser lights are combined, the light combined through an optical path difference shorter than the coherent length causes strong interference. For this reason, scintillation (interference fringes) clearer than that of the ultra-high pressure mercury lamp appears, causing a great deterioration in display quality.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a light source device including a wavelength conversion element that can efficiently emit light having low coherence. It is another object of the present invention to provide a projector that includes the light source device described above and can obtain high display quality by efficiently suppressing scintillation.

  In order to achieve the above object, a light source device according to the present invention includes a light source having a plurality of light emitting portions and a plurality of wavelength conversions each having an optical crystal for wavelength-converting a plurality of lights emitted from the plurality of light emitting portions. And light emitted from at least one light emitting unit among the plurality of light emitting units is incident on one of the plurality of wavelength conversion elements and is emitted from the plurality of light emitting units. Among the plurality of light wavelengths, the wavelength of light emitted from at least one light emitting unit is different from the wavelength of light emitted from another light emitting unit.

  In the light source device of the present invention, light is emitted from a plurality of light emitting units included in the light source, and at least one light emitted from at least one of the plurality of light emitting units is a wavelength conversion element. And is wavelength-converted. At this time, since the wavelength of light emitted from at least one light emitting unit is different from the wavelength of light emitted from other light emitting units, the coherence between lights emitted from different light emitting unit groups is reduced. Can be made.

  In addition, since at least one light emitted from at least one light emitting unit is incident on one wavelength conversion element, the number of wavelength conversion elements is the same as the number of light emitting parts, or Even a small number is enough. That is, one wavelength conversion element may be phase-matched to at least one light emitted from one light emitting unit group. That is, in the present invention, since each wavelength conversion element only needs to correspond to only a part of the light emitting units among all the light emitting units, it is easy to optimize the periodic polarization inversion structure of the wavelength conversion element. Therefore, the phase matching shift of the wavelength conversion element can be kept small, and the wavelength conversion efficiency can be increased.

  In the present invention, the plurality of light emitting units are composed of a plurality of light emitting unit groups including a plurality of light emitting units, and are emitted from a plurality of light emitting units belonging to at least one light emitting unit group among the plurality of light emitting unit groups. The average wavelength of the plurality of lights may be different from the average wavelength of the plurality of lights emitted from the plurality of light emitting units belonging to the other light emitting unit group.

  When the average value of the wavelengths of a plurality of lights emitted from a plurality of light emitting units belonging to one light emitting unit group is defined as an “average wavelength”, the average wavelength in at least one light emitting unit group is equal to the average wavelength in other light emitting unit groups. Since they are different, the coherence between lights emitted from different light emitting unit groups can be reduced. Further, since a plurality of lights emitted from the plurality of light emitting units are incident on one wavelength conversion element, the number of wavelength conversion elements is smaller than that of the light emitting units. Thereby, the wavelength conversion efficiency can be increased and the cost can be reduced.

In the light source device of the present invention, the wavelength of at least one light out of the plurality of light emitted from the plurality of light emitting units belonging to one light emitting unit group may be different from the wavelength of the other light.
According to this configuration, since the wavelengths of light from adjacent light emitting units belonging to one light emitting unit group are different, the coherence can be more effectively reduced.

Or it is good also as a structure where all the wavelengths of the some light inject | emitted from the some light emission part which belongs to one light emission part group are equal.
According to this configuration, the wavelength conversion element only needs to be phase-matched to light having the same wavelength from all the light-emitting parts belonging to one light-emitting part group, so that the overall phase-matching deviation can be minimized, and the wavelength Conversion efficiency can be maximized.

Further, the distance from the center position between the plurality of light emitting sections belonging to one light emitting section group to the light emitting section farthest is the distance between the center positions of the one light emitting section group and the adjacent light emitting section group. It is good also as a structure smaller than 1/2.
According to this configuration, since the pitch between the light emitting parts in each light emitting part group is small and the distance between the light emitting parts facing each other in the two adjacent light emitting part groups can be increased, the heat generated in the light emitting part Accumulation of the light suppresses the central portion of the light source from becoming high temperature, and the temperature between the light emitting portions can be made uniform. Moreover, the freedom degree of arrangement | positioning of the wavelength conversion element with respect to the several light emission part in each light emission part group becomes high.

Further, as the optical crystal, a crystal having a growth fringe in which the crystal composition or the impurity concentration is periodically changed, and the growth fringe constitutes a periodically poled structure can be used.
Conventional wavelength conversion elements are generally bulk-type elements cut out from an optical crystal having a periodically poled structure. However, in the case where the average wavelengths of the light emitting unit groups are different as in the present invention, for example, in order to match the phase to it, arranging a plurality of types of optical crystals having different pitches of the periodically poled structure in a bulk type is very difficult to manufacture. At the same time, it has the problem that the manufacturing cost increases.

  In this respect, the above problem can be solved by using an optical crystal having a growth fringe in which the crystal composition and the impurity concentration are periodically varied and the growth fringe constitutes a periodically poled structure. That is, in the optical crystal having the above characteristics, the growth stripes are generated in the crystal by periodically changing the temperature of the growth interface (melt surface) during pulling growth of the single crystal. A domain-inverted structure is formed. Therefore, optical crystals with different pitches of the periodically poled structure can be produced simply by controlling the melt temperature during crystal production by the pulling method, and bulk-type photolithography is not required. Thus, since an optical crystal can be produced in a short time and at a low cost, it is suitable for use in the wavelength conversion element of the present invention.

In addition, among the optical crystals of the plurality of wavelength conversion elements, the pitch of the periodic polarization inversion structure of the optical crystal of at least one wavelength conversion element is equal to the pitch of the periodic polarization inversion structure of the optical crystal of another wavelength conversion element. It is good also as a different structure.
In the case where the wavelengths of the light emitting parts are different, as a method of phase matching to each, there are, for example, a method of changing the pitch of the periodically poled structure of the optical crystal corresponding to each light emitting part, a method of changing the temperature of each optical crystal, etc. . When the former method is adopted, since the temperature of the plurality of optical crystals may be equal, it is only necessary to perform common temperature control for the plurality of optical crystals, and there is an advantage that the temperature control becomes easy. On the other hand, when the latter method is adopted, since the pitch of the periodically poled structure of the optical crystal is good, there is an advantage that the optical crystal can be easily manufactured even in the bulk type.

Further, a holding member that holds the plurality of wavelength conversion elements may be provided, and the plurality of wavelength conversion elements and the holding member may constitute a wavelength conversion element unit.
Whereas the conventional bulk optical crystal has a rectangular parallelepiped shape, the optical crystal produced by the above pulling method has a circular or elliptical cross-sectional shape perpendicular to the crystal growth direction, and currently has a diameter of 0.5 mm. The following is very thin. Therefore, a wavelength conversion element made of an optical crystal produced by a pulling method has a drawback that it is difficult to handle. In that regard, if a holding member that holds a plurality of wavelength conversion elements is provided and handled as a wavelength conversion element unit, the optical crystal can be handled easily, and for example, the alignment operation of the wavelength conversion elements can be easily performed. It also becomes possible to increase the manufacturing yield of the wavelength conversion element.

A projector according to the present invention includes the light source device according to the present invention, and an image forming apparatus that displays an image of a desired size on a display surface using light emitted from the light source device. And
According to this configuration, since the light source device according to the present invention is provided, light with low coherence is efficiently emitted, so that it is possible to efficiently suppress scintillation and realize a projector capable of obtaining high display quality. .

[First Embodiment]
A first embodiment of the present invention will be described below with reference to FIGS.
The light source device of this embodiment is an example of a wavelength conversion type laser light source device that converts the wavelength of laser light emitted from a semiconductor laser and outputs it.
FIG. 1 is a perspective view showing the overall configuration of the laser light source apparatus of this embodiment. FIG. 2 is a cross-sectional view (plan view) showing a state in which the laser light source device is cut along a plane parallel to the laser light emission direction. FIG. 3 is a cross-sectional view (front view) showing a state in which a portion of the wavelength conversion element of the laser light source device is cut along a plane perpendicular to the laser light emission direction. FIG. 4 is a perspective view showing an optical crystal of the wavelength conversion element.
In the following drawings, the scales of dimensions and positional relationships may be different for each component in order to make each component easier to see.

  As shown in FIG. 1, the laser light source device 1 (light source device) of the present embodiment is roughly composed of a semiconductor laser 2 (light source), a wavelength conversion element unit 3, and a resonance mirror 4. In addition, although not shown, the laser light source device 1 includes a carrier substrate for fixing the semiconductor laser 2, a heat sink, wiring for supplying power to the semiconductor laser 2, and the like.

  The semiconductor laser 2 of the present embodiment is an infrared laser that emits infrared light, for example. The semiconductor laser 2 has an external resonance structure, and an amplifying action is generated while light reciprocates between the resonance mirror 4 and the semiconductor laser 2 installed outside the semiconductor laser 2, and the laser light is oscillated. . At the same time, when the light reciprocates between the semiconductor laser 2 and the resonant mirror 4, the laser light passes through the wavelength conversion element 3. At this time, a part of the laser light is subjected to a wavelength conversion action (for example, the wavelength is converted to ½), becomes visible light (for example, green light), and is emitted from the wavelength conversion element unit 3. The resonant mirror 4 constitutes an external resonant structure together with the semiconductor laser 2 and also has a wavelength selection function for selectively transmitting visible light converted by the wavelength conversion element unit 3. Therefore, the visible light converted by the wavelength conversion element unit 3 passes through the resonance mirror 4 and is emitted outside the apparatus. On the other hand, the infrared light that has not been converted by the wavelength conversion element unit 3 is reflected by the resonant mirror 4 and travels toward the semiconductor laser 2 again.

  In the semiconductor laser 2, a plurality of emitters 6 (light emitting portions) are formed at a predetermined pitch. Although the arrangement pitch of the emitters 6 will be described later, in the case of this embodiment, the plurality of emitters 6 are arranged in a row, and a total of 21 emitters 6 are arranged in groups of three. In the following description, the three emitters 6 arranged in this manner are referred to as an emitter group 7 (light emitting unit group). Since the specific configuration of the semiconductor laser 2 is not different from the conventional one, a detailed description is omitted. Since this semiconductor laser 2 includes a plurality of emitters 6, even if the output of one emitter 6 is small, a high output as a whole is possible. Further, as the resonance mirror 4, for example, an optical element such as a hologram having a periodic grating can be used.

The wavelength conversion element unit 3 includes a wavelength conversion element 9 made up of a number of nonlinear optical crystals equal to the number of the emitter groups 7 (seven in this embodiment), and a holding member 10 that holds these wavelength conversion elements 9. Has been. As a nonlinear optical crystal constituting the wavelength conversion element 9, a bulk type crystal cut from a wafer made of a material such as lithium niobate (LiNbO ₃ ) has been conventionally used. Bulk-type nonlinear optical crystals are used to form polarization reversal processing electrodes in the wafer state, cut out multiple chips from the wafer, polarization reversal processing by applying voltage, polishing the incident surface and exit surface, and to the entrance surface and exit surface. The non-reflective coating was manufactured through each step.

  Although the above bulk type crystal may be used, in this embodiment, a nonlinear optical crystal that can be manufactured simply by pulling up the crystal is formed as the wavelength conversion element 9 by forming a periodically poled structure simultaneously with crystal growth. desirable. As shown in FIG. 4, the nonlinear optical crystal 9 'is a columnar single crystal whose section cut in a direction perpendicular to the crystal pulling direction (hereinafter referred to as the growth axis direction) is elliptical or circular. The nonlinear optical crystal 9 ′ has a growth stripe 9S in which the crystal composition and the impurity concentration are periodically changed in the crystal growth axis direction (corresponding to the laser beam traveling direction). Constitutes a periodically poled structure. The growth stripes 9S can be formed by periodically changing the temperature of the growth interface (melt surface) during the pulling growth of the single crystal. Therefore, the nonlinear optical crystal 9 ′ having a different pitch of the periodically poled structure can be produced simply by controlling the melt temperature during crystal production by the pulling method. Thus, since the nonlinear optical crystal 9 'can be produced in a short time and at a low cost, it is suitable for use in the wavelength conversion element 9 of this embodiment as compared with the conventional bulk crystal.

  Furthermore, in the case of a bulk type nonlinear optical crystal, a photolithography step is necessary in the step of forming the polarization inversion processing electrode, whereas in the case of the present embodiment, a photolithography step is unnecessary. Therefore, a tool such as a photomask is not required, initial cost is not required, and specification changes such as a pitch change of the periodically poled structure can be easily performed. Therefore, when the light wavelengths of the plurality of emitters 6 are changed for the purpose of reducing the light coherence, it becomes easy to manufacture the wavelength conversion elements 9 corresponding to the respective emitter groups 7. Further, since the deviation in the aspect direction of polarization is less likely to occur than in the case of a rectangular parallelepiped bulk type nonlinear optical crystal, the in-plane distribution in the light traveling direction can be made more uniform. Therefore, the positioning accuracy in the plane of the nonlinear optical crystal with respect to each emitter 6 does not have to be so strict, and the positioning operation can be easily performed.

  As shown in FIGS. 1 and 2, the holding member 10 is configured by a block having a plurality of through holes 10 a into which a plurality of wavelength conversion elements 9 are inserted. The constituent material of the block is not particularly limited. For example, a metal material, a resin material, etc. can be used. The inner diameter of the through hole 10a is not the same from end to end, and the inner diameter of the one end side 10c that accommodates the wavelength conversion element 9 is substantially the same as or slightly larger than the outer diameter of the wavelength conversion element 9, and The inner diameter is smaller than the outer diameter of the wavelength conversion element 9. That is, a slight step 10b is formed on the inner wall of the through hole 10a.

  With the above configuration, since the end portion of the wavelength conversion element 9 is caught by the step 10b only by dropping the wavelength conversion element 9 from the one end side 10c of the holding member 10 into each through hole 10a, the holding member 10 The wavelength conversion element 9 is positioned with respect to 10 in the growth axis direction. That is, the step 10 b on the inner wall of the through hole 10 a functions as a positioning means for the wavelength conversion element 9. Further, since the radial direction of the wavelength conversion element 9 has very little clearance between the wavelength conversion element 9 and the through hole 10a, the wavelength conversion element 9 can be simply inserted into each through hole 10a. 9 is substantially positioned in the radial direction. In this way, each wavelength conversion element 9 and the holding member 10 are fixed by a UV curable adhesive (not shown) in a state where each wavelength conversion element 9 is positioned with respect to the holding member 10.

  In FIG. 2, the upper end of each wavelength conversion element 9 (the end opposite to the side in contact with the step 10 b) protrudes from the holding member 10, but the protruding portion is flush with the end surface of the holding member 10. The end face of the wavelength conversion element 9 may be subjected to non-reflection coating treatment. In this way, the process is simplified and the manufacturing yield is improved as compared with the case where the wavelength conversion elements 9 are individually polished one by one and subjected to non-reflective coating. In addition, since the positions of the end faces are uniform between the wavelength conversion elements 9, the wavelength conversion element 3 having stable characteristics as a whole can be obtained.

  Although not shown, the substrate of the semiconductor laser 2 is provided with a heat sink, a cooling mechanism, and the like, and cools the semiconductor laser 2 that rises in temperature due to heat generated by the emitter 6. In this embodiment, as shown in FIG. 3, one emitter group 7 composed of three emitters 6 corresponds to one wavelength conversion element 9. That is, three laser beams emitted from three emitters 6 belonging to one emitter group 7 are incident on one wavelength conversion element 9 (the position of the corresponding emitter 6 is indicated by a symbol L). In addition, the distance D1 from the center position of the three emitters 6 belonging to one emitter group 7 (the position of the center emitter 6 among the three emitters 6) to the emitter 6 at the end is equal to that of one emitter group 7. It is smaller than 1/2 of the distance D2 between the center position and the center position of the adjacent emitter group 7. Further, the pitch P 1 between the emitters 6 in one emitter group 7 is smaller than the pitch P 2 between the emitter 6 at the end of one emitter group 7 and the emitter 6 at the end of the adjacent emitter group 7.

  In the present embodiment, since the semiconductor laser 2 has seven emitter groups 7, if the average value of the wavelengths of the three emitters 6 belonging to each emitter group 7 is referred to as "average wavelength", seven Mean wavelength. Among these, the average wavelength in at least one emitter group 7 is different from the average wavelength in the other emitter groups 7. Further, when attention is paid to the three emitters 6 belonging to one emitter group 7, the wavelengths may be different among the three laser beams emitted from the three emitters 6, or the three laser beams may be changed. The wavelengths may be all equal. When the wavelengths of the laser beams emitted from the respective emitters 6 are made different from each other in this way, in consideration of the color purity of the output laser beams, the compatibility with the wavelength conversion element 9 and the resonant mirror 4, etc., at most 10 nm or less. It is desirable to set a wavelength difference of.

  As shown in FIG. 3, each wavelength conversion element 9 constituting the wavelength conversion element unit 3 corresponds to one emitter group 7 (three emitters 6). Wavelength matching. For example, if the wavelengths of the laser beams from the three emitters 6 in one emitter group 7 are all equal, the wavelength conversion element 9 is wavelength-matched to that wavelength. Alternatively, if the wavelengths of the laser beams from the three emitters 6 in one emitter group 7 are different, for example, the wavelength conversion element 9 is wavelength-matched to the average value of those wavelengths. As a wavelength matching method, a method of changing the pitch of the periodically poled structure of each wavelength conversion element 9 or a temperature of each wavelength conversion element 9 can be considered, but the former method is adopted in this embodiment. To do. In order to change the pitch of the periodically poled structure, the fluctuation period of the melt surface temperature may be changed when pulling the single crystal.

  According to the laser light source device 1 of the present embodiment, since the average wavelength in at least one emitter group 7 is different from the average wavelength in other emitter groups 7, the coherence of light emitted from different emitter groups 7 can be improved. Can be reduced. Therefore, by adopting the laser light source device 1 of the present embodiment, it is possible to realize a projector that hardly causes scintillation. In addition, since three laser beams emitted from one emitter group 7 are incident on one wavelength conversion element 9, all the light beams from all (21) emitters 6 included in the semiconductor laser 2 are obtained. However, it is not necessary to phase-match one wavelength conversion element 9 with respect to the laser beam emitted from one emitter group 7. That is, since one wavelength conversion element 9 only needs to correspond to one emitter group 7, it is easy to optimize the periodic polarization inversion structure of the wavelength conversion element 9. As a result, it is possible to suppress a shift in phase matching of the wavelength conversion element 9 with respect to a plurality of lights, and to increase the wavelength conversion efficiency.

  In addition, when the wavelengths of the three laser beams emitted from the three emitters 6 belonging to one emitter group 7 are made different, the wavelengths of the light beams from the neighboring emitters 6 in the one emitter group 7 are different. Therefore, the coherence can be reduced more effectively. On the other hand, when the wavelengths of the three laser beams emitted from the three emitters 6 belonging to one emitter group 7 are all made equal, the effect of reducing the coherence in one emitter group 7 is obtained. However, the wavelength conversion element 9 only needs to be phase-matched to light of the same wavelength from all the emitters 6 in one emitter group 7, so that the overall phase-matching shift can be minimized and wavelength conversion is possible. Efficiency can be maximized.

  In addition, as a method of phase matching the wavelength conversion element 9 with respect to the emitter group 7 having different average wavelengths, a method of changing the pitch of the periodic polarization inversion structure of the wavelength conversion element 9 corresponding to each emitter group 7, There is a method of changing the temperature of each wavelength conversion element 9 without changing the pitch of the inversion structure. In the present embodiment, since the former method is adopted, the temperatures of the plurality of wavelength conversion elements 9 may be equal. In the present embodiment, a plurality of wavelength conversion elements 9 are held by one holding member 10, but common temperature control may be performed on the plurality of wavelength conversion elements 9 via the holding member 10. Temperature control becomes easy. For example, the plurality of wavelength conversion elements 9 can be maintained at the same temperature by feedback-controlling the temperature of the holding member 10 using an arbitrary temperature control device.

  In addition, since the holding member 10 that holds the plurality of wavelength conversion elements 9 is provided and the wavelength conversion element unit 3 is provided, the wavelength conversion element 9 can be easily handled. For example, the wavelength conversion element 9 is aligned with the semiconductor laser 2. Can be easily performed. It is also possible to increase the manufacturing yield of the wavelength conversion element 9. Further, the distance D1 from the center of one emitter group 7 to the emitter 6 at the end is smaller than ½ of the center distance D2, and the pitch P1 between the emitters in one emitter group 7 is Since the pitch is smaller than the inter-emitter pitch P <b> 2, accumulation of heat generated in the emitter 6 prevents the center of the semiconductor laser 2 from becoming high temperature, and the temperature between the emitters 6 can be made uniform. Further, the degree of freedom of arrangement of the wavelength conversion element 9 with respect to each emitter group 7 is increased.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.
The light source device of this embodiment is also an example of a wavelength conversion type laser light source device that converts the wavelength of laser light from a semiconductor laser.
FIG. 5 is a perspective view showing the overall configuration of the laser light source device of the present embodiment. FIG. 6 is a cross-sectional view (front view) showing a state where the wavelength conversion element portion of the laser light source device is cut along a plane perpendicular to the laser light emission direction.
Since the basic configuration of the laser light source device of this embodiment is the same as that of the first embodiment, the same reference numerals are given to the same components as those used in the first embodiment in FIGS. The detailed explanation is omitted.

  In the laser light source device 1 of the first embodiment, one wavelength conversion element 9 corresponds to the emitter group 7 including the three emitters 6. In contrast, in the laser light source device 12 of the present embodiment, as shown in FIGS. 5 and 6, one wavelength conversion element 15 of the wavelength conversion element unit 14 corresponds to one emitter 6 of the semiconductor laser 13. Are arranged as follows. The semiconductor laser 13 includes a plurality (15 in this embodiment) of emitters 6, and at least one of the emitters 6 has a wavelength different from that of the other emitters 6. When making the wavelengths of the emitters 6 different, it is desirable to set the wavelength difference to 10 nm or less, as in the first embodiment. The pitch between the emitters 6 may be constant or different. The wavelength conversion element 15 is held by one holding member 16 and constitutes a wavelength conversion element unit 14.

  Also in the laser light source device 12 of the present embodiment, phase matching by changing the pitch of the periodic polarization reversal structure of the nonlinear optical crystal, which can realize a laser light source device having low coherence of light output as a whole and high wavelength conversion efficiency. It is possible to obtain the same effects as those of the first embodiment, which can be easily performed and the temperature control of the wavelength conversion element can be easily performed. In particular, in the case of this embodiment, since one wavelength conversion element 15 corresponds to one emitter 6, the wavelength conversion element 15 can be phase-matched on a one-to-one basis with respect to the wavelength of light from the corresponding emitter 6. The wavelength conversion efficiency can be maximized.

  As described above, the wavelength conversion efficiency is maximized if the wavelength conversion element 15 is individually phase-matched for each emitter 6, but instead of the configuration, the wavelength conversion element 15 has a predetermined wavelength range. A phase matching that includes the emitter 6 may be provided, and the types of the wavelength conversion elements 15 may be reduced. Thereby, cost reduction can be achieved.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.
FIG. 7 is a cross-sectional view (plan view) showing the overall configuration of the laser light source device of the present embodiment.
Since the basic configuration of the laser light source device of this embodiment is the same as that of the first embodiment, the same reference numerals are given to the same components as those used in the first embodiment in FIG. Omitted.

  In the laser light source device 18 of this embodiment, as shown in FIG. 7, a plurality of (6 in this embodiment) emitters 6 of the semiconductor laser 19 are arranged in groups of three, and four emitter groups 7 are arranged. It is composed. The wavelength conversion element 9 of the wavelength conversion element unit 21 corresponds to each emitter group 7, and four wavelength conversion elements 9 are used as a whole. In the first and second embodiments, the plurality of wavelength conversion elements 9 are collectively held by one holding member 10, whereas in this embodiment, the wavelength conversion elements 9 are individually held one by one. Is held in. The point etc. which the level | step difference 20b which functions as a positioning means of the wavelength conversion element 9 is formed in the inner wall of the through-hole 20a of the holding member 20 are the same as that of 1st Embodiment. Other configurations are the same as those in the first embodiment.

  Also in the laser light source device 18 of the present embodiment, phase matching is achieved by changing the pitch of the periodically poled structure of the nonlinear optical crystal, which can realize a laser light source device with low coherence of light output as a whole and high wavelength conversion efficiency. The same effects as those of the first and second embodiments can be obtained, which can be easily performed and the temperature control of the wavelength conversion element can be easily performed.

  In the first and second embodiments, since a plurality of wavelength conversion elements 9 are held by one holding member 10, it is difficult to perform independent temperature control for each wavelength conversion element 9. In order to achieve phase matching with light, it is preferable to change the pitch of the periodically poled structure of each wavelength conversion element 9. On the other hand, in the present embodiment, each wavelength conversion element 9 is held by a separate holding member 20, and each wavelength conversion element 9 and the holding member 20 are thermally separated. The temperature of the set of holding members 20 can be controlled independently. Therefore, even if nonlinear optical crystals having the same pitch of the periodically poled structure are used, it is possible to correspond to the emitters 6 having different wavelengths by changing the temperature of the wavelength conversion element 9. In addition, if nonlinear optical crystals with the same pitch of the periodically poled structure are used, in addition to the nonlinear optical crystals that form the periodically poled structure when pulling up the crystals used in the above embodiment, the conventional bulk type nonlinear optical crystals are also compared. Easy to use.

[Fourth Embodiment]
The fourth embodiment of the present invention will be described below with reference to FIG.
FIG. 8 is a cross-sectional view (front view) of the wavelength conversion element portion of the laser light source device of the present embodiment.
Since the basic configuration of the laser light source device of this embodiment is the same as that of the first embodiment, the same reference numerals are given to the same components in FIG. 8 as those used in the first embodiment in FIG. Is omitted.

  In the case of the first embodiment, the plurality of emitters 6 are arranged in groups of three in a state where they are arranged in a line. On the other hand, in the case of the present embodiment, a plurality of emitters 6 are arranged in two rows, and each of the three emitters 6 forms one emitter group 7 and is arranged so as to line up at the apex of the triangle. . An arbitrary emitter group 7 composed of three emitters 6 has a triangle formed by one emitter 6 in the upper stage and two emitters 6 in the lower stage, and the adjacent emitter group 7 has two emitters 6 in the upper stage. In the lower stage, one emitter 6 forms a triangle. The wavelength relationship of each emitter 6 is the same as in the first embodiment.

  In the case of this embodiment as well, as in the first embodiment, the distance D1 from the center position of the three emitters 6 belonging to one emitter group 7 to the emitter 6 at the end is adjacent to the center position of one emitter group 7. It is smaller than ½ of the distance D2 from the center position of the emitter group 7. Further, the pitch P 1 between the emitters 6 in one emitter group 7 is smaller than the pitch P 2 between the emitter 6 at the end of one emitter group 7 and the emitter 6 at the end of the adjacent emitter group 7.

  Also in the laser light source device of this embodiment, the phase matching by changing the pitch of the periodically poled structure of the nonlinear optical crystal is easy, which can realize a laser light source device with low coherence of light output as a whole and high wavelength conversion efficiency. It is possible to obtain the same effects as those of the first and second embodiments, such that the temperature control of the wavelength conversion element can be easily performed.

  Further, when the arrangement as in the present embodiment is adopted, more emitters 6 and wavelength conversion elements 9 can be arranged in a predetermined area than in the first embodiment in which the emitters 6 are arranged in a line, and the cross section is reduced. The circular wavelength conversion element 9 can be effectively used to reduce the size of the apparatus.

[Fifth Embodiment]
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.
In the present embodiment, a projector including the laser light source device of the first to fourth embodiments will be described. The projector according to the present embodiment is an example of a so-called three-plate type liquid crystal projector including three sets of liquid crystal light valves that respectively modulate red light, green light, and blue light.
FIG. 9 is a schematic configuration diagram of the projector according to the present embodiment. In FIG. 9, the projector housing is omitted for simplification of the drawing.

  In the projector 30 of the present embodiment, the red laser light source (light source device) 31R, the green laser light source (light source device) 31G, and the blue laser light source (light source device) 31B that emit red light, green light, and blue light, respectively, The laser light source devices of the first to fourth embodiments are used. The projector 30 includes images formed by liquid crystal light valves (light modulation devices) 32R, 32G, and 32B that modulate laser beams emitted from the laser light sources 31R, 31G, and 31B, and liquid crystal light valves 32R, 32G, and 32B, respectively. And an image forming apparatus having a projection lens (projection device) 34 that projects the image on a screen (display surface) 33. The projector 30 also includes a cross dichroic prism (color light combining means) 35 that combines the light emitted from the liquid crystal light valves 32R, 32G, and 32B and guides the light to the projection lens 34.

  Furthermore, the projector 30 has an illuminance uniformizing optical system 36R, 36G, and an optical system 36R, 36G, and a rear stage of each laser light source 31R, 31G, 31B in order to uniformize the illuminance distribution of the laser light emitted from the laser light sources 31R, 31G, 31B. 36B is provided, and the liquid crystal light valves 32R, 32G, and 32B are illuminated by the light having a uniform illuminance distribution. The uniformizing optical systems 36R, 36G, and 36B are constituted by, for example, a hologram 37 and a field lens 38.

  The three colored lights modulated by the liquid crystal light valves 32R, 32G, and 32B are incident on the cross dichroic prism 35. 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. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 33 by the projection lens 34, which is a projection optical system, and an enlarged image is displayed.

  Since the projector 30 of the present embodiment includes the laser light source devices of the first to fourth embodiments described above, light with low coherence is efficiently emitted, so that scintillation can be efficiently suppressed and high display quality can be achieved. The obtained projector can be realized.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the number and arrangement of emitters (light emitting units) included in one laser light source and the number and arrangement of nonlinear optical crystals constituting the wavelength conversion element are not limited to the above embodiment, and can be changed as appropriate. is there. In the above embodiment, an external resonant semiconductor laser having a resonant mirror disposed outside the semiconductor laser is used. However, a semiconductor laser having an internal resonant structure may be used.

  In the embodiment of the projector, the transmissive liquid crystal light valve is used as the light modulation device, but a light valve other than the liquid crystal may be used, or a reflective light valve may be used. Examples of such a light valve include a reflective liquid crystal light valve and a digital micromirror device. The configuration of the projection optical system is appropriately changed depending on the type of light valve used. Further, the present invention is applied to a scanning image display device (projector) provided with a scanning unit that displays an image of a desired size on a display surface by scanning laser light from a laser light source (light source device) on a screen. It is also possible to do.

It is a perspective view showing the whole laser light source device composition of a 1st embodiment of the present invention. It is sectional drawing (plan view) of the laser light source device. It is sectional drawing (front view) of the laser light source device. It is a perspective view which shows the nonlinear optical crystal of the wavelength conversion element of the laser light source device. It is a perspective view which shows the whole structure of the laser light source apparatus of 2nd Embodiment of this invention. It is sectional drawing (front view) of the laser light source device. It is sectional drawing (plan view) which shows the laser light source device of 3rd Embodiment of this invention. It is sectional drawing (front view) of the laser light source apparatus of 4th Embodiment of this invention. It is a schematic block diagram of the projector of 5th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 12, 18 ... Laser light source device (light source device), 2, 13, 19 ... Semiconductor laser (light source), 3, 14, 21 ... Wavelength conversion element unit, 6 ... Emitter (light emitting part), 7 ... Emitter group ( (Light emitting part group), 9, 15 ... wavelength conversion element, 9 '... nonlinear optical crystal (optical crystal), 10, 16, 20 ... holding member, 30 ... projector.

Claims (9)

A light source having a plurality of light emitting units, and a plurality of wavelength conversion elements each having an optical crystal for wavelength-converting a plurality of lights emitted from the plurality of light emitting units,
Light emitted from at least one light emitting unit among the plurality of light emitting units is incident on one of the plurality of wavelength conversion elements,
The wavelength of light emitted from at least one light emitting unit among the wavelengths of light emitted from the plurality of light emitting units is different from the wavelength of light emitted from another light emitting unit. Light source device. The plurality of light emitting units are composed of a plurality of light emitting unit groups including a plurality of light emitting units,
Among the plurality of light emitting unit groups, an average wavelength of a plurality of lights emitted from a plurality of light emitting units belonging to at least one light emitting unit group is a plurality of light emitted from a plurality of light emitting units belonging to another light emitting unit group. The light source device according to claim 1, wherein the light source device is different from an average wavelength of light.   The light source device according to claim 2, wherein a wavelength of at least one light among a plurality of lights emitted from a plurality of light emitting units belonging to one light emitting unit group is different from a wavelength of other light.   The light source device according to claim 2, wherein the wavelengths of the plurality of lights emitted from the plurality of light emitting units belonging to one light emitting unit group are all equal.   The distance from the center position between a plurality of light emitting sections belonging to one light emitting section group to the farthest light emitting section is 1 / of the distance between the center positions of the one light emitting section group and the adjacent light emitting section group. 5. The light source device according to claim 2, wherein the light source device is smaller than 2. 5.   6. The optical crystal according to claim 1, wherein the optical crystal has a growth stripe whose crystal composition or impurity concentration is periodically changed, and the growth stripe constitutes a periodically poled structure. The light source device according to 1.   Among the optical crystals of the plurality of wavelength conversion elements, the pitch of the periodic polarization inversion structure of the optical crystal of at least one wavelength conversion element is different from the pitch of the periodic polarization inversion structure of the optical crystal of other wavelength conversion elements. The light source device according to claim 6.   The holding member that holds the plurality of wavelength conversion elements is provided, and the plurality of wavelength conversion elements and the holding member constitute a wavelength conversion element unit. Light source device.   9. A light source device according to claim 1, and an image forming device that displays an image of a desired size on a display surface using light emitted from the light source device. A projector characterized by that.

Images