Abstract:
A flash-lamp envelope for a solid state flash lamp pumped laser in which the flash-lamp envelope is an extrusion-shaped optically transparent housing designed to act both as a glass sealing envelope and an optical coupler, efficiently transferring radiation from the flash lamp to a solid lasing rod.

Description:
CROSS REFERENCE TO APPLICATIONS 
       [0001]    This application is related to, and claims priority from U.S. Provisional Patent application No. 61/026,281 filed on Feb. 5, 2008, by R. Battis titled “Pump Chamber Integrated Lamps”, the contents of which are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to flash lamps, and more particularly to flash lamps used to pump solid state lasers. 
       BACKGROUND ART 
       [0003]    In the field of solid state lasers, flash lamps are commonly used to provide the energy to power the laser. 
         [0004]      FIG. 1  is a schematic plan view of an exemplary flash lamp pumped solid state laser  10 . A typical flash lamp pumped solid state laser  10  includes a flash lamp  12 , a laser optical coupler  16 , a laser rod  18 , a high reflector mirror  20 , an optical coupling mirror  24 . In typical operation, the flash lamp  12  emits radiation  14  that is fed to or focused on the a laser rod  18  by the laser optical coupler  16 . The laser optical coupler  16  may, for instance, be an elliptical mirror having the flash lamp  12  at one foci and the a laser rod  18  at the other foci of the ellipse. The laser optical coupler  16  is typically cooled using external heat fins, air cooling, water cooling or a combination thereof. 
         [0005]    The radiation  14  from the flash lamp  12  typically has a broad bandwidth. When coupled into the laser rod  18  in sufficient quantity, the radiation  14  pumps electrons from lower levels to populate higher levels, with subsequent spontaneous photon emission when the electron returns to a lower level. By locating the a laser rod  18  photon emission when the electron returns to a lower level. By locating the a laser rod  18  between two mirrors, any spontaneous photon emission along the axis of the a laser rod  18  bounces back and forth between the mirrors generating stimulated emission  22  at the same wavelength. Each pass through the energized laser rod  18  results in amplification of the stimulated emission  22 , termed gain. If the gain exceeds the losses due to imperfect mirrors, any absorption or any other factors, the intensity of the stimulated emission  22  builds and a coherent beam of light is created. By making the optical coupling mirror  24  partially transparent, a controlled percentage of the stimulated emission  22  may be extracted as a coherent beam of light  26 . 
         [0006]      FIG. 2  is a schematic side view of part of an exemplary prior art solid optical coupler  30 . The prior art solid optical coupler  30  in  FIG. 2  is an exemplary configuration designed to have two flash lamps  12  and one laser rod  18 . The prior art solid optical coupler  30  has a reflecting surface  32 , that typically has a nearly elliptical shape. The prior art solid optical coupler  30  also has two flash lamp sized semi-circular grooves  34  and one laser rod sized semi-circular groove  36 . A prior art solid optical coupler  30  is typically made of a heat conduction material such as, but not limited to, sapphire or cerium doped quartz. 
         [0007]      FIG. 3  is a schematic side view of an exemplary prior art laser cavity  40 . The prior art laser cavity  40  has two solid optical couplers  30  that between them retain the two flash lamps  12  and the laser rod  18 . 
         [0008]    The efficiency of the laser cavity  40 , i.e., the ration of output power in the coherent beam of light  26  to the flash lamp  12  power, is dependant on the optical coupling efficiency of the optical couplers  30 . 
         [0009]    Although the prior art laser cavity  40  is a convenient mechanical arrangement, the efficiency of the cavity may be limited by optical losses, such as, but not limited to, the optical loses as radiation  14  leaves the flash lamp  12  and enters the flash lamp sized semi-circular grooves  34 . It is highly desirable to make the coupling of radiation  14  emitted by the flash lamp  12  to the laser rod  18  as efficient as possible. 
       SUMMARY OF INVENTION 
       [0010]    The present invention is a flash-lamp envelope for a solid state flash lamp pumped laser in which the flash-lamp envelope is an extrusion-shaped optically transparent housing designed to act both as a glass sealing envelope and an optical coupler, efficiently transferring radiation from the flash lamp to a solid lasing rod. 
       Technical Problem 
       [0011]    The technical problem addressed by the present invention includes the construction of optical couplers for flash lamp pumped lasers that have efficient transfer of radiation from the flash lamp to the lasing rod, are capable of reliable manufacture and capable of being readily assembled into a laser cavity. 
       Solution to Problem 
       [0012]    The present invention solves the problem by effectively making the flash lamp housing part of the optical coupler, thereby reducing the number of surfaces that radiation from the flash lamp has to traverse before reaching the lasing rod. The reduced number of surfaces improves the efficiency of the flash lamp housing. 
       ADVANTAGEOUS EFFECTS OF INVENTION 
       [0013]    Advantages of the invention include, but are not limited to, the increased efficiency of laser cavities constructed using the pump chamber integrated optical couplers of the present invention. 
         [0014]    These and other features of the invention will be more fully understood by references to the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a schematic plan view of an exemplary flash lamp pumped solid state laser. 
           [0016]      FIG. 2  is a schematic side view of part of an exemplary prior art solid optical coupler 
           [0017]      FIG. 4  is a schematic side view of an exemplary pump chamber integrated lamp  50  of the present invention. 
           [0018]      FIG. 5  shows a two flash lamp, one laser rod, laser resonant cavity. 
           [0019]      FIG. 6  that shows a cross section of a four flash lamp, one laser rod embodiment of a quad chamber integrated lamp laser resonant cavity. 
           [0020]      FIG. 7  shows a cross section of a four flash lamp, one laser rod embodiment of a two chamber integrated lamp laser resonant cavity. 
           [0021]      FIG. 8  that shows a cross section of a two flash lamp, one laser rod embodiment of a two chamber integrated lamp laser resonant cavity. 
           [0022]      FIG. 9  shows a cross section of a four flash lamp, one laser rod embodiment of a four chamber integrated lamp laser resonant cavity. 
           [0023]      FIG. 10  shows a cross section of a two flash lamp, one laser rod embodiment of a two chamber integrated lamp laser resonant cavity with coupling elements. 
           [0024]      FIG. 11  shows a cross section of a two flash lamp, one laser rod embodiment of a two chamber integrated lamp laser resonant cavity  82  with coupling elements. 
           [0025]      FIG. 12  shows a cross section of a four flash lamp, one laser rod embodiment of a four chamber integrated lamp laser resonant cavity with coupling elements. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    Embodiments of the present invention will now be described in detail by reference to the accompanying drawings in which, as far as possible, like elements are designated by like numbers. 
         [0027]    Although every reasonable attempt is made in the accompanying drawings to represent the various elements of the embodiments in relative scale, it is not always possible to do so with the limitations of two-dimensional paper. Accordingly, in order to properly represent the relationships of various features among each other in the depicted embodiments and to properly demonstrate the invention in a reasonably simplified fashion, it is necessary at times to deviate from absolute scale in the attached drawings. However, one of ordinary skill in the art would fully appreciate and acknowledge any such scale deviations as not limiting the enablement of the disclosed embodiments. 
         [0028]      FIG. 4  shows a side view of an exemplary pump chamber integrated lamp  50  of the present invention. The chamber integrated lamp  50  may include a hollow, extrusion-shaped, optically transparent housing  48 . An extrusion shape is typically defined as one in which a two dimensional shape is extended along a third dimension that is orthogonal to the plane of the two dimensional shape. The chamber integrated lamp  50  also includes a reflective surface  54 , a transparent surface  56 , a hollow portion  52  and, optionally a transparent laser rod shaped semi-circle  58 . The reflective surface  54  is configured to reflect light emanating from within the hollow portion  52  of the chamber integrated lamp  50 . The hollow portion  52  is typically a cylinder and may be designed to directly incorporate a flash lamp filament, a flash lamp gas or electrodes or some combination thereof, so that the extrusion-shaped, optically transparent housing  48  acts both as a glass sealing envelope and an optical coupler. Alternately, the flash lamp  12  may be imbedded in a conventional circular glass sealing envelope that may then be fitted or embedding into the hollow portion  52 . The reflective surface  54  may include a metallic or dielectric coating on the surface of the extrusion-shaped, optically transparent housing  48  or it may be a metallic or other foil in close contact. The extrusion-shaped, optically transparent housing  48  may be made of some light transparent, heat conducting material such as, but not limited to, cerium doped quartz or sapphire. 
       EXAMPLES 
     Example 1 
       [0029]    Example 1 of the use of the present invention is illustrated in, for instance,  FIG. 5 , that shows a two flash lamp  12 , one laser rod  18 , laser resonant cavity  60  formed of two chamber integrated lamp  50 . The reflective surface  54  in such an embodiment may for instance be, but is not limited to, a portion of an ellipse having the center of the hollow portion  52  coincide with one focus of the ellipse, while the center of the laser rod  18  coincides with the other focus of the ellipse. 
         [0030]    The laser resonant cavity  60  includes two chamber integrated lamps  50  each of which include a reflective surface  54 , a transparent surface  56 , a hollow portion  52  and a transparent laser rod shaped semi-circle  58 . The reflective surface  54  is configured to reflect light emanating from within the hollow portion  52  of the chamber integrated lamp  50  toward transparent laser rod shaped semi-circle  58 . 
       Example 2 
       [0031]    Example 2 is illustrated in, for instance,  FIG. 6  that shows a cross section of a four flash lamp  12 , one laser rod  18  embodiment of a quad chamber integrated lamp laser resonant cavity  70 . 
         [0032]    The quad laser resonant cavity  70  includes four chamber integrated lamps  50  each of which include a reflective surface  54 , a transparent surface  56 , a hollow portion  52  and a transparent laser rod shaped sector of a circle  72 . The reflective surface  54  is configured to reflect light emanating from within the hollow portion  52  of the chamber integrated lamp  50  toward the laser rod shaped sector of a circle  72 . 
       Example 3 
       [0033]    Example 3 is illustrated in, for instance,  FIG. 7  that shows a cross section of a four flash lamp  12 , one laser rod  18  embodiment of a two laser resonant cavity  74 . 
         [0034]    The two laser resonant cavity  74  includes two chamber integrated lamps  50  each of which include a reflective surface  54 , a transparent surface  56 , two hollow portion  52  and a transparent laser rod shaped semi-circle  52 . The reflective surface  54  is configured to reflect light emanating from within the hollow portion  52  of the chamber integrated lamp  50  toward the transparent laser rod shaped semi-circle  58 . 
       Example 4 
       [0035]    Example 4 is illustrated in, for instance,  FIG. 8  that shows a cross section of a two flash lamp  12 , one laser rod  18  embodiment of a two chamber integrated lamp laser resonant cavity  76 . 
         [0036]    The two chamber integrated lamp laser resonant cavity  76  includes two chamber integrated lamps  50  each of which include a reflective surface  54 , a transparent surface  56 , a hollow portion  52  and a transparent laser rod shaped sector of a circle  72 . The reflective surface  54  is configured to reflect light emanating from within the hollow portion  52  of the chamber integrated lamp  50  toward the transparent laser rod shaped sector of a circle  72 . 
       Example 5 
       [0037]    Example 5 is illustrated in, for instance,  FIG. 9  that shows a cross section of a four flash lamp  12 , one laser rod  18  embodiment of a four chamber integrated lamp laser resonant cavity  78 . 
         [0038]    The four chamber integrated lamp laser resonant cavity  78  includes four chamber integrated lamps  50  each of which include a reflective surface  54 , a transparent surface  56 , a hollow portion  52  and a transparent laser rod shaped sector of a circle  72 . The reflective surface  54  is configured to reflect light emanating from within the hollow portion  52  of the chamber integrated lamp  50  toward the transparent laser rod shaped sector of a circle  72 . 
       Example 6 
       [0039]    Example 6 is illustrated in, for instance,  FIG. 10  that shows a cross section of a two flash lamp  12 , one laser rod  18  embodiment of a two chamber integrated lamp laser resonant cavity  82  with coupling elements  80 . 
         [0040]    The two chamber integrated lamp laser resonant cavity  82  includes two chamber integrated lamps  50  each of which include a reflective surface  54 , a transparent surface  56 , a hollow portion  52  and two coupling elements  80 . The coupling elements  80  include two transparent surfaces  56  and a transparent laser rod shaped semi-circle  58 . 
         [0041]    An advantage of this embodiment is the relative simplicity of each of the components. 
       Example 7 
       [0042]    Example 7 is illustrated in, for instance,  FIG. 11  that shows a cross section of a two flash lamp  12 , one laser rod  18  embodiment of a two chamber integrated lamp laser resonant cavity  82  with coupling elements  80 . 
         [0043]    The two chamber integrated lamp laser resonant cavity  82  includes two chamber integrated lamps  50  each of which include a reflective surface  54 , a transparent surface  56 , two hollow portion  52  and two coupling elements  80 . The coupling elements  80  include two transparent surfaces  56  and a transparent laser rod shaped semi-circle  58 . 
         [0044]    An advantage of this embodiment is the relative simplicity of each of the components. 
       Example 8 
       [0045]    Example 8 is illustrated in, for instance,  FIG. 12  that shows a cross section of a four flash lamp  12 , one laser rod  18  embodiment of a four chamber integrated lamp laser resonant cavity  82  with coupling elements  80 . 
         [0046]    The four chamber integrated lamp laser resonant cavity  82  includes four chamber integrated lamps  50  each of which include a reflective surface  54 , a transparent surface  56 , a hollow portion  52  and two coupling elements  80 . The coupling elements  80  include two transparent surfaces  56  and a transparent laser rod shaped semi-circle  58 . 
         [0047]    An advantage of this embodiment is the relative simplicity of each of the components. 
         [0048]    Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed invention. Modifications may readily be devised by those ordinarily skilled in the art without departing from the spirit or scope of the present invention. 
       INDUSTRIAL APPLICABILITY 
       [0049]    In the field of solid state lasers there is significant interest in optical couplers to improve the efficiency of laser. Such an improved optical coupler would be of considerable utility in, for instance, the medical and industrial application of lasers.