Patent Publication Number: US-10786584-B2

Title: Anti-biofouling of submerged lighting fixtures

Description:
This application is a continuation-in-part of U.S. patent application Ser. No. 16/537,739, filed Aug. 16, 2019, which is a continuation-in-part of U.S. patent application Ser. No. 14/957,812, filed Dec. 3, 2015, the entire disclosures of which are incorporated herein by reference thereto, which applications claim the benefit of U.S. Provisional Patent Application Ser. No. 62/089,315, filed Dec. 9, 2014, the subject matter of which is incorporated herein by reference thereto. 
    
    
     The present invention relates generally to lighting fixtures constructed for installation where the lighting fixtures will be submerged and thereby exposed to biological organisms that can become attached in such manner as to interfere with the transmission of visible light from the lighting fixtures, and pertains, more specifically, to retrofits for providing anti-biofouling constructions and methods for maintaining such submerged lighting fixtures substantially free of such attachment of undesirable biological organisms. 
     With the advent of more effective, more efficient lighting apparatus, there has arisen a greater demand for lighting fixtures that can serve in submerged installations where these fixtures will be exposed to biological organisms that can become attached in a manner that will defeat the ability to serve the purpose of the installation. Thus, for example, lighting fixtures installed in marine environments, such as for the illumination of piers, pilings, seawalls and the like, as well as providing lighting for a variety of marine vessels, for illumination that is meant to serve either or both functional and decorative purposes, when placed at locations where the lighting fixtures will be submerged and thereby exposed to the attachment of biological organisms, such as barnacles, algae and the like, will soon lose effectiveness due to biofouling which will defeat the ability to transmit the desired illumination. 
     It has been suggested that ultraviolet radiation (UV) can be effective in combating biofouling of optical surfaces of various equipment immersed for service in marine environments. The present invention provides specific retrofit constructions and methods for rendering current, conventional lighting fixtures practical and effective in serving to illuminate a wide variety of installations where the lighting fixtures already are or will be submerged and thereby exposed to the presence of biological organisms that can defeat the ability of the lighting fixtures to provide effective illumination for either functional or decorative purposes. Accordingly, the present invention attains several objects and advantages, some of which are summarized as follows: Provides retrofit constructions and methods for effectively combating biofouling of lighting fixtures installed or ready to be installed to furnish lighting for either or both functional and decorative lighting purposes in environments where the lighting fixtures are submerged and thus exposed to biological organisms that can interfere with the proper transmission of light from the lighting fixtures; enables more widespread use of lighting fixtures for both functional and decorative lighting purposes where such lighting fixtures are submerged and exposed to the detrimental adherence of biological organisms and the concomitant impedance of the transmission of usable light as a result of biofouling; renders more economical the use of lighting fixtures in submerged environments, thereby opening the employment of submerged lighting fixtures over a wider and more diverse range of uses; simplifies the provision of practical anti-biofouling measures in connection with lighting fixtures utilized in installations wherein the lighting fixtures are submerged and exposed to unwanted biological organisms; allows increased flexibility in the choice of design and construction of lighting fixtures to be submerged in environments where the lighting fixtures are exposed to potential biofouling; simplifies the installation of submerged anti-biofouling lighting fixtures in connection with a wide variety of marine structures, as well as marine vessels, without disturbing the integrity of such structures and vessels; exhibits a high degree of operating efficiency and effectiveness for more economical performance over an extended service life. 
     The above objects and advantages are attained by the present invention, which may be described briefly as a retrofit device for being positioned in juxtaposition with an existing lighting fixture that furnishes illumination through a primary window when placed at a marine installation location, the retrofit device being constructed for providing the lighting fixture with resistance to bio-fouling that can impede the transmission of visible light furnished by the lighting fixture through the primary window when submerged in a surrounding marine environment wherein the primary window is exposed to visible light-impeding bio-fouling marine biological organisms within that environment, the retrofit device comprising: an auxiliary window member for transmitting illumination from the primary window of the lighting fixture into the surrounding marine environment, the auxiliary window member having an outer surface through which outer surface illumination from the primary window is to pass upon placement of the retrofit device in position in juxtaposition with the lighting fixture; and a source of ultraviolet radiation carried within the retrofit device and arranged to direct ultraviolet radiation comprised of UVC radiation for transmission to the outer surface of the auxiliary window member, such that the UVC radiation at the outer surface of the auxiliary window member is of an intensity limited to essentially that which is effective in rendering the outer surface of the auxiliary window member immune to adherence of visible light-impeding bio-fouling marine biological organisms to which the outer surface of the auxiliary window member will be exposed when juxtaposed with a lighting fixture submerged within the surrounding marine environment; the auxiliary window member being constructed of a material capable of transmitting the UVC radiation from the source of ultraviolet radiation, through the material of the auxiliary window member, to the outer surface of the auxiliary window member such that when the retrofit device is juxtaposed with a lighting fixture submerged within the surrounding marine environment, visible light-impeding bio-fouling marine biological organisms will be inhibited from adhering permanently to the outer surface of the auxiliary window member by UVC radiation emanating from the source of UVC radiation carried within the retrofit device and transmitted through the material of the auxiliary window member to the outer surface of the auxiliary window member. 
     In addition, the present invention provides a method for retrofitting an existing lighting fixture that furnishes illumination through a primary window when placed at a marine installation location, the retrofitting providing the lighting fixture with resistance to bio-fouling that can impede the transmission of visible light furnished by the lighting fixture through a primary window when submerged in a surrounding marine environment wherein the primary window is exposed to visible light-impeding bio-fouling marine biological organisms within that environment, the method comprising: juxtaposing with the existing lighting fixture an auxiliary window member in position for transmitting illumination from the primary window of the lighting fixture into the surrounding marine environment, the auxiliary window member having an outer surface through which outer surface illumination from the primary window is to pass upon placement of the auxiliary window member in juxtaposition with the lighting fixture; arranging a source of ultraviolet radiation to direct ultraviolet radiation comprised of UVC radiation for transmission to the outer surface of the auxiliary window member, such that the UVC radiation at the outer surface of the auxiliary window member is of an intensity limited to essentially that which is effective in rendering the outer surface of the auxiliary window member immune to adherence of visible light-impeding bio-fouling marine biological organisms to which the outer surface of the auxiliary window member will be exposed when juxtaposed with a lighting fixture submerged within the surrounding marine environment; and constructing the auxiliary window member of a material capable of transmitting the UVC radiation from the source of ultraviolet radiation, through the material of the auxiliary window member, to the outer surface of the auxiliary window member such that when the auxiliary window member is juxtaposed with a lighting fixture submerged within the surrounding marine environment, visible light-impeding bio-fouling marine biological organisms will be inhibited from adhering to the outer surface of the auxiliary window member by UVC radiation emanating from the source of UVC radiation and transmitted through the material of the auxiliary window member to the outer surface of the auxiliary window member. 
    
    
     
       The invention will be understood more fully, while still further objects and advantages will become apparent, in the following detailed description of preferred embodiments of the invention illustrated in the accompanying drawing, in which: 
         FIG. 1  is a partially diagrammatic, longitudinal cross-sectional view of a submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 2  is a plan view of a component part of the lighting fixture of  FIG. 1 ; 
         FIG. 3  is a partially diagrammatic, longitudinal cross-sectional view of another submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 4  is a top plan view of a component part of the lighting fixture of  FIG. 3 ; 
         FIG. 5  is a partially diagrammatic, longitudinal cross-sectional view of still another submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 6  is a top plan view of component parts of the lighting fixture of  FIG. 5 ; 
         FIG. 7  is a top plan view of a component part of the lighting fixture of  FIG. 5 ; 
         FIG. 8  is a top plan view of yet another submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 9  is a partially diagrammatic cross-sectional view taken along line  9 - 9  of  FIG. 8 ; 
         FIG. 10  is a partially diagrammatic cross-sectioned pictorial view of another submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 11  is a partially diagrammatic cross-sectioned pictorial view of another submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 12  is a partially diagrammatic cross-sectioned pictorial view of another submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 13  is a partially diagrammatic cross-sectioned pictorial view of another submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 14  is a partially diagrammatic cross-sectional view of a submersible lighting fixture constructed in accordance with the present invention and shown installed on a marine vessel; 
         FIG. 15  is a partially diagrammatic, longitudinal cross-sectional view of another submersible lighting fixture constructed in accordance with the present invention; 
         FIG. 16  is a bottom plan view of a component part of the lighting fixture of  FIG. 15 ; 
         FIG. 17  is a cross-sectional view taken along line  17 - 17  of  FIG. 16 ; 
         FIG. 18  an exploded pictorial view, partially diagrammatic, illustrating another embodiment of the present invention; 
         FIG. 19  is an enlarged cross-sectional view taken along line  19 - 19  of  FIG. 18 ; 
         FIG. 20  is a pictorial view of the embodiment illustrated in  FIG. 18 ; 
         FIG. 21  is a pictorial view showing another embodiment of the invention; 
         FIG. 22  is a pictorial view showing still another embodiment of the invention; 
         FIG. 23  is a pictorial view, partially broken away, of the embodiment of  FIG. 22 ; 
         FIG. 24  is a pictorial view showing the embodiment of  FIG. 22  installed for use: 
         FIG. 25  is a side elevational view of yet another embodiment of the invention; and 
         FIG. 26  is an enlarged, cross-sectional view taken along line  26 - 26  of  FIG. 25 . 
     
    
    
     Referring now to the drawing, and especially to  FIGS. 1 and 2  thereof, a submersible lighting fixture constructed in accordance with the present invention is shown, partially diagrammatically, at  20  and is seen to include a housing  22  having a base  24  and a flange  26 . Base  24  is shown mounted upon an underwater post  30  by means of a threaded connection at  32 . A window member  40  includes a peripheral rim  42  having a plurality of holes  44  spaced apart circumferentially around the rim  42 , and the window member  40  is secured to base  24  by a retaining ring  46  through which a plurality of threaded bolts  48  extend within holes  44  to be threaded into complementary threaded sockets  50  in flange  26  of housing  22 . A first seal  52  is interposed between retaining ring  46  and rim  42  and a second seal  54  is interposed between rim  42  and flange  26 , the first and second seals  52  and  54  serving to close and seal a chamber  56  within housing  22 . 
     A circuit board  60  is placed within chamber  56 , mounted upon base  24 , and sealed against the environment outside lighting fixture  20  by virtue of placement within the sealed chamber  56 . A source of illumination is provided by a plurality of light sources shown in the form of light emitting diodes (LEDs)  62  carried by circuit board  60  and operated by electronic circuitry  64  powered by an external power supply (not shown). LEDs  62  provide illumination which is directed through window member  40  to light the environment outside lighting fixture  20 . In the illustrated embodiment, post  30  is mounted upon an underwater structure (not shown) and lighting fixture  20  is submerged, exposing lighting fixture  20 , and especially window member  40 , to biological organisms in the water within which lighting fixture  20  is submerged. These biological organisms, such as barnacles, algae and the like, will tend to adhere to window member  40  and obscure visible light being directed to the window member  40  by the LEDs  62  for transmission through the window member  40 . This phenomenon is known as “biofouling” and will defeat the ability of a submerged lighting fixture to furnish the visible light desired at the installation. 
     It has been well established that ultra violet radiation is effective in countering the adherence of biological organisms to surfaces where it is desired to maintain these surfaces free of such biological organisms. In particular, ultra violet radiation identified as “UVC” radiation has been found effective in combating those biological organisms encountered in aquatic environments, and especially in marine environments. Accordingly, in order to maintain window member  40  immune to and substantially clear of any accumulation of biological organisms that could impede the transmission of illumination through window member  40 , a source of UVC radiation is located within chamber  56 , here shown in the form of a UVC LED  80  placed upon circuit board  60  and located so that UVC radiation is directed to window member  40 . Window member  40  is constructed of a material, such as quartz, that is capable of transmitting UVC radiation, so that UVC radiation emanating from LED  80  will be transmitted through window member  40  to inhibit adhering of biological organisms upon the exterior surface  82  of window member  40  and thereby combat biofouling of window member  40 . Energy is conserved by limiting the intensity of the transmitted UVC radiation at the external surface  82  to essentially that which is effective in rendering the external surface  82  immune to adherence of biological organisms. In the illustrated embodiment, window member  40  advantageously is constructed with exterior surface  82  having a domed configuration, and LED  80  is placed at a focal point of the domed configuration so that the intensity of UVC radiation is substantially uniform over the exterior surface  82 . LED  80  is controlled by electronic circuitry  64  and, in the preferred arrangement, LED  80  need not be activated continuously, and is activated periodically, in timed, intermittent sessions, so as to conserve energy. 
     Housing  22  preferably is constructed, or at least coated, with a material that will resist biofouling, as well as corrosion, for long-term service. In addition, sealed chamber  56  preferably is evacuated, or is filled with an inert gas, such as nitrogen, to promote reliability and longevity of LEDs  62  and  80 , as well as electronic circuitry  64 . 
     The embodiment illustrated in  FIGS. 3 and 4  is shown in the form of a submersible lighting fixture  120  and is constructed similar to submersible lighting fixture  20  described in connection with  FIGS. 1 and 2 . Accordingly, corresponding component parts are labeled with the same reference characters and operate in the same manner as described above in connection with lighting fixture  20 . However, in lighting fixture  120 , window member  140  has a flat configuration, with a flat exterior surface  182 , as opposed to the domed configuration of window member  40 , the flat configuration providing both functional and decorative differences better suited to particular installations. 
     Turning now to  FIGS. 5 through 7 , another embodiment of the present invention is illustrated in the form of submersible lighting fixture  220  and is seen to have a housing  222  with a base  224 , a flange  226  and a recess  228 . Base  224  is shown mounted upon an underwater post  230  by means of a threaded connection at  232 . A window member  240  includes a peripheral section  242 , and is secured to base  224  by a retaining frame  246  juxtaposed with peripheral section  242  through which frame  246  a plurality of threaded bolts  248  extend within holes  244  to be threaded into complementary threaded sockets  250  in flange  226  of base  224 . A first seal  252  is interposed between retaining frame  246  and peripheral section  242 , and a second seal  254  is interposed between peripheral section  242  and base  224 , the seals  252  and  254  serving to close and seal a chamber  256  within housing  222 . 
     A circuit board  260  is placed within chamber  256 , mounted upon base  224 , and sealed against the environment outside lighting fixture  220  by virtue of placement within the sealed chamber  256 . A plurality of light emitting diodes (LEDs)  262  are carried by circuit board  260  and are operated by electronic circuitry  264  powered by an external power supply (not shown). LEDs  262  provide illumination which is directed through window member  240  to light the environment outside lighting fixture  220 . 
     Window member  240  has a predetermined thickness T, and a perimetric edge  270  that follows a largely rectangular path. A flat portion  272  is located along the perimetric edge  270  of window member  240 , the flat portion  272  being adjacent flange  226  and spaced laterally a short distance from flange  226  to provide clearance for a source of UVC radiation, shown in the form of a UVC LED  280  coupled with window member  240  at the flat portion  272  along the perimetric edge  270  of window member  240 . A lead  282  connects LED  280  to electronic circuitry  264  for operating LED  280 . In the preferred construction, semi-rectangular portion  284  of perimetric edge  270  is coated with a UVC reflective material  286  such that upon activation of LED  280 , UVC radiation is directed into window member  240  and, by virtue of internal reflection, normally is not dissipated out of window member  240  until such time as a biological organism comes into sufficient attachment to the outer surface  290  of window member  240 , at which time UVC radiation within the window member  240  will be transmitted, by virtue of such attachment, to the interfering biological organism, resulting in the offending biological organism being neutralized so as to maintain the outer surface  290  sufficiently clear. In this manner, window member  240  functions similar to a waveguide, assisted by thickness T, providing UVC radiation only where, when and in an intensity limited essentially to that needed to maintain the outer surface  290  sufficiently clear of biofouling, thereby conserving energy. 
     With reference to  FIGS. 8 and 9 , another submersible lighting fixture constructed in accordance with the present invention is shown, partially diagrammatically, at  320  and is seen to include a housing  322  having a base  324  and a flange  326 . Base  324  carries a threaded post  330 . A window member  340  includes a peripheral rim  342  having a plurality of holes  344  spaced apart circumferentially around the rim  342 , and the window member  340  is secured to base  324  by a retaining ring  346  through which a plurality of threaded bolts  348  extend within holes  344  to be threaded into complementary threaded sockets  350  in flange  326  of base  324 . A first seal  352  is interposed between retaining ring  346  and rim  342  and a second seal  354  is interposed between rim  342  and flange  326 , the first and second seals  352  and  354  serving to close and seal a chamber  356  within housing  322 . 
     A circuit board  360  is placed within chamber  356 , mounted upon base  324 , and sealed against the environment outside lighting fixture  320  by virtue of placement within the sealed chamber  356 . A plurality of light emitting diodes (LEDs)  362  are carried by circuit board  360  and are operated by electronic circuitry  364  powered by an external power supply (not shown). LEDs  362  provide illumination which is directed through window member  340  to light the environment outside lighting fixture  320 . In the illustrated embodiment, lighting fixture  320  is mounted upon an underwater structure, shown in the form of a hull  370  of a marine vessel, and is submerged, exposing lighting fixture  320 , and especially window member  340 , to biological organisms in the water within which lighting fixture  320  is submerged. Lighting fixture  320  is secured in place by advancing a threaded nut  372  along threaded post  330  until lighting fixture  320  is secured upon hull  370 . A sealing member  374  is interposed between base  324  and hull  370 , and a further sealing member  376  is interposed between threaded nut  372  and hull  370  to seal the hull  370 . As described hereinbefore, biological organisms, such as barnacles, algae and the like, will tend to adhere to window member  340  and obscure visible light being directed to the window member  340  by the LEDs  362  for transmission through the window member  340 . This phenomenon, known as “biofouling,” will defeat the ability of a submerged lighting fixture to furnish the visible light desired at the installation. 
     Accordingly, in order to maintain window member  340  immune to and substantially clear of any accumulation of biological organisms that could impede the transmission of illumination through window member  340 , a source of UVC radiation is located within chamber  356 , here shown in the form of a UVC LED  380  placed upon circuit board  360  and located so that UVC radiation is directed to window member  340 . Window member  340  is constructed of a material, such as quartz, that is capable of transmitting UVC radiation, so that UVC radiation emanating from LED  380  will be transmitted through window member  340  in an intensity limited essentially to that which is effective to inhibit adhering of biological organisms upon the exterior surface  382  of window member  340  and thereby combat biofouling of window member  340 . 
     The embodiment of the invention illustrated in  FIG. 10  is in the form of a submersible strip lighting fixture  420  having a housing  422  of a selected extended length, with a base  424  and a flange  426 . Base  424  carries a number of threaded posts  430  along the length of the base  424  for mounting lighting fixture  420  upon a length of underwater structure. A window member  440  includes laterally opposite edges  442 . The window member  440  is secured to base  424  by retaining members  446  through which a plurality of threaded bolts  448  extend to be threaded into flange  426  of base  424 . A first seal  452  is interposed between each retaining member  446  and window member  440 , and second seals  454  are interposed between window member  440  and base  424 . The seals  452  and  454 , together with opposite end caps, one of which end caps is shown at  458 , serve to close and seal a chamber  456  within housing  422 . 
     A circuit board  460  is placed within chamber  456 , mounted upon base  424 , and sealed against the environment outside lighting fixture  420  by virtue of placement within the sealed chamber  456 . A plurality of light emitting diodes (LEDs)  462  are carried by circuit board  460  and are operated by electronic circuitry  464  powered by an external power supply (not shown). LEDs  462  provide illumination which is directed through window member  440  to light the environment outside lighting fixture  420 . 
     In order to maintain window member  440  immune to and substantially clear of any accumulation of biological organisms that could impede the transmission of illumination through window member  440 , sources of UVC radiation are located within chamber  456 , here shown in the form of LEDs  480  placed within corresponding waveguides  482  carried by circuit board  460  and located so that UVC radiation of an effective limited intensity is directed to window member  440 , distributed throughout the extended length of lighting fixture  420 . Waveguides  482  and window member  440  are constructed of a material, such as quartz, that is capable of transmitting UVC radiation, so that UVC radiation emanating from LEDs  480  will be distributed to and pass through window member  440  to inhibit adverse accumulation of biological organisms upon the longitudinally extended exterior surface  484  of window member  440  and thereby combat biofouling of window member  440 . 
     In the embodiment shown in  FIG. 11 , visible light emanates from both faces  500  of a submersible lighting fixture constructed in accordance with the present invention. Here again, a lighting fixture is in the form of strip lighting fixture  520  of selected, extended longitudinal length, having a housing  522  with a base  524 . However, here base  524  includes opposite flanges  526 . A window member  540  extends longitudinally along each face  500 , and each window member  540  includes laterally opposite edges  542 . Each window member  540  is secured to base  524  by retaining members  546  through which a plurality of threaded bolts  548  extend to be threaded into a corresponding flange  526  of base  524 . Seals  552  and  554  are provided, as before, together with opposite end caps, one of which end caps is shown at  558 , to close and seal chambers  556  within housing  522 . 
     A plurality of light emitting diodes (LEDs)  562  are placed within each chamber  556 , sealed against the environment outside lighting fixture  520  by virtue of placement within a corresponding sealed chamber  556 , and are operated by corresponding electronic circuitry powered by an external power supply (not shown). LEDs  562  provide illumination which is directed through window members  540  to light the environment outside lighting fixture  520 . 
     In order to maintain window members  540  immune to and substantially clear of any accumulation of biological organisms that could impede the transmission of illumination through window members  540 , sources of UVC radiation are located within each chamber  556 , here shown in the form of LEDs  580  placed within corresponding waveguides  582  located along the extended length of lighting fixture  520  so that UVC radiation is directed to window members  540 , distributed throughout the extended length. Waveguides  582  and window members  540  are constructed of a material, such as quartz, that is capable of transmitting UVC radiation, so that UVC radiation emanating from LEDs  580  will be distributed to and pass through window members  540  to inhibit adverse accumulation of biological organisms upon the exterior surfaces  584  of window members  540  and thereby combat biofouling of window members  540 . 
     Turning now to  FIG. 12 , another submersible lighting fixture constructed in accordance with the present invention is shown in the form of an elongate lighting fixture  620  of selected, extended longitudinal length, having a housing  622  with a base  624  and a flange  626 . A window member  640  includes laterally opposite edges  642  and is secured to base  624  by retaining members  646  which, together with end caps (not shown), establish a sealed chamber  656  in a manner similar to that described above. 
     A circuit board  660  is placed within chamber  656 , mounted upon a bracket  658  affixed to housing  622 , and sealed against the environment outside lighting fixture  620  by virtue of placement within the sealed chamber  656 . A plurality of light emitting diodes (LEDs)  662  are carried by circuit board  660  and are operated by electronic circuitry  664  placed within sealed chamber  656  and powered by an external power supply (not shown). LEDs  662  provide illumination which is directed through window member  640  to light the environment outside lighting fixture  620 . 
     In order to maintain window member  640  immune to and substantially clear of any accumulation of biological organisms that could impede the transmission of illumination through window member  640 , sources of UVC radiation are located within chamber  656 , here shown in the form of LEDs  680  placed within a waveguide  682  carried by circuit board  660  and located so that UVC radiation is directed to window member  640 , distributed throughout the extended length of lighting fixture  620 . Waveguide  682  and window member  640  are constructed of a material, such as quartz, that is capable of transmitting UVC radiation, so that UVC radiation emanating from LEDs  680  will be distributed to and pass through window member  640  to inhibit adverse accumulation of biological organisms upon the exterior surface  684  of window member  640  and thereby combat biofouling of window member  640 . 
     In the embodiment of the invention illustrated in  FIG. 13 , another submersible lighting fixture constructed in accordance with the present invention is shown in the form of an elongate lighting fixture  720  of selected, extended longitudinal length, having a housing member  722  extending longitudinally along the selected length. Housing member  722  has a semi-tubular configuration including a C-shaped cross-sectional contour. A window member  740  is in the form of a tubular structure  742  having a circular cross-sectional configuration essentially complementary to the cross-sectional configuration of housing member  722  so that window member  740  is received and retained within housing member  722 , along the length of lighting fixture  720 , while providing a window  744 . End caps (not shown) are secured to housing member  722  to establish a sealed chamber  756  in a manner similar to that described above. 
     A circuit board  760  is placed within chamber  756 , mounted upon a bracket  758  secured within window member  740 , and is sealed against the environment outside lighting fixture  720  by virtue of placement within the sealed chamber  756 . A plurality of light emitting diodes (LEDs)  762  are carried by circuit board  760 , along the extended length of lighting fixture  720 , and are operated by electronic circuitry  764  placed within sealed chamber  756  and powered by an external power supply (not shown). LEDs  762  provide illumination which is directed through window  744  to light the environment outside lighting fixture  720 . 
     In order to maintain window  744  immune to and substantially clear of any accumulation of biological organisms that could impede the transmission of illumination through window  744 , sources of UVC radiation are located within chamber  756 , here shown in the form of LEDs  780  placed within a waveguide  782  carried by circuit board  760  and located along the extended longitudinal length of lighting fixture  720  so that UVC radiation is directed to window  744 , distributed along the extended longitudinal length. Waveguide  782  and window member  740  are constructed of a material, such as quartz, that is capable of transmitting UVC radiation, so that UVC radiation emanating from LEDs  780  will be distributed to and pass through window  744  to inhibit adverse accumulation of biological organisms upon the exterior surface  784  of window  744  and thereby combat biofouling of window  744 . 
     With reference to  FIG. 14 , another submersible lighting fixture constructed in accordance with the present invention is shown, partially diagrammatically, at  820  and is seen to include a housing  822  having a base  824  and a flange  826 . Lighting fixture  820  is shown mounted upon the hull  830  of a marine vessel  832  having a wall  834  constructed of a material now in common use in marine vessels, namely, a fiberglass reinforced synthetic polymeric material. The construction of lighting fixture  820  enables the lighting fixture  820  to be mounted upon hull  830  without compromising the integrity of wall  834 . To that end, housing  822  is placed against outer face  836  of wall  834 , in registration with an internal housing  838  placed against inner face  840  of wall  834 , as shown. Housing  822  carries self-aligning rare earth magnets  842  affixed within housing  822  and which align with self-aligning rare earth magnets  844  carried by and affixed within internal housing  838 . In this manner, corresponding magnets  842  and  844  are attracted to one another to secure in place housing  822 , without the necessity for creating an unwanted opening or other compromising structural element in wall  834 . Preferably, a resilient pad  846  is interposed between housing  822  and wall  834  to inhibit further any tendency toward unwanted movement of lighting fixture  820  along hull  830 . 
     A window member  850  includes a peripheral rim  852  and is secured to base  824  by a retaining ring  856  through which a plurality of threaded bolts  858  extend to be threaded into flange  826  of base  824 . First and second seals  862  and  864  close and seal a chamber  866  within housing  822 . 
     A plurality of light emitting diodes (LEDs)  872  are placed within chamber  866 , sealed against the environment outside lighting fixture  820  by virtue of placement within the sealed chamber  866  and are operated by electronic circuitry  874  powered by an external power supply  880 . In order further to assure that wall  834  is maintained uncompromised, power supply  880  is coupled to a power induction transmitter  882  placed within internal housing  838 , located within hull  830 , and a power induction receiver  884  is placed within housing  822 , in proximity to power induction transmitter  882 . Power is transmitted to induction receiver  884  which is connected to an LED controller  886  which, in turn, is connected to electronic circuitry  874 , all within housing  822 . An RF transmitter/controller  888  within the vessel  832  communicates with LED controller  886  for enabling control of the LEDs  872 , through electronic circuitry  874 . In this manner, controlled power is furnished to LEDs  872  so as to provide desired illumination directed through window member  850  to light the environment outside lighting fixture  820 . As described herein above, biological organisms, such as barnacles, algae and the like, will tend to adhere to window member  850  and obscure visible light being directed to the window member  850  by the LEDs  872  for transmission through the window member  850 . This phenomenon, known as “biofouling,” will defeat the ability of a submerged lighting fixture to furnish the visible light desired at the installation. 
     Accordingly, in order to maintain window member  850  immune to and substantially clear of any accumulation of biological organisms that could impede the transmission of illumination through window member  850 , a source of UVC radiation is located within chamber  866 , here shown in the form of a UVC LED  890  placed upon circuit board  870  and located so that UVC radiation is directed to window member  850 . Window member  850  is constructed of a material, such as quartz, that is capable of transmitting UVC radiation, so that UVC radiation emanating from LED  890  will be transmitted through window member  850  to inhibit adverse accumulation of biological organisms upon the exterior surface  892  of window member  850  and thereby combat biofouling of window member  850 . 
     Turning now to  FIGS. 15 through 17 , another embodiment of the present invention is illustrated in the form of submersible lighting fixture  920  and is seen to have a housing  922  with a base  924 , a flange  926  and a recess  928 . A threaded post  930  extends from base  924  for mounting lighting fixture  920  in place at a selected installation site. A window member  940  includes a peripheral border  942 , and is attached to base  924  by being securely fitted within flange  926  of base  924  to close and seal a chamber  956  within housing  922 . 
     A circuit board  960  is placed within chamber  956 , mounted upon base  924 , and sealed against the environment outside lighting fixture  920  by virtue of placement within the sealed chamber  956 . A plurality of light emitting diodes (LEDs)  962  are carried by circuit board  960  and are powered by an external power supply (not shown). LEDs  962  provide illumination which is directed through window member  940  to light the environment outside lighting fixture  920 . 
     Window member  940  has a predetermined thickness T, and a perimetric edge  970  that preferably follows a largely circular path. A cavity  972  is located within window member  940 , the cavity  972  preferably being adjacent perimetric edge  970  and spaced laterally a short distance from perimetric edge  970 , cavity  972  being dimensioned and configured to accommodate a source of UVC radiation, shown in the form of a UVC LED  980  inserted within window member  940  adjacent the perimetric edge  970  of window member  940 . LED  980  is coupled with circuit board  960  for operating LED  980 . In the preferred construction, window member  940  is constructed of a material, such as quartz, that is capable of transmitting UVC radiation, so that UVC radiation emanating from LED  980  will be transmitted through window member  940 . Perimetric edge  970  is provided with a coating  986  of UVC reflective material along the perimetric edge  970  such that upon activation of LED  980 , UVC radiation is directed into window member  940  and, by virtue of internal reflection, normally is not dissipated out of window member  940  until such time as a biological organism comes into sufficient attachment to the outer surface  990  of window member  940 , at which time UVC radiation within the window member  940  will be transmitted, by virtue of such attachment, to the interfering biological organism, resulting in the offending biological organism being neutralized and detached so as to maintain the outer surface  990  sufficiently clear. In this manner, window member  940  functions similar to a waveguide, assisted by thickness T, providing UVC radiation only where and when needed, essentially in an intensity limited to that which is effective to maintain the outer surface  990  sufficiently clear of biofouling, thereby conserving energy. 
     With reference now to  FIGS. 18 through 20 , there is illustrated a conventional lighting fixture  1000  constructed for use at locations where lighting fixture  1000  will be exposed to biological organisms which cause biofouling that interferes with the transmission of visible light furnished by such lighting fixtures. Lighting fixture  1000  is seen to include a casing  1100  having a flange  1110  surrounding a primary window  1112  through which visible light is projected from inside casing  1100  into a surrounding environment. In order to combat biofouling of primary window  1112  when lighting fixture  1000  is installed in a marine environment, a further embodiment of the present invention is provided in the form of a retrofit device, shown at  1120 . 
     Retrofit device  1120  includes an auxiliary window member in the form of auxiliary window  1122  secured within a retention band  1124  that extends around the perimetric edge  1126  of the auxiliary window  1122 . A housing  1128  is integrated with retention band  1124  and houses electronic circuitry  1130  that accepts power from an external power source  1132 , through power cable  1134  which directs power to a UVC LED  1140  inserted into the material of auxiliary window  1122  such that UVC radiation from UVC LED  1140  is transmitted into auxiliary window  1122  and is presented to and distributed over surface  1142  of auxiliary window  1122 . 
     In the illustrated preferred embodiment, retrofit device  1120  includes an affixation construct shown in the form of an adhesive  1150  extending along retention band  1124 , provided either as an adhesive tape or a layer of adhesive applied directly to retention band  1124 , in place to juxtapose auxiliary window  1122  with primary window  1112  by affixing retention band  1124  to flange  1110  of lighting fixture  1000  and to seal primary window  1112  against exposure to the surrounding environment while, at the same time, securing in place auxiliary window  1122  which, when UVC LED  1140  is activated, presents UVC radiation at outer surface  1142  of an intensity limited essentially to that which is effective in rendering the outer surface  1142  of auxiliary window  1122  immune to permanent adherence of visible light impeding biofouling marine biological organisms to which the outer surface  1142  of the auxiliary window  1122  will be exposed when lighting fixture  1000  is submerged within the marine environment. 
     Turning now to  FIG. 21 , a conventional lighting fixture is shown in the form of lighting fixture  2000  mounted upon a hull, a fragment of which is illustrated in phantom at  2010 , of a marine vessel wherein lighting fixture  2000  will be exposed to surrounding seawater (not shown). Lighting fixture  2000  includes a casing  2012  that extends into the interior  2014  of the hull  2010  while a flange  2016  of housing  2012  is sealed against the exterior  2017  of hull  2010 , and presents a lighting fixture primary window  2018 . As described above in connection with lighting fixture  1000 , a retrofit device  2020  is affixed to flange  2016  and provides UVC radiation, from a UVC LED (not shown) placed within a housing  2022  to an auxiliary window  2024 . In a manner described in connection with retrofit device  1120 , auxiliary window  2024  is secured within a retention band  2026  and an affixation construct shown in the form of an adhesive  2028  affixes and seals retention band  2026  in place upon flange  2016  to juxtapose auxiliary window  2024  with primary window  2018 . 
     Housing  2022  is extended along hull  2010 , at an extension  2030 , and power is transmitted through hull  2010  by induction from a source  2032  within the hull  2010 . In this manner, the integrity of hull  2010  is maintained, while installation of retrofit device  2020  is facilitated. 
     With reference now to  FIGS. 22 through 24 , a conventional lighting fixture  3000  is adapted for use in a salt water marine environment wherein surrounding saltwater enables the incorporation into a retrofit device, shown at  3010 , a self-powered system  3012  for powering the retrofit device  3010 . Thus, in the present embodiment, retrofit device  3010  is provided with first and second electrodes  3022  and  3024 , affixed in place on a retention band  3026  for exposure to salt seawater within which lighting fixture  3000  is to be immersed. First electrode  3022  serves as an anode and may be constructed of a suitable material, such as magnesium, while second electrode  3024  serves as a cathode and may be constructed of stainless steel, copper or titanium. When affixed and sealed to conventional lighting fixture  3000  at adhesive  3028 , as seen in  FIG. 24 , in a manner similar to that described above, and immersed in salt seawater, which then serves as an electrolyte, electrodes  3022  and  3024  generate power that is transmitted to electronic circuitry  3030  placed within a housing  3032 , as seen in  FIGS. 22 and 23 , to power a UVC LED  3034  located adjacent perimetric edge  3035  of auxiliary window  3036 , coupled to the material of auxiliary window  3036 , all within housing  3032 , as seen in  FIGS. 22 and 23 , rendering retrofit device  3010  self-powered, and simplifying the adapting of conventional lighting fixture  3000  to combat biofouling when submerged in seawater. 
     Turning now to  FIGS. 25 and 26 , another retrofit device constructed in accordance with the present invention is shown at  4000  and is seen to include an auxiliary window  4010  constructed of a material, such as quartz, that is capable of transmitting UVC radiation. A slot  4012  within auxiliary window  4010  is located in juxtaposition with perimetric edge  4014  of auxiliary window  4010  and receives a UVC LED  4020  carried by a depending leg  4022  of a circuit board  4024 , the depending leg  4022  being inserted into slot  4012 . Power delivered by a cable  4030  is directed to circuit board  4024  and powers UVC LED  4020  to generate UVC radiation which is confined to and distributed throughout auxiliary window  4010 , enhanced by a reflective material in the form of coating  4032  that extends along the perimetric edge  4034  of auxiliary window  4010 . A housing  4040  encloses the circuit board  4024 , and an adhesive layer  4042  is juxtaposed with the perimetric edge  4014  of auxiliary window  4010 , enabling auxiliary window  4010  to be secured and sealed directly to a conventional lighting fixture (not shown) in place to combat biofouling when that lighting fixture is submerged in a marine environment. 
     It will be seen that the present invention attains all of the objects and advantages summarized above, namely: Provides retrofit constructions and methods for effectively combating biofouling of lighting fixtures installed or ready to be installed to furnish lighting for either or both functional and decorative lighting purposes in environments where the lighting fixtures are submerged and thus exposed to biological organisms that can interfere with the proper transmission of light from the lighting fixtures; enables more widespread use of lighting fixtures for both functional and decorative lighting purposes where such lighting fixtures are submerged and exposed to the detrimental adherence of biological organisms and the concomitant impedance of the transmission of usable light as a result of biofouling; renders more economical the use of lighting fixtures in submerged environments, thereby opening the employment of submerged lighting fixtures over a wider and more diverse range of uses; simplifies the provision of practical anti-biofouling measures in connection with lighting fixtures utilized in installations wherein the lighting fixtures are submerged and exposed to unwanted biological organisms; allows increased flexibility in the choice of design and construction of lighting fixtures to be submerged in environments where the lighting fixtures are exposed to potential biofouling; simplifies the installation of submerged anti-biofouling lighting fixtures in connection with a wide variety of marine structures, as well as marine vessels, without disturbing the integrity of such structures and vessels; exhibits a high degree of operating efficiency and effectiveness for more economical performance over an extended service life. 
     It is to be understood that the above detailed description of preferred embodiments of the invention is provided by way of example only. Various details of design, construction and procedure may be modified without departing from the true spirit and scope of the invention, as set forth in the appended claims.