Abstract:
The present invention relates to a laser light source having a structure that has high durability to support high power output. The laser light source is an optical device that pulse-oscillates laser light and has a resonator, a rare earth element doped fiber, pumping means, Q switch means, and a condensing lens. The resonator forms a resonance optical path. A fiber is inserted on the resonance optical path and outputs radiation light by supply of pumping energy. The pumping means continuously supplies pumping energy to the fiber. The Q switch means modulates resonator loss of the resonator. The condensing lens condenses the radiation light whose spot size has been expanded and which propagates from the fiber to the Q switch means. The Q switch means is disposed such that a portion contributing to at least a resonator loss modulation is located at the condensing point of radiation light which is condensed by the condensing lens, and mechanically changes formation and interruption of the resonance optical path by transmitting or interrupting the radiation light in the contributing portion.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a laser light source which pulse-oscillates laser light. 
         [0003]    2. Related Background of the Invention 
         [0004]    A laser light source that pulse-oscillates laser light has a resonator in which a laser medium, generating radiation light by supplied pumping energy, is disposed on the resonance optical path, Q switch means for modulating resonator loss of the resonator, and pumping means for continuously supplying pumping energy to the laser medium. 
         [0005]    In such a laser light source, the inverted population of the laser medium is increased by the pumping means supplying the pumping energy, when the Q switch means sets the resonator loss of the resonator to a large value, and when the Q switch means sets the resonator loss of the resonator to a small value thereafter, an induced emission is quickly generated in the laser medium disposed on the resonance optical path of the resonator. The induced radiation light is outputted from the resonator to the outside as laser light. By performing the modulation periodically, pulsed laser light having high peak power are output. Such a laser light source, which can output pulsed light having high peak power, is used in many fields that include laser processing, optical measurement and optical communication. 
         [0006]    Japanese Patent No. 3331726 discloses a method for using an acousto-optical (AO) element for the Q switch means. 
       SUMMARY OF THE INVENTION 
       [0007]    The present inventors have examined the conventional laser light source, and as a result, have discovered the following problems. 
         [0008]    That is, recently demands for a laser light source that can output pulsed laser light having high peak power are increased due to the expanded application uses. Therefore, a laser light source that has high durability supporting a much higher power output is demanded compared with the case of using an acousto-optical element for Q switch means, as the case of an optical fiber laser device according to Japanese Patent No. 3331726 (Document 1). 
         [0009]    The present invention has been developed to eliminate the problems described above. It is an object of the present invention to provide a laser light source having a structure to implement high durability supporting high power output. 
         [0010]    In order to achieve the above object, a laser light source according to the present invention is a laser light source that pulse-oscillates laser light, and has, as a first configuration, a resonator, a rare earth element doped fiber, pumping means, Q switch means and a condensing lens. The resonator forms a resonation optical path. The rare earth element doped fiber is inserted on the resonance optical path and outputs radiation light by supply of pumping energy. The pumping means continuously supplies pumping energy to the rare earth element doped fiber. The Q switch means modulates resonator loss of the resonator. The condensing lens is disposed on the resonance optical path between an end face of the rare earth element doped fiber and the Q switch means, and condenses the radiation light whose spot size has been expanded (radiation light of which beam diameter has been enlarged) and which propagates from the rare earth element doped fiber to the Q switch means. In order to expand the radiation light that enters the condensing lens, a lens is disposed on the resonance optical path between the end face of the rare earth element doped fiber and the condensing lens, and the radiation light, propagating from the rare earth element doped fiber to the Q switch means, is collimated by the lens in a state of being expanded to be a predetermined beam diameter. The Q switch means is disposed such that a portion contributing to at least a resonator loss modulation is located in the condensing point of the condensing lens, and mechanically changes formation and interruption of the resonance optical path. 
         [0011]    In the laser light source having the above first configuration, the radiation light outputted from the fiber, to which pumping energy is continuously supplied, is condensed by the condensing lens and enters the Q switch means. Here. In the case that the radiation light is transmitted by the Q switch means at this time, the resonation optical path of the radiation light is formed between the reflection face and the emission face. In the case that the radiation light is interrupted by the Q switch means, on the other hand, the resonance optical path is not formed, so the resonator loss becomes the maximum. In this way, in accordance with the laser light source, formation and interruption of the resonance optical path are implemented by periodically changing transmission and interruption of the radiation light by the Q switch means, and pulsed light is emitted. The Q switch means constituting the laser light source has a higher durability supporting radiation light, which is output at high power, than the Q switch means based on an acousto-optical element, and can suppress damage of the laser light source. Hence the laser light source having high durability supporting high power output can be provided. By disposing the Q switch means in the condensing point of the condensing lens, it becomes easier to increase the cyclic frequency related to switching of the Q switch means, and high frequency pulsed light can be emitted. This configuration can be created with less cost than the Q switch means based on an acousto-optical element. 
         [0012]    As a configuration to effectively implement the above function, the Q switch means includes a disk, disposed such that a part thereof is located on the resonance optical path, and a driving section. The disk has a plate portion absorbing or scattering the radiation light, and a plurality of openings arranged on a circumference centered around a rotation axis penetrating the center of the disk. The driving section rotates the disk centered around the rotation axis. 
         [0013]    As another configuration for effectively implementing the above function, the Q switch means may includes a masking portion and a driving section. The masking portion absorbs or scatters the radiation light. The driving section moves the position of the masking portion periodically by vibrating the masking portion along a direction crossing the optical axis of the resonance optical path at a predetermined angle (including a right angle). 
         [0014]    The laser light source according to the present invention, as a second configuration, may have a resonator forming a resonation optical path between a reflection face and an emission face, a rare earth element doped fiber, pumping means, and Q switch means. In this configuration, the rare earth element doped fiber is inserted on the resonance optical path, and outputs radiation light by supply of pumping energy. The pumping means continuously supplies pumping energy to the rare earth element doped fiber. The Q switch means modulates resonator loss of the resonator. The Q switch means, in particular, mechanically changes formation and interruption of the resonance optical path by adjusting the position of the reflection face. 
         [0015]    In accordance with the laser light source having the second configuration, the formation and interruption of the resonance optical path is mechanically changed by the periodic positional change of the reflection face constituting the resonator. This allows functioning as a Q switch means for modulating the resonator loss, and a laser light source having higher durability than the Q switch means based on an acousto-optical element, even during high power output, can be provided. 
         [0016]    As a configuration to effectively implement the above function, the Q switch means includes a polygonal prism-shaped rotation body and a driving section. The rotation body has a central axis matching the axis perpendicular to the optical axis of the resonance optical path, and has a polygonal profile of the cross-section perpendicular to the central axis. The rotation body has a reflection mirror constituting a part of the resonator on each side face which includes the side of the polygonal cross-section, and is disposed such that each of the reflection mirror sequentially functions as the reflection portion in the resonator when the rotation body rotates around the central axis as the rotation axis. The driving section rotates the rotation body around the central axis as the rotation axis. By this configuration, the rotation body changes formation and interruption of the resonance optical path by rotating around the central axis as the rotation axis. 
         [0017]    As another configuration to effectively implement the above function, the Q switch means includes a disk that includes a plate portion and a reflection portion constituting a part of the resonator, and a driving section. The disk is disposed such that a part thereof is located on the resonance optical path. The plate portion transmits, absorbs or scatters the radiation light. The reflection portion is disposed on a circumference centered around a rotation axis penetrating the center of the disk, and reflects the radiation light so as to constitute a part of the resonator. The driving section rotates the disk centered around the rotation axis. By this configuration, the disk mechanically changes, by rotation thereof, formation and interruption of the resonance optical path. 
         [0018]    As another configuration to effectively implement the above function, the Q switch means includes a reflection plate that constitutes a part of the resonator and reflects the radiation light, and a driving section. The driving section periodically moves the position of the reflection plate by vibrating the reflection plate along the direction perpendicular to the optical axis of the resonance optical path. By this configuration, the reflection plate mechanically changes, by changing the position thereof, formation and interruption of the resonance optical path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a diagram showing a configuration of a first embodiment of a laser light source according to the present invention; 
           [0020]      FIGS. 2A to 2C  are diagrams showing a structure of a chopper disk and other arrangement examples; 
           [0021]      FIGS. 3A and 3B  are diagrams showing a configuration of a second embodiment of a laser light source according to the present invention; 
           [0022]      FIG. 4  is a diagram showing a configuration of a third embodiment of a laser light source according to the present invention; 
           [0023]      FIG. 5  is a diagram showing a configuration of a fourth embodiment of a laser light source according to the present invention; 
           [0024]      FIG. 6  is a diagram showing a structure of a disk; and 
           [0025]      FIG. 7  is a diagram showing a configuration of a fifth embodiment of a laser light source according to the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    In the following, embodiments of a laser light source according to the present invention will be described in detail with reference to  FIGS. 1 ,  2 A to  3 B and  4  to  7 . In the description of the drawings, identical or corresponding components are designated by the same reference numerals, and overlapping description is omitted. 
       First Embodiment 
       [0027]    A first embodiment of the laser light source according to the present invention will now be described.  FIG. 1  is a diagram showing a configuration of a laser light source  1  according to a first embodiment. The laser light source  1 , shown in  FIG. 1 , has an optical amplification fiber  11 , pumping light source  12 , dichroic mirror  13 , output mirror (low reflection mirror)  14 , condensing lens  15 , total reflection mirror  16 , lenses  17 ,  18  and  19  and Q switch means  20 . 
         [0028]    The optical amplification fiber  11  is an amplification medium constituted by an optical fiber whose optical waveguide region is doped with a rare earth element having fluorescent characteristics. When pumping light, having a wavelength that can pump the fluorescent element, is supplied to the optical amplification fiber  11 , the rare earth element emits fluorescent light. The rare earth element is preferably a Yb element, Nd element, Pr element or Er element. 
         [0029]    The pumping light source  12  continuously outputs pumping light for pumping the fluorescent element doped to the optical amplification fiber  11 . This pumping light source  12  preferably includes a laser diode. The dichroic mirror  13  emits the pumping light, which is outputted from the pumping light source  12 , to the lens  15 . The dichroic mirror  13  also outputs the light, which is reflected by the output mirror  14 , to the lens  15 . The dichroic mirror  13  also outputs the radiation light, which is emitted from the fluorescent element of the optical amplification fiber  11 , outputted from the end face  11   a , enters the lens  15 , and emitted from the lens  15 , to the output mirror  14 . 
         [0030]    The lens  15  is disposed such that the focal point thereof matches the end face  11   a  of the optical amplification fiber  11 , and condenses the light outputted from the dichroic mirror  13  to the end face  11   a  of the optical amplification fiber  11 . The lens  15  also collimates the radiation light outputted from the end face  11   a  of the optical amplification fiber  11 . The radiation light collimated by the lens  15  reaches the dichroic mirror  13 . 
         [0031]    The lens  17  is disposed such that the focal point thereof matches the end face  11   b  of the optical amplification fiber  11 , and collimates the radiation light outputted from the end face  11   b  of the optical amplification fiber  11 . The lens  17  also condenses the radiation light outputted from the lens  18  to the end face  11   b  of the optical amplification fiber  11 . 
         [0032]    The lens  18  functions as a condensing lens that condenses the radiation light having being outputted from the end face  11   a  of the optical amplification fiber  11  and then collimated by the lens  17 . The radiation light collimated by the lens  17  is condensed to the condensing point of the lens  18 , and is inputted to the Q switch means  20  disposed in the condensing point. The lens  18 , on the other hand, collimates the radiation light outputted from the Q switch means  20 , and this collimated radiation light reaches the lens  17 . For the lens  18 , a condensing lens (achromatic lens) of which chromatic aberration is corrected, for example, is used. 
         [0033]    The lens  19  collimates the radiation light outputted from the Q switch means  20 , and outputs it to the totals reflection mirror  16 , and also condenses the radiation light from the total reflection mirror  16 . The lens  18  and the lens  19  are disposed so that the focal point at the side of the Q switch means  20  of the lens  18  and the focal point at the side of the Q switch means  20  of the lens  19  match. And the Q switch means  20 , particularly the portion that contributes to the modulation of the resonance optical path loss, is disposed in this focal point. 
         [0034]    The Q switch means  20  has a chopper disk (disk)  21 , a rotation axis  22  and a driving section  23 . The chopper disk  21  has a plate portion of which surface scatters or absorbs light, and a plurality of openings  21   a  disposed on a circumference centered around the rotation axis  22 , as shown in  FIG. 2A . The openings  21   a  are disposed on the circumference centered around the rotation axis  22  of the chopper disk  21  with equal spacing. The chopper disk  21  and the rotation axis  22  thereof are disposed so that the openings  21   a  pass the condensing position of the radiation light by the lens  18  when the chopper disk  21  is rotated around the rotation axis  22 . The driving section  23  is disposed for rotating this rotation axis  22 . The driving section  23  includes a motor. By the driving section  23  rotating the rotation axis  22  and the chopper disk  21  at a predetermined speed, the plate portion and the openings  21   a  of the chopper disk  21  alternately pass through the condensing point of the radiation light, which is condensed by the lens  18 . 
         [0035]    In the configuration shown in  FIG. 1 , the chopper disk  21  is disposed so as to be perpendicular to the optical axis AX of the resonance optical path, but may be disposed in a state inclined from the optical axis AX by the angle θ, as shown in  FIGS. 2B and 2C . In this case, the plate portion of the chopper disk  21  may be constituted by a material that reflects light from the optical amplification fiber  11 . In this example, when the opening  21   a  is located in the condensing point of the lens  18  which is a condensing lens, as shown in  FIG. 2B  the light condensed by the lens  18  transmits through the opening  21   a  to the lens  19 , and the resonance optical path is formed. When the plate portion of the chopper disk  21  is located in the condensing point of the lens  18 , on the other hand, the light condensed by the lens  18  is reflected and cannot reach the lens  19 , as shown in  FIG. 2C  (resonance optical path interrupted state). 
         [0036]    In the laser light source  1  having the above configuration, the pumping light, which is continuously outputted from the pumping light source  12 , is outputted to the lens  15  by the dichroic mirror  13 . The pumping light condensed by the lens  15  is inputted to the optical amplification fiber  11 , which is a laser medium, through the end face  11   a , and pumps the fluorescent element doped to the optical amplification fiber  11 . In other words, the output mirror  14  and the total reflection mirror  16  constitutes a Fabry-Perot resonator, and the optical amplification fiber  11  as a laser medium is disposed on the resonance optical path of the resonator. 
         [0037]    The radiation light emitted from the end face  11   b  of the optical amplification fiber is collimated by the lens  17  and is condensed by the lens  18 . When the opening  21   a  of the chopper disk  21  constituting the Q switch means  20  is located in the focal point of the lens  18  (lens  19 ) at this time, the radiation light that is outputted from the lens  18  transmits through the opening  21   a  of the chopper disk  21 , and reaches the lens  19 . Then the radiation light collimated by the lens  19  reaches the total reflection mirror  16 . The radiation light reflected by the total reflection mirror  16  is condensed again by the lens  19 . And when the opening  21   a  of the chopper disk  21  is located in the focal point of the lens  18  (lens  19 ), the light which is inputted to the lens  18  through the opening  21   a , collimated by the lens  18 , and then condensed by the lens  17 , enters the end face  11   b  of the optical amplification fiber  11 . The radiation light, which is outputted from the end face  11   a  of the optical amplification fiber  11 , transmits through the dichroic mirror  13 , and reaches the output mirror  14 . Out of the radiation light that reached the output mirror  14 , a part transmits through the output mirror  14 , and the rest is reflected by the output mirror  14 , and enters the lens  15  again via the dichroic mirror  13 . 
         [0038]    As described above, when the opening  21   a  of the chopper disk  21  is located in the condensing position of the lens  18  (condensing position of lens  19 ), the radiation light can transmit through this opening  21   a.  When the plate portion of the chopper disk  21  is located in the condensing point of the lens  18 , the radiation light, having been outputted from the lens  18  and reached the chopper disk  21 , is absorbed or scattered by the surface of the chopper disk  21 . This makes the resonator loss of the resonator the maximum. As described above, the chopper disk  21  according to the present embodiment can function as the Q switch means  20  by rotating and switching the transmission and interruption of the radiation light, and output the pulsed light from the resonator. 
         [0039]    A concrete configuration example of the laser light source  1  according to the first embodiment is as follows. The optical amplification fiber  11  is an optical fiber whose optical waveguide region is doped with a Yb element. The pumping light source  12  outputs pumping light with a wavelength of 975 nm that can pump the Yb element. In the case that the pumping light with the wavelength of 975 nm is supplied, the optical amplification fiber  11  emits a fluorescence with a wavelength of 1.06 μm. The dichroic mirror  13  disposed in the position where the pumping light, outputted from the pumping light source  12 , reaches reflect light with the wavelength of 975 nm, and transmits light with the wavelength of 1.06 μm. The lenses  15 ,  18  and  19  are lenses with focal distance f=50 mm, and the lens  17  is an achromatic lens with focal distance f=50 mm. The chopper disk  21  constituting the Q switch means  20  is an SUS of which diameter is 40 mm and thickness is 0.3 mm, and the surface thereof is processed so that the light is absorbed or scattered as the plate portion. The diameter of the opening  21   a  formed in the chopper disk is 1 mm. The rotation speed of the driving section  23  that rotates the chopper disk  21  is 8000 rpm. 
         [0040]    In accordance with the laser light source  1  according to the first embodiment, the Q switch means  20  constituted by the chopper disk  21  having the openings  21   a  mechanically opens transmission and interruption of the radiation light to change the formation and interruption of the resonance optical path, as mentioned above. Thereby the resistance to irradiation intensity becomes stronger than the case of using an acousto-optical element as the Q switch means, and as a result, high durability supporting high power output can be implemented. 
         [0041]    In this laser light source  1 , the lenses  17  and  18  are disposed between the Q switch means  20  and the end face  11   b  of the optical amplification fiber  11 . Therefore, volatile constituents generated by thermal damage (e.g. aberration) of the chopper disk  21 , by irradiation of the radiation light to the chopper disk  21  by the Q switch means  20 , does not adhere to the end face  11   b  of the optical amplification fiber  11 , and a drop in performance of the laser light source  1 , due to contamination of the end face  11   b,  can be suppressed. 
         [0042]    In the laser light source  1 , the Q switch means  20  is disposed at the condensing point of the lenses  18  and  19 , and the radiation light condensed by the lenses  18  and  19  enters the Q switch means  20 . Since the Q switch means  20  is used for the condensed radiation light like this, the formation and interruption of the resonance optical path can be switched at high-speed by the chopper disk  21  constituting the Q switch means  20  rotating at high-speed. Furthermore, the time width of the laser pulsed light that is outputted from the laser light source  1  can be decreased. 
       Second Embodiment 
       [0043]    A second embodiment of the laser light source according to the present invention will now be described.  FIG. 3A  is a diagram showing a configuration of a laser light source  2  according to the second embodiment. The laser light source  2  according to the second embodiment is the same as the laser light source  1  according to the first embodiment ( FIG. 1 ), except that the Q switch means  24  is comprised of a plate type shielding plate  25  and a driving section  26  that moves this shielding plate  25  by vibration. 
         [0044]    In other words, in the laser light source  2  according to the second embodiment, when the shielding plate  25  constituting the Q switch means  24  is located in the condensing point of the lenses  18  and  19 , the light is absorbed or scattered by the shielding plate  25 , so the radiation light, which is outputted from the end face  11   b  of the optical amplification fiber  11 , is interrupted. Therefore, the resonance optical path of the resonator is interrupted, and resonator loss becomes the maximum. When the shielding plate  25  is not located in the condensing point of the lenses  18  and  19 , namely, when the edge of the shielding portion  25  or the opening  25   a  or slit created in the shielding portion  25  is located in the condensing point of the lenses  18  and  19 , the radiation light outputted from the lens  18  is inputted to the lens  19 , and the radiation light outputted from the lens  19  is inputted to the lens  18 . As  FIG. 3B  shows, an opening  25   a  where the radiation light can transmit is created in the shielding portion  25 . Therefore, a resonance optical path is formed when the radiation light transmits through the opening  25   a  of the shielding portion  25 . And, the position of the shielding portion  25  is changed by the driving section  26  vibrating the shielding plate  25  along a direction perpendicular to the optical axis AX of the resonance optical path. By implementing this positional change of the shielding portion  25 , the formation and interruption of the resonance optical path can be switched. The vibrating shielding portion itself can function as the Q switch means  20 , and output the pulsed light from the laser light source  2 . 
         [0045]    A concrete configuration example of the laser light source  2  according to the second embodiment ( FIG. 3 ) is the same as the laser light source  1  according to the first embodiment, except for the Q switch means  24 . The shielding plate  25  constituting the Q switch means  24  is an SUS of which size is 10 mm×20 mm, with a 0.3 mm thickness, and is processed so as to absorb or scatter the light irradiated on the surface thereof. The driving section  26  is constituted by a piezoelectric element. 
         [0046]    In the configuration example of  FIG. 3 , the shielding portion  25 , on which the above mentioned surface processing is performed, is disposed such that the surface thereof is perpendicular to the optical axis AX of the resonance optical path, but the present invention is not limited to this arrangement. In particular, when the above mentioned surface processing is not performed on the shielding portion  25 , it is preferable to dispose the shielding portion  25  so as to incline from the optical path AX of the resonance optical path by a predetermined angle θ, as shown in  FIGS. 2B and 2C . In this case, the shielding portion  25  vibrates in a direction inclined from the optical axis AX by angle θ, so the transmission and reflection of the radiation light, that is directed from the end face of the optical amplification fiber  11  to the total reflection mirror  16 , can be implemented. In other words, the resonance optical path is formed when the radiation light transmits through the opening  25   a  of the shielding portion  25 , and the resonance optical path is interrupted when the radiation light from the optical amplification fiber  11  is absorbed or reflected by the shielding portion  25 . 
         [0047]    In the case of the laser light source  2  according to the second embodiment as well, just like the laser light source  1  according to the first embodiment, the Q switch means  24 , for switching formation and interruption of the resonance optical path, has higher resistance to irradiation intensity than the case of using the acousto-optical element as the Q switch means, so high durability supporting high power output can be implemented. 
         [0048]    Also just like the laser light source  1  according to the first embodiment, volatile constituents, generated by thermal damage of the shielding plate  25  by irradiation of the radiation light to the shielding plate  25  constituting the Q switch means  24 , do not adhere to the end face  11   b  of the optical amplification fiber  11 , and a drop in performance of the laser light source  2  due to contamination of the end face  11   b  can be suppressed. 
         [0049]    Furthermore, just like the laser light source  1  according to the first embodiment, the Q switch means  24  is disposed in the condensing point of the lenses  18  and  19 , and the radiation light condensed by the lenses  18  and  19  enters the Q switch means  24 . Therefore, formation and interruption of the resonance optical path can be switched at high-speed by moving the position of the shielding plate  25  constituting the Q switch means  24  at high-speed, and the time width of the laser pulsed light that is outputted from the laser light source  2  can be decreased. 
       Third Embodiment 
       [0050]    A third embodiment of the laser light source according to the present invention will now be described.  FIG. 4  is a diagram showing a configuration of a laser light source  3  according to the third embodiment. The laser light source  3  according to the third embodiment The laser light source  4  according to the fourth embodiment is different from the laser light source  1  according to the first embodiment ( FIG. 1 ) in the point that the reflection plane constituting the resonator is constituted by a plurality of mirrors, and these mirrors are sequentially moved so as to function as the Q switch means. 
         [0051]    In other words, instead of the total reflection mirror  16  of the laser light source  1  according to the first embodiment, the laser light source  3  according to the third embodiment has a rotary drive mirror  32 . Specifically, for the radiation light which is outputted from the end face  11   b  of the optical amplification fiber  11 , the rotary drive mirror  32  is in concrete terms a polygonal prism (hexagonal prism of which profile of the cross-section perpendicular to the rotation axis  320  is a hexagon, in the case of  FIG. 4 ), that can rotate around the rotation axis  320  that is perpendicular to the optical axis of light collimated by the lens  17  (matching the optical axis AX of the resonance optical path), and the side face  32   a  thereof is covered with a reflection mirror. By the driving section, which is not illustrated, rotating the rotary drive mirror  32  around the rotation axis, the reflection mirror of the side face  32   a  moves. The rotary drive mirror  32  is in a black box  31 , and a pin hole  33  with a 3 mm diameter, for example, is created only on the surface where the radiation light collimated by the lens  17  enters. 
         [0052]    In the laser light source  3  having this configuration, the radiation light, that is emitted from the end face  11   b  of the optical amplification fiber  11  and is collimated by the lens  17 , enters into the black box  31  via the pin hole  33 , and irradiates the side face  32   a  of the rotary drive mirror  32  disposed inside the black box  31 . 
         [0053]    When one of the side faces  32   a  of the rotary drive mirror  32  is perpendicular to the entry direction of the radiation light, at this time, the radiation light that reached the side face  32   a  is reflected by the side face  32   a.  Then the radiation light reflected by the side face  32   a  is emitted from the pin hole  33  again, and enters the lens  17 , whereby the resonance optical path is formed. When the side face  32   a  is not perpendicular to the entry direction of the radiation light, on the other hand, the radiation light that reached the side face  32   a  is reflected in a direction different from the entry direction by the side face  32   a.  At this time, the reflected radiation light is not emitted to the outside from the black box  31  (resonance optical path is interrupted), and resonator loss becomes the maximum. By the driving section rotating the rotary drive mirror  32 , the rotary drive mirror  32  functions as the Q switch means, and the state of forming and the state of interrupting the resonance optical path are alternately repeated by the side face  32   a.  As a result, the pulsed light can be outputted from the laser light source  3 . 
         [0054]    In the case of the laser light source  3  according to the third embodiment, the reflection plane constituting the resonance optical path functions as the Q switch means for switching formation and interruption of the resonance optical path, so higher durability supporting high power output can be implemented compared with the case of using an acousto-optical element as the Q switch means. 
         [0055]    The side faces  32   a  of the rotary drive mirror  32  that function as the Q switch means are covered with the total reflection mirror, and thermal damage of the mirror due to irradiation of the radiation light is not generated, therefore generation of damage on the end face  11   b  of the optical amplification fiber  11  is suppressed. Furthermore, the lens  17  is disposed between the black box  31 , in which the rotary drive mirror  32  is disposed, and the end face  11   b  of the optical amplification fiber  11 , therefore even when the black box  31  is damaged by heat of the radiation light reflected by the rotary drive mirror  32 , a drop in performance, caused by contaminants adhering to the end face  11   b  of the optical amplification fiber  11  due to this thermal damage, can be suppressed. 
       Fourth Embodiment 
       [0056]    A fourth embodiment of a laser light source according to the present invention will now be described.  FIG. 5  is a diagram showing a configuration of the laser light source  4  according to the fourth embodiment. The laser light source  4  according to the fourth embodiment is the difference from the laser light source  3  according to the third embodiment ( FIG. 4 ) in the point that a reflection face constituting the resonator is disposed on the surface of a disk that rotates around the rotation axis, and moves so as to function as the Q switch means. 
         [0057]    In the laser light source  4  according to the fourth embodiment, a disk  35  that is rotated around the rotation axis  36  by the driving section  37  is disposed inside the black box  31 , instead of the rotary drive mirror  32  of the laser light source  3  according to the third embodiment. The disk  35  is an alumite-treated aluminum plate with a diameter of 40 mm, for example, and has the rotation axis  36  at the center thereof. The disk  35  also has a plurality of reflection portions  35   a  on the circumference centered around the rotation axis  36 , as shown in  FIG. 6 . The reflection portions  35   a,  which are circular total reflection mirrors with a 3.5 mm diameter, for example, are disposed on the circumference centered around the rotation axis  36  at an equal interval. The surface of the reflection portion  35   a  forms a surface perpendicular to the radiation light which was emitted from the lens  17 , and enters the black box  31  via the pin hole  33 . The disk  35  and the rotation axis  36  thereof are disposed such that the reflection portion  35   a  is located in the irradiation position of the radiation light, which is outputted from the lens  17  and enters via the pin hole  33 , when the disk  35  is rotated around the rotation axis  36 . The driving section  37  is disposed to rotate the rotation axis  36 . The driving section  37  is constituted by a motor or the like, and rotates the rotation axis  36  and the disk  35  at a predetermined speed, so that the plate portion (portion that is not the reflection portion  35   a ) and the reflection portion  35   a  of the disk  35  alternately passes the irradiation position of the radiation light. In  FIG. 5 , the driving section  37  is disposed outside the black box  31 , but may be disposed inside the black box  31 . 
         [0058]    In this laser light source  4 , when the reflection portion  35   a  of the disk  35  is located in the irradiation position of the radiation light which enters the black box  31  via the pin hole  33 , the radiation light is reflected by the reflection portion  35   a,  and enters the lens  17  again via the pin hole  33 . Thereby, the resonance optical path is formed. When the plate portion of the disk  35  is located in the irradiation position of the radiation light, on the other hand, the radiation light that enters the black box  31  via the pin hole  33  is absorbed or scattered by the surface of the disk  35 , and is not emitted from the pin hole  33  of the black box  31 . Hence, the resonance optical path is interrupted and the resonator loss of the resonator becomes the maximum. In the case of the laser light source  4  according to the fourth embodiment, the disk  35  functions as the Q switch means by rotating and locating the reflection portion  35   a  and the plate portion alternately in the irradiation portion of the radiation light so as to switch formation and interruption of the radiation optical path, and as a result, pulsed light can be outputted from the resonator. 
         [0059]    In the laser light source  4  having the above configuration, the reflection plane constituting the resonance optical path is a disk  35 , and functions as the Q switch means for switching the formation and interruption of the resonance optical path by rotating, so high durability supporting high power output can be implemented compared with the case of using an acousto-optical element as the Q switch means. 
         [0060]    The disk  35 , functioning as the Q switch means, is covered by the black box  31 , and the lens  17  is disposed between the black box  31  and the end face  11   b  of the optical amplification fiber  11 , therefore even when the disk  35  and black box  31  are damaged by heat of the radiation light, a drop in performance, caused by contaminants adhering to the end face  11   b  of the optical amplification fiber  11  due to this thermal damage, can be suppressed. 
       Fifth Embodiment 
       [0061]    A fifth embodiment of a laser light source according to the present invention will now be described.  FIG. 7  is a diagram showing a configuration of the laser light source  5  according to the fifth embodiment. The laser light source  5  according to the fifth embodiment is the same as the laser light source  4  according to the fourth embodiment ( FIG. 5 ), except that a total reflection mirror  39  of which reflection face constituting the resonator is a plate, and a driving section  41  moves this total reflection mirror  39  by vibration so as to constitute the Q switch means. 
         [0062]    In the laser light source  5  according to the fifth embodiment, the total reflection mirror  39 , which is moved by the driving section  41  via the support portion  40 , is disposed in the black box  31 , instead of the disk  35  of the laser light source  4  according to the fourth embodiment. The driving section  41  is constituted by a piezoelectric element, for example. The total reflection mirror  39  is disposed to be perpendicular to the optical path of the radiation light when the total reflection mirror  39  is located in the irradiation position of the radiation light that entered the black box  31  via the pin hole  33 . And, when the total reflection mirror  39  is located in the irradiation position of the radiation light, the radiation light is reflected by the total reflection mirror  39 , and enters the lens  17  again via the pin hole  33 . Thereby the resonance optical path is formed. On the other hand, when the total reflection mirror  39  is not located in the irradiation position of the radiation light, that is, when the edge of the total reflection mirror  39  or an opening or slit created in the total reflection mirror  39  is located in the irradiation position of the radiation light, the radiation light which entered the black box  31  via the pin hole  33  reaches the inner wall of the black box  31 . Therefore, the resonance optical path is interrupted and the resonator loss of the resonator becomes the maximum. The shape of the total reflection mirror  39  is the same as the shape of the shielding portion  25 , shown in  FIG. 3B . The driving section  40  repeats formation and interruption of the resonance optical path by moving the total reflection mirror  39 . As a result, the black box  31  enclosing the total reflection mirror  39  functions as the Q switch means, and can output the pulsed light from the resonator. 
         [0063]    Therefore, in the case of the laser light source  5  according to the fifth embodiment as well, the reflection face constituting the resonance optical path is the total reflection mirror  39  that is moved by the driving section  41 , and functions as a Q switch means that switches formation and interruption of the resonance optical path by movement of the total reflection mirror  39 , therefore higher durability supporting high power output can be implemented than with the case of using the acousto-optical element as the Q switch means. 
         [0064]    The disk  35  that functions as the Q switch means is covered by the black box  31 , and the lens  17  is disposed between the black box  31  and the end face  11   b  of the optical amplification fiber  11 , therefore even when the disk  35  and black box  31  are damaged by heat of the radiation light, a drop in performance, caused by contaminants adhering to the end face  11   b  of the optical amplification fiber  11  due to this thermal damage, can be suppressed. 
         [0065]    As a variant form of the laser light source  5  according to the fifth embodiment, the total reflection mirror  39  can function as the Q switch means by changing the angle of the total reflection mirror  39  with respect to the radiation light using the driving section  41 , instead of the position of the total reflection mirror  39 . In concrete terms, when the total reflection mirror  39  is a plane perpendicular to the radiation light that enters the black box  31  via the pin hole  33 , the radiation light is reflected to the pin hole  33 , so the resonance optical path is formed. 
         [0066]    When the total reflection mirror  39  is not a plane perpendicular to the radiation light, on the other hand, the radiation light is reflected by the total reflection mirror  39  in a direction different from the direction to the pin hole  33 , so the resonance optical path is interrupted, and resonator loss becomes the maximum. In the case of changing the angle of the total reflection mirror  39  like this as well, the pulsed light can be outputted from the laser light source  5 . According to this variant form as well, high durability supporting high power output can be implemented. 
         [0067]    Embodiments of the present invention were described above, but the present invention is not limited to these embodiments, but can be modified in various ways. 
         [0068]    For example, according to the first embodiment and the second embodiment, the Q switch means  20  or  24  is disposed between the end face  11   b  of the optical amplification fiber  11  and the total reflection mirror  16 , but may be disposed in another location in the resonator, such as a location between the lens  15  and dichroic mirror  13 . 
         [0069]    As described above, in accordance with the present invention, a laser light source having high durability supporting high power output can be implemented.