Abstract:
A laser crystal evaluating system, comprising a light emitting source for emitting an excitation light, a laser crystal support base for supporting a laser crystal, a photodetection unit for receiving a laser beam emitted from the laser crystal, a moving device for relatively moving the light emitting source and the laser crystal in parallel to an end surface of the laser crystal, and an arithmetic operation control device for acquiring an amount of relative movement from the moving device and a result of photodetection from the photodetection unit, wherein a position in the end surface of the laser crystal where the excitation light enters is moved by the moving device, and the arithmetic operation control device obtains output distribution within the end surface of the laser crystal based on the incident position of the excitation light and on the result of photodetection.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a laser crystal evaluating system for evaluating quality of a laser crystal to be used in a solid-state laser.  
         [0002]     In a solid-state laser, an excitation light is projected to a laser crystal. Then, the excitation light is resonated by the laser crystal, and a laser beam is emitted.  
         [0003]     Crystal quality of the laser crystal exerts influence on the quality (such as light intensity, light intensity distribution, polarization, stability, etc.) of the outputted laser beam. Also, due to micro-size flaws caused during cutting, or to residual stress or to diffraction, the laser beam emitted from the laser crystal is instable or the laser beam is not emitted when the excitation light enters peripheral portion of the laser crystal. Even when the excitation light enters the central portion, a predetermined light intensity may not be obtained or the site to emit the highest light intensity is not at the center of the incident surface. That is, there are individual differences depending on each laser crystal, and there may be variations in the quality of the laser beam emitted according to each laser crystal.  
         [0004]     In the past, the quality of the laser crystal itself has not been evaluated. After the laser crystal is incorporated in a solid-state laser, evaluation test is performed as the solid-state laser. In this respect, performance characteristics as required may not be obtained due to the quality of the laser crystal in some cases, and this has caused the decrease in yield of the solid-state laser.  
       SUMMARY OF THE INVENTION  
       [0005]     It is an object of the present invention to provide a laser crystal evaluating system, by which it is possible to evaluate performance characteristics of a laser crystal itself, to improve yield of the solid-state laser, to detect a site where intensity of an emitted laser beam is equal to or more than a predetermined intensity, and to effectively utilize the performance characteristics of the laser crystal.  
         [0006]     To attain the above object, the present invention provides a laser crystal evaluating system, which comprises a light emitting source for emitting an excitation light, a laser crystal support base for supporting a laser crystal, a photodetection unit for receiving a laser beam emitted from the laser crystal, a moving device for relatively moving the light emitting source and the laser crystal in parallel to an end surface of the laser crystal, and an arithmetic operation control device for acquiring an amount of relative movement from the moving device and a result of photodetection from the photodetection unit, wherein a position in the end surface of the laser crystal where the excitation light enters is moved by the moving device, and the arithmetic operation control device obtains output distribution within the end surface of the laser crystal based on the incident position of the excitation light and on the result of photodetection. Also, the present invention provides the laser crystal evaluating system as described above, wherein the arithmetic operation control device has a display unit, graphically represents the output distribution of the photodetection result to correspond relative movement, and displays the output distribution on the display unit. Further, the present invention provides the laser crystal evaluating system as described above, wherein the arithmetic operation control device has criteria for evaluation, the criteria for evaluation include at least one output value reference, an output area and a position of the area, and if the criteria are met, evaluation is performed according to the output value reference. Also, the present invention provides the laser crystal evaluating system as described above, wherein the laser crystal support base comprises a cooler to maintain the laser crystal at a predetermined temperature. Further, the present invention provides the laser crystal evaluating system as described above, wherein the laser crystal contains a laser crystal and a wavelength conversion crystal integrated with each other. Also, the present invention provides the laser crystal evaluating system as described above, wherein a polarizing plate is provided on an exit side of the laser crystal to evaluate polarizing characteristics. Further, the present invention provides the laser crystal evaluating system as described above, wherein maintaining temperature of the laser crystal is changed and temperature characteristics of the laser crystal is evaluated. Also, the present invention provides the laser crystal evaluating system as described above, wherein there is provided an optical filter which is arranged on the laser beam emitted from the laser crystal, and the optical filter allows a wavelength of a fundamental wave light to pass. Further the present invention provides the laser crystal evaluating system as described above, wherein the arithmetic operation control unit has two or more output value references, and the laser crystal is classified based on the result of photodetection. Also, the present invention provides the laser crystal evaluating system as described above, wherein the laser crystal is evaluated at two or more temperatures, and the laser crystal is classified according to the operation temperatures. Further, the present invention provides the laser crystal evaluating system as described above, wherein the laser crystal and the wavelength conversion crystal are attached with each other by adhesive agent. Also, the present invention provides the laser crystal evaluating system as described above, wherein a first dielectric reflection film is formed on an incident end surface of the laser crystal, and a second dielectric reflection film is formed on the other end surface.  
         [0007]     The present invention provides a laser crystal evaluating system, which comprises a light emitting source for emitting an excitation light, a laser crystal support base for supporting a laser crystal, a photodetection unit for receiving a laser beam emitted from the laser crystal, a moving device for relatively moving the light emitting source and the laser crystal in parallel to an end surface of the laser crystal, and an arithmetic operation control device for acquiring an amount of relative movement from the moving device and a result of photodetection from the photodetection unit, wherein a position in the end surface of the laser crystal where the excitation light enters is moved by the moving device, and the arithmetic operation control device obtains output distribution within the end surface of the laser crystal based on the incident position of the excitation light and the result of photodetection. As a result, it is possible to identify the quality of the crystal itself in advance, and this contributes to the improvement of production yield by eliminating defects caused by the laser crystal when a diode pumped solid-state laser is produced.  
         [0008]     According to the present invention, a laser crystal evaluating system is provided wherein the arithmetic operation control device has a display unit, graphically represents the output distribution of the photodetection result to correspond relative movement, and displays the output distribution on the display unit. Thus, the results of evaluation can be visually judged.  
         [0009]     According to the present invention, a laser crystal evaluating system is provided wherein the arithmetic operation control device has criteria for evaluation, the criteria for evaluation include at least one output value reference, an output area and a position of the area, and if the criteria are met, evaluation is performed according to the output value reference. As a result, evaluation can be made to match each application purpose of the laser crystal, and the laser crystal can be effectively utilized.  
         [0010]     According to the present invention, a laser crystal evaluating system is provided wherein the laser crystal support base comprises a cooler to main maintain the laser crystal at a predetermined temperature. As a result, evaluation accuracy is improved. Also, by varying temperature during the evaluation of the laser crystal, evaluation can be made to match each temperature. This makes it possible to select a laser crystal by taking the condition of use of the diode pumped solid-state laser into consideration.  
         [0011]     According to the present invention, a laser crystal evaluating system is provided wherein the laser crystal contains a laser crystal and a wavelength conversion crystal integrated with each other. Thus, it is possible to perform overall evaluation of the laser crystal, which has been turned to form of a chip. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a drawing to explain basic arrangement of a diode pumped solid-state laser, to which the present invention is applied;  
         [0013]      FIG. 2  is a schematical perspective view of an embodiment of the present invention;  
         [0014]      FIG. 3  shows a result of evaluation by using a laser crystal evaluating system according to the embodiment of the present invention.  FIG. 3  (A) is a 3-dimensional graph to show the results of evaluation of a laser crystal, and  FIG. 3  (B) is a 2-dimensional graph to show the results of evaluation of the laser crystal;  
         [0015]      FIG. 4  shows other examples of the results of evaluation by the laser crystal evaluating system of the embodiment of the present invention.  FIG. 4  (A) is a 3-dimensional graph to show the results of evaluation of a laser crystal, and FIG.  4  (B) is a 2-dimensional graph to show the results of evaluation of the laser crystal;  
         [0016]      FIG. 5  represents a flow chart of a process of evaluation in an embodiment of the present invention;  
         [0017]      FIG. 6  is a drawing of a laser crystal chip to be evaluated by the laser crystal evaluating system of the embodiment of the present invention; and  
         [0018]      FIG. 7  is a drawing of a laser crystal chip to be evaluated by the laser crystal evaluating system of the embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]     Description will be given below on the best mode to carry out the present invention referring to the drawings.  
         [0020]     First, description will be given on a diode pumped solid-state laser  1  referring to  FIG. 1 .  
         [0021]     In  FIG. 1 , reference numeral  2  denotes a light emitting unit, and reference numeral  3  denotes an optical resonator. The light emitting unit  2  comprises an LD light emitter  4  and a condenser lens  5 . Further, the optical resonator  3  comprises a first optical crystal (laser crystal  8 ) with a first dielectric reflection film  7  formed thereon, a second optical crystal (nonlinear optical crystal (NLO) (wavelength conversion crystal  9 )), and a concave mirror  11  with a second dielectric reflection film  10  formed thereon. At the optical resonator  3 , a laser beam is pumped, resonated and amplified, and a wavelength is converted and the laser beam is outputted.  
         [0022]     In the diode pumped solid-state laser  1 , the LD light emitter  4 , which emits a semiconductor laser, is used as an excitation light source for projecting an excitation light to the optical resonator  3 , for instance.  
         [0023]     The laser crystal  8  converts the excitation light to a fundamental wave and amplifies the light. As the laser crystal  8 , Nd:YVO 4  with an oscillation line of 1064 nm is used. Or, YAG (yttrium aluminum garnet) doped with Nd 3 + ions is used. YAG has oscillation lines of 946 nm, 1064 nm, 1319 nm, etc. Also, Ti (sapphire) with oscillation lines of 700-900 nm may be used.  
         [0024]     The wavelength conversion crystal  9  performs wavelength conversion to turn the fundamental wave to ½. As the wavelength conversion crystal  9 , KTP (KTiOPO 4 ; titanyl potassium phosphate) is used.  
         [0025]     On a side of the laser crystal  8  closer to the LD light emitter  4 , the first dielectric reflection film  7  is formed. The first dielectric reflection film  7  is highly transmissive to the laser beam from the LD light emitter  4 , and the first dielectric reflection film  7  is highly reflective to an oscillation wavelength (fundamental wavelength) of the laser crystal  8 . The first dielectric reflection film  7  may be highly reflective to secondary higher harmonic wave or second harmonic generation (SHG). Naturally, for the second harmonic generation, the first dielectric reflection film  7  may be provided on an end surface of the laser crystal  8  opposite to the excitation side or on an excitation side of the wavelength conversion crystal  9 .  
         [0026]     The concave mirror  11  is arranged to face the laser crystal  8 . A face of the concave mirror  11  closer to the laser crystal  8  is worked out in form of a concave spherical face with an adequate radius, and the second dielectric reflection film  10  is formed on the concave spherical face. The second dielectric reflection film  10  is highly reflective to the fundamental wavelength and the second dielectric reflection film  10  is highly transmissive to the second harmonic generation.  
         [0027]     As described above, when the first dielectric reflection film  7  of the laser crystal  8  is combined with the second dielectric reflection film  10  of the concave mirror  11  and an excitation light from the LD light emitter  4  is pumped to the laser crystal  8  via the condenser lens  5 , the light runs reciprocally between the first dielectric reflection film  7  of the laser crystal  8  and the second dielectric reflection film  10 . Because the light can be confined for long time, it is possible to resonate and amplify the light.  
         [0028]     The wavelength conversion crystal  9  is placed within the optical resonator  3 , which comprises the first dielectric reflection film  7  of the laser crystal  8  and the concave mirror  11 . When a strong coherent light such as a laser beam enters the wavelength conversion crystal  9 , the secondary higher harmonic wave is generated, which doubles a frequency of the light. The generation of the secondary higher harmonic wave is called “second harmonic generation”. Thus, from the diode pumped solid-state laser  1 , a laser beam with a wavelength of 532 nm is emitted, for instance.  
         [0029]     When wavelength conversion is not required for the laser beam projected from the diode pumped solid-state laser  1 , the wavelength conversion crystal  9  is removed from the arrangement shown in  FIG. 1 . In this case, the second dielectric reflection film  10  allows several % of the fundamental wave to pass. The condenser lens  5  may not be used. In such case, a distance between the LD light emitter  4  and the laser crystal  8  may be shortened.  
         [0030]     The laser crystal  8  used in the diode pumped solid-state laser  1  determines quality of the laser beam emitted from the diode pumped solid-state laser  1 . Some of the manufactured laser crystals  8  may not emit a laser beam of required quality. Also, a central portion of an incident end surface of the laser crystal  8  does not necessarily emit a laser beam of the highest quality such as the highest intensity.  
         [0031]     In order to evaluate quality of the laser crystal  8 , the laser crystal evaluating system described below inspects whether the laser crystal  8  emits a laser beam of predetermined quality and inspects oscillating condition of the laser beam corresponding to an incident position of an excitation light  12  (described later) at an incident surface of the laser crystal  8 , and investigates distribution of intensity of the oscillated laser beam.  
         [0032]     Referring to  FIG. 2 , description will be given on a laser crystal evaluating system  14 .  
         [0033]     On a laser crystal support base  15 , the laser crystal  8  is removably mounted by using a fixing means  16  as required. The laser crystal support base  15  comprises a cooler  17  such as thermoelectric cooling element (TEC), and the laser crystal  8  can be cooled down by the cooler  17 . The laser crystal  8  to be evaluated may be a single body or the laser crystal  8  may be provided with a first dielectric reflection film  7  and a second dielectric reflection film  10  formed on end surfaces respectively.  
         [0034]     A triaxial moving unit  18  is provided so as to face an incident end surface  8   a  side of the laser crystal  8 . The triaxial moving unit  18  comprises an X-Z-axes moving unit  21  for moving an X-Z-axes stage  19  in two directions of X-axis and Z-axis, a Y-axis moving unit  22  provided on the X-Z-axes stage  19 , and a Y-axis stage  23  to be moved in a Y-axis direction by the Y-axis moving unit  22 . On the Y-axis stage  23 , a light emitting source  24  for emitting an excitation light such as LD is arranged.  
         [0035]     On an exit side of the light emitting source  24 , a condenser lens  25  is mounted on the Y-axis stage  23 . An excitation light  26  emitted from the light source  24  is converged and is projected to the laser crystal  8 .  
         [0036]     The excitation light  26  is oscillated by the laser crystal  8 , and a laser beam of fundamental wave (hereinafter referred as “fundamental wave light  27 ”) is projected from the laser crystal  8 .  
         [0037]     On an exit end surface side of the laser crystal  8 , an optical filter  28  allowing a wavelength of the fundamental wave light  27  to pass is provided. Further, a photodetection unit  29  is provided on a transmission side of the optical filter  28 . As the photodetection unit  29 , PD (photodiode), CCD (charge coupled device), etc. may be used. As the optical filter  28 , a filter is used, which cuts off unnecessary light and to allow only the light to be evaluated to pass.  
         [0038]     It is designed in such manner that the X-Z-axes moving unit  21  and the Y-axis moving unit  22  are driven and controlled by an arithmetic operation control unit  31 , e.g. a personal computer. Moving position can be determined in directions of X-axis, Y-axis and Z-axis from a reference point O (origin of the coordinate). An amount of movement in each of the directions of 3 axes is detected by a position detector  30  respectively, and the result of the detection is sent to the arithmetic operation control unit  31 .  
         [0039]     The reference point O is determined by installing the laser crystal  8  on the laser crystal support base  15 . For instance, the laser crystal  8  is pressed against the fixing means  16 , and the reference point O is determined by the fixing means  16 . For instance, the reference point O is defined as a point formed at a site where a vertical plane, in which the laser crystal  8  is abutted to the fixing means  16 , crosses a horizontal plane, in which the laser crystal  8  is abutted to the laser crystal support base  15 . In  FIG. 2 , a right lower corner of the incident end surface of the laser crystal  8  is defined as the reference point O.  
         [0040]     For instance, when the reference point O is determined as a point where the vertical plane, in which the laser crystal  8  is abutted to the fixing means  16 , crosses the horizontal plane, in which the laser crystal  8  is abutted to the laser crystal support base  15 , the reproducibility of the position of the reference point O is ensured even when the laser crystal  8  is replaced.  
         [0041]     It is so designed that the cooler  17  is driven according to a control signal from the arithmetic operation control unit  31 . Temperature of the laser crystal  8  is detected by a temperature sensor  32 . The result of the detection is fed back to the arithmetic operation control unit  31 , and cooling temperature of the laser crystal  8  is controlled.  
         [0042]     From the photodetection unit  29 , a photodetection signal depending on the photodetecting condition is sent to the arithmetic operation control unit  31 . At the arithmetic operation control unit  31 , the position of the light emitting source  24  is associated with the photodetection signal from the photodetection unit  29 , and the result is recorded.  
         [0043]     Now, description will be given on operation.  
         [0044]     The laser crystal  8  is installed on the laser crystal support base  15 . The X-Z-axes moving unit  21  and the Y-axis moving unit  22  are driven by the arithmetic operation control unit  31 , and the X-Z-axes stage  19  and the Y-axis stage  23  are restored to the reference point.  
         [0045]     The light emitting source  24  is driven and the excitation light  26  is emitted. The excitation light  26  may be a continuous light or a pulsed light.  
         [0046]     By driving the X-Z-axes moving unit  21 , the X-Z-axes stage  19  is moved in the direction of Z-axis, and exit condition of the excitation light  26  is adjusted. Next, by driving the X-Z-axes moving unit  21 , the X-Z-axes stage  19  is moved in the direction of X-axis (+), and an incident point  26   a  of the excitation light  26  on the incident end surface  8   a  is moved in the direction of X-axis (+). With the movement of the incident point  26   a , a photodetection signal from the photodetection unit  29  is sent to the arithmetic operation control unit  31  at a predetermined pitching. An amount of displacement from the reference point O is detected by the position detector  30 , and the detection result is sent to the arithmetic operation control unit  31 . By the arithmetic operation control unit  31 , position data from the position detector  30  of the triaxial moving unit  18  is associated with the photodetection signal, and the data is stored. The movement of the X-Z-axes stage  19  may be performed by pitch feeding or by continuous feeding.  
         [0047]     When the incident point  26   a  is moved over the entire width in the direction of X-axis of the laser crystal  8 , the Y-axis moving unit  22  is driven, and the incident point  26   a  is moved in the direction of Y-axis by a predetermined pitch. By driving the X-Z-axes moving unit  21 , the X-Z-axes stage  19  is moved in the direction of X-axis (−) . Then, the position data from the position detector  30  is associated with the photodetection signal from the photodetection unit  29 , and the data is stored. The range of scanning may be limited only to the central portion when necessary.  
         [0048]     When the movement is made over the entire X-axis width of the laser crystal  8  in the direction of X-axis (−), the Y-axis stage  23  is driven, and the Y-axis moving unit  22  is driven. The incident point  26   a  is moved again in the direction of Y-axis by a predetermined pitch. The X-Z-axes stage  19  is moved in the X-axis (+) direction by the X-Z-axes moving unit  21 . Then, the position data from the position detector  30  is associated with the photodetection signal from the photodetection unit  29 , and the data is stored in the same manner as the above.  
         [0049]     Through cooperative operation of the movement of the incident point  26   a  in the X-axis direction over the entire width of the laser crystal  8  by the driving of the X-Z-axes moving unit  21  and stepwise feeding in the Y-axis direction by the driving of the Y-axis moving unit  22 , the incident point  26   a  of the excitation light  26  is moved and scans over the entire surface of the incident end surface  8   a . Then, the photodetection signal over the entire surface of the incident end surface  8   a  and the position signal associated with the photodetection signal are acquired.  
         [0050]     Based on the data of the incident position of the excitation light  26  on the incident end surface  8   a  and based on the data of the photodetection signal corresponding to the incident position (light intensity of the fundamental wave light  27  emitted from the laser crystal  8 ), the arithmetic operation control unit  31  prepares a 3-dimensional distribution graph of light intensity as shown in  FIG. 3  (A) or in  FIG. 4  (A), and the light intensity distribution is displayed on a display unit  33  of the arithmetic operation control unit  31 . In  FIG. 3  (A) and  FIG. 4  (A), the symbol X-Y respectively represents coordinate in the incident end surface of the laser crystal  8 , and the symbol Z represents output intensity of the photodetection unit  29 . Also, a 2-dimensional light intensity distribution graph as shown in  FIG. 3  (B) or in  FIG. 4  (B) is prepared, and the graph is displayed on the display unit  33 . In  FIG. 3  (B) and in  FIG. 4  (B), each of the symbols X-Y represents coordinate in the incident end surface of the laser crystal  8 , and contour lines in the figure show output intensities of the photodetection unit  29 .  
         [0051]     By 3-dimensional display, oscillation characteristics of the laser crystal  8  can be visually judged. Further, by using different colors to match different intensities, the value of light intensity of the emitted fundamental wave light  27  can be easily identified. In case of 2-dimensional display, the distribution of light intensity is shown by contour lines or by display of different colors. Thus, it can be easily identified whether the contour lines or the colors showing the predetermined light intensity is spreading over the predetermined area or not, or the position of the area can be easily identified. This contributes to the accurate evaluation of whether the product is acceptable or defective.  
         [0052]     For instance, when evaluation result shown in  FIG. 3  is compared with the evaluation result shown in  FIG. 4 , the light intensity is high at the central portion in the evaluation result shown in  FIG. 4 . Also, the area is large and wide and there is no recess on the top portion. Thus, the laser crystal  8  evaluated in  FIG. 4  is determined as an acceptable product compared with laser crystal  8  evaluated in  FIG. 3 .  
         [0053]     Next, referring to  FIG. 5 , description will be given on a case where evaluation is made whether the laser crystal  8  is acceptable or defective by the arithmetic operation control unit  31 .  
         [0054]     Criteria for determining whether the product is acceptable or defective are as follows: whether the light intensity acquired by the laser crystal evaluating system  14  (i.e. output of the photodetection signal from the photodetection unit  29 ) is equal to or higher than the predetermined light intensity or not; whether the area with the light intensity equal to or higher than the predetermined light intensity is equal to or larger than the range (area) as predetermined; whether the area is in adequate shape or not such that the area is not divided. Regarding the light intensity, it is judged whether an output to match the light intensity required for the laser crystal  8  has been obtained or not.  
         [0055]     For instance, when the laser crystal  8  is installed on the laser crystal support base  15 , judgment is made based on the data of the incident position of the excitation light  26  on the incident end surface  8   a  and on the data of the photodetection signal corresponding to the incident position. It is judged whether the output of the photodetection signal from the photodetection unit  29  is equal to or more than a first reference level, e.g. equal to or more than 12 mW (Step  01 ).  
         [0056]     When the output is 12 mW, it is judged whether or not the light emitting area is equal to or larger than a predetermined area, e.g. 0.3×0.3 mm (Step  02 ). If the light emitting area is 0.3×0.3 mm or more, it is further judged whether or not the position of the light emitting area (e.g. the center of gravity of the graphical form) is within 0.3 mm from the center of the incident end surface  8   a  (Step  03 ).  
         [0057]     In case it is judged that the position of the light emitting area is within 0.3 mm from the center of the incident end surface  8   a  in Step  03 , it is evaluated that the laser crystal  8  under evaluation is an acceptable product for high output.  
         [0058]     In case the light emitting area is found to be less than 0.3×0.3 mm in Step  02  or in case the position of the light emitting area is deviated by more than 0.3 mm from the center of the incident end surface  8   a , and if the output is lower than 12 mW in Step  01 , it is further judged whether it is equal to or more than the second reference level, e.g. it is equal to or more than 6 mW (Step  04 ). In case the output is 6 mW or more, it is judged in Step  05  whether the light emitting area is equal to or more than 0.3×0.3 mm, and it is further judged in Step  06  whether the position of the light emitting area is within 0.3 mm from the center of the incident end surface  8   a  or not. If the light emitting area is equal to or more than 0.3×0.3 mm and the position of the light emitting area is within 0.3 mm from the center of the incident end surface  8   a , the laser crystal  8  is evaluated as an acceptable product for low output.  
         [0059]     The laser crystal  8  not satisfying the criteria in Steps  04 ,  05  and  06  is evaluated as a defective product. The reference level may be divided to 3 stages and the product may be evaluated as an acceptable product for high output, an acceptable product for medium output, and an acceptable product for low output.  
         [0060]     In the above, as the criteria for evaluation, explanation has been given on the output, the light emitting area and the position of the light emitting area, while the change of output in association with the temperature of the laser crystal  8  may be included in the criteria. In general, the condition of the output of the laser crystal  8  varies according to the temperature of the laser crystal  8 , and temperature may be used as a parameter. During the evaluation by the laser crystal evaluating system  14 , the laser crystal  8  may be maintained at a constant temperature by using the arithmetic operation control unit  31  and the laser crystal  8  may be evaluated at two or more temperature values, and the laser crystal may be classified to a laser crystal  8  for high temperature and a laser crystal  8  for low temperature.  
         [0061]     Further, by using a polarizing plate as the optical filter  28 , it is possible to evaluate 2-dimensional distribution of the polarizing characteristics.  
         [0062]     Also, the laser crystal evaluating system  14  may be designed in such manner that the laser crystal support base  15  is moved in triaxial directions by fixing the light emitting source  24 .  
         [0063]     In addition to the laser crystal  8  itself, the laser crystal evaluating system  14  can evaluate a diode pumped solid-state laser  1 , which has the first dielectric reflection film  7  and the second dielectric reflection film  10  directly formed on the end surfaces of the laser crystal  8  and in which the optical resonator  3  is turned to form of a chip.  
         [0064]     Referring to  FIG. 6 , description will be given on the optical resonator  3 , in which the first dielectric reflection film  7 , the laser crystal  8 , and the second dielectric reflection film  10  are integrated and which is turned to form of a chip.  
         [0065]     A first dielectric reflection film  7  is formed on an end surface of the laser crystal  8  such as Nd:YVO 4  or Nd:YAG where the excitation light  12  enters. A second dielectric reflection film  10  is formed on the other end surface of the laser crystal  8 . The first dielectric reflection film  7  is highly transmissive to the excitation light  12 , and the first dielectric reflection film  7  is highly reflective to an oscillation wave (fundamental wave) of the laser crystal  8 . The second dielectric reflection film  10  is highly transmissive to the oscillation wave, and the laser crystal  8  serves as the optical resonator  3 .  
         [0066]     When the optical resonator  3  is evaluated by the laser crystal evaluating system  14 , overall performance characteristics can be evaluated including parallelism of both end surfaces of the laser crystal  8  and performance characteristics of the first dielectric reflection film  7  and the second dielectric reflection film  10 .  
         [0067]     A wavelength conversion crystal  9  is attached on the laser crystal  8  by using adhesive agent, and an optical resonator  3  with a wavelength conversion function can be produced in form of a chip. This is illustrated in  FIG. 7 . The first dielectric reflection film  7  is formed on an incident end surface of the laser crystal  8 , and the second dielectric reflection film  10  is formed on an exit end surface of the wavelength conversion crystal  9 . The optical resonator  3  can also be evaluated by the laser crystal evaluating system  14  in similar manner. In this case, overall performance characteristics can be evaluated including the evaluation of the first dielectric reflection film  7 , the wavelength conversion crystal  9 , and the second dielectric reflection film  10 , and also including the evaluation of the adhesive agent and adhesive condition between the wavelength conversion crystal  9  and the laser crystal  8 .