Abstract:
In accordance with the present invention, there is provided a radiation system that includes at least one wireless radiative element which is powered with microwaves in a microwave cavity. The wireless element comprises a vacuum tight encapsulated envelope (i.e., a preliminarily evacuated tube) which is permeable to ultraviolet, visible and infrared light. The encapsulated envelope is filled with inert gas or inert gas mixtures under pressures in the range of about 0.1 to about 100 tors, and may contain additives of mercury and halogen gases. The microwave excitation of the one or more wireless radiative elements may be facilitated by the placement thereof inside a multi-mode microwave cavity with dimensions formulated in accordance with the teachings of Applicant&#39;s U.S. Pat. No. 5,931,557 entitled ENERGY EFFICIENT ULTRAVIOLET VISIBLE LIGHT SOURCE issued Aug. 3, 1999, the disclosure of which is incorporated herein by reference in its entirety.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable 
       STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
       [0002]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Technical Field of the Invention 
         [0004]    The present invention relates generally to infrared, ultra violet, and visible light sources, and more particularly to a multi-element radiation system which includes one or more wireless radiative elements and is particularly suited for applications including the drying of paints and coatings and radiative treatment of surfaces. 
         [0005]    2. Description of the Related Art 
         [0006]    Infrared, ultraviolet, and visible radiation is increasingly being used for a wide variety of applications in different industries. One such known radiation system which includes multiple radiators of different infrared (IR), ultraviolet (UV), and visible wavelengths based on heated metal wires, carbon ribbons and electrode wired UV lamps is described in U.S. Pat. No. 6,577,816 entitled INFRARED RADIATION SYSTEM WITH MULTIPLE IR RADIATORS OF DIFFERENT WAVELENGTHS issued Jun. 10, 2003. More particularly, U.S. Pat. No. 6,577,816 describes a radiation system that includes at least two elongated envelope tubes which are permeable to light and infrared radiation, and are joined together and sealed from ambient atmosphere. One of these tubes contains an incandescent coil which is electrically connected through sealed tube ends and external contacts to an external power supply, and emits infrared radiation in the near IR range. A second tube is provided with an elongated carbon strip as an infrared radiator for radiation in the medium IR range. Like the first tube, the second tube is itself connected through sealed ends and external contacts with the external power supply, or with an additional external power supply. The radiation system described in U.S. Pat. No. 6,577,816 may optionally include a third elongated tube which is joined to the first and second tubes and adapted to facilitate the emission of UV radiation. 
         [0007]    Though U.S. Pat. No. 6,577,816 describes a radiation system which can be used, for example, in relation to the drying of paints and pigments, it possesses certain deficiencies which detract from its overall utility. The primary deficiency lies in the structural attributes of the IR generating envelope tubes, and the need to energize the incandescent coil or carbon radiator ribbon thereof through the use of a hard wired connection (consisting of terminal contacts) to one or more external power supplies. These hard wired connections add to the complexity of the radiation system, and result in a shortened effective operational lifespan for the IR producing envelope tubes. The present invention addresses these and other deficiencies in a manner which will be described in more detail below. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    In accordance with the present invention, there is provided a radiation system that includes at least one wireless radiative element which is powered with microwaves in a microwave cavity. The wireless element comprises a vacuum tight encapsulated envelope (i.e., a preliminarily evacuated tube) which is permeable to ultraviolet, visible and/or infrared light. The encapsulated envelope is filled with inert gas or inert gas mixtures under pressures in the range of about 0.1 to about 100 tors, and may contain additives of mercury and halogen gases. The microwave excitation of the one or more wireless radiative elements may be facilitated by the placement thereof inside a multi-mode microwave cavity with dimensions formulated in accordance with the teachings of Applicant&#39;s U.S. Pat. No. 5,931,557 entitled ENERGY EFFICIENT ULTRAVIOLET VISIBLE LIGHT SOURCE issued Aug. 3, 1999, the disclosure of which is incorporated herein by reference in its entirety. 
         [0009]    In more detail, as indicated above, each wireless radiative element integrated into the radiation system of the present invention is microwave excited, and comprises an encapsulated dielectric envelope or tube which is preliminarily evacuated and filled with a single inert gas or an inert gas mixture to a relatively low pressure in the range of about 0.1 to about 100 tors. Microwaves ignite an electrical discharge in the low pressure inert gas, and microwave power heats up the gas filled envelope to temperatures of up to about 200° C., depending on ambient air temperature and cavity cooling conditions. Multiple wireless radiative elements serving as IR and/or visible and UV radiators may be included in the radiation system, and are capable of heating up a particular target to temperatures of approximately 70° C. and above, and are further able to maintain the target at this elevated temperature in a length of time sufficient to dry a particular paint or coating applied thereto, or treat the surface of the target for moisture removal or disinfections. 
         [0010]    In order to enhance the drying and/or treatment process, the encapsulated dielectric envelope of the wireless radiative element(s) integrated into the radiation system of the present invention can be made of glass, quartz, Vycor™, Pyrex™, sapphire, ceramics or other dielectric materials transparent to visible, infrared and/or ultraviolet light. Each envelope may further be fully or partially coated internally with phosphors which are adapted to emit desirable wavelengths which are matched to the coating or paint applied to the target, and provide the most efficient drying wavelength match to the color of the target. By way of example and not by way of limitation, for efficient excitation of UV, visible light and IR, mercury in metal or amalgamas form is added to the inert gas in a volume or quantity of greater than or equal to about 0.001 of the individual envelope volume. In addition to the foregoing, a dielectric reflective material may also be applied to the outer or inner surfaces of the envelope to effectively cover the elongated envelope along the full length thereof, leaving only a narrow window along the length of about 30° to about 180° for the more efficient transfer of UV, visible and IR light radiation from inside the envelope (and hence the wireless radiative element) to the target. 
         [0011]    The present invention is best understood by reference to the following detailed description when read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    These, as well as other features of the present invention, will become more apparent upon reference to the drawings wherein: 
           [0013]      FIG. 1  is a top perspective view of a wireless radiation system constructed in accordance with a first embodiment of the present invention; 
           [0014]      FIG. 2  is a top perspective view of a wireless radiation system constructed in accordance with a second embodiment of the present invention; 
           [0015]      FIG. 3  is a perspective view of a panel which may be integrated into the radiation system shown in  FIGS. 1  or  2 , and includes multiple wireless radiative elements; 
           [0016]      FIG. 4  is a side-elevational view of one of the wireless radiative elements included in the panel shown in  FIG. 3 ; 
           [0017]      FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 4 ; and 
           [0018]      FIG. 6  is a perspective view of a radiation system constructed in accordance with a third embodiment of the present invention. 
       
    
    
       [0019]    Common reference numerals are used throughout the drawings and detailed description to indicate like elements. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only, and not for purposes of limiting the same,  FIG. 1  illustrates an wireless radiative system  10  constructed in accordance with a first embodiment of the present invention. The system  10  comprises a housing  12  which defines a microwave cavity  14  having a volume Vo. More particularly, the housing  12  has a generally quadrangular (e.g., rectangular) configuration, and includes a top wall  22 , an opposed pair of longitudinally extending side walls  24  which extend generally perpendicularly relative to the top wall  22 , and an opposed pair of laterally extending side walls  26  which also extend generally perpendicularly relative to the top wall  22  and generally perpendicularly between the side walls  24 . In addition to the top wall  22  and side walls  24 ,  26 , the housing  12  includes a bottom wall  28  which is attached to the side walls  24 ,  26  so as to extend in spaced, generally parallel relation to the top wall  22 . The bottom wall  28  preferably comprises a generally quadrangular (e.g., rectangular) frame having a metal mesh sheet or metal louver disposed within the interior thereof. The purpose for fabricating the bottom wall  28  to primarily comprise metal mesh sheet or metal louver will be discussed in more detail below. In the housing  12 , the top and side walls  22 ,  24 ,  26  are each preferably fabricated from a sheet metal material formed of steel, stainless steel, aluminum, aluminum alloy, or nickel. Those of ordinary skill in the art will recognize that the shape of the housing  12  as shown in  FIG. 1  is exemplary only, and that other shapes and sizes for the housing  12  are contemplated to be within the spirit and scope of the present invention, including but not limited to cylindrical, hollow cylinder, oval and other shapes. 
         [0021]    As further seen in  FIG. 1 , each laterally extending side wall  26  and a corresponding laterally extending side of the outer frame of the bottom wall  28  collectively define at least one generally quadrangular (e.g., rectangular) opening  32  within the housing  12 . Each opening  32  may also be formed in alternative shapes, such as an oval shape. Thus, the housing  12  includes at least a pair of openings  30  which are disposed in respective ones of the opposed lateral sides or ends thereof. Each opening  30  is preferably covered by a metal mesh sheet  32  or a metal louver which is identically configured to, though smaller in size than, the metal mesh sheet disposed within the interior of the outer frame of the bottom wall  28 . The purpose for covering the openings  30  with respective ones of the metal mesh sheets  32  or metal louvers will also be discussed in more detail below. In the system  10 , the microwave cavity  14  is collectively defined by the top wall  22 , bottom wall  28  (including the metal mesh sheet thereof), and side walls  24 ,  26  (including the metal mesh sheets  32  or metal louvers). It is contemplated that the bottom wall  28  may be detachable from the remainder of the housing  12  for purposes of providing access to the microwave cavity  14 . 
         [0022]    In the system  10 , it is contemplated that one or more air circulation fans  33  may be attached to the housing  12  adjacent the opening(s)  30  defined thereby. More particularly, as seen in  FIG. 1 , the fans  33  are positioned adjacent respective ones of the metal mesh sheets  32  or metal louvers so that, when activated, they are operative to facilitate the circulation of cool ambient air into and through the microwave cavity  14  of the housing  12  via respective ones of the openings  30 . As will be recognized, the metal mesh sheets  32  or metal louvers covering each of the openings  30  are effectively disposed between the microwave cavity  14  and the circulation fans  33 . Though two fans  33  are depicted in  FIG. 1  as being positioned adjacent each metal mesh sheet  32  or metal louver, those of ordinary skill in the art will recognize that more or less than two fans  33  may be positioned adjacent each such metal mesh sheet  32  or metal louver without departing from the spirit and scope of the present invention. 
         [0023]    Disposed within the microwave cavity  14  is at least one, and preferably a number N of wireless radiative elements  34 , which are shown in more detail in  FIGS. 3-5 . Each of the radiative elements  34  comprises an elongate, tubular body or envelope  36  which defines an outer surface  38  and an inner surface  40 . The envelope  36  has an inner diameter D and an overall length L as shown in  FIG. 4 . In each radiative element  34  included in the system  10 , the envelope  36  is preferably fabricated from a dielectric material which is transparent to ultraviolet and/or visible, and/or infrared light. Exemplary materials include, but are not limited to, glass, quartz, Vycor™, Pyrex™, sapphire, ceramics or other vacuum tight dielectric materials. The envelope  36  may also be fabricated from a microwave absorbing dielectric material such as, but not limited to, soft borosilicate glass, or ceramics. Additionally, as seen in  FIG. 4 , the envelope  36  preferably has a generally cylindrical configuration, with the length L being in the range of from about 5 inches to about 100 inches, and the diameter D being in the range of from about 0.1 inches to about 2.0 inches. The envelope  36 , which is preliminarily evacuated, is filled with a single inert gas or an inert gas mixture to a relatively low pressure in the range of about 0.1 to about 100 tors. In this regard, each radiative element  34  is adapted to be microwave excited, with the exposure of each element  34  to microwaves being operative to ignite an electrical discharge in the low pressure inert gas or inert gas mixture contained within the envelope  36 . 
         [0024]    As seen in  FIG. 5 , it is contemplated that the inner surface  40  of the envelope  36  of each radiative element  34  may be fully or partially coated with a phosphor layer  42  which is adapted to cause the radiative element  34  to emit visible, infrared or ultraviolet light in a desired wavelength band when energized or excited by the exposure thereof to microwave power. More particularly, the phosphor layer  42  may comprise ultraviolet, visible, or infrared phosphors or blends of phosphors for the enhancement of radiation in specific wavelength bands or multiple bands related to the emission of the specific phosphor wavelengths. Such radiation emission wavelength band or multiple bands may be matched to the spectra of the most efficient drying or treatment wavelengths for specific paints or coatings and targets which are to be dried or cured by the ultraviolet, visible and/or infrared light produced by the system  10 . In addition, to facilitate increased efficiency in the excitation of ultraviolet, visible light or infrared from each radiative element  34 , it is contemplated that additives may be included in the inert gas or inert gas mixture. Such additive may comprise mercury in metal or amalgamas form which may be added to the inert gas within the envelope  36  of the radiative element  34  in a physical volume or quantity in a range of from about 0.001% to about 0.5% of the individual internal volume of the envelope  36 , and preferably in a physical volume or quantity of greater than or equal to about 0.001% of the individual internal volume of the envelope  36 . The additive may also comprise halogen containing gases such as, but not limited to, Cl2, F2, HCl, CCl4 or other halogen containing gases with pressures no more than about 1% of the total pressure of the inert gas or inert gas mixture. 
         [0025]    In addition, it is contemplated that each radiative element  34  may include a dielectric reflective coating layer  44  which may be applied to a portion of the outer surface  38  or the inner surface  40  of the envelope  36 . As seen in  FIG. 5 , if the reflective coating layer  44  is applied to a portion of the inner surface  40  of the envelope  36 , the same is preferably covered by the internal phosphor layer  42  described above. The reflective coating layer  44 , if included in the radiative element  34 , preferably extends along the axis of the full length L of the envelope  36 , and is formed so as to define a window (i.e., an area of the envelope  36  not covered by the reflective coating layer  44 ) which spans a circumferential distance in the range of from about 30° to about 180°. Such window is used to facilitate the transmission of ultraviolet, visible or infrared light from inside the envelope  36  of the radiative element  34  toward a prescribed target, as will also be discussed in more detail below. In the system  10 , each radiative element  34  requires a nominal power p (in the form of microwave power) to facilitate the radiation of ultraviolet, visible or infrared light at a desired wavelength therefrom. 
         [0026]    As seen in  FIG. 3 , the radiative elements  34  of the system  10  are preferably included in a radiative panel  46  which is disposed within the microwave cavity  14  and covers one side of the microwave cavity  14 . The panel  46  includes a peripheral frame member  48  which is preferably fabricated from a material such as metal. The radiative elements  34  are arranged within the frame member  48  so as to extend between an opposed pair of sides thereof in substantially parallel relation to each other. The panel  46  is arranged within the microwave cavity  14  so as to extend between and in generally parallel relation to the top and bottom walls  22 ,  28  of the housing  12 . The outer part of the panel  46  is covered with metal sheet mesh or a metal louver keeping microwaves inside the microwave cavity  14  and preventing their escape from the microwave cavity  14  to open space. 
         [0027]    The system  10  further comprises at least one, or preferably pair or Nm of microwave magnetrons (or solid state) generators  50 , each of which is disposed on the top wall  22  of the housing  12  and communicates with the microwave cavity  14 . Each microwave magnetron generator  50  has a microwave power Pm, where P/Nm=Pm, and where P is a total microwave power of all microwave generators  50  together and produces microwaves having a wavelength λ. Though not shown, electrically connected to each of the generators  50  is a power supply. As shown in  FIG. 1 , the generators  50  are attached to the top wall  22  of the housing  12  so as to communicate directly with the microwave cavity  14 . However, though not shown, the generators  50  may communicate with the microwave cavity  14  via waveguides. The microwave cavity  14  of the system  10  has a maximum cross-sectional dimension d which is greater than λ/2 for allowing microwaves to enter therein either directly from the generators  50  or from a waveguide. 
         [0028]    In the first embodiment, the optimal operating condition for the system  10  to maximize the output and longevity of the wireless radiative elements  34 , with individual radiative power p, diameter D, quantity N, length L, and minimize system power consumption is governed by the relationships: 
         [0000]        Vo≧V  min 1 wherein  V  min 1=8 πλ 3 /3   [formula (1)] 
         [0000]        Vo&gt;V  min 2 wherein  V  min 2=π( D+ 1) 2    N L/ 4   [formula (2)] 
         [0000]        P=kNp √{square root over (1 +Vo/V min)}  [formula (3)] 
         [0000]    wherein V min is the larger of V min  1  and V min  2 , and k is a constant with a value in the range of 0.3≦k≦3 (low values of k are used in case of extended life time for the wireless radiative elements  34 , while high values of k are used in the case of highest power and radiation production rate). In formulas (1), (2), and (3), the units for λ, D and L are in cm; the units for Vo, V min, V min  1 , and V min  2  are in cm 3 ; the units for p and p are in watts; and π=3.14. 
         [0029]    In the operation of the system  10 , the activation of the generators  50  facilitates the transmission of microwave power into the microwave cavity  14 . As a result, the panel  46  disposed within the microwave cavity  14 , and hence the radiative elements  34  thereof, are exposed to the microwaves, which facilitates the excitation of the radiative elements  34  in the aforementioned manner, and hence the transmission of ultraviolet, visible and/or infrared light therefrom. Importantly, the metal mesh sheet or metal louver of the bottom wall  28  of the housing  12  or panel  46 , while being transparent to ultraviolet, visible and/or infrared light, does not allow microwaves to pass therethrough. As such, any parts or materials (i.e., targets) disposed below or adjacent the bottom wall  28  may be exposed to ultraviolet, visible and/or infrared light from the system  10 , but will not be exposed to microwaves produced by the generators  50 . Similarly, the metal mesh sheets  32  or metal louvers disposed within respective ones of the openings  30  defined by the housing  12  prevent the escape from microwaves from the housing  12 , despite air being drawn into the interior of the housing  12  (i.e., the microwave cavity  14 ) via the openings  30 . 
         [0030]    Importantly, when the radiative elements  34  disposed within the panel  46  are energized or excited, the reflective coating layer  44  preferably included in each radiative element  34  is operative to concentrate the infrared, ultraviolet or visible light output thereof in a common direction which is preferably toward the metal mesh sheet or metal louver of the bottom wall  28  of the housing  12 . It is contemplated that the panel  46  may be configured such that all of the radiative elements  34  therein are identical so that they each produce either ultraviolet light within a desired wavelength band, visible light in a desired wavelength band, and/or infrared light. However, if all of the radiative elements  34  of the panel  46  are identical and adapted to produce only one of infrared, ultraviolet or visible light when excited, it is contemplated that the panel  46  may be selectively changed out for one which includes radiative elements  34  adapted to transmit a different light when excited. As an alternative, the panel  46  may include a mix of radiative elements  34  which transmit ultraviolet, visible and/or infrared light in any combination of the three. 
         [0031]    When the microwaves ignite an electrical discharge in the low pressure inert gas of each radiative element  34  included in the panel  46 , such microwave power heats up the gas filled envelope  36  to a temperature of up to about 60° C. to about 200° C., depending on ambient air temperature and the cooling conditions of the microwave cavity  14 . As a result, in the system  10 , the multiple radiative elements  34  included in the panel  46  are capable of heating up a particular target which is exposed to the ultraviolet, visible, and/or infrared light produced by the system  10  to temperatures of approximately 60° C. and above, and are further capable of maintaining the target at this elevated temperature. In this regard, as is shown in  FIG. 1 , cool air drawn into the openings  30  and hence the microwave cavity  14  by the operation of the fans  33  is effectively circulated over the radiative elements  34  in the panel  46 , thus effectively cooling the radiative elements  34 . However, due to the above-described operating temperatures of the radiative elements  34 , the circulating air is heated, and discharged through the metal mesh sheet of the bottom wall  28  to the target, thus elevating the temperature of the target in the aforementioned manner. Thus, the warm air produced by and exhausted from the system  10  may be used, in combination, with the ultraviolet, visible and/or infrared light produced thereby, to assist in the drying of a particular paint of coating applied to the target. 
         [0032]    Referring now to  FIG. 2 , there is shown a wireless radiative system  100  constructed in accordance with a second embodiment of the present invention. The system  100  is substantially similar to the above-described system  10 , with only the distinctions between the systems  10 ,  100  being described below. 
         [0033]    The primary distinction between the systems  10 ,  100  lies in the substitution of the fans  33  described above in relation to the system  10 , with the single fan  133  included in the system  100 . More particularly, whereas the system  10  described above is adapted to facilitate the exposure of the target to warm air flow in addition to its exposure to ultraviolet, visible and/or infrared light produced by the system  10 , the system  100  is adapted only to expose the target to the ultraviolet, visible and/or infrared light, and not to any warm air flow. In this regard, the sole circulation fan  133  included in the system  100  is attached to the top wall  22  of the housing  12  and fluidly communicates with the microwave cavity  14  via an opening  135  disposed within the top wall  22 . As seen in  FIG. 2 , the opening  135  is covered by a metal mesh sheet  137  or metal louver which mimics the functionality of the metal mesh sheets  32 , i.e., prevents the escape of microwaves from the microwave cavity  14  via the opening  135 , while at the same time allowing heated air to be drawn from within and exhausted from the microwave cavity  14  upon the activation of the fan  133 . In this regard, as is apparent from  FIG. 2 , the activation of the fan  133  effectively causes cool, ambient air to be drawn into the microwave cavity  14  via each of the openings  30  of the housing  12  which, as indicated above, are each covered by a respective one of the metal mesh sheets  32  or metal louvers. The air drawn into the microwave cavity  14  via the openings  30  is circulated over the radiative elements  34  within the panel  46 , thereby effectively cooling the same when the radiative elements  34  are excited by the exposure thereof to microwaves. The heated air is drawn out of the microwave cavity  14  and exhausted by the fan  133  in a direction away from (i.e., opposite) the bottom wall  28 , and hence the target. 
         [0034]    Referring now to  FIG. 6 , there is shown a wireless radiative system  200  constructed in accordance with a third embodiment of the present invention. The system  200  comprises a housing  202  having a generally quadrangular (e.g., rectangular) configuration. More particularly, the housing  202  comprises a quadrangular peripheral frame  204  having a solid metal sheet  206  attached to one side thereof. It is contemplated that the frame  204  may be provided to have a length L in the range of from about 1 foot to about 10 feet, and a width W in the range of from about 1 foot to about 8 feet, or larger ranges. In addition, the housing  202  comprises a metal mesh sheet  208  or metal louver (shown partially in  FIG. 6 ) which is attached to that side of the frame  204  opposite that having the solid metal sheet  206  attached thereto. In this regard, the metal sheet  206  and the metal mesh sheet  208  extend in spaced, generally parallel relation to each other, and are separated from each other by a gap having a width substantially equal to the thickness of the frame  204 , i.e., the distance separating those sides of the frame  204  to which respective ones of the sheets  206 ,  208  are attached. In this regard, the frame  204  and the sheets  206 ,  208  collectively define a microwave cavity  209  of the housing  202 . Though the housing  202  is shown as having generally rectangular configuration, those of ordinary skill in the art will recognize that other shapes for the housing  202  are contemplated to be within the spirit and scope of the present invention. 
         [0035]    In addition to the housing  202 , the system  200  comprises a plurality of wireless radiative elements  210  which are disposed in the microwave cavity  209 . In particular, the radiative elements  210  are attached to and extend between the longitudinally extending sides of the frame  204  in spaced, generally parallel relation to each other in the manner shown in  FIG. 6 . Each of the radiative elements  210  is substantially identically configured to and functions in the same manner described above in relation to the wireless radiative elements  34  included in the systems  10 ,  100 . In this regard, the sole distinction between the radiative elements  34 ,  210  lies in that it is contemplated that the radiative elements  210  included in the system  200  may each be fabricated to have a length in the range of from about 12 inches to about 96 inches. 
         [0036]    The system  200  of the third embodiment further comprises a compact microwave power supply  212  which is connected to the microwave cavity  209  via a microwave wave guide  214  (e.g., a microwave cable or hollow metal wave guide) which may have a length of up to about 30 feet. The wave guide  214  is operative to communicate microwave power from the power supply  212  into the microwave cavity  209  of the housing  202 . The system  200  of the third embodiment may comprise multiple microwave power supplies  212  which are connected to the microwave cavity  209  directly or via multiple microwave wave guides  214 . 
         [0037]    The system  200  operates in essentially the same manner described above in relation to the systems  10 ,  100 . In this regard, the transmission of microwave energy from the power supply  212  into the microwave cavity  209  via the wave guide  214  facilitates the excitation of the radiative elements  210 , and thus the transmission of ultraviolet, visible and/or infrared light therefrom. The metal mesh sheet  208  or metal louver, while being transparent to infrared, ultraviolet and/or visible light, does not allow microwaves to pass therethrough. As such, any targets disposed below or adjacent the metal mesh sheet  208  may be exposed to ultraviolet, visible and/or infrared light from the system  200 , but will not be exposed to microwaves produced by the power supply  212 . Though not shown, it is contemplated that the solid metal sheet  206  may optionally be replaced by a metal mesh sheet identical to the metal mesh sheet  208  or a metal louver, thus allowing infrared, ultraviolet and/or visible light to be transmitted from each side of the housing  209 . In this instance, it is contemplated that none of the radiative elements  210  will include a reflective coating layer like the reflective coating layer  44  described above in relation to the radiative elements  34 . It is also contemplated that the system  200  may be configured such that all of the radiative elements  210  therein are identical so that they each produce either infrared light within a desired wavelength band, ultraviolet light in a desired wavelength band, or visible light. As an alternative, the system  200  may include a mix of radiative elements  210  which transmit infrared, ultraviolet and/or visible light in any combination of the three. 
         [0038]    The various embodiments described above may be used in various applications. Such applications include the illumination of objects such as photosensitive materials, and the infrared-ultraviolet-visible curing, solidifying or hardening of paints, polymer coatings, glues, etc. Other applications include stabilizing or etching semi-conductors, wafers or other substrates, sterilizing medical materials and instruments, and large area homogenous light illumination for displays, light emitting panels, and light emitting screens and walls. The various embodiments of the present invention are based on the fundamental principles of simultaneously and uniformally powering by microwave energy highly efficient infrared, ultraviolet and/or visible light/radiation producing radiative elements. Each embodiment of the present invention is economical to manufacture and is adapted to generate infrared, ultraviolet, and/or visible light, while being more compact and consuming lower levels of energy than prior art systems, and eliminating the expensive wiring and ballasts for multi-lamp light emitting systems. 
         [0039]    Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art. Thus, the particular combination of parts described and illustrated herein is intended to represent only certain embodiments of the present invention, and is not intended to serve as limitations of alternative devices within the spirit and scope of the invention.