JP4815641B1 - Laser light source device - Google Patents

Abstract

An output of a laser beam can be increased by adjusting a position and an angle of a wavelength conversion element with respect to an optical axis of the laser beam.
A wavelength conversion element holder 57 for holding a wavelength conversion element 35 is provided so as to be movable in a depth direction of a domain-inverted region and tiltable in an arbitrary direction with respect to a holder support portion 59. In particular, the wavelength conversion element holder 57 is provided with a spherical convex portion 91, and the holder support portion 59 is provided with a cylindrical concave portion 92 in a groove shape so as to extend in the depth direction of the domain-inverted region.
[Selection] Figure 6

Description

  The present invention relates to a laser light source device using a semiconductor laser, and more particularly to a laser light source device used for a light source of an image display device.

  In recent years, a technique using a semiconductor laser as a light source of an image display device has attracted attention. This semiconductor laser has better color reproducibility, instantaneous lighting, longer life, and higher power consumption compared to mercury lamps that have been widely used in image display devices. It has various advantages, such as being able to be made and being easy to miniaturize.

  In the laser light source device used for such an image display device, since there is no high-power semiconductor laser that directly outputs green laser light, the pumping laser light is output from the semiconductor laser, and this pumping laser light is used. A technique is known in which a laser medium is excited to output infrared laser light, and the wavelength of the infrared laser light is converted by a wavelength conversion element to output green laser light (see, for example, Patent Document 1). ).

JP 2008-16833 A

  In the green laser light source device configured as described above, since the output of the laser light changes according to the position and angle of the wavelength conversion element with respect to the optical axis of the laser light, the wavelength conversion element is at the position and angle at which the output is maximized. It is desirable to arrange. However, there is a limit to increasing the manufacturing accuracy and assembly accuracy of the wavelength conversion element, and the output varies depending on the product. Therefore, a configuration that can adjust the position and angle of the wavelength conversion element with respect to the optical axis of the laser light is desired.

  The present invention has been devised to solve such problems of the prior art, and its main purpose is to adjust the position and angle of the wavelength conversion element with respect to the optical axis of the laser light to adjust the laser light. An object of the present invention is to provide a laser light source device configured to increase output.

The laser light source device of the present invention includes a wavelength conversion element that converts a wavelength of laser light in which a domain-inverted region has a wedge shape in which the depth direction is gradually narrowed and the region is periodically formed, and the wavelength conversion device And a base having a support portion that supports the holding body, and the holding body is movable in the depth direction of the polarization inversion region with respect to the support portion. In addition, a spherical convex portion is provided in one of the holding body and the support portion, and a concave portion into which the convex portion is fitted is provided in the polarization inversion region. It is provided in a groove shape so as to extend in the depth direction, and an optical path hole through which laser light passes is formed at the center of each of the convex portion and the concave portion .

According to the present invention, the holding body can be moved and tilted with respect to the support portion with a simple configuration, and the convex portion and the concave portion are in contact with each other on the optical axis. The position in the depth direction of the polarization inversion region of the wavelength conversion element and the tilt angle with respect to the optical axis direction can be optimized without greatly changing the position of the direction , thereby increasing the output of the laser beam. .

1 is a schematic configuration diagram of an image display device 1 according to the present invention. The schematic diagram which shows the condition of the laser beam in the green laser light source apparatus 2 Perspective view of green laser light source device 2 A perspective view of the wavelength conversion element 35 Disassembled perspective view of wavelength conversion element holder 57 The perspective view which shows the wavelength conversion element holder 57 and the holder support part 59 of the base 38 Side view schematically showing the convex portion 91 of the wavelength conversion element holder 57 and the concave portion 92 of the holder support portion 59 in an enlarged manner. The figure which shows the change condition of wavelength conversion efficiency (eta) according to inclination-angle (theta) of the wavelength conversion element 35 with respect to an optical axis direction. The figure which shows the point of the position angle adjustment work of the wavelength conversion element holder 57 The perspective view which shows the adjustment condition of the position and angle of the wavelength conversion element 35 with respect to the optical axis of a laser beam The perspective view which shows the example which incorporated this image display apparatus 1 in the notebook-type information processing apparatus 111

A first invention made to solve the above-mentioned problem is a wavelength conversion for converting the wavelength of laser light in which the domain-inverted region has a wedge shape that gradually narrows in the depth direction and the region is periodically formed. An element, a holding body that holds the wavelength conversion element, and a base that includes a support portion that supports the holding body, and the holding body has the polarization inversion region with respect to the support portion. It is provided so as to be movable in the depth direction and tiltable in any direction . Further, a spherical convex portion is provided on one of the holding body and the support portion, and the convex portion is fitted on the other side. The concave portion is provided in a groove shape so as to extend in the depth direction of the domain-inverted region, and an optical path hole through which laser light passes is formed at the center of the convex portion and the concave portion .

According to this, since the holding body can be moved and tilted with respect to the support portion with a simple configuration, and the convex portion and the concave portion are in contact with each other on the optical axis, the wavelength conversion element in the optical axis direction can be adjusted according to the tilting of the holding body. Without greatly changing the position, the position in the depth direction of the polarization inversion region of the wavelength conversion element and the tilt angle with respect to the optical axis direction can be optimized, whereby the output of the laser beam can be increased.

  The wavelength conversion element includes a wedge-shaped polarization inversion region whose width gradually narrows in the depth direction of the polarization inversion region, and the wavelength conversion element is moved in the depth direction of the polarization inversion region, so that the light of the laser beam can be obtained. The ratio of the domain-inverted region on the road changes, the wavelength conversion efficiency changes accordingly, and the position of the wavelength conversion element is adjusted so that the wavelength conversion efficiency is maximized.

  In addition, by tilting the wavelength conversion element with respect to the optical axis, the path of the laser light is shifted by the refraction of the laser light on the incident surface and the output surface of the wavelength conversion element, thereby avoiding a decrease in output due to interference of the laser light. The inclination angle of the wavelength conversion element with respect to the optical axis direction is adjusted so that the output of the laser beam is maximized.

Moreover, 2nd invention sets it as the structure which has a spring which hold | maintains the said holding body in the state contact | abutted to the said support part in the said 1st invention.

  According to this, since the holding body can be prevented from falling off from the support portion during the position and angle adjustment work, the adjustment work is facilitated. In addition, it is good to use a spring for the use of the temporary fixation at the time of adjustment work, and to fix a holding body and a support part with an adhesive agent after adjustment work.

According to a third invention, in the first or second invention, the semiconductor laser that outputs the excitation laser beam and the infrared laser beam that is excited by the excitation laser beam output from the semiconductor laser is output. A laser medium that converts the wavelength of infrared laser light output from the laser medium to output green laser light, the semiconductor laser, and the laser medium. The wavelength conversion element is configured to be integrally supported by the base.

  According to this, a high output green laser beam can be output. In this case, after the semiconductor laser is fixed to the base, the position adjustment of the condenser lens, the laser medium, and the wavelength conversion element is performed with respect to the optical axis of the laser light output from the laser chip.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an image display device 1 according to the present invention. The image display device 1 projects and displays a required image on a screen, and outputs a green laser light source device 2 that outputs green laser light, a red laser light source device 3 that outputs red laser light, and a blue laser light. The blue laser light source device 4 to output, the liquid crystal reflection type spatial light modulator 5 that modulates the laser light from each laser light source device 2 to 4 according to the video signal, and the laser from each laser light source device 2 to 4 A polarization beam splitter 6 that reflects light to irradiate the spatial light modulator 5 and transmits the modulated laser light emitted from the spatial light modulator 5, and polarizes the laser light emitted from each of the laser light source devices 2 to 4. A relay optical system 7 that leads to the beam splitter 6 and a projection optical system 8 that projects the modulated laser light transmitted through the polarization beam splitter 6 onto a screen are provided.

  The image display device 1 displays a color image by a so-called field sequential method. Laser beams of each color are sequentially output from the laser light source devices 2 to 4 in a time-sharing manner, and an image by the laser beam of each color is generated by an afterimage. Recognized as a color image.

  The relay optical system 7 includes collimator lenses 11 to 13 that convert the laser beams of the respective colors emitted from the laser light source devices 2 to 4 into parallel beams, and the laser beams of the respective colors that have passed through the collimator lenses 11 to 13 in a predetermined direction. First and second dichroic mirrors 14 and 15, a diffusion plate 16 for diffusing the laser light guided by the dichroic mirrors 14 and 15, and a field lens for converting the laser light that has passed through the diffusion plate 16 into a convergent laser 17.

  Assuming that the side from which the laser light is emitted from the projection optical system 8 toward the screen S is the front side, the blue laser light is emitted backward from the blue laser light source device 4 and is green with respect to the optical axis of the blue laser light. The green laser beam and the red laser beam are emitted from the green laser light source device 2 and the red laser light source device 3 so that the optical axis of the laser beam and the optical axis of the red laser beam are orthogonal to each other. , And green laser light are guided to the same optical path by the two dichroic mirrors 14 and 15. That is, the blue laser light and the green laser light are guided to the same optical path by the first dichroic mirror 14, and the blue laser light, the green laser light, and the red laser light are guided to the same optical path by the second dichroic mirror 15.

  The first and second dichroic mirrors 14 and 15 are formed with a film for transmitting and reflecting laser light having a predetermined wavelength on the surface, and the first dichroic mirror 14 transmits blue laser light. And reflects the green laser light. The second dichroic mirror 15 transmits red laser light and reflects blue laser light and green laser light.

  Each of these optical members is supported by the casing 21. The housing 21 functions as a radiator that dissipates heat generated by the laser light source devices 2 to 4 and is formed of a material having high thermal conductivity such as aluminum or copper.

  The green laser light source device 2 is attached to an attachment portion 22 formed in the housing 21 in a state of protruding toward the side. The mounting portion 22 is provided in a state of projecting in a direction perpendicular to the side wall portion 24 from a corner portion where the front wall portion 23 and the side wall portion 24 located respectively in front and side of the accommodation space of the relay optical system 7 intersect. ing. The red laser light source device 3 is attached to the outer surface side of the side wall portion 24 while being held by the holder 25. The blue laser light source device 4 is attached to the outer surface side of the front wall portion 23 while being held by the holder 26.

  The red laser light source device 3 and the blue laser light source device 4 are configured by a so-called CAN package, and the optical axis is positioned on the central axis of the can-shaped exterior portion with the laser chip that outputs the laser light supported by the stem. The laser beam is emitted from a glass window provided in the opening of the exterior part. The red laser light source device 3 and the blue laser light source device 4 are fixed to the holders 25 and 26 by, for example, press-fitting into mounting holes 27 and 28 provided in the holders 25 and 26. The heat generated by the laser chips of the blue laser light source device 4 and the red laser light source device 3 is transmitted to the housing 21 through the holders 25 and 26 to be dissipated, and each of the holders 25 and 26 has a thermal conductivity such as aluminum or copper. It is made of a high material.

  The green laser light source device 2 includes a semiconductor laser 31 that outputs excitation laser light, a FAC (Fast-Axis Collimator) lens 32 that is a condensing lens that condenses the excitation laser light output from the semiconductor laser 31, and a rod. The lens 33, the laser medium 34 that is excited by the excitation laser light and outputs the basic laser light (infrared laser light), and converts the wavelength of the basic laser light to output the half-wavelength laser light (green laser light). A wavelength conversion element 35, a concave mirror 36 that constitutes a resonator together with the laser medium 34, a glass cover 37 that prevents leakage of excitation laser light and fundamental wavelength laser light, a base 38 that supports each part, and each part A cover body 39 for covering.

  The green laser light source device 2 is fixed by attaching a base 38 to the mounting portion 22 of the housing 21, and a required width (for example, 0.5 mm) between the green laser light source device 2 and the side wall portion 24 of the housing 21. The following gaps are formed. This makes it difficult for the heat of the green laser light source device 2 to be transmitted to the red laser light source device 3, suppresses the temperature rise of the red laser light source device 3, and allows the red laser light source device 3 with poor temperature characteristics to operate stably. Can do. Further, in order to secure a required optical axis adjustment allowance (for example, about 0.3 mm) of the red laser light source device 3, a required width (for example, 0.3 mm or more) is provided between the green laser light source device 2 and the red laser light source device 3. ) Is provided.

  FIG. 2 is a schematic diagram showing a state of laser light in the green laser light source device 2. The laser chip 41 of the semiconductor laser 31 outputs excitation laser light having a wavelength of 808 nm. The FAC lens 32 reduces the spread of the first axis of the laser light (the direction orthogonal to the optical axis direction and along the drawing sheet). The rod lens 33 reduces the spread of the slow axis of laser light (in the direction orthogonal to the drawing sheet).

The laser medium 34 is a so-called solid laser crystal, and is excited by excitation laser light having a wavelength of 808 nm that has passed through the rod lens 33 and outputs a fundamental wavelength laser light (infrared laser light) having a wavelength of 1064 nm. This laser medium 34 is obtained by doping Nd (neodymium) into an inorganic optically active substance (crystal) made of Y (yttrium) VO ₄ (vanadate), and more specifically, Y of YVO _{4 as} a base material. And doped with Nd ⁺³ which is an element that emits fluorescence.

  On the side of the laser medium 34 facing the rod lens 33, a film 42 having a function of preventing reflection of excitation laser light having a wavelength of 808 nm and high reflection of laser light having a fundamental wavelength of 1064 nm and half-wavelength laser light having a wavelength of 532 nm. Is formed. On the side of the laser medium 34 facing the wavelength conversion element 35, a film 43 having an antireflection function for the fundamental wavelength laser beam having a wavelength of 1064 nm and the half wavelength laser beam having a wavelength of 532 nm is formed.

  The wavelength conversion element 35 is a so-called SHG (Second Harmonics Generation) element, which converts the wavelength of a fundamental wavelength laser beam (infrared laser beam) having a wavelength of 1064 nm output from the laser medium 34 to generate a half-wavelength laser beam having a wavelength of 532 nm. (Green laser light) is generated.

  On the side of the wavelength conversion element 35 facing the laser medium 34, a film 44 having functions of preventing reflection of the fundamental wavelength laser beam having a wavelength of 1064 nm and highly reflecting the half wavelength laser beam having a wavelength of 532 nm is formed. On the side facing the concave mirror 36 in the wavelength conversion element 35, a film 45 having an antireflection function for the fundamental wavelength laser beam having a wavelength of 1064 nm and the half wavelength laser beam having a wavelength of 532 nm is formed.

  The concave mirror 36 has a concave surface on the side facing the wavelength conversion element 35, and this concave surface has a function of high reflection with respect to a fundamental wavelength laser beam with a wavelength of 1064 nm and antireflection with respect to a half wavelength laser beam with a wavelength of 532 nm. A film 46 is formed. As a result, the fundamental wavelength laser beam having a wavelength of 1064 nm resonates and is amplified between the film 42 of the laser medium 34 and the film 46 of the concave mirror 36.

  In the wavelength conversion element 35, a part of the fundamental wavelength laser light having a wavelength of 1064 nm incident from the laser medium 34 is converted into a half-wavelength laser light having a wavelength of 532 nm and passed through the wavelength conversion element 35 without being converted. The laser beam is reflected by the concave mirror 36 and is incident on the wavelength conversion element 35 again, and is converted into a half-wavelength laser beam having a wavelength of 532 nm. The half-wavelength laser light having a wavelength of 532 nm is reflected by the film 44 of the wavelength conversion element 35 and is emitted from the wavelength conversion element 35.

  Here, the laser beam B1 incident on the wavelength conversion element 35 from the laser medium 34, wavelength-converted by the wavelength conversion element 35 and emitted from the wavelength conversion element 35, and the wavelength conversion element once reflected by the concave mirror 36. In the state where the laser beam B2 that is incident on 35 and reflected by the film 44 and emitted from the wavelength conversion element 35 overlaps with each other, the half-wavelength laser beam having a wavelength of 532 nm and the fundamental wavelength laser beam having a wavelength of 1064 nm interfere with each other. Wake up and output decreases.

  Therefore, here, the wavelength conversion element 35 is inclined with respect to the optical axis direction so that the laser beams B1 and B2 do not overlap with each other by the refracting action at the entrance surface 35a and the exit surface 35b. Thus, interference between the half-wavelength laser beam and the fundamental wavelength laser beam having a wavelength of 1064 nm is prevented, so that a reduction in output can be avoided.

  The glass cover 37 shown in FIG. 1 is formed with a film that does not transmit these laser beams in order to prevent the excitation laser beam having a wavelength of 808 nm and the fundamental wavelength laser beam having a wavelength of 1064 nm from leaking to the outside. ing.

  FIG. 3 is a perspective view of the green laser light source device 2. The semiconductor laser 31, FAC lens 32, rod lens 33, laser medium 34, wavelength conversion element 35, and concave mirror 36 are integrally supported by a base 38. The bottom surface 51 of the base 38 is parallel to the optical axis direction. Here, the direction orthogonal to the bottom surface 51 of the base 38 is defined as the height direction, and the direction orthogonal to the height direction and the optical axis direction is defined as the width direction. In addition, the side close to the bottom surface 51 of the base 38 will be described below, and the side opposite to the bottom surface 51 will be described above, but this does not necessarily coincide with the vertical direction of the actual apparatus.

  The semiconductor laser 31 is obtained by mounting a laser chip 41 that outputs laser light on a mount member 52. The laser chip 41 has a long strip shape in the optical axis direction, and is fixed to a substantially central position in the width direction of one surface of the plate-shaped mount member 52 in a state where the light emission surface faces the FAC lens 32 side. Yes. The semiconductor laser 31 is supported by a support portion 53 formed integrally with the base 38.

  The FAC lens 32 and the rod lens 33 are held by a condenser lens holder 54. The condenser lens holder 54 is supported by a support portion 55 formed integrally with the base 38. The condensing lens holder 54 is coupled to the support portion 55 so as to be movable in the optical axis direction, whereby the positions of the condensing lens holder 54, that is, the FAC lens 32 and the rod lens 33 are adjusted in the optical axis direction. . The FAC lens 32 and the rod lens 33 are fixed to the condenser lens holder 54 with an adhesive before the position adjustment work, and after the position adjustment work, the condenser lens holder 54 and the support portion 55 are fixed to each other with an adhesive. .

  The laser medium 34 is held by a holding portion 56 formed integrally with the base 38. The laser medium 34 and the holding unit 56 are fixed to each other with an adhesive.

  The wavelength conversion element 35 is held by a wavelength conversion element holder 57. The wavelength conversion element holder 57 is positioned relative to a holder support portion 59 formed integrally with the base 38 so that the position of the wavelength conversion element 35 in the width direction and the inclination angle with respect to the optical axis direction can be adjusted. , So as to be movable in the width direction and tiltable in an arbitrary direction. The wavelength conversion element holder 57 will be described in detail later. The wavelength conversion element 35 is fixed to the wavelength conversion element holder 57 with an adhesive before the position adjustment work, and after the position adjustment work, the wavelength conversion element holder 57 and the holder support portion 59 are fixed to each other with an adhesive.

  The wavelength conversion element holder 57 is held in a state of being pressed against the holder support portion 59 by the urging force of the spring 58. The spring 58 is provided in a compressed state between the concave mirror support 60 integrally formed on the base 38 and the wavelength conversion element holder 57, and in a direction to press the wavelength conversion element holder 57 against the holder support 59. Energize. The biasing force of the spring 58 is used for temporary fixing at the time of position angle adjustment, and the wavelength conversion element holder 57 and the holder support portion 59 are fixed with an adhesive after the position angle adjustment work. Here, although the spring 58 is a coil spring, other types of springs such as a leaf spring may be used.

  The concave mirror 36 is supported by a concave mirror support portion 60 formed integrally with the base 38. The glass cover 37 is held by the cover body 39 shown in FIG.

  The adhesive used for fixing each member, for example, the wavelength conversion element holder 57 and the holder support 59, is preferably a UV curable adhesive, for example.

  FIG. 4 is a perspective view of the wavelength conversion element 35. The wavelength conversion element 35 is provided with a periodic polarization inversion structure in which polarization inversion regions 71 and non-polarization inversion regions 72 are alternately formed in a ferroelectric crystal. The fundamental wavelength laser light is incident in the direction (71). As a result, it is possible to obtain a laser beam having a double frequency, that is, a half wavelength, by the second harmonic generation of incident light by quasi phase matching.

  When an electric field in a direction opposite to the polarization direction is applied to a unipolar ferroelectric crystal using the periodic electrode 73 and the counter electrode 74, the polarization direction of the portion corresponding to the periodic electrode 73 is reversed, and the polarization inversion region 71 is A wedge shape is formed from the electrode 73 toward the counter electrode 74.

  Actually, after forming a domain-inverted structure on a ferroelectric crystal substrate and cutting it to a required dimension, one wavelength conversion element 35 is obtained. The incident surface 35a and the exit surface 35b are precisely It is formed on a plane parallel to the depth direction of the domain-inverted region 71 by appropriate optical polishing. Finally, the periodic electrode 73 and the counter electrode 74 on the side surfaces 35c and 35d are removed by polishing. As the ferroelectric crystal, for example, LN (lithium niobate) added with MgO is used.

  The domain-inverted region 71 has a wedge shape whose width is gradually narrowed along the depth direction, and the wavelength conversion element 35 is moved in the depth direction of the domain-inverted region 71 with respect to the incident laser light. The ratio between the polarization inversion region 71 and the non-polarization inversion region 72 located on the optical path of light changes, and the wavelength conversion efficiency changes accordingly. Therefore, the position of the wavelength conversion element 35 with respect to the optical axis of the laser beam is adjusted so that the wavelength conversion efficiency is maximized, that is, the output of the laser beam is maximized. The position adjustment of the wavelength conversion element 35 will be described in detail later.

  FIG. 5 is an exploded perspective view of the wavelength conversion element holder 57. FIG. 6 is a perspective view showing the wavelength conversion element holder 57 and the holder support portion 59 of the base 38. FIG. 7 is a side view schematically showing the convex portion 91 of the wavelength conversion element holder 57 and the concave portion 92 of the holder support portion 59 in an enlarged manner.

  As shown in FIG. 5, the wavelength conversion element holder 57 is loaded with an accommodation hole 81 for accommodating the wavelength conversion element 35 and an adhesive for fixing the wavelength conversion element 35 to the wavelength conversion element holder 57. A loading hole 82, an opening 84 for bringing the ground plate 83 into contact with the wavelength conversion element 35 in the accommodation hole 31, and an optical path hole 85 for guiding laser light to the wavelength conversion element 35 in the accommodation hole 31 are provided. Yes.

  The incident surface 35a and the exit surface 35b of the wavelength conversion element 35 have a high degree of parallelism secured by precise polishing, but the side surfaces 35c and 35d, the top surface 35e, and the bottom surface 35f of the wavelength conversion element 35 are incident. The perpendicularity with respect to the surface 35a and the emission surface 35b and the parallelism between the opposing surfaces are not ensured, and there is a manufacturing error that occurs when cutting out from the substrate. For this reason, the wavelength conversion element 35 is positioned by bringing the incident surface 35a, which ensures accuracy, into contact with the reference surface 87 where the optical path hole 85 is opened.

  The ground plate 83 is configured by a leaf spring having a substantially U shape, and is made of a conductive material such as a metal material. The ground plate 83 is assembled to the wavelength conversion element holder 57 so as to sandwich the wavelength conversion element 35, and is elastically applied to the two side surfaces 35c and 35d facing the depth direction of the polarization inversion region 71 in the wavelength conversion element 35. The contact part 86 which contacts is provided. Thereby, the side surfaces 35c and 35d of the wavelength conversion element 35 are electrically connected to each other, and the side surfaces 35c and 35d can be maintained at the same potential, thereby suppressing a change in refractive index due to charge-up.

  As shown in FIG. 6, the wavelength conversion element holder 57 is provided with a spherical convex portion 91, while the holder support portion 59 is provided with a cylindrical concave portion 92. The wavelength conversion element holder 57 is assembled in a state in which the convex portions 91 are brought into contact with the concave portions 92 of the holder support portion 59 so that the opposed surfaces 93 and 94 of the wavelength conversion element holder 57 and the holder support portion 59 are substantially parallel to each other. . The concave portion 92 of the holder support portion 59 is provided in a groove shape so as to extend in the depth direction of the polarization inversion region of the wavelength conversion element 35 in the assembled state of the wavelength conversion element holder 57. As a result, the wavelength conversion element holder 57 can move in the depth direction of the domain-inverted region of the wavelength conversion element 35 and tilt in any direction with respect to the holder support portion 59.

  As shown in FIG. 7, the convex portion 91 of the wavelength conversion element holder 57 is formed into a spherical surface having a larger diameter than the cylindrical surface of the concave portion 92 of the holder support portion 59. Thereby, since the convex part 91 contacts at the two points P1 and P2 of the both end edges of the concave part 92, it is possible to prevent play between the convex part 91 and the concave part 92, and the depth direction of the polarization inversion region It is possible to restrict the wavelength conversion element holder 57 from moving in different directions. On the other hand, when the convex portion 91 is formed in a spherical surface having a smaller diameter than the cylindrical surface of the concave portion 92, play occurs between the convex portion 91 and the concave portion 92, and the convex portion 91 is If it is formed in a spherical surface having the same diameter as the cylindrical surface of 92, the rotation of the convex portion 91 with respect to the concave portion 92 is not smooth, which is not desirable.

  As shown in FIG. 6, the optical path hole 85 for guiding the laser beam to the wavelength conversion element 35 held by the wavelength conversion element holder 57 is formed at the center of the convex portion 91. The holder support portion 59 is formed integrally with the holding portion 56 of the laser medium 34, and an optical path hole 95 that guides the laser light emitted from the laser medium 34 is opened at the center of the concave portion 92 of the holder support portion 59. Yes. In this way, when the optical path holes 85 and 95 through which the laser beam passes are formed at the centers of the convex portion 91 and the concave portion 92 so that the convex portion 91 and the concave portion 92 are in contact with each other on the optical axis, the wavelength conversion element holder 57 It can be avoided that the position of the wavelength conversion element 35 in the optical axis direction greatly changes in accordance with the tilt of.

  Further, as shown in FIG. 7, the optical path hole 85 on the wavelength conversion element holder 57 side is formed in a circular shape having a larger diameter than the optical path hole 95 on the holder support part 59 side. As a result, even if the positional relationship between the optical path hole 85 on the wavelength conversion element holder 57 side and the optical path hole 95 on the holder support portion 59 side is slightly shifted with the movement and tilting of the wavelength conversion element holder 57 during the position angle adjustment. The optical path holes 85 and 95 can be prevented from being blocked.

  As described above, the wavelength conversion element holder 57 and the holder support portion 59 are fixed with an adhesive after the position angle adjustment operation, but a groove is provided using the recess 92 of the holder support portion 59 or separately. In this case, it is preferable to fix the adhesive 91 in the vicinity of the convex portion 91, so that the change of the angle of the wavelength conversion element holder 57 due to the shrinkage at the time of curing of the adhesive can be suppressed.

  FIG. 8 is a diagram illustrating a change state of the wavelength conversion efficiency η according to the inclination angle θ of the wavelength conversion element 35 with respect to the optical axis direction. The wavelength conversion efficiency η of the wavelength conversion element 35 changes according to the inclination angle θ of the wavelength conversion element 35 with respect to the optical axis direction, and in a state where the wavelength conversion element 35 is not inclined with respect to the optical axis direction (θ = 0), the wavelength conversion efficiency η The wavelength conversion efficiency η can be increased by tilting with respect to the optical axis direction.

  As shown in FIG. 2, when the tilt angle θ is 0, the laser beam beams B1 and B2 overlap each other, so that the half-wavelength laser beam having a wavelength of 532 nm and the fundamental wavelength laser beam having a wavelength of 1064 nm interfere with each other. By tilting the wavelength conversion element 35 with respect to the optical axis direction, the laser beams B1 and B2 are shifted due to refraction at the entrance surface 35a and the exit surface 35b. Can tilt output drop.

  In particular, here, the wavelength conversion element 35 is inclined so as to enter a high-efficiency region within a required range (for example, ± 0.4 degrees) centered on a peak point of wavelength conversion efficiency (here, θ = ± 0.6 degrees). The angle θ is adjusted, and the dimensions of each part are set so that the wavelength conversion element holder 57 can be tilted with respect to the holder support part 59 within an angle range corresponding to the adjustment allowance.

  FIGS. 9A and 9B are diagrams showing the procedure for adjusting the position angle of the wavelength conversion element holder 57, FIGS. 9A and 9B are top views, and FIG. 9C is a side view. FIG. 10 is a perspective view showing an adjustment state of the position and angle of the wavelength conversion element 35 with respect to the optical axis of the laser beam.

  FIG. 9A shows a situation in which the wavelength conversion element holder 57 is moved in the width direction. Here, when a portion close to the convex portion 91 in the wavelength conversion element holder 57 is pressed with a pair of jigs 101 and 102 facing in the width direction, the convex portion 91 of the wavelength conversion element holder 57 becomes a concave portion of the holder support portion 59. The wavelength conversion element holder 57 can be moved in the width direction by sliding along the line 92. Thereby, as indicated by an arrow A in FIG. 10, the wavelength conversion element 35 can be moved in the depth direction of the polarization inversion region 71 with respect to the optical axis of the laser light.

  FIG. 9B shows a situation in which the wavelength conversion element holder 57 is tilted in the width direction. Here, when a portion of the wavelength conversion element holder 57 away from the convex portion 91 is pressed with a pair of jigs 101 and 102 facing in the width direction, the wavelength is centered on the convex portion 91 of the wavelength conversion element holder 57. The conversion element holder 57 can be tilted in the width direction. As a result, as indicated by an arrow B in FIG. 10, the wavelength conversion element 35 can be tilted in the width direction with respect to the optical axis of the laser light.

  FIG. 9C shows a situation in which the wavelength conversion element holder 57 is tilted in the height direction. Here, when a portion away from the convex portion 91 in the wavelength conversion element holder 57 is pressed with a pair of jigs 103 and 104 facing in the height direction, the convex portion 91 of the wavelength conversion element holder 57 is centered. The wavelength conversion element holder 57 can be tilted in the height direction. Thereby, as shown by the arrow C in FIG. 10, the wavelength conversion element 35 can be tilted in the height direction with respect to the optical axis of the laser beam.

  Next, the procedure for adjusting the position angle of the wavelength conversion element 35 will be described. First, the position of the wavelength conversion element 35 in the width direction (the depth direction of the domain-inverted region) is adjusted. This position adjustment is performed while monitoring the output with a power meter. As shown in FIG. 9A, the wavelength conversion element holder 57 is moved in the width direction so that the output is maximized.

  Next, the angle of the wavelength conversion element holder 57 is adjusted so that the inclination angle θ of the wavelength conversion element 35 with respect to the optical axis direction becomes 0 degree (see FIG. 8). This angle adjustment is performed while monitoring the shape of the laser beam. As shown in FIGS. 9B and 9C, the wavelength conversion element holder 57 is tilted in both the height direction and the width direction. Thus, the laser beam is adjusted to be one. As a result, the inclination angle θ of the wavelength conversion element 35 becomes 0 degrees.

  Finally, the angle of the wavelength conversion element holder 57 is adjusted so that the inclination angle θ of the wavelength conversion element 35 falls within a predetermined high efficiency region (see FIG. 8). This angle adjustment is performed while monitoring the output with a power meter. As shown in FIGS. 9B and 9C, the wavelength conversion element holder 57 is moved in either the height direction or the width direction. Tilt to adjust the angle to maximize the output. Thereby, the inclination angle θ of the wavelength conversion element 35 enters a predetermined high efficiency region, and as shown in FIG. 2, it is possible to prevent interference due to the overlap of the two beams B1 and B2 of the laser light.

  FIG. 11 is a perspective view showing an example in which the image display apparatus 1 is built in a notebook information processing apparatus 111. In the housing 112 of the information processing device 111, a housing space in which the image display device 1 is retractable is formed on the back side of the keyboard, and the image display device 1 is housed in the housing 112 when not in use. In use, the image display device 1 is pulled out from the housing 112, and the image display device 1 is rotated at a required angle with respect to the base portion 113 that supports the image display device 1 so as to be rotatable. Laser light from the display device 1 can be projected onto the screen.

  In the above example, as shown in FIG. 6, the wavelength conversion element holder 57 is provided with the convex portion 91, and the holder support portion 59 is provided with the concave portion 92. A recess may be provided in the holder, and a protrusion may be provided in the holder support portion 59.

  In the above example, the convex portion 91 is formed in a spherical shape and the concave portion 92 is formed in a cylindrical surface shape. However, as shown in FIG. The concave portions 92 are not necessarily formed in a cylindrical surface shape, and may be formed in, for example, a trapezoidal shape or a square cross-sectional shape.

  In the above example, the laser chip 41, the laser medium 34, and the wavelength conversion element 35 of the green laser light source device 2 are respectively the excitation laser beam having a wavelength of 808 nm and the fundamental wavelength laser beam (infrared laser beam) having a wavelength of 1064 nm. In addition, although half-wavelength laser light (green laser light) having a wavelength of 532 nm is output, the present invention is not limited to this. The laser light finally outputted from the green laser light source device 2 may be anything that can be recognized as green. For example, it is preferable to output laser light in a wavelength region in which the peak wavelength is in the range of 500 nm to 560 nm.

  In the above example, as shown in FIG. 5, the reference surface 87 for positioning the wavelength conversion element 35 is a single plane, and the emission surface 35b of the wavelength conversion element 35 is in contact with the entire surface. However, at the position where the reference surface 87 is provided, three convex portions having the same height are provided so as to surround the optical path hole 85, and the wavelength conversion element 35 is provided on the top surface of the convex portion. It may be a reference plane for positioning. In this configuration, the wavelength conversion element 35 is supported at three points.

  As in the example shown in FIG. 5, when the reference surface 87 is a single plane, there is a limit to increasing the accuracy of the flatness of the reference surface 87, and thus the wavelength conversion element 35 slightly fluctuates. In this case, the mounting angle of the wavelength conversion element 35 is not fixed to one. The angle change due to the backlash of the wavelength conversion element 35 is difficult to predict, and the mounting angle of the wavelength conversion element 35 varies. Furthermore, there is also a variation in the shrinkage when the adhesive is cured, and this increases the variation in the mounting angle of the wavelength conversion element 35.

  On the other hand, in the configuration in which the wavelength conversion element 35 is supported at three points by the three convex portions, the wavelength conversion element 35 is not rattled and the wavelength conversion element 35 is stably supported. Furthermore, since it becomes difficult to be affected by variation factors such as dents, foreign object biting, and component deformation, variation in the mounting angle of the wavelength conversion element 35 is reduced. Therefore, the range of angle adjustment of the wavelength conversion element 35 can be set narrow, the yield can be improved, and the angle adjustment work of the wavelength conversion element 35 can be simplified.

  The laser light source device according to the present invention has the effect of adjusting the position and angle of the wavelength conversion element with respect to the optical axis of the laser light to increase the output of the laser light, and is used for the light source of the image display device It is useful as a device.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 2 Green laser light source apparatus 3 Red laser light source apparatus 4 Blue laser light source apparatus 31 Semiconductor laser 34 Laser medium 35 Wavelength conversion element 38 Base 57 Wavelength conversion element holder (holding body)
58 Spring 59 Holder support part (support part)
71 Polarization inversion region 72 Non-polarization inversion region 85 Optical path hole 91 Convex part 92 Concave part 95 Optical path hole 101 to 104 Jig

Claims (3)

A wavelength conversion element that converts the wavelength of laser light in which the domain-inverted region has a wedge shape that gradually narrows in the depth direction, and the region is periodically formed;
A holder for holding the wavelength conversion element;
A base having a support portion for supporting the holding body,
The holding body is provided so as to be movable in the depth direction of the domain-inverted region and tiltable in an arbitrary direction with respect to the support portion .
Furthermore, a spherical convex portion is provided on one of the holding body and the support portion, and on the other side, a groove shape is formed so that a concave portion into which the convex portion is fitted extends in the depth direction of the polarization inversion region. Provided in
An optical path device through which a laser beam passes is formed at the center of each of the convex portion and the concave portion . The laser light source device according to claim 1, further comprising a spring that holds the holding body in a state of being in contact with the support portion. A semiconductor laser that outputs excitation laser light, and a laser medium that is excited by the excitation laser light output from the semiconductor laser and outputs infrared laser light,
The wavelength conversion element converts the wavelength of infrared laser light output from the laser medium and outputs green laser light,
3. The laser light source device according to claim 1 , wherein the semiconductor laser, the laser medium, and the wavelength conversion element are integrally supported by the base. 4.

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