Abstract:
An apparatus for applying light radiation to an object include: a source of light radiation including infrared radiation, a light guide having a proximal end optically coupled to the source of light radiation and a distal end with a light radiation emitting end surface, a power supply which supplies power to the light radiation source, a photo light energy detector disposed within the apparatus so as to receive energy output emitted from the light radiation source, the photo light energy detector producing an output in response to the received energy output; and a controller coupled to the photo light energy detector and the light radiation source; wherein the controller receives the output from the photo light energy detector and controls the source of light radiation to produce a predetermined light radiation intensity in response to the output.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority to United States Provisional Patent Application No. 60/106,401 filed Oct. 30, 1998, entitled INFRARED COAGULATOR WITH DISPOSABLE TIP LIGHT GUIDE. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an apparatus for causing thermal coagulation and, more particularly, relates to an apparatus for applying intense light radiation to a limited area of tissue for causing thermal coagulation that results in tissue necrosis. 
     Various medical procedures require an apparatus to cause hemorrhoid shrinkage or cause coagulation at a site of bleeding. For example, coagulation may be induced at the site of a bleeding hemorrhoid or at a site of hemorrhaging at a bleeding blood vessel stump. Known coagulation systems, for example, use high frequency electric currents to cause coagulation. These systems, however, use the human body as an electrical conductor and thus require external grounding using a grounding pad. Further, such electrosurgical devices do not readily induce coagulation in a controllable and reproducible manner, and thus the depth of necrosis cannot be precisely controlled. Additionally, the metallic probes used tend to adhere to the tissue, thereby impeding homeostasis. 
     Alternatively, thermal coagulation is induced by exposure to a laser beam or an infrared light source. Though both sources have advantages over electrocoagulation, the infrared light sources are preferred because the light source is cheaper than and-YAG laser or other laser sources. 
     Known infrared light source thermal coagulation systems typically include a probe with a light radiation source enclosed in a housing. The source emits light radiation through a light exit surface for transmission along a light guide. The light guide is a light transmissive material which delivers the light radiation to the tissue surface and heats the surface. Examples of known apparatus for causing thermal coagulation using a light source are described in U.S. Pat. No. 4,233,493, issued Nov. 11, 1980, and U.S. Pat. No. 4,539,987, issued Sep. 10, 1985, the disclosures of which are incorporated herein by reference, and by Redfield Corporation Brochure Ĉ 1988 attached hereto as Appendix A. 
     In the known systems, however, the light guide is typically a straight rod or slightly bent and is thus often difficult to apply specific to the desired tissue region to be treated. 
     Further, the intensity of the emitted light cannot be precisely controlled and thus the coagulation is also not readily controlled. Another disadvantage is that the probe must be sterilized each time prior to its use. 
     It is therefore desirable to have an infrared coagulation device which overcomes the above-mentioned problems. 
     SUMMARY OF THE INVENTION 
     The present invention provides an infrared coagulation apparatus in which light is transmitted along a light guide having a bend that changes the direction of the light at a greater angle than in known systems, in which the intensity of the infrared light source is controlled by a feedback loop and which includes a disposable tip at the end of the light guide. 
     The infrared coagulation apparatus of this invention includes a non-coherent, multispectral light source having a spectral maximum of about 10,000 angstroms. A portion of the visible light spectrum is also emitted to ascertain operation of the lamp. The light emitted from the lamp is transmitted along a light guide which may be comprised entirely of quartz or which may include other light transmissive materials, such as sapphire, with a quartz portion located at the distal end. Advantageously, the distal end of the light guide includes a bend that causes the light to exit at angles up to an angle substantially perpendicular to the axis of the light guide and thus permits the probe to more easily contact the tissue area. A reflective coating surrounds the cylindrical walls of the light guide to further promote transmission of the light radiation along the path of the light guide as well as around the bend. A cladding layer, such as neoprene, surrounds the reflective coating to protect the coating, and an additional support cladding typically surrounds the neoprene cladding. A metal end cap is secured around the light guide near the distal end. 
     Alternatively, a straight quartz rod serves as the light guide and is covered with the reflective coating along the walls and at the distal end. A portion of the wall near the distal end is left uncoated so that the light reflects off the coating and exits at an angle substantially perpendicular to the axis of the rod. 
     Further, in accordance with this invention, a disposable contact tip covers the distal end of the light guide. The disposable tip includes a plastic cap that is secured onto the metal end cap and a Teflon or PVC plate optical window that covers the polished end surface of the light guide. 
     Alternatively, the disposable tip and sheath includes a plastic cylindrical body having a Teflon or PVC optical window which covers the contact end of the cylindrical body. A step-down section is attached to the opposite end of the cylindrical body and is arranged to be concentric with the cylindrical body but with a smaller diameter than the cylindrical body for secure insertion into the metal end cap of the light guide. A clear plastic sheath is also attached at this end of the cylindrical body and is sealed over the step-down section and extends over the surface of the cladding. The proximal end of the sheath is attached to a retainer ring having another step-down section which is capable of sliding over a retaining collar in the cladding to secure the proximal end of the sheath to the cladding. A pull tab is provided at the proximal ring so that the sheath and end cap can be removed after use by pulling on the pull tab and tearing a weakened notch in the step-down section to permit the sheath to be torn off the cladding and prevent its reuse. 
     In further accordance with the,invention, a power supply and control circuit controls the operation of the infrared lamp. A microcontroller delivers control signals to a triac which controls the current supplied by a step-down transformer to the infrared lamp. The microcontroller also receives a dwell time adjustment signal which controls the length of the pulses of the infrared lamp. The microcontroller also controls a lamp-on indicator LED and a digital read out lamp which indicates the length of the light pulses. Advantageously, a feedback circuit is also provided which includes a photo-diode that delivers a signal proportional to the intensity of the infrared lamp to an operational amplifier. The op-amp delivers the signal to an analog-to-digital converter which supplies a converted signal to the microcontroller which, in turn, controls the triac accordingly in response to the intensity detected. 
     The infrared coagulator apparatus of the invention causes thermal coagulation by elevating the tissue temperature to about 100° C. without smoke or odor. The apparatus may be used for coagulation of bleeding, such as at the donor sites of hair transplant plugs. The coagulator is also suitable for causing coagulation at a hemorrhoidal plexus to cause the plexus to shrink and recede. Additionally, the coagulator may be used to remove decorative tattoos, reduce swollen nose membranes caused by chronic rhinitis, dry up genital warts or to remove warts or other skin lesions. 
     Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in greater detail in the following detailed description with the reference to the drawings in which: 
     FIG. 1 shows a perspective view of an embodiment of the invention. 
     FIG. 2 shows a side view of the hand piece assembly of FIG.  1 . 
     FIG. 3 shows a rear view of the console unit of FIG.  1 . 
     FIG. 4 shows an exploded view of the hand piece assembly of FIG.  2 . 
     FIGS. 5A-5E illustrate an example of the preparation of the light guide in accordance with an aspect of the invention. 
     FIG. 6 shows a cross-sectional view of the light guide of FIG. 5 with an embodiment of a disposable contact tip of the invention. 
     FIG.  7 . shows another embodiment of a disposable contact- tip and sheath of the invention. 
     FIG. 8 shows a portion of the contact tip and sheath of FIG. 7 in greater detail. 
     FIG. 9A is a cross-sectional view of a disposable sheath and contact tip in accordance with the invention. 
     FIG. 9B is a sectional view of the sheath of FIG.  9 A. 
     FIG. 9C is a sectional view of the contact tip of FIG.  9 A. 
     FIG. 9D is a left side elevation view of FIG.  9 C. 
     FIG. 9E is a sectional detail taken from FIG.  9 C. 
     FIG. 10 is block diagram showing an embodiment of the power supply and control circuit of the invention. 
     FIG. 11 is top perspective view of the IRC assembly comprising the base housing and control unit on the left, the light guide and handle assembly on the right, and the connecting cable. 
     FIG. 12 is a sectional elevation view of the handle portion of the light guide. 
     FIG. 12A is an elevation view of the left side hand grip. 
     FIG. 13 is a sectional elevation view of one embodiment of the light guide assembly. 
     FIG. 14 is a sectional view taken along line B—B of FIG.  13 . 
     FIG. 15 is a sectional line taken along line C—C of FIG.  13 . 
     FIG. 16 is a sectional view taken along line D—D of FIG.  13 . 
     FIG. 17 is a fragmentary detailed view enlarged and taken at point A in FIG.  13 . 
     FIG. 18 is an exploded top front perspective view of the IRC housing and control unit. 
     FIG. 18A is an exploded bottom rear perspective view of the assembly of FIG.  18 . 
     FIG. 19 is a top front exploded perspective view of the assembly of FIG. 18 showing the component parts before they are assembled together. 
     FIG. 19A is a bottom front perspective view of the FIG.  19 . 
     FIG. 20 is an exploded top front perspective view of the IRC chasse which is situated within the housing and control unit of FIGS. 18 and 19. 
     FIG. 20A is an exploded top rear perspective view of FIG.  20 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention provides an infrared coagulation device that delivers short pulses of infrared and visible light from a light transmission source along a light guide to a small contact tip applicator that is applied directly to the target tissue. The transmitted light causes thermal coagulation that results in tissue necrosis. The depth of the coagulation is determined by the total amount of energy delivered which is controlled by adjusting the pulse duration. 
     Referring first to FIGS. 1-4, there is shown an embodiment of an infrared coagulator apparatus in accordance with the present invention. The coagulator includes a console unit  1 , and a hand piece assembly  2 . An on/off switch  5  is located at the front of the console unit and controls the 120 volt AC power that is preferably supplied to the console unit. Also located on the front of the console unit is a pulse duration control knob  6  that is adjusted to control the length of the infrared light pulses which are displayed on a digital timer display  16 . An activation indicator light  8  illuminates when the device is activated. 
     The hand piece assembly includes a removable light guide  3  and a disposable contact tip and sheath  4 . The hand piece assembly is also connected to the console unit by a cable which is inserted into receptacle  7  of the console unit. The hand piece assembly includes a handle with an activation trigger  9  and an insert receptacle for the light guide  3 . 
     Situated within the hand piece assembly is a tungsten-halogen lamp which serves as a light source. A gold plated reflector is positioned to reflect infrared energy generated by the lamp and maximize transmission into the light guide. Such an arrangement is shown, for example, in U.S. Pat. Nos. 4,233,493 and 4,539,987. 
     The light guide includes a shielded quartz rod that has a threaded locking nut  10  at its proximal end. The locking nut  10  secures the removable light guide within an insert receptacle located on the hand piece assembly. 
     The disposable contact tip  4  is a single use sterile device that is attached to the distal end of the light guide by a user prior to each procedure. Typically, the disposable contact tip includes a 6 mm or 3 mm diameter optical window  16  that is placed in direct contact with the tissue and through which the infrared light radiation passes. Also included is a barrier sheath that protects the light guide  3  from contamination during use. Preferably, the disposable contact tips are supplied ETO sterile in individual packages. 
     The infrared coagulation apparatus of the invention generates timed pulses of light within a set range of from 0.5 to 3.0 second duration, preferably, with 0.1 second intervals between each pulse. The pulse duration is determined by the estimated depth of tissue necrosis required. 
     The apparatus is activated by depressing and holding the activation trigger  9  on the hand piece assembly to activate the lamp. Also activated is a digital timer  16  that will deactivate the lamp after a predetermined time interval based on the preset pulse duration selected. The activation indicator light  8  located on the top of the console unit  1  illuminates when the tungsten-halogen lamp is activated indicating that the tissue is being irradiated with infrared energy. A plastic part located at the rear of the hand piece assembly also glows to indicate that the lamp is on. 
     FIGS. 5A-5E illustrate an example of a process for preparing a quartz glass light guide in accordance with the invention. An initially straight, cylindrical section of quartz  50 , shown in FIG. 5A, having a diameter of preferably 3.5 mm is heated and bent to have a 30° bend  51 , for example, shown in FIG. 5B. A reflective coating  52  and a neoprene cladding  54  are then successively deposited on the outer wall of the quartz, as FIG. 5C shows. Then, as shown in FIG. 5D, a section of the quartz is removed, the cut surface is polished, as FIG. 5E shows, and a support cladding  56  is formed around the straight portion of the light guide. 
     Advantageously, the combination of the bend in the light guide and the reflective coating allows the transmitted light to exit the bent end of the light guide at angles up to about a 90° with respect to the axis of a cylinder. 
     Thereafter, an aluminum end cap  58  is epoxied onto the end of the support cladding adjacent to the bent portion of the light guide, shown in FIG.  6 . 
     Alternatively, a straight quartz rod serves as the light guide and is covered with the reflective coating along the walls and at the distal end. A portion of the wall near the distal end is left uncoated so that the light exits at an angle substantially perpendicular to the axis of the rod. 
     FIG. 6 also shows an embodiment of a disposable contact tip  60  that fits over the bent end of the light guide. The disposable contact tip includes a substantially hemispherical plastic cap  62  which is preferably polyethylene and which securely fits into the aluminum end cap  58 . A Teflon or PVC plate optical window  64  is secured to the plastic cap. The light is transmitted through the optical window  64  which directly contacts the tissue that is to be exposed to by the light. 
     FIG. 7 illustrates another embodiment of a disposable contact tip and sheath according to the invention. Here, the contact tip and sheath are suitable for protecting a light guide structure having no bend or a slight bend at the distal end. The cylindrical light guide  70  includes a straight portion that is covered with support cladding and includes a retaining collar  74  near the proximal end of the light guide. A bent portion  75  may be incorporated into the distal end. The bent portion is coated with reflective coating  72  but is without cladding. The bend causes the light exiting at an oblique angle with respect to the axis of the cylindrical light guide that is substantially less than 90°. An aluminum end cap  78  is permanently attached to the end of the cladding at the distal end of the light guide. 
     In accordance with the invention, a disposable contact tip and sheath includes a body section  82  and sheath  84 . The body section is a hollow cylindrical shape and fits over the end cap  78 . A Teflon or PVC optical window  86  is held in place at one end of body portion  82  and contacts and protects the distal-end of the quartz light guide  70 . At the opposing end of the body portion  82  is a step-down section  83  which is concentrically arranged with the body portion but has a smaller outer diameter and securely fits into end cap  78 . The distal end of the plastic sheath  84  fits over the step-down section  83 . Located at the proximal end of sheath  84  is a retainer ring  88  which includes another step-down section  87 . When the sheath is slid over the light guide, cladding  72 , the retaining ring  88  and step-down section  87  slide over retaining collar  74  and secure the sheath to prevent unintentional or accidental removal. 
     In further accordance with the invention, FIG. 8 shows a pull tab  89  which is attached to ring  88  to facilitate removal of the sheath and contact tip  80  after its use. The sheath is removed by pulling on the tab  89  which causes the ring to tear at a weakened notch  90  and thus permits the sheath to tear along its length and be freed from the light guide. Advantageously, the sheath is damaged during its removal so that it is no longer suitable for reuse. Thus, a non-sterile, used sheath, cannot be reapplied over the light guide. 
     Preferably, two injection molded plastic parts serve as the body section  82  and the retainer ring  88 , respectively, and are all heat-treated together with a Teflon disc and a tubular sheath to seal the components into one unit. 
     FIGS. 9A-9E show example views of another embodiment of the disposable sheath and contact tip in accordance with the invention. FIG. 9A shows the assembly  91  comprising a disposable sheath  92  and attached contact tip  93 . These components are further shown in greater detail in FIGS. 9B-9E, where contact tip  93  has a proximal end  94  for insertion into the distal end  95  of the sheath  92  where it is sealed. This sheath is made of Unichem 18575 SF which is detailed in Appendix B attached hereto. The contact tip  93  is made of Georgia Gulf CL-7049 vinyl compound which is detailed in Appendix C attached hereto. In an alternative construction of the disposable sheath and contact tip, a single plastic or other compound is used for making the entire component as a single element, with the contact tip being generally stiff, particularly including the distal end light transmissive window  96  and the sheath part  92  being generally flexible sheet material. 
     FIG. 10 shows a block diagram of an embodiment of a power supply and control circuit for controlling the infrared coagulator apparatus of the invention. A step-down transformer  104  is supplied with 120 volts AC and delivers a 19.5 volt, 8 amp supply power to triac  102  which, in turn, controls the current supplied to the infrared lamp  120  in response to a control signal supplied by a microcontroller  100 . The control signals delivered by the microcontroller  100  control the length of the light pulses generated by the lamp  120  in response to a signal supplied by dwell time adjustment  106 . The microcontroller also displays the length of the pulses on digital read out lamp  108 . The microcontroller also controls lamp on indicator LED  110  to indicate that the lamp is turned on. 
     Also included is a lamp brightness feedback control loop  122  which includes a photo-diode detector  114  that delivers a signal to operational amplifier  116  as a function of the brightness of infrared  120 . The op-amp  116  then delivers an amplified signal to an analog-to-digital converter  118  which in turn supplies a digital signal to microcontroller  100 . The microcontroller thus, controls track  102  to vary the current supplied to the lamp  120  until the detected brightness reaches a desired predefined level. 
     FIG. 11 illustrates the IRC assembly consisting of the housing and control unit  130  and the handle assembly and light guide  132 ,  134  connected to the control unit by cable  136 , which principal components will be described in much greater details as follows. 
     FIG. 12 shows the detailed construction of the hand piece assembly  132  which includes a handle  133  and a trigger  134 , and a light housing  135  formed as rear cup  136  and funnel  137  which are joined together and contain a light source  138  which is a 20 watt parabolic Osram lamp mounted in socket  139  at the rear of cup  136 . Funnel  137  is a tapered partial cylindrical section  140  which receives the proximal end of the light guide as explained later. Within housing  140  guide ribs  141  to receive said proximal end of the light guide and position and center and support same. At the forward or front end of the hand piece is a male thread section  142  which eventually receives the lock nut  166  which is on the light guide and thereby secures light guide to the hand piece. The various components of this hand piece, namely the rear cup  136 , the funnel  137 , the front housing  140  are all of typical molded plastic known in the industry such as ABS polycarbonate, which is strong and heat resistant. 
     The lamp shown is a tungsten-halogen lamp which delivers visible and infrared radiation focused generally conically to a spot at the proximal end surface of said quartz rod. 
     Within this hand piece is trigger  134  which when activated closes the circuit of the system conducted through cable  143  to the control unit  130  described earlier. 
     FIG. 12A illustrates the left hand grip molded plate which covers the handle portion. A mirror image element covers the right side, the clamp shell-like elements enclosing the hand piece and trigger unit. 
     FIG. 13 illustrates the light guide assembly  150  for the embodiment where the central quartz rod  151  has dimensions of 6 mm diameter by 120 mm in length. In this light guide assembly the central quartz rod  151  has a proximal end  152  and a distal end  153 , the latter being bent at area  154  to an approximate 15° angle. As further explained in FIGS. 14,  15 ,  16  and  17  which are sectional views through FIG. 13, this light guide assembly  150  is formed of said quartz rod  151  covered by a sheet of aluminum foil of typical heavy duty Reynolds® wrap as is readily obtainable in grocery or hardware stores. This foil is a single sheet wrapped around the quartz rod until about one inch overlies the other and is secured thereto by small pieces of Mylar® tape  155 . Four such pieces of tape are shown axially spaced along the length of the foil covering the quartz rod. 
     Radially outward of the foil is an inner layer of shrink tubing made of Teflon® which is positioned to extend along the length of the quartz rod radially outward of the foil and covering same. The foil  156  is thus covered by inner tube shrink layer  157  which initially is oversized in diameter and is easily positioned to surround and enclose the foil layer until it is heated and shrunk to fit snugly thereon and protect it. The shiny highly reflective side of foil  156  is placed against the outer surface of the quartz rod, and as seen in FIG. 17, the foil  156  extends about {fraction (1/32)} nd  of an inch farther along the length of the quartz rod than the shrink tubing so that the light reflected within the quartz rod strikes the foil at all relevant places and is not allowed to escape and strike the shrink tubing which would absorb the light. 
     Radially outside of the inner tube  157  is yet another sleeve or tube  158  made of brass which fits about shrink tube  157  and extends along most of its length. However, as seen in FIG. 13, support sleeve  158  extends from position  159  near the proximal end forward to position  160  near the distal end. In the vicinity of  159  and Sectional Line B—B, the support sleeve is crimped along a length approximately 1 ¼ inches into a hexagonal shape as seen in FIGS. 14 and 15 where it resides snugly against the inner shrink tube layer. The support sleeve is similarly crimped in the area of Section Line C—C. In the area of Section Line D—D between B—B and C—C the support tube remains essentially round and uncrimped. 
     Radially outward of this support sleeve is yet another Teflon® shrink tube layer  161  which extends most of the length of the assembly from point  162  at the distal end back to point  163  somewhat near the mid-length. 
     The distal end  153  of the light guide as seen in FIG. 13 directs the light radiation outward at an angle of about  15  degrees. As discussed earlier, this angle may vary, and also, this distal end may be modified to be essentially side-looking by rounding or otherwise shaping its terminal end surface and cladding said surface with highly reflective material such as aluminum foil, and leaving a transverse-directed window in the foil for directing the output light radiation transversely of the light propagation direction along the main length of the quartz rod. 
     FIGS. 5B and 5C show one embodiment of a quartz rod with a bent distal end. If nothing more was done, the light emission direction would be essentially outward in the direction of the bent end. 
     FIGS. 5D,  5 E and  6  show the quartz rod of FIG. 5C with its distal end cut to provide a transverse light exit surface. Preferably, this exit surface would define a side-looking window of predefined area, with the remainder of this distal end clad with highly reflective aluminum foil. In a still further embodiment the quartz or other suitable rod would be generally straight along its length, which length and distal end are clad with said foil except for a side-looking window. 
     There is a connection assembly  165  positioned at the generally proximal end of the light guide assembly. This consists of locknut  166  having internal threads  167 , and housing  168  which has a forward extending sleeve  169  that engages the locknut, and a threaded aperture  170  for receiving set screw  171  not shown, and has a rear portion  172  with external threads for receiving funnel  173  screwed thereon. The funnel has proximal end  173 A which helps guide light from the lamp to the proximal end of the quartz rod. The outer diameter of the funnel engages ribs  141  in the hand piece as described below. 
     In this sub-assembly the set screw  171  which extends through aperture  170  continues radially inward until it engages a flat surface  174  seen in FIG. 14 which securely couples this housing to the support sleeve  158  about the quartz rod. 
     In subsequent assembly of said light guide  150  and said handle and hand piece  132 , the proximal end of the light guide assembly, namely the funnel  173  is extended into aperture  180  (see FIG. 12) at the front end of the hand piece until it reaches ribs  141  which guide, center, position and stop it. The internal threads  167  of the locknut  166  are screwed onto the male threads  142  at the front end of the hand piece, and this securely locks the light guide assembly to the hand piece assembly. 
     Returning to FIG.  13  and the distal end of the light guide, the quartz rod has aluminum foil with the shiny reflective side facing radially inward against the quartz rod along the bent area as further shown in FIG.  15 . Radially outward of this foil is the inner shrink tube which again extends less in length than the foil so that the light is reflected off the foil and cannot reach the shrink tube. At the tip or distal end of this assembly is secured an aluminum ferrule  164  or tube extending until its opening is flush with the end of the quartz rod. The terminal end of the ferrule sleeve has a reduced outer diameter for receiving a disposable sheath of the type generally disclosed above with reference to FIGS. 7-9. The removable and disposable sheath allows this IR coagulator instrument to remain uncontaminated even though it is used on a succession of patients. The cylindrical cap of aluminum or other rigid material at the distal end of the sheath secures the light transmissive window at the terminal end thereof and provides a stable coupling with the distal end of the light guide. Since the sheath material comprises this flexible plastic sheet material, it can easily be slid onto a light guide even if there is a bend at the distal end. The sheath may be made from a variety of plastic materials or latex rubber. 
     The locknut  166  is made of molded ABS polycarbonate plastic, the housing  168  is made of a plastic called ULTEM® having an outer diameter of about 0.590 inches; the funnel  173  is made of aluminum and has an outer diameter of 0.55 inches; the ferrule  164  at the distal end of the light guide has a 0.274 outer diameter as it surrounds the quartz rod of 6 mm diameter. 
     FIGS. 18,  18 A shows the base unit  190  including therein the IRC control power supply and control sub-assembly. There is outer housing  191 , timer control knob  192 , digital time display window  193 , power on/or switch  194 , on/or light indicator  195 . Also in FIG. 18, beneath the housing  191  is the chassis  192  which includes sub-housing  193  to receive and hold the handle of the hand guide or hand piece sub-assembly. 
     FIGS. 19,  19 A show the housing and control unit of FIGS. 18 and 18A before they are assembled so that control knob  192  is shown in exploded position above the housing  191  and the power switch  194  as shown before it is moved inward to its final position. The same is true of the LED Lens  195  showing the on/off condition of the unit. Also, there is a DIN connection  196  in FIG.  19 . FIGS. 20 and 20A show the chassis and inner components which fit within the control housing of FIGS. 18 and 19. These components include the transformer  200 , the PCB (printed circuit board) control board  201  and the programmed chip  202 . Another minor component as shown in FIG. 20A is the low blow fuse  203 . The circuit diagram of FIG. 10 discussed above discloses the overall circuit of this apparatus and is applicable to the apparatus of FIGS. 12-20. 
     A copy of an Operating and Reference Manual for the embodiment of FIGS. 11-20 of the new Infrared Coagulation apparatus is attached hereto as Appendix D. 
     Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.