Patent Abstract:
Included are, a module fixing body having a plurality of mounting holes into which laser modules are fitted and accommodated, respectively; an electricity-supplying member having an end provided with electricity-supplying terminals, which are connected to electricity-receiving terminals of the laser module accommodated in the mounting hole; and a cooling member that cools each of the laser modules. A groove in which the electricity-supplying member is accommodated is formed in a surface of the module fixing body, and the cooling member is closely arranged on the surface of the module fixing body.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a light source device used for a picture display device or the like, and more particularly to a light source device that synthesizes laser beams emitted from a plurality of semiconductor laser devices and concentrates the beams into an optical fiber in order to obtain a predetermined light output. 
     2. Description of the Related Art 
     A conventional light source device, which synthesizes laser beams emitted from a plurality of semiconductor laser devices and concentrates the beams into an optical fiber, in order to obtain a predetermined light output, is configured to include: a plurality of chip-like semiconductor lasers arranged and fixed on a heat block; collimator lens arrays provided corresponding to the semiconductor lasers; a condenser lens that concentrates collimator light flux generated by the collimator lens arrays into one optical fiber; and a box-like package that air-tightly seals these multiplexing optical systems. 
     According to the light source device of this kind, to concentrate laser beams emitted from the semiconductor laser devices into an optical fiber, the semiconductor laser devices, the collimator lens arrays, the condenser lens, and the optical fiber must be fixed with a predetermined positional precision in a state that inclinations of these parts precisely match with each other. To fix these parts in this manner, there is proposed a structure in which inclinations of precisely formed parts are measured by a laser automatic collimator and in this state, these parts are positioned precisely by a mechanical hand and are adhered and fixed (see, for example, Japanese Patent Application Laid-open No. 2006-284851 (Page 7 and FIG. 1)). 
     When a semiconductor laser device having an emission wavelength in a range of 350 to 450 nanometers is used, organic gas (out gas) components of e.g., an adhesive for fixing multiplexing optical systems are deposited on a light emitting unit and an optical member, and this deteriorates laser characteristics. To solve this problem, there is proposed a light source device in which the concentration of organic gas in a package is limited to less than 1000 parts per million (ppm), and inert gas having an oxygen concentration in a range of 1 to 100 ppm is enclosed into the package (see, for example, Japanese Patent No. 4115732 (Page 5 and FIG. 2)). 
     However, the conventional light source device has a problem in that, due to the above configuration, a structure for taking wires for driving the semiconductor laser out of the hermetic package becomes complicated. 
     The semiconductor laser device generates a large quantity of heat by emitting light, and accordingly has characteristics such that its light emitting efficiency is deteriorated by the heat and thus its lifetime is reduced, and its wavelength is shifted. Therefore, it is important to control heat radiation and the temperature thereof. However, the semiconductor laser device has a problem in that it cannot efficiently release the heat to outside from a fixed heat block to which the semiconductor laser device is fixed. Because the condenser lens and the semiconductor laser device are arranged on the same base plate, the thermal capacity of a portion whose temperature is to be controlled is large, and the cooling operation cannot be efficiently performed. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     A light source device according to an aspect of the present invention having a plurality of laser modules, in each of which a semiconductor laser is arranged on one side of a stem and electricity-receiving terminals, which receive electricity for driving the semiconductor laser, are arranged on the other side of the stem, and configured to concentrate laser beams emitted from the laser modules and emit the concentrated laser beams, includes: a module fixing body having a plurality of mounting holes into which the laser modules are fitted and accommodated, respectively; an electricity-supplying member having an end provided with electricity-supplying terminals, which are connected to the electricity-receiving terminals of the laser module accommodated in the mounting hole; and a cooling member that cools each of the laser modules, wherein a groove in which the electricity-supplying member is accommodated is formed in a surface of the module fixing body, and the cooling member is closely arranged on the surface of the module fixing body. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a sectional view of a configuration of a light source device according to a first embodiment of the present invention; 
         FIG. 2  depicts a bottom view of a configuration of the light source device according to the first embodiment; 
         FIG. 3  depicts an exploded view of a configuration of the light source device according to the first embodiment; 
         FIGS. 4A and 4B  depict perspective views of a detailed configuration of an LD holder according to the first embodiment; 
         FIG. 5  depicts an enlarged view of a state after the LD holder into which an LD according to the first embodiment is press-fitted is adhered and fixed to a base; 
         FIG. 6  depicts another enlarged view of a state after the LD holder into which the LD according to the first embodiment is press-fitted is adhered and fixed to a base; 
         FIG. 7  depicts a perspective view explaining an adjusting and fixing method of an LD-I according to the first embodiment; 
         FIG. 8  depicts a bottom view explaining the adjusting and fixing method of the LD-I according to the first embodiment; 
         FIG. 9  depicts a perspective view explaining an adjusting and fixing method of an LD-III according to the first embodiment; 
         FIG. 10  depicts a bottom view explaining the adjusting and fixing method of the LD-III according to the first embodiment; 
         FIG. 11  depicts a bottom view explaining a method of additionally applying and curing an adhesive according to the first embodiment; 
         FIG. 12  depicts a schematic diagram explaining a method of sucking out gas according to the first embodiment; 
         FIG. 13  depicts an exploded view of a configuration of the entire light source device according to the first embodiment; 
         FIG. 14  depicts a perspective view of a configuration of the light source device according to the first embodiment in its entirety after assembling; 
         FIG. 15  depicts a sectional view of a configuration of the entire light source device according to the first embodiment; 
         FIG. 16  depicts a configuration of a flexible printed board according to the first embodiment; 
         FIG. 17  depicts a sectional view explaining a soldering method of the flexible printed board according to the first embodiment; 
         FIG. 18  depicts a bottom view explaining the soldering method of the flexible printed board according to the first embodiment; 
         FIG. 19  depicts an exploded view of a configuration of relevant parts of a light source device according to a second embodiment the present invention; 
         FIG. 20  depicts an assembly diagram of a configuration of relevant parts of the light source device according to the second embodiment; 
         FIG. 21  depicts a sectional view of a configuration of relevant parts of the light source device according to the second embodiment; 
         FIG. 22  depicts a bottom view of a soldering method of a flexible printed board according to the second embodiment; and 
         FIG. 23  depicts a sectional view of a configuration of the entire light source device according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Exemplary embodiments of a light source device according to the present invention will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments. 
     First Embodiment 
       FIGS. 1 to 3  depict a configuration of a light source device according to a first embodiment of the present invention, where  FIG. 1  is a sectional view,  FIG. 2  is a bottom view, and  FIG. 3  is an exploded view.  FIG. 1  is the sectional view taken along a line  1 - 1  in  FIG. 2 . 
     A base  1  is formed from aluminum die-cast, seven stepped holes  1   a  to  1   g  in total are formed in the base  1  at a center and on a circumference around this center at equal distances from one another on the circumference. Semi-circular notches  1   h  and  1   i  having different sizes are precisely formed in outer peripheral portions of the base  1 . Centers of the notches  1   h  and  1   i  are asymmetric about a center of the stepped hole  1   d  formed at the central portion. A first collimator lens  2 , a first spacer  3 , and a second collimator lens  4  are fitted to each of the seven stepped holes  1   a  to  1   g , and the second collimator lens  4  slightly projects from an upper surface  1   j  of the base  1 . A leaf spring  5  is formed into a flat-plate shape by etching a spring stainless steel (SUS301) such that gimbal spring-like spring portions are provided at positions corresponding to the seven stepped holes  1   a  to  1   g  of the base  1 . Notches  5   a  and  5   b  are provided at positions corresponding to the notches  1   h  and  1   i  of the base  1 . A restraining plate  6  is formed into a flat-plate shape by stamping a stainless material (SUS304) thicker than the leaf spring  5  such that holes corresponding to the seven stepped holes  1   a  to  1   g  of the base  1  and notches  6   a  and  6   b  corresponding to the notches  1   h  and  1   i  of the base  1  are formed. The restraining plate  6  presses the leaf spring  5  so that a portion thereof except the spring portion is not deformed. The leaf spring  5  and the restraining plate  6  are fixed without deviation by a plurality of screws  7  such that the notches  5   a ,  5   b ,  6   a , and  6   b  match with the notches  1   h  and  1   i  of the base  1 , and the leaf spring  5  and the restraining plate  6  are pressed against the upper surface  1   j  of the base  1 . Because the notches  1   h  and  1   i  are arranged asymmetric around the center of the stepped hole  1   d  that is arranged at the central portion, front and back surfaces of the leaf spring  5  and the restraining plate  6  are determined uniquely. Also, the leaf spring  5  and the restraining plate  6  do not float or deviate from each other due to a burr or a flatness of the part. With the above configuration, a collimator lens group, which includes the first collimator lens  2 , the first spacer  3 , and the second collimator lens  4 , is precisely fixed to the base  1  such that a deviation is not generated even if a vibration or an impact is applied. Because an adhesive is not used, even if it becomes necessary to disassemble the device for removing a foreign matter, the device can be disassembled such that all of the parts can be reused, and the optics such as the first collimator lens  2  and the second collimator lens  4  are not contaminated by out gas of an adhesive. 
     A lens barrel  8  is made by cutting aluminum. A first condenser lens  9 , a second spacer  10 , and a second condenser lens  11  are fitted into the lens barrel  8 , and they are fixed by a screw ring  12 . The second spacer  10  and the screw ring  12  are made of brass. A recess  12   a  is provided in a central portion of a side surface of the screw ring  12 . A setscrew  13  is screwed from a side surface of the lens barrel  8 , and a tip end of the setscrew  13  is inserted into the recess  12   a . With this arrangement, the recess  12   a  is fixed to the lens barrel  8  such that it is not loosened. A receptacle  14  made of brass is fixed to an upper surface of the lens barrel  8  by screws  15  such that an optical fiber  16  can be attached and detached. With this configuration, a condenser lens group formed of the first condenser lens  9 , the second spacer  10 , and the second condenser lens  11  is precisely fixed to the base  1  such that the group is not deviated even if a vibration or an impact is applied to the group. Because an adhesive is not used, even if it becomes necessary to disassemble the device for removing a foreign matter, the device can be disassembled such that all of parts can be reused without damaging the screw portion of the screw ring  12 . Also, the optics such as the first condenser lens  9 , the second condenser lens  11  and the optical fiber  16  are not contaminated by out gas of an adhesive. 
     A spacer  17  is a molded article made of polycarbonate having glass fibers, and the base  1  is fitted into a cylindrical portion of the spacer  17 . Projections  17   a  and  17   b  corresponding to the notches  1   h  and  1   i  of the base  1  are formed inside of the cylindrical portion. A projection  17   c  corresponding to the notch  8   a  provided in the lens barrel  8  is provided on outside of the cylindrical portion. In a state that the base  1  and the lens barrel  8  are positioned precisely, they are fastened to the spacer  17  by four conductive screws  18  so that they are restrained from rotating, and a light source module  24  is formed. Because thermal conductivity of the spacer  17  is sufficiently lower than those of the base  1  and the lens barrel  8 , heat is not easily transmitted between the base  1  and the lens barrel  8 . In addition, because the base  1  and the lens barrel  8  are fastened to each other by the conductive screws  18 , they are electrically conductive. 
     Semiconductor lasers (hereinafter, Laser Diodes (LDs))  19  are light sources that emit blue light having wavelength of 445 nanometers. Relative orientations in rotating directions of optical axes (polarizing directions) of the seven LDs  19  with respect to an LD holder  20  are all the same, and the LDs  19  are press-fitted to the LD holder  20 . There are seven LDs  19  and LD holders  20  corresponding to the collimator lens group. In the following explanations, when it is necessary to distinguish a certain one among the LDs  19  from each other, they are described as LD-I to LD-VII. When it is necessary to distinguish a certain one among the LD holders  20  from each other, they are described as LD holders I to VII. An upper surface  20   a  of the LD holder  20  to which the LD  19  is press-fitted is arranged such that the upper surface  20   a  abuts against a bottom surface  1   k  of the base  1 . Optical axes of the LDs  19  and the optical axes of the collimator lens groups are adjusted to appropriate positions on the abutment surfaces, and the LD holder  20  is adhered and fixed to the base  1  by acrylic-based ultraviolet cure adhesives  21   a  and  21   b.    
     By fixing the lens barrel  8  made of metal to the base  1  by the conductive screws  18  through the plastic spacer  17 , the ground of the LD  19  is electrically connected to the lens barrel  8  through the LD holder  20 , the base  1 , and the screws  18 . Therefore, it is possible to suppress generation of unnecessary radiation when the LD  19  is pulse-driven at high frequencies. The lens barrel  8  can be fixed to a later-described Peltier module  34  through the plastic spacer  17  by using a conductive screw. 
       FIGS. 4A and 4B  are perspective views of a detailed configuration of the LD holder  20 . The LD holder  20  is of a substantially cylindrical shape, and an outer peripheral surface of the LD holder  20  includes two pairs of notched portions  20   b  and  20   c , as well as  20   d  and  20   e  that are symmetric about a center axis of an inner surface hole  20   l . A stepped portion  20   g  and two pairs of hole portions  20   h  and  20   i  as well as  20   j  and  20   k , which are symmetric about the optical axis of the LD  19 , are provided in a lower surface  20   f  of the LD holder  20 . The lower surface  20   f  is opposite from the upper surface  20   a  that abuts against the base  1 . The hole portions  20   h  to  20   k  are provided such that a line connecting centers of the hole portions  20   h  and  20   i  and a line connecting centers of the hole portions  20   j  and  20   k  intersects with each other at a right angle. The inner surface hole  20   l  that is a cylindrical inner surface of the LD holder  20  is slightly larger in diameter than a press-fit hole  20   m  into which the LD  19  is inserted. 
       FIGS. 5 and 6  are enlarged views of a state after the LD holder  20  into which the LD  19  is press-fitted is adhered and fixed to the base  1 . The LD  19  is a standard CAN package of φ5.6 millimeters, and includes a notch  19   a  on a stem and conduction leads  19   b . A laser beam is emitted from a laser-beam emitting window  19   c . A light emitting point  19   d  of the LD  19  is flush with the upper surface  20   a  of the LD holder  20  so that even if the LD holder  20  is inclined when adjusting its optical axis in position, an amount of positional deviation of the optical axis of the light emitting point  19   d  in the vertical direction can be suppressed to the minimum. With this configuration, its centering operability and reliability of a product are enhanced. The LD holder  20  is designed such that when the LD  19  is press-fitted, a through hole  22  is formed between the LD  19  and the inner surface hole  20   l  of the LD holder  20  by the notch  19   a  of the LD  19 . That is, in a state that the LDs  19  are press-fitted into the LD holders  20  and are adhered and fixed to the base  1 , small chambers  23 , which are formed by the stepped holes  1   a  to  1   g  of the base  1 , the first collimator lenses  2 , the LD holders  20 , and the LDs  19 , are in communication with outside air through the through hole  22 . The adhesive  21   a  that fixes the LD holder  20  is applied to four points that are substantially symmetric about the optical axis of the LD  19 . The adhesive  21   a  straddle the bottom surface  1   k  of the base  1  and the notched portions  20   b  and  20   c , which are an outer peripheral side surface of the LD holder  20 . The adhesive  21   b  is applied substantially symmetrically about the optical axis of the LD  19  and straddle the bottom surface  1   k  of the base  1  and the notched portions  20   d  and  20   e , which are the outer peripheral side surface of the LD holder  20 . As shown in  FIG. 2 , the LD holders III to VII are arranged such that the stepped portions  20   g  are oriented to the same direction; however, the LD holder I is arranged in a direction rotated 90° and the LD holder II is arranged in a direction rotated −90°. The light source module  24  has the configuration described above. 
     The substantially cylindrical LD holder  20  has the notched portions  20   b  and  20   c  as well as  20   d  and  20   e  that are symmetric about the center axis thereof, and the adhesives  21   a  and  21   b  are applied to the notched portions  20   b  to  20   e . This configuration can suppress the increase in adhering margins, narrow a distance between the optical axes, and reduce the sizes of the entire device. Because the adhesive is applied to a plurality of locations that are substantially symmetric about the optical axis of the LD  19 , even if the adhesive is cured and shrunk or linearly expanded, these phenomena cancel out each other, and a positional deviation is not generated in the LD holder  20 . With this configuration, the yield of the light source device can be enhanced. 
     An operation of the present embodiment is described next. Diverging light  25   a  emitted from the LD  19  is converted into parallel light  25   b  by the collimator lens group formed of the first collimator lens  2  and the second collimator lens  4 . Furthermore, the light  25   b  is concentrated on an end surface of the optical fiber  16  having a diameter of 400 micrometers by the condenser lens group formed of the first condenser lens  9  and the second condenser lens  11 . Incidentally, precision of the parts and precision of assembling position have errors from design center values. A focal point  25   c  can be deviated from the end surface of the optical fiber  16  and a loss can be generated, and the amount of light entering the optical fiber  16  can be reduced in some cases. In this embodiment, when the LD  19  is moved in a direction intersecting with the optical axis at right angles, the optical axis of the parallel light  25   b  is inclined, and the focal point  25   c  can be moved in the direction intersecting with the optical axis at right angles. Therefore, a positional deviation of the light emitting point  19   d  of the LD  19 , positional deviations of the optical axes of the first collimator lenses  2   a  to  2   g  and the second collimator lenses  4   a  to  4   g , inclinations of the first condenser lens  9  and the second condenser lens  11 , and a positional deviation of the receptacle  14  can be absorbed by adjusting the position of the LD  19  in the direction intersecting with the optical axis at right angles. Thus, the focal point  25   c  can be aligned with the end surface of the optical fiber  16 . 
     An adjusting and fixing method according to the present embodiment is explained next with reference to  FIGS. 7 to 10 . A movable block  26  is driven in X, Y, and Z directions by an electric inching stage (not shown). Two pointed adjusting pins  27   a  and  27   b  capable of moving in the Z direction, and two UV fibers  28   a  and  28   b  for applying ultraviolet light (hereinafter, UV light) for curing the adhesive are fixed. The two adjusting pins  27   a  and  27   b  are elastically supported independent from each other to push the LD holder  20  against the bottom surface  1   k  of the base  1  (in a +Z direction in  FIGS. 7 and 9 ). At this time, the pushing force of each of the adjusting pins  27   a  and  27   b  is set to about 0.05 Newton (5-gram weight) so that the LD holder  20  does not float from the bottom surface  1   k  of the base  1 , but smoothly moves on the abutment surface. The UV fibers  28   a  and  28   b  are arranged such that a pair of the notched portions  20   b  and  20   c  of the LD holder  20  and the bottom surface  1   k  of the base  1  near the notched portions are irradiated with light at those spots. A socket (not shown) for supplying current is mounted on the LD  19  so that the LD  19  can emit light at a predetermined current. 
     The light source module  24  before the LD  19  and the LD holder  20  are fixed thereto is mounted on a fixing block  29  with no backlash. To facilitate understanding of the configuration, the fixing block  29  is shown with broken lines in  FIGS. 7 and 9  and members located behind the fixing block  29  are shown through the fixing block  29 . The optical fiber  16  is mounted on the receptacle  14 , and a laser beam emitted from the end surface of the opposite end surface of the optical fiber  16  is received by an optical power meter  30 . 
     When the LID-I is to be adjusted and fixed, as shown in  FIGS. 7 and 8 , the LD holder  20  into which the LD  19  is press-fitted is set, and the adjusting pins  27   a  and  27   b  are inserted into a pair of the hole portions  20   h  and  20   i . At this time, the stepped portion  20   g  of the LD holder  20  is set such that it is oriented rightward (the +X direction) in  FIG. 8 . In this state, current of a predetermined current value is made to flow through the LID-I, the movable block  26  is made to move in the X and Y directions such that laser power emitted from the optical fiber  16  becomes maximum, a user checks that the laser power becomes greater than a standard power that was previously obtained by calculation. The adhesive  21   a  is applied to the four locations about the optical axis of the LD  19  so as to straddle the bottom surface  1   k  of the base  1  and the notched portions  20   b  and  20   c  of the outer peripheral surface of the LD holder  20 . Then, the adhesive  21   a  is irradiated with UV light from the UV fibers  28   a  and  28   b  and the adhesive  21   a  is cured. There is nothing that cuts off UV light emitted to the adhesive  21   a , and the adhesive  21   a  can be reliably irradiated with UV light and cured. Because the adhesive  21   a  is applied to the locations symmetric about the ED holder  20 , a deviation of the ED holder  20  is not easily generated when the adhesive is cured and shrunk or linearly expanded. Even if the LD holder  20  is inclined, because the positional deviation of the light emitting point  19   d  is not easily generated, a value of the optical power meter  30  is not varied at the time of adjustment. Thus, the adjusting operability is excellent. Also, because the position of the light emitting point  19   d  is not easily changed with respect to the inclination of the LD holder  20 , a light source device having higher reliability can be provided. 
     Next, when the LD-II is to be adjusted and fixed, the LD holder  20 , into which the LD  19  is press-fitted, is set on the left side of the LD-I that is adhered and fixed as shown in  FIG. 8  such that the stepped portion  20   g  is oriented leftward (the −X direction). Thus, LD-II is adjusted and fixed in the same manner as the LD-I. 
     When the LD-III is to be fixed, as shown in  FIGS. 9 and 10 , the LD holder  20 , into which the LD  19  is press-fitted, is set such that the stepped portion  20   g  is oriented rightward (the +X direction) in  FIG. 10  in a state that the fixing block  29  is rotated 90° in a counterclockwise direction. Then, the adjusting pins  27   a  and  27   b  are inserted into a pair of the hole portions  20   h  and  20   i , and the LD-III is adjusted and fixed in the same manner as the LD-I. The LD-IV to LD-VII are adjusted and fixed in the same manner. In the method described above, the fixing block  29  is rotated 90° in the counterclockwise direction when the LD-III to LD-VII are adjusted and fixed; however, they can be also adjusted and fixed by inserting the adjusting pins  27   a  and  27   b  into a pair of the hole portions  20   j  and  20   k  without rotating the fixing block. 
     When the adjusting and fixing operations of the LD-I to LD-VII are completed, the light source module  24  is removed from an adjusting device. The adhesive  21   b , which is the same kind as the adhesive  21   a , is applied to two locations of each of the seven LD holders  20  so as to straddle the bottom surface  1   k  of the base  1  and the notched portions  20   d  and  20   e  that are outer peripheral surface of the LD holder  20  as shown in  FIG. 11 . The seven LD holders  20  are collectively irradiated with UV light and adhesive is cured. Because the adhesive  21   b  is additionally applied to the locations of the LD holder  20  symmetrically and is cured, the positional deviation of the LD holder  20  is not caused by curing and shrinking of the adhesive  21   b  and the adhering strength of the LD holder  20  can be enhanced. Because the adhesives  21   a  and  21   b  are arranged symmetrically on the LD holder  20 , to which the LD  19  is fixed, near the abutment surface between the base  1  and the LD holder  20 , they are fixed such that a deviation of the LD holder  20  caused by linear expansion of the adhesives  21   a  and  21   b , the positional deviation of the optical axis of the LD  19 , and inclination of the optical axis are not generated almost at all. The stepped portions  20   g  of the LD-III to LD-VII of the LD holders  20  are arranged such that they are oriented in the same direction as shown in  FIG. 2 ; on the contrary, the LD-I is arranged in the orientation rotated 90° and the LD-II is arranged in the orientation rotated 90° in the opposite direction. With this, the polarizing direction of the LD  19  is not constant, a polarizing direction of a laser beam that enters the optical fiber  16  is mixed, and thus color unevenness of a picture when an image is displayed can be suppressed (uniformity can be improved). That is, the LDs  19  are press-fitted into the LD holders  20  such that the polarizing directions thereof are set the same, and the LD holders  20  are fixed to the base  1  such that orientations of some of the LD holders  20  are changed. Therefore, the polarizing directions of the LDs  19  are mixed, and the color unevenness of a picture can be suppressed. 
     Because the positions of the lens and the optical axis of the LD  19  are adjusted on the abutment surface between the base  1  to which the lens barrel  8  is fixed and the LD holder  20  to which the LD  19  is fixed, the adjusting operations can be performed at one location. Also, variation in part size and variation in optical characteristics can be absorbed, and the centering operation to the optimal position can be performed. That is, by relatively moving the LD holder  20 , to which the LD  19  is fixed, within the abutment surface with respect to the base  1  to which the optics (the first collimator lens  2 , the second collimator lens  4 , the first condenser lens  9 , and the second condenser lens  11 ) is fixed, the position of the optical axis of the LD  19  can be adjusted with one positioning operation. Because the abutment surface of the base  1  and the side surface of the LD holder  20  are adhered to each other, they can be reliably fixed to each other even if the LD holder  20  and the base  1  do not have UV-permeability, and durability is enhanced. The adjusting pins  27   a  and  27   b  of the adjusting device are pressed against the position-adjusting recesses (the hole portions  20   h  to  20   k ) provided in the lower surface  20   f  of the LD holder  20  and the position adjustment is performed. Therefore, the position adjustment in the order of micron can be easily performed, a shadow of an adjusting jig does not appear on the adhesive, and the adhesive can be reliably irradiated with UV. 
     The LD holder  20  is adhered and cured with high reliability such that the LD holder  20  is not deviated when it is adhered and after it was adhered. However, because the adhesives  21   a  and  21   b  generate acrylate-based monomer (monomer of acrylic ester) as out gas when they are cured, the out gas enters the small chamber  23  through a gap of several microns due to surface roughness formed on the abutment surface of between the base  1  and the LD holder  20 , and the out gas exists in a form of gas. If the LD  19  lights up in this state, out gases are superposed on each other by photon energy, and the out gasses become fine particles and adhere to peripheries. This fouling causes a problem that it adheres also to surfaces of the laser-beam emitting window  19   c  of the LD  19  and the first collimator lens  2 , at which photon energy density is particularly high. The permeability of the laser beam emitted from the LD  19  is lowered over time. To avoid this problem, in the present embodiment, as shown in  FIG. 12 , the base  1  on the side of the bottom surface  1   k  is intimately mounted on a decompressor  31 , and out gases dispersed in the small chambers  23  at seven locations are collectively sucked and removed from the through hole  22 . As described above, the out gas generated when the adhesive is cured is removed from an optical path, and contamination generated by interaction between the LD  19  and the photon energy is suppressed. Generally, an acrylic-based UV cure adhesive discharges gas even by heat. Therefore, out gas components are exhausted from the adhesives  21   a  and  21   b  by subjecting the light source module  24  to thermal processing. For example, if the acrylic-based UV cure adhesive is heated at 65° C. for 9 hours, remaining out gas amount can be reduced by 10% or less as compared with UV cure adhesive. At this time, because out gas generated from the adhesives  21   a  and  21   b  enters the small chamber  23  through a gap between the abutment surfaces of the base  1  and the LD holder  20 . For this reason, the base  1  on the side of the bottom surface  1   k  is intimately mounted on the decompressor  31  after the thermal processing as shown in  FIG. 12 , so that out gases dispersed in the small chambers  23  at the seven locations are collectively sucked and eliminated via the through hole  22 . The out gas is eliminated from the optical path in the manner described above, contamination generated by interaction between the LD  19  and the photon energy is further suppressed, and deterioration in permeability of the laser beam emitted from the LD  19  is prevented. The light source module  24  is adjusted and assembled as described above. 
     A UV cure adhesive is used as the adhesive  21  for fixing the LD holder  20  to the base  1 , thermal processing is performed after the UV curing operation to generate out gas from the adhesive  21 , out gas in the small chambers  23 , each of which is formed by the stepped holes  1   a  to  1   g  of the base  1 , the first collimator lens  2 , the LD holder  20 , and the LD  19 , is sucked and exhausted from the through hole  22 . Thus, it is possible to reliably remove the out gas and to prevent out gas from being generated with time. 
       FIGS. 13 to 15  depict a configuration of the light source device in its entirety, in which a flexible printed board (FPC)  32  as a feeding unit, a radiation unit  36  as a cooling unit, and an optical sensor are mounted on the light source module  24 .  FIG. 13  is an exploded view,  FIG. 14  is a perspective view after assembling, and  FIG. 15  is a sectional view taken along a line  15 - 15  in  FIG. 14 . The FPC  32  for supplying current to the LD  19  is made of polyimide, which has excellent light resistance and heat resistance. The FPC  32  passes through the stepped portion  20   g  of the LD holder  20  and is soldered to the conduction leads  19   b  that are an anode and a cathode of the LD  19 .  FIGS. 16 to 18  show details of the FPC  32 . As shown in  FIGS. 16 to 18 , the FPC  32  includes substantially circular LD-mounting portions  32   a  on which the LD  19  is mounted. Each of the LD-mounting portions  32   a  includes a soldering land  32   b  having holes, and a projection  32   c  formed on a tip end of the LD-mounting portion  32   a . Because the projection  32   c  comes into elastic contact with an inner surface hole  20   l  of the LD holder  20 , the conduction leads  19   b , and the holes of the soldering land  32   b  are pushed against one side (see  FIGS. 17 and 18 ). The LD-mounting portion  32   a  is fixed such that it is not pulled from the LD holder  20  and does not rattle even before the LD-mounting portion  32   a  is soldered to the LD  19 . With this configuration, because the LD-mounting portions  32   a  of the FPC  32  are stably fixed independently, the LDs  19  can be easily and reliably soldered even when there are a plurality of the LDs  19 . Because the through hole  22  is closed with the projection  32   c  of the FPC  32 , flux at the time of the soldering operation does not scatter, its fumes do not enter the small chamber  23  easily, and thus it is possible to prevent unwanted material from adhering to surfaces of the laser-beam emitting window  19   c  of the LD  19  and the first collimator lens  2 . It is also possible to prevent scattered light emitted from the LD  19  from leaking out from the through hole  22 . Therefore, it is possible to avoid a case that a material that can be a cause of contamination is generated from a part that is arranged therearound by leaked scattered light. 
     A thermal-conductive sheet  33  is made of a silicon-based elastic material having thickness of 0.5 millimeter. The Peltier module  34  includes a Peltier device, and a surface temperature thereof can be controlled by flowing a current through the Peltier device. The thermal-conductive sheet  35  has the same configuration as that of the thermal-conductive sheet  33 . The radiation unit  36  includes a heat block  36   a , a heat pipe  36   b , and a fin  36   c . A Peltier cover  37  is a molded article of polycarbonate having glass fibers like the spacer  17 . The Peltier cover  37  is designed such that it can be positioned with respect to the base  1 , the Peltier module  34  and the heat block  36   a . Four fixing screws  38  are uniformly fastened to the heat block  36   a  through the Peltier cover  37  from the side of the base  1 . With this configuration, the thermal-conductive sheet  33  and the thermal-conductive sheet  35  are elastically deformed, and the ID holder  20 , the thermal-conductive sheet  33 , the Peltier module  34 , the thermal-conductive sheet  35 , and the heat block  36   a  are intimately fixed. The Peltier cover  37  is positioned to a height where the Peltier cover  37  comes into contact with the spacer  17  and the heat block  36   a  that are fixed to the base  1  in a state that the fixing screws  38  are fastened, and the base  1  and the heat block  36   a  cannot approach each other more than this. Therefore, it is possible to avoid a case where an excessive force is applied to the Peltier module  34  due to excessive fastening of the fixing screws  38 , or a vibration or an impact from outside, and the Peltier module  34  is damaged. 
     The heat block  36   a  is fixed to the base  1  by the conductive fixing screws  38  through the plastic Peltier cover  37 . With this configuration, a thermal capacity of a portion thereof cooled by the Peltier module  34  is reduced, and the LD  19  can be efficiently cooled. That is, the energy required for cooling the LID  19  can be reduced. Also, the lifetime of the LD  19  can be increased. 
     An optical sensor is fixed to an optical sensor module  39 . The optical sensor module  39  is fixed to the lens barrel  8  by a screw  41  through a sensor holder  40  so that a laser beam leaking from a hole  8   b  formed in a side surface of the lens barrel  8  can be detected. A position and a diameter of the hole  8   b  are designed such that the optical sensor is not saturated. 
     The operation of the light source device is described. First, to make the LD  19  emit light, a predetermined current flows through the FPC  32  in a state that the LDs  19  are connected to the control board in series. At this time, because the LD  19  generates heat, the LD  19  is cooled to a predetermined temperature by the Peltier module  34  through the LD holder  20  and the thermal-conductive sheet  33  based on temperature information of a thermistor (not shown) fixed to the base  1 . Because the lens barrel  8  is thermally separated from the base  1  by the spacer  17 , a thermal capacity in a range where the temperature is adjusted does not become large more than necessary, and it is possible to efficiently adjust the temperature. Heat generated on a surface opposite from the thermal-conductive sheet  33  when the Peltier module  34  is driven is transmitted to the heat block  36   a  through the thermal-conductive sheet  35 , and transmitted to the fin  36   c  through the heat pipe  36   b  and is radiated in the air. The optical sensor module  39  can detect a laser beam that reflects on an inner surface of the lens barrel  8  when the LD  19  emits light and that leaks from the hole  8   b . The optical sensor module  39  compares the laser beam with laser power emitted from the optical fiber  16 , thereby monitoring whether there is abnormality such as bending or deterioration of the optical fiber  16 . When abnormal condition is detected, the optical sensor module  39  is used for emergency stopping processing for interrupting the current that is supplied to the LD  19 . The LD  19  is driven at necessary temperature and current, and is operated while monitoring that power is normally emitted from the optical fiber  16 . 
     According to the light source device of the embodiment, the conduction lead  19   b  of the LD  19  and the FPC  32  are soldered to each other in the inner surface hole  20   l  of the LD holder  20 , and the Peltier module  34  is intimately arranged on the lower surface  20   f  of the LD holder  20  through the thermal-conductive sheet  33 . With this configuration, the FPC  32  can be connected using a small space, and LD  19  can be cooled efficiently and easily without sealing the LD  19  air-tightly. 
     The through hole that is in communication with outside air is provided in the LD holder  20  to which the LD  19  is fixed, the position of the LD holder is adjusted, and it is adhered and fixed. With this configuration, laser beams are synthesized, light is concentrated into the optical fiber, and the productivity and reliability are high although the device is inexpensive. 
     Second Embodiment 
       FIGS. 19 to 21  depict a configuration of relevant parts of a light source device according to a second embodiment the present invention.  FIG. 19  depicts an exploded view,  FIG. 20  depicts an assembly diagram, and  FIG. 21  depicts a sectional view taken along a line  21 - 21  in  FIG. 20 . Parts shown in the drawings are components corresponding to the base  1 , the collimator lens group, the leaf spring  5 , the restraining plate  6 , the screws  7 , the LDs  19 , and the LD holders  20  according to the first embodiment. The members identical to those of the first embodiment are denoted by like reference numerals. In the second embodiment, six LDs  19  are press-fitted and fixed into press-fit holes  50   m  of single base holder  50  from the side of the conduction leads  19   b . To suppress unevenness and ensure uniformity, the LDs  19  are arranged three each in a state in which rotating directions of optical axes of the LDs  19  are different from each other through 90° so that polarizing directions of the LDs  19  are not directed to the same orientation. Six first collimator lenses  2 , six first spacers  3 , and six second collimator lenses  4  are fitted into the base holder  50  corresponding to the six LDs  19 . The collimator lens groups are precisely fixed to the base holder  50  such that the groups are not deviated even if a vibration or an impact is applied. This is made by fixing the one leaf spring  5  and the one restraining plate  6  to each other by the screws  7  without a deviation. 
     Inner surface holes  501  which are arranged corresponding to the six LDs  19  so as to accommodate the conduction leads  19   b , and a groove  50   g  in which the FPC  32  passes are formed in a back surface  50   f  of the base holder  50 . The FPC  32  and tip ends of the conduction leads  19   b  are configured not to protrude from the back surface  50   f  of the base holder  50 . As shown in  FIG. 22 , the substantially circular LD-mounting portion  32   a  of the FPC  32 , which is attached to the LD  19 , has the soldering lands  32   b  each having a hole and the projection  32   c  at a tip end thereof. As the projection  32   c  comes into elastic contact with the inner surface hole  501  of the base holder  50 , the conduction leads  19   b  and the holes of the soldering lands  32   b  are pressed against one side. Then, the LD-mounting portion  32   a  is fixed such that it is not pulled out from the base holder  50  and it does not rattle even before the LD-mounting portion  32   a  is soldered to the LD  19 . With this configuration, even when there are plural LDs  19  to be soldered, because the LD-mounting portions  32   a  of the FPC  32  are stably fixed, it is possible to achieve soldering of the LDs  19  with better operability and higher reliability. A thermistor  42  that measures a temperature of the base holder  50  is fixed to a recess formed in the back surface  50   f  of the base holder  50  by a screw  43  such that the thermistor  42  does not protrude from the back surface  50   f . Furthermore, the thermistor  42  is soldered to the FPC  32 . The LDs  19  and a connector  44  that connects the thermistor  42  and an external board with each other are soldered to an end of the FPC  32 , and they are positioned and fixed to a side surface of the base holder  50  by screws  45 . 
       FIG. 23  depicts a sectional view of the light source device after assembling a condenser lens and a cooling unit  46 . The cooling unit  46  that can perform temperature adjustment by using a tiller or a Peltier module is closely arranged on the back surface  50   f  of the base holder  50  through a thermal-conductive sheet  33  by screws, thereby cooling the LDs  19 . The lens barrel  8  to which the condenser lens  9  is fixed is fastened to the cooling unit  46  by conductive screws  38  through the spacer  17  that is a molded article made of polycarbonate having glass fibers. The spacer  17  has sufficiently lower thermal conductivity than those of the cooling unit  46  and the lens barrel  8 . With this configuration, heat is easily transferred from the base holder  50  to the cooling unit  46 ; however, heat is not easily transferred from the lens barrel  8  (in other words, a thermal capacity of a portion that is cooled by the cooling unit  46  is small), and thus the LDs  19  can be efficiently cooled. That is, the energy required for cooling the LDs  19  can be reduced, and the lifetime of the LD  19  can be increased. 
     The ground of the LD  19  is electrically connected to the lens barrel  8  through the base holder  50  and the fixing screws  38  by fixing the metal lens barrel  8  to the cooling unit  46  by the conductive fixing screws  38  through the plastic spacer  17 . Thus, it is possible to suppress generation of parasitic emissions when the LD  19  is pulse-driven at high frequencies. Similarly to the first embodiment, the lens barrel  8  can be fixed to the base holder  50  through the plastic spacer  17  using a conductive screw. 
     Because the FPC  32  and the conduction leads  19   b  of the LD  19  are soldered to each other in the inner surface hole  501  of the base holder  50 , the FPC  32  can be connected with a small space. Also, because the cooling unit  46  is closely arranged on the back surface  50   f  of the base holder  50 , the LD  19  can be efficiently cooled easily without air-tightly sealing it. 
     In the first embodiment, laser beams are concentrated on the end of the optical fiber having the diameter of 400 micrometers. Thus, positions of the optical axis of the LD and the optical axis of the collimator lens are adjusted. Meanwhile, as in the second embodiment, when beams are concentrated on a rod  56  having an end of a large area, it is possible to assemble the LD and the collimator lens with mechanical precision. That is, the optical axes adjustment is not necessarily required. Even with this configuration, it is possible to realize a light source device that can efficiently cool the semiconductor laser with excellent assembling operability. 
     According to the present invention, it is possible to increase the lifetime of a light source device while suppressing deterioration in light emitting efficiency of a semiconductor laser device due to heat. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.

Technology Classification (CPC): 7