Abstract:
A light emitting apparatus includes a first radiation source without a dome, a substantially transparent and light transmissive optic device, a lens, a down conversion material, and a heat sink. The optic device is devoid of scattering particles and phosphor, and includes a planar top surface distal the first radiation source, a bottom surface proximal the first radiation sources, and a transparent sidewall extending between the top surface and the bottom surface. The down conversion material includes a flat layer including phosphor that is disposed on the planar top surface of the optic device between the lens and the radiation source. The heat sink, upon which the radiation source is mounted, has a recess formed therein in which an air space is defined between a boundary of the recess and the optic device.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a Continuation Application of U.S. patent application Ser. No. 14/172,308, filed Feb. 4, 2014, which is a Divisional Application of U.S. patent application Ser. No. 13/453,301, filed Apr. 23, 2012 (Abandoned) which is a Continuation Application of U.S. patent application Ser. No. 12/987,315, filed Jan. 10, 2011, now U.S. Pat. No. 8,164,825, issued Apr. 24, 2012 which is a Divisional Application of U.S. patent application Ser. No. 11/644,815 filed Dec. 22, 2006, now U.S. Pat. No. 7,889,421, issued Feb. 15, 2011 which claims the benefit of priority to U.S. Provisional Application Ser. No. 60/859,633 filed Nov. 17, 2006, the contents of which is incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Solid state light emitting devices, including solid state lamps having light emitting diodes (LEDs) and resonant cavity LEDs (RCLEDs) are extremely useful, because they potentially offer lower fabrication costs and long term durability benefits over conventional incandescent and fluorescent lamps. Due to their long operation (burn) time and low power consumption, solid state light emitting devices frequently provide a functional cost benefit, even when their initial cost is greater than that of conventional lamps. Because large scale semiconductor manufacturing techniques may be used, many solid state lamps may be produced at extremely low cost. 
         [0003]    In addition to applications such as indicator lights on home and consumer appliances, audio visual equipment, telecommunication devices and automotive instrument markings, LEDs have found considerable application in indoor and outdoor informational displays. 
         [0004]    With the development of efficient LEDs that emit short wavelength (e.g., blue or ultraviolet (UV)) radiation, it has become feasible to produce LEDs that generate white light through down conversion (i.e., phosphor conversion) of a portion of the primary emission of the LED to longer wavelengths. Conversion of primary emissions of the LED to longer wavelengths is commonly referred to as down-conversion of the primary emission. An unconverted portion of the primary emission combines with the light of longer wavelength to produce white light. 
         [0005]    Phosphor conversion of a portion of the primary emission of the LED is attained by placing a phosphor layer in an epoxy that is used to fill the reflector cup which houses the LED within the LED lamp. The phosphor is in the form of a powder that is mixed into the epoxy prior to curing the epoxy. The uncured epoxy slurry containing the phosphor powder is then deposited onto the LED and subsequently cured. 
         [0006]    The phosphor particles within the cured epoxy generally are randomly oriented and interspersed throughout the epoxy. A portion of the primary light emitted by the LED passes through the epoxy without impinging on the phosphor particles, and another portion of the primary radiation emitted by the LED chip impinges on the phosphor particles, causing the phosphor particles to emit longer wavelength radiation. The combination of the primary short wavelength radiation and the phosphor-emitted radiation produces white light. 
         [0007]    Current state of the art phosphor-converted LED (pc-LED) technology is inefficient in the visible spectrum. The light output for a single pc-white LED is below that of typical household incandescent lamps, which are approximately 10 percent efficient in the visible spectrum. An LED device having a light output that is comparable to a typical incandescent lamp&#39;s power density necessitates a larger LED chip or a design having multiple LED chips. Moreover, a form of direct energy absorbing cooling must be incorporated to handle the temperature rise in the LED device itself. More particularly, the LED device becomes less efficient when heated to a temperature greater than 100° C., resulting in a declining return in the visible spectrum. The intrinsic phosphor conversion efficiency, for some phosphors, drops dramatically as the temperature increases above approximately 90° C. threshold. 
         [0008]    A conventional LED chip is encapsulated by an epoxy that may be referred to as a dome or an epoxy dome. Light from the encapsulated LED passes through the encapsulating substance of the dome before passing through a transmission medium, such as air. The encapsulating substance of the dome performs at least two functions. First, allows for beam control; i.e., it helps to control the direction of light rays passing from the LED chip to a destination. Second, it increases the efficiency of light transmission between the LED and air. The encapsulating substance of the dome performs these two functions at least in part because the value of the refractive index of the encapsulating medium is between the refractive index of the LED chip and the refractive index of air. In a conventional LED chip, the height of the dome may be in the range of 2 mm to 10 mm. 
       SUMMARY OF THE INVENTION 
       [0009]    An embodiment of this invention is a light emitting apparatus having a radiation source for emitting short wavelength radiation. A down conversion material receives and down converts at least some of the short wavelength radiation emitted by the radiation source and back transfers a portion of the received and down converted radiation. An optic device adjacent the down conversion material at least partially surrounds the radiation source. The optic device is configured to extract at least some of the back transferred radiation. A sealant substantially seals a space between the radiation source and the optic device. 
         [0010]    Another embodiment of the invention is a light emitting apparatus having a plurality of radiation sources for emitting short wavelength radiation. A down conversion material receives and down converts at least some of the short wavelength radiation from at least one of the plurality of radiation sources and back transfers a portion of the received and down converted radiation. An optic device adjacent the down conversion material at least partially surrounds the plurality of radiation sources and is configured to extract at least some of the radiation back transferred from the down conversion material. A sealant substantially seals a space between the plurality of radiation sources and the optic device. 
         [0011]    Still another embodiment of the invention is a light emitting apparatus having a plurality of radiation sources for emitting short wavelength radiation. A plurality of down conversion material layers respectively receives and down converts at least some of the short wavelength radiation emitted by respective ones of the radiation sources and back transfers respective portions of the respectively received and down converted radiation. There are a plurality of optic devices. Respective optic devices are adjacent respective down conversion material layers. Respective ones of the optic devices at least partially surround respective ones of the radiation sources. Respective optic devices are each configured to extract at least some of the radiation back transferred from respective down conversion material layers or radiation from respective radiation sources. A plurality of sealants substantially seal respective spaces between respective radiation sources and respective optic devices. 
         [0012]    Another embodiment of the invention is a method of manufacturing a light emitting apparatus. A down conversion material is placed on a first portion of an optic device that is configured to extract at least one of radiation back transferred from the down conversion material or radiation emitted from a short wavelength radiation source. An aperture is formed in a second portion of the optic device. A sealant is placed on a surface of the second portion of the optic device. The radiation source is inserted into the aperture wherein at least one surface of the radiation source contacts the sealant. The optic device is placed on a support. 
         [0013]    Another embodiment of the invention is another method of manufacturing alight emitting apparatus. A down conversion material is placed on a first portion of an optic device that is configured to extract at least one of radiation back transferred from the down conversion material or radiation emitted from a short wavelength radiation source. An aperture is formed in a second portion of the optic device. A sealant is placed on a surface of the second portion of the optic device inside the aperture. The radiation source is placed on a support. The optic device is placed onto the support and over the radiation source so that the optic device at least partially surrounds the radiation source. 
         [0014]    Yet another embodiment of the invention is a light emitting apparatus having a radiation source for emitting short wavelength radiation. A down conversion material receives and down converts at least some of the short wavelength radiation emitted by the radiation source and back transfers a portion of the received and down converted radiation. An optic device adjacent the down conversion material and the radiation source is configured to extract from the optic device at least one of back-transferred radiation or radiation from the radiation source. A first reflective surface at least partially surrounds the optic device for reflecting at least some of the light extracted from the optic device. A second reflective surface at least partially surrounds the radiation source for reflecting at least some of the radiation emitted by the radiation source. 
         [0015]    Still another embodiment of the invention is a light emitting apparatus having a plurality of radiation sources for emitting short wavelength radiation. A down conversion material receives and down converts at least some of the short wavelength radiation from at least one of the plurality of radiation sources and back transfers a portion of the received and down converted radiation. An optic device adjacent the down conversion material at least partially surrounds the plurality of radiation sources and is configured to extract at least some of the radiation that is back transferred from the down conversion material. A sealant substantially seals a space between the plurality of radiation sources and the optic device. 
         [0016]    Another embodiment of the invention is another method of manufacturing a light emitting apparatus having a first reflective cup and a second reflective cup. A down conversion material is placed on a first portion of an optic device that is configured to extract one of radiation back transferred from the down conversion material or radiation emitted from a short wavelength radiation source. A first surface of the radiation source is placed on a first surface of a well that is formed by the second reflective cup. A first sealant is placed between at least a second surface of the radiation source and a second surface of the well. A second sealant is placed on at least a third surface of the radiation source. The optic device is placed within the first reflective cup and in contact with the second sealant. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    It will be understood that the figures are not drawn to scale and that the relative size of certain features may be exaggerated for ease of illustration. 
           [0018]      FIG. 1  is a diagram illustrating the exemplary radiation rays that may result when an exemplary radiation ray from a short-wavelength radiation source such as an LED chip impinges on a layer of down conversion material; 
           [0019]      FIG. 2  is a partial cross-section view of an optic device making use of a down conversion material that is remote from a short wavelength radiation source; 
           [0020]      FIG. 3  is a partial cross-section view of a light emitting apparatus according to an exemplary embodiment of the present invention; 
           [0021]      FIG. 4  is a partial cross-section view of the optic device illustrated in  FIG. 3  having an exemplary embodiment of an aperture; 
           [0022]      FIG. 5  is a partial cross-section view of the optic device illustrated in  FIG. 3  having an alternative embodiment of an aperture; 
           [0023]      FIG. 6  is a partial cross-section of an embodiment of the invention having an exemplary embodiment of a lens adjacent the down conversion material; 
           [0024]      FIG. 7  is a partial cross-section of an alternative embodiment of the invention that does not have a lens adjacent the down conversion material; 
           [0025]      FIG. 8  is a partial cross-section of another alternative embodiment of the invention having an alternative embodiment of a lens adjacent the down conversion material; 
           [0026]      FIG. 9  is a partial cross-section of yet another alternative embodiment of the invention having yet another alternative embodiment of a lens adjacent the down conversion material; 
           [0027]      FIG. 10  is another embodiment of the invention wherein a plurality of short wavelength radiation sources are used; 
           [0028]      FIG. 11  is another embodiment of the invention having a plurality of short wavelength radiation sources; 
           [0029]      FIG. 12  is yet another embodiment of the invention having a plurality of short wavelength radiation sources; 
           [0030]      FIG. 13  is still another embodiment of the invention having a plurality of reflective surfaces adjacent the radiation source and the optic device; 
           [0031]      FIG. 14  illustrates an exemplary embodiment of a method that may be used to manufacture any of the embodiments of the invention described in connection with  FIGS. 3-12 ; 
           [0032]      FIG. 15  illustrates another embodiment of a method of manufacturing any of the embodiments of the invention described in connection with  FIGS. 3-12 ; 
           [0033]      FIG. 16  illustrates an exemplary embodiment of a method that may be used to manufacture the embodiment of the invention described in connection with  FIG. 13 ; 
           [0034]      FIG. 17  is a partial cross-section view of an optic device in accordance with still another embodiment of the invention; 
           [0035]      FIG. 18  is another partial cross-section view of the embodiment illustrated in  FIG. 17 ; 
           [0036]      FIG. 19  is a partial cross-section view of still another embodiment of the invention; 
           [0037]      FIG. 20  is another partial cross-section view of the embodiment illustrated in  FIG. 19 ; 
           [0038]      FIG. 21  illustrates an exemplary embodiment of a method of manufacturing either of the embodiments illustrated in  FIGS. 17-20 ; and 
           [0039]      FIG. 22  illustrates another embodiment of a method of manufacturing either of the embodiments illustrated in  FIGS. 17-20 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]      FIG. 1  is a diagram illustrating the exemplary radiation rays that may result when an exemplary radiation ray  2000  from a short-wavelength radiation source such as an LED chip  2002  impinges on a layer of down conversion material  2004 . The impingement of exemplary short-wavelength radiation  2000  from a short-wavelength source such as an LED chip  2002  onto a down conversion material layer  2004  may produce radiation with four components: back transferred short-wavelength radiation  2006  reflected from the down conversion material layer  2004 ; forward transferred short-wavelength radiation  2008  transmitted through the down conversion material layer  2004 ; forward transferred down-converted radiation  2010  transmitted through the down conversion material  2004 ; and back transferred down-converted radiation  2012  reflected from the down conversion material  2004 . The four components may combine to produce white light. 
         [0041]    Two of the four components  2010  and  2012  may each be comprised of two sub-components. One of the sub-components of forward transferred down-converted radiation may be emitted radiation  2014 ; i.e., down-converted radiation having a longer wavelength than the short-wavelength radiation that impinges onto the down conversion material layer  2004 . The emitted radiation sub-component  2014  of forward transferred down-converted radiation may be produced by short-wavelength radiation  2000  impinging on particles of the down conversion material  2004  as it is transmitted through the down conversion material  2004 . The second sub-component of forward transferred down-converted radiation may be forward scattered emitted radiation  2016 ; i.e., other down-converted radiation having a longer wavelength than the short-wavelength radiation  2000  that impinges onto the down conversion material layer  2004 . The forward scattered emitted radiation sub-component  2016  of forward transferred down-converted radiation  2010  may be produced by short-wavelength radiation  2000  impinging on particles of the down conversion material  2004  and that also bounces back and forth on the particles of the down conversion material  2004  before being transmitted through the down conversion material  2004 . 
         [0042]    One of the sub-components of back transferred down-converted radiation  2012  may be emitted radiation  2020 ; i.e., down-converted radiation having a longer wavelength than the short-wavelength radiation  2000  that impinges onto the down conversion material layer  2004 . The emitted radiation sub-component  2018  of back transferred down-converted radiation  2012  may be produced by short-wavelength radiation  2000  impinging on particles of the down conversion material  2004  as it is reflected from the down conversion material  2004 . The second sub-component of back transferred down-converted radiation  2012  may be back scattered emitted radiation  2020 ; i.e., other down-converted radiation having a longer wavelength than the short-wavelength radiation  2000  that impinges onto the down conversion material layer  2004 . The back scattered emitted radiation sub-component  2020  of back transferred down-converted radiation  2012  may be produced by short-wavelength radiation  2000  impinging on particles of the down conversion material  2004  and that also bounces back and forth on the particles of down conversion material  2004  before being reflected from the down conversion material  2004 . 
         [0043]    White light may be produced by the combinations of the various components discussed above. In the forward transferred direction (i.e., for radiation  2008 ,  2014 ,  2016 ,  2010  that is transmitted through the down conversion material layer), white light may be produced by the combination of forward transferred short-wavelength radiation  2008  with either or both of the sub-components  2014 ,  2016  of the forward transferred down-converted radiation  2010 . That is, white light may be produced in the forward transferred direction by the combination of forward transferred short-wavelength light  2008  with transmitted emitted radiation  2014  and/or with transmitted forward scattered emitted radiation  2016 . 
         [0044]    In the back transferred direction (i.e., for radiation  2006 ,  2018 ,  2020 ,  2012  that is reflected from the down conversion material layer), white light may be produced by the combination of back transferred short-wavelength radiation  2006  with either or both of the sub-components  2018 ,  2020  of the back transferred down-converted radiation  2012 . That is, white light may be produced in the back transferred direction by the combination of back transferred short-wavelength light  2006  with reflected emitted radiation  2018  and/or with reflected back scattered emitted radiation  2020 . 
         [0045]    The wavelength of the forward transferred short-wavelength radiation  2008  may be about the same as the wavelength of the radiation  2000  emitted by a radiation source such as an LED chip  2002 . The wavelength of the back transferred short wavelength radiation  2006  may be about the same as the wavelength of the radiation  2000  emitted by the radiation source  2002 . The wavelength of the forward transferred short-wavelength radiation  2008  may be about the same as the wavelength of the back transferred short-wavelength radiation  2006 . In an exemplary embodiment, the radiation source  2002  may emit radiation exhibiting a wavelength that is less than 550 nm, more particularly in a range of about 200 nm to less than 550 nm. Accordingly, the wavelength of the forward transferred short-wavelength radiation  2008  and the wavelength of the back transferred short-wavelength radiation  2006  may be less than 550 nm, more particularly in a range of about 200 nm to less than 550 nm. 
         [0046]    The wavelength of the forward transferred down-converted radiation  2010  (including its sub-components  2014 ,  2016 ) and the wavelength of the back transferred down-converted radiation  2012  (including its sub-components  2018 ,  2020 ) may be any wavelength that is longer that the excitation spectrum of the down conversion material  2004 . In an exemplary embodiment, the excitation spectrum of the down conversion material  2004  may be in the range of about 300 nm to about 550 nm. In alternative embodiments, other down conversion materials may be used that have an excitation spectrum other than in the range of about 300 nm to about 550 nm. The excitation spectrum of the down conversion material  2004  should produce radiation having a wavelength that is longer than the wavelength of the radiation produced by the short-wavelength emitting radiation source  2002 . In an exemplary embodiment, the down conversion material  2004  may produce radiation in the range of from about 490 nm to about 750 nm. 
         [0047]    The inventors have discovered that the performance of phosphor converted LEDs is negatively affected when placing the down-conversion phosphor close to the LED die. Poor performance is mainly due to the fact that the phosphor medium surrounding the die behaves like an isotropic emitter, and some portion of the back transferred radiation towards the die circulates between the phosphor layer, the die, and the reflector cup. As a result, the back transferred radiation increases the junction temperature, thus reducing system efficacy and increasing the yellowing of the encapsulant. All of these factors reduce the light output over time. 
         [0048]    The literature shows that 60 percent of the light impinging on the phosphor layer is back transferred, contributing to the described effects (Yamada, et al., 2003). Lab measurements of eight YAG:Ce phosphor plates proved that nearly 60% of the radiant energy is transferred back in the direction of the blue LED source. The absolute magnitude of the radiant energy reflected depends, among other factors, on the density of the phosphor coating. 
         [0049]    Such effects are expected to be of a higher magnitude in RCLEDs, because their light output is much more collimated. Consequently, the packaging attempts to capture the transmitted, emitted, and reflected components to improve system efficiency. Additionally, the inventors have created packaging that allows the phosphor layer to be moved away from the die, preventing radiation feedback into the LED and RCLED. As a result, the packaging increases the efficiency of the device by allowing more of the radiation reflected off and emitted by the phosphor layer to exit the device. At the same time, radiation from the RCLED impinges on the phosphor layer uniformly to obtain a uniform white light source. In addition, the life of the LED and RCLED is improved. 
         [0050]    In traditional phosphor-converted white LEDs, where the phosphor is placed adjacent the die, more than 65% of the light generated by the phosphor is back-scattered and lost within the LED package. Based on these findings, a technique referred to as Scattered Photon Extraction™ (SPE™) has been developed. An aspect of the technique has been disclosed in pending International Application No. PCT/US2005/015736 filed on May 5, 2005 and published at WO 2005/107420 A2 on Nov. 17, 2005. 
         [0051]    To increase the light output from a phosphor-converted white LED (pc-LED) and to achieve higher luminous efficacy, the down-conversion material (e.g., phosphor or quantum dots) is removed to a remote location and a properly tailored optic device is placed between the LED chip and the down-conversion material layer. Then, the back transferred light can be extracted to increase the overall light output and efficacy. This technique significantly increases the overall light output and luminous efficacy of a pc-white LED by extracting the phosphor emitted and back scattered reflected radiation, and the reflected short-wavelength radiation that otherwise would be lost. The invention described in this specification may achieve a 1500-lumen package at 150 lm/W, for example, using an LED chip array. In an exemplary embodiment, the LED chip array may be nitride-based. In alternative embodiment, the LED chip array may be AlInN-based or any other short wavelength emitter. 
         [0052]      FIG. 2  illustrates a device using the SPE™ technique. It illustrates a high efficiency light source that may use one or more solid state emitters and down conversion material. It illustrates an optic device making use of a down conversion material that is remote from a short wavelength radiation source. The down conversion material may be a phosphor or quantum dots. As shown, device  200  may include a radiation source  202  for emitting short wavelength radiation. Radiation source  202  is separated from phosphor layer  204  by optic device  250  which may be made of a substantially transparent medium that may be substantially light transmissive. The substantially transparent medium may be, for example, air, glass or acrylic. Optic device  250 , as well as all of the embodiments disclosed in the application, may be cylindrical in shape or may have another curved or linear shape. For purposes of illustration, optic device  250  is shown as having walls  252  and  254 , which may be substantially transparent and substantially light transmissive walls. Phosphor layer  204  may be placed adjacent to or on a portion  206  of optic device  250 . 
         [0053]    Phosphor or quantum dot layer  204  may include additional scattering particles (such as micro spheres) to improve mixing light of different wavelengths. Also, the phosphor or quantum dot layer  204  may be of a single phosphor (or quantum dot) or multiple phosphors (or quantum dots) to produce different colored down-converted radiation that may be in several different spectral regions. Alternatively, a layer with scattering particles only may be placed above, or below, or above and below the down conversion material layer  204  to improve color mixing. 
         [0054]    The portion  206  of optic device  250  upon which phosphor layer  204  may be deposited may be an end of optic device  250 . Radiation source  202  may be located at another portion of optic device  250 . For example, radiation source  202  may be located at another end  208  of optic device  250 . Optic device  250  may be placed upon a base  256 . 
         [0055]    Short wavelength radiation source  202  may be located between walls  252  and  254 . Both the short wavelength radiation source  202  and the optic device  250  may be positioned on the base  256 . 
         [0056]    Exemplary radiation rays  214  may comprise radiation transmitted through phosphor layer  204  including forward transferred short-wavelength radiation transmitted through the phosphor layer  204  and forward down-converted radiation transmitted through the phosphor layer  204 . 
         [0057]    Exemplary radiation rays  215  may comprise back transferred short-wavelength radiation and back transferred down-converted reflected radiation that may be emitted and/or scattered back by phosphor layer  204 . Exemplary radiation rays  216  may comprise radiation scattered back by phosphor layer  204 . Exemplary radiation rays  216  may comprise the radiation rays  215  that may be transmitted through the substantially transparent, substantially light transmissive walls  252 ,  254 . Although exemplary arrows  215  show back transferred radiation being transferred around the middle of side walls  252  and  254 , it will be understood that back transferred radiation may be transferred through side walls  252  and  254  at multiple locations along the side walls  252  and  254 . The transfer of radiation outside the optic device  250  may be referred to as extraction of light. Accordingly, both radiation rays  215  and radiation rays  216  may include short wavelength radiation reflected from the phosphor layer  204  and down-converted reflected radiation that may be emitted and/or scattered from the phosphor layer  204 . Some or all of radiation rays  215  and/ 216  may be seen as visible light. 
         [0058]    The transfer (extraction) of radiation through side walls  252  and  254  may occur because optic device  250  may be configured and designed with substantially transparent, substantially light transmissive walls  252  and  254  to extract radiation from inside optic device  250  to outside optic device  250 . In addition, various widths of optic device  250  may be varied in order to extract a desired amount of radiation out of the optic device  250 . The widths that may be varied are the width at the end  206  and the width at the end  208 . Similarly, widths between ends  206  and  208  may be varied. The widths between ends  206  and  208  may result in walls  252  and  254  being substantially straight, curved, or having both straight and curved portions. 
         [0059]    The dimensions of the features of optic device  250  discussed above may be varied depending upon the application to which the optic device  250  may be used. The dimensions of the features of optic device  250  may be varied, and set, by using the principles of ray tracing and the principles of total internal reflection (TIR). When principles of TIR are applied, reflectivity of radiation off of one or both of walls  252  and  254  may exceed 99.9%. The principles of TIR may be applied to all of the embodiments disclosed in this application. 
         [0060]    The dimensions of optic device  250  may be set in accordance with the use to which the optic device may be put. For example, the dimensions of the optic device may be set in order to maximize the amount of radiation from radiation source  202  that enters into optic device  250 . Alternatively, the dimensions of optic device  250  may be set in order to maximize the amount of radiation from radiation source  202  that impinges upon down conversion material  204 . Also alternatively, the dimensions of optic device  250  may be set in order to maximize the amount of radiation that is back transferred from down conversion material  204 . Also alternatively, the dimensions of optic device  250  may be set in order to maximize the amount of radiation that is extracted through walls  252  and  254 . Also alternatively, the dimensions of optic device  250  may be set in order to provide a device that, to the extent possible, simultaneously maximizes each of the radiation features discussed above: the amount of radiation entering into optic device  250 ; the amount of radiation that impinges upon down conversion material  204 ; the amount of radiation that is back transferred from down conversion material  204 ; and the amount of radiation that is extracted through walls  252  and  254 . In addition, the dimensions of optic device  250  may be set so that any or all of the features discussed above are not maximized. The principles of ray tracing and the principles of TIR may be used in order to implement any of these alternatives. 
         [0061]    Some of the dimensions that may be varied are the diameter of end  206  of the optic device; the diameter of end  208  of optic device; the angle of walls  252  and/or  254  relative to end  208 ; the shape of walls  252  and/or  254 . For example, walls  252  and/or  254  may be straight, curved, or combinations of straight and curved. A height  260  of the optic device  250  may be less than 30 mm. 
         [0062]    The refractive index of optic device  250  may be in a range from about 1.4 to about 1.7. Radiation source  202  may have a refractive index in the range of about 1.7 to about 2.6. Radiation source  202  may be encapsulated by a material such a radiation transmissive epoxy  220 . The encapsulating material may be referred to as a dome  220 . The height of dome  220  may be about 2 mm to about 10 mm. Dome  220  may be used for beam control and to improve the efficiency of the radiation source, such as when the radiation source  202  is an LED. In order to provide these advantages, the refractive index of the dome  220  may be in range of about 1.4 to about 1.7. The refractive index of dome  220  may be selected to be between the refractive index of radiation source  202  and the refractive index of optic device  250  so that the dome  220  may provide a transition for radiation between the output of radiation source  202  and optic device  250 . 
         [0063]    An aperture is provided in end  208  of optic device  250 . The aperture may be sized and shaped to receive the dome  220  along with the encapsulated radiation source  202 . Accordingly, the height of the aperture may be about 2 mm to about 15 mm in order to fully receive dome  220 . 
         [0064]      FIG. 3  is a partial cross-section view of a light emitting apparatus according to an exemplary embodiment of the present invention.  FIG. 3  shows a short wavelength radiation source  302  that may be a light emitting diode (LED), a laser diode (LD), or a resonant cavity light emitting diode (RCLED). Radiation emitting source  302  is not encapsulated by a dome. Radiation emitting source  302  may either be manufactured without a conventional dome or it may be manufactured with a dome, which may be removed as needed. Radiation emitting source  302  may emit short wavelength radiation. One side of radiation source  302  may be positioned on a heat sink  304  which may transfer heat away from radiation source  302 . An inside surface  306  of heat sink  304  may be a reflective surface to form a reflective cup. In an exemplary embodiment, the shape of reflective surface  306  may be a parabola for illustration purposes, but it may take any geometric shape such as a concave shape, an elliptical shape, or a flat shape. In an exemplary embodiment, the length  370  of heat sink  304  may be about 5 mm. Reflective surface  306  may direct some of the light extracted from optic device toward down conversion material  310  and may direct some of the extracted light toward a lens  340  without impinging upon down conversion material  310 . 
         [0065]    An optic device  308  may be positioned on the heat sink  304  and over the radiation source  302 . Optic device  308  may make use of a down conversion material  310  that is placed on a portion  316  of optic device that is remote from radiation source  302 . The down conversion material  310  may be a phosphor or quantum dots. Radiation source  302  is separated from phosphor layer  310  by optic device  308  which may be made of a substantially transparent medium that may be substantially light transmissive. The substantially transparent medium may be, for example, air, glass or acrylic. Optic device  308  may have substantially transparent and substantially light transmissive walls  312  and  314 . 
         [0066]    Phosphor or quantum dot layer  310  may include additional scattering particles (such as micro spheres) to improve mixing light of different wavelengths. Also, the phosphor or quantum dot layer  310  may be of a single phosphor (or quantum dot) or multiple phosphors (or quantum dots) to produce different colored down-converted radiation that may be in several different spectral regions. Alternatively, a layer with scattering particles only may be placed above, or below, or above and below the down conversion material layer  310  to improve color mixing. 
         [0067]    The portion  316  of optic device  308  upon which phosphor layer  310  may be deposited may be an end of optic device  308 . Radiation source  302  may be located at another portion of optic device  308 . For example, radiation source  302  may be located at another end  318  of optic device  308 . As indicated, optic device  308  may be placed upon a base which may be heat sink  304 . 
         [0068]    Short wavelength radiation source  302  may be located between walls  312  and  314  of optic device  308 . Both the short wavelength radiation source  302  and the optic device  308  may be positioned on the heat sink  304 . 
         [0069]    The operation of, and the interrelationship between, radiation source  302 , optic device  308 , and down conversion material  310  may be the same as the operation and interrelationship between corresponding elements described and illustrated in  FIGS. 1 and 2 . Short wavelength radiation emitted by radiation source  302  may result in radiation transmitted through phosphor layer  310  including forward transferred short-wavelength radiation transmitted through the phosphor layer  310  and forward down-converted radiation transmitted through the phosphor layer  310 ; and back transferred short-wavelength radiation and back transferred down-converted reflected radiation that may be emitted and/or scattered back by phosphor layer  310 . It will be understood that back transferred radiation may be transferred through side walls  312  and  314  at multiple locations along the side walls  312  and  314 . The transfer of radiation outside the optic device  308  may be referred to as extraction of light. Accordingly, radiation rays that may be extracted from optic device  308  may include short wavelength radiation reflected from the phosphor layer  310  and down-converted reflected radiation that may be emitted and/or scattered from the phosphor layer  310 . Some short wavelength radiation emitted from the top and the sides of the radiation source  302  may leave optic device  308  without impinging upon down conversion material  310 . Some or all of the extracted short wavelength reflected radiation and the extracted down converted reflected radiation may be seen as visible light. 
         [0070]    The transfer (extraction) of radiation through side walls  312  and  314  may occur because optic device  308  may be configured and designed with substantially transparent, substantially light transmissive walls  312  and  314  to extract radiation from inside optic device  308  to outside optic device  308 . In addition, various widths of optic device  308  may be varied in order to extract a desired amount of radiation out of the optic device  308 . The widths that may be varied are the width at the end  316  and the width at the end  318 . Similarly, widths between ends  316  and  318  may be varied. Variations in the widths of walls  312  and  314  between ends  316  and  318  may be created by varying shapes of walls  312  and  314 . Walls  312  and  314  may be substantially straight, curved, or have both straight and curved portions. 
         [0071]    The dimensions of the features of optic device  308  discussed above may be varied depending upon the application to which the optic device  308  may be used. The dimensions of the features of optic device  308  may be varied, and set, by using the principles of ray tracing and the principles of total internal reflection (TIR). When principles of TIR are applied, reflectivity of radiation off of one or both of walls  312  and  314  may exceed 99.9%. The principles of TIR may be applied to all of the embodiments disclosed in this application. 
         [0072]    The dimensions of optic device  308  along with characteristics of down conversion material  310  may be set or adjusted in accordance with the use to which the optic device may be put. For example, the dimensions of the optic device may be set in order to maximize the amount of radiation from radiation source  302  that enters into optic device  308 . Alternatively, the dimensions of optic device  308  may be set in order to maximize the amount of radiation from radiation source  302  that impinges upon down conversion material  310 . Also alternatively, the dimensions of optic device  302  may be set in order to maximize the amount of radiation that is back transferred from down conversion material  310 . Also alternatively, the dimensions of optic device  308  may be set in order to maximize the amount of radiation that is extracted through walls  312  and  314 . 
         [0073]    It will also be understood that dimensions of other embodiments of optic device  308  and characteristics of down conversion material  310  may be set or adjusted to produce radiation features that are not maximized. In these other embodiments, one or more of the amounts of radiation entering into optic device  308 ; impinging upon down conversion material  310 ; back transferred from down conversion material  310 ; and extracted through walls  312  and  314  may be adjusted to a one or more of a variety of levels that may be less than their respective maximum levels, depending upon the use to which the optic device is put. The dimensions of optic device  308  may also be varied depending upon relative cost needs versus the needed efficiency of light extraction for a particular use of the optic device. 
         [0074]    The principles of ray tracing and the principles of TIR may be used in order to implement any of these alternatives. 
         [0075]    Some of the dimensions that may be varied are the diameter of end  316  of the optic device; the diameter of end  318  of optic device; the angle of walls  312  and/or  314  relative to end  318 ; the shape of walls  312  and/or  314 . For example, walls  312  and/or  314  may be straight, curved, or combinations of straight and curved. In an exemplary embodiment, a height  360  of the optic device  308  may be about 3 mm. 
         [0076]      FIG. 4  is a partial cross-section view of the optic device illustrated in  FIG. 3  having an exemplary embodiment of an aperture. More specifically,  FIG. 4  is a partial cross-section view of optic device  308  having an exemplary embodiment of an aperture  320 .  FIG. 4  shows optic device  308  and down conversion material  310  on an end  316  of optic device  308 .  FIG. 4  shows the aperture  320  in end  318  of optic device  308 . The aperture  320  may be sized and shaped to receive the radiation source  302  so that optic device  308  at least partially surrounds radiation source  302  because a substantial amount of radiation source  302  is within the aperture  320 . As shown in the exemplary embodiment illustrated in  FIGS. 3 and 4 , when radiation source  302  is within aperture  320 , substantially all of the radiation source  302  may be surrounded by optic device  308 . The only portion of radiation source  302  that may not be surrounded by optic device  308  is the portion that rests on heat sink  304 . When the radiation source  302  is positioned within the aperture  320  of optic device  308  as shown in  FIGS. 3 and 4 , it may be said that radiation source  302  is fully immersed within the optic device  308 . In an exemplary embodiment, the dimensions of radiation source  302  may be about 1 mm by about 1 mm by about 0.3 mm and the diameter of aperture  320  may be about 2 mm. By using a radiation source without a dome, the height  360  of the optic device  308  may be smaller than, for example, the height  260  of the optic device  250  shown in  FIG. 2 . 
         [0077]    It will be understood that the aperture in the optic device may have a variety of shapes. As shown in  FIG. 4 , for example, aperture  320  may have a curved shape.  FIG. 5  is a partial cross-section view of the optic device illustrated in  FIG. 3  having an alternative embodiment of an aperture. In the alternative embodiment shown in  FIG. 5 , an aperture  322  may be in a shape that more nearly approximates the shape of the radiation source  302 . For example, as shown in  FIG. 5 , the shape of aperture  322  of optic device  308  may be a trapezoid. In an exemplary embodiment, the dimensions of aperture  322  may be equal to or somewhat larger than the diameter of the radiation source  302 . As indicated by arrow  50  in  FIG. 5 , optic device  308  with trapezoid shaped aperture  322  may be placed on top of, and substantially surround, radiation source  302 . When an aperture such as aperture  322  is used, and when optic device  308  is placed on top of radiation source  302 ,  FIG. 3  may illustrate the radiation source  308  within aperture  322  of optic device  308 . As shown in  FIGS. 3 and 5 , the aperture in optic device  308  may be shaped to closely match the shape of the radiation source  302 . Regardless of which aperture shaped is used, the radiation source  302  may be fully immersed within the optic device  308  and may be substantially surrounded by optic device  308 , except for the side of radiation source  302  that may rest on heat sink  304  or other supporting base if a heat sink is not used, in an alternative embodiment. 
         [0078]    The refractive index of optic device  308  may be in a range from about 1.4 to about 1.7. Radiation source  302  may have a refractive index in the range of about 1.7 to about 2.6. Referring to  FIG. 4 , there may be air spaces such as spaces  324 ,  326 , and  328  between radiation source  302  the inside of optic device  308 . Referring to  FIG. 4 , there may also be an air space (not shown) between corner  330  of radiation source  302  and the adjacent point of the optic device  308  inside aperture  320  and between corner  332  of radiation source  302  and the adjacent point of the optic device  308  inside aperture  320 . Referring to  FIGS. 3 and 5 , there may also be air spaces between the sides of radiation source  302  and the inside of optic device  308  within aperture  322 . There may also be air spaces between radiation source  302  and the inside of optic device  308  within the aperture regardless of the respective shapes of the radiation source and the aperture. In order to provide a transition for radiation passing from radiation source  302  to optic device  308 , a sealant may be placed to fill the spaces between radiation source  302  and optic device  308 . Accordingly, a sealant may be placed in the spaces for any shape of the radiation source and any shape of the aperture within the optic device. The sealant may provide a transition for radiation passing from the respective radiation source to the optic device. 
         [0079]    In an exemplary embodiment, the sealant may fill in each of the spaces as much as possible in order to obtain the best efficiency of radiation transfer from the radiation source  302  to the optic device  308 . The efficiency of transferring radiation from radiation source  302  to optic device  308  may decrease if each of the spaces are not completely filled. The sealant may also be used as a binding material to bind the optic device  308  to the radiation source  302 . A better bond between the optic device  308  and the radiation source  302  may result in better efficiency of radiation transfer from radiation source  302  to optic device  308 . 
         [0080]    In an exemplary embodiment, the sealant material may be a silicon gel, epoxy, polymer or any other sealant that is substantially light transmissive, that has the necessary refractive index, and that is pliable enough to substantially seal the spaces. The sealant material may have a refractive index that is between the refractive index of radiation source  302  and optic device  308 . In an exemplary embodiment, the refractive index of the sealant may be in a range that is between the refractive index of the radiation source  302  and the refractive index of optic device  308 . For example, the refractive index of the sealant may be in the range of about 1.5 to about 2.3. In an exemplary embodiment enough sealant should be used that may effect substantially filling of all spaces including, but not limited to, spaces  320 ,  324  and  326 . Using a radiation source without a dome and using a sealant such as a gel as an interface between the radiation source and the optic device may allow the design of an optic device that is substantially shorter than an optic device that uses a radiation source that is encapsulated with a dome. For example, referring to  FIG. 2 , the height  260  of apparatus  200  may be about 20 mm. In contrast, referring to  FIG. 3 , the height  360  of apparatus  300  may be about 3 mm. Using a sealant instead of a dome therefore gives a user much more flexibility in the design and manufacture of a light emitting apparatus that incorporates the features of SPE™ technique. For example, by using more or less sealant, a light emitting apparatus may be manufactured that has a height in a range of about 2 mm to about 10 mm. 
         [0081]    Referring back to  FIG. 3 , a lens  340  may be placed on top of, and over, the optic device  308  and the down conversion material  310 . Lens  340  may be used to focus light that may be forward transferred from the down conversion material  310  and light that may be reflected by the reflector  306 . Lens  340  may also have a refractive index that may compensate for the refractive index of the air contained in space  342  that is formed when the lens  340  is placed on the optic device  308  and down conversion material  310 . Lens  340  may be a spherical lens or may be any other shape that may direct the light as needed. Lens  340  may be attached to down conversion material using adhesive material. In an alternative embodiment, lens  340  may also be attached to the heat sink  304 . In yet another alternative embodiment, lens  340  may be attached to both the down conversion material  310  and the reflective cup  306 . 
         [0082]      FIGS. 6 to 9  illustrate alternative embodiments of the apparatus shown in  FIGS. 3-5 . In each of these embodiments, the optic device  308 , down conversion material  310 , radiation source  302  and aperture (not shown in  FIGS. 6-9 ) may be the same as discussed with respect to any of  FIGS. 3-5 .  FIG. 6  illustrates the apparatus as having a thin film with a micro-lens array  342  on top of the optic device  308  and the down conversation material  310 . In this embodiment, the lens array  342  may be attached to the down conversion material  310  alone, to the heat sink  304  alone, or to both the down conversion material  310  and the heat sink  304 .  FIG. 7  illustrates the apparatus without any lens on top of the optic device  308  and the down conversion material  310 .  FIG. 8  illustrates a lens  344  that may be attached only to the down conversion layer  310 . The lens  344  in this embodiment may be the any of the lenses illustrated and described in connection with  FIGS. 3-5  and  7 .  FIG. 9  illustrates a lens  346  that may be any of the lenses illustrated and described in this application and a heat sink  348  with reflective surfaces  350  and  352 . The reflective surfaces  350  and  352  of heat sink  348  may not have a parabolic shape or an elliptical shape. Instead, one or both of reflective surfaces  350  and  352  may have a linear shape. 
         [0083]      FIG. 10  illustrates another embodiment of the invention. This embodiment has a plurality of short wavelength radiation sources.  FIG. 10  illustrates an optic device  308  with a down conversion material  310  and an aperture  322  as illustrated in  FIG. 5 . These elements may have the same sizes as the corresponding elements illustrated in  FIG. 5 . However, instead of a single short wavelength radiation source  302  as shown in  FIG. 5 , the embodiment illustrated in  FIG. 10  may have three short wavelength radiation sources  400 ,  402 ,  404  resting on heat sink  304 . None of the short wavelength radiation sources  400 ,  402 ,  404  may be encapsulated by a dome. Because the size of aperture  322  in  FIG. 10  may be the same size as aperture  322  in  FIG. 5 , the sizes of one or more of radiation sources  400 ,  402 ,  404  may be smaller than the size of radiation source  302  shown in  FIG. 5 . In an exemplary embodiment, the sizes of one or more of radiation sources  400 ,  402 , and  404  may be about 0.3 mm by about 0.3 mm by about 0.3 mm. Although  FIG. 10  shows three radiation sources being placed on heat sink  304 , it will be understood that two short wavelength radiation sources may be used; or more than three short wavelength radiation sources may be used as long as they fit within aperture  322 . A sealant may be used between at least one of the radiation sources and the surface inside aperture  322 . The sealant for this embodiment of the invention and for all embodiments of the invention disclosed in this application may be the same sealant discussed with respect to  FIGS. 3-5 . 
         [0084]      FIG. 11  illustrates another embodiment of the invention having a plurality of short wavelength radiation sources. In  FIG. 11 , three short wavelength radiation sources  302 A,  302 B, and  302 C, each of which may be the same size as short wavelength radiation source  302  that is illustrated in  FIG. 5 . None of the radiation sources  302 A,  302 B, and  302 C may be encapsulated by a dome. In order to accommodate these three radiation sources, the optic device  408  having a down conversion material  410  on portion  416  which may be an end of optic device  408  may be a larger version of optic device  308  illustrated in  FIGS. 3 ,  5 , and  10 . In an exemplary embodiment, the size of aperture  422  illustrated in  FIG. 11  may be about 6 mm. In addition, the size of heat sink  412  may be a larger version of heat sink  304  that is illustrated in  FIGS. 3 ,  5 , and  10 . In an exemplary embodiment, the length  470  of heat sink  412  may be about 10 mm. Although  FIG. 11  shows three short wavelength radiation sources  302 A,  302 B,  302 C placed on heat sink  412 , it will be understood that two short wavelength radiation sources may be used; or more than three short wavelength radiation sources may be used. If the number of radiation sources is different than the embodiment illustrated in  FIG. 11 , the size of aperture  422  and the size of heat sink  412  may be changed to accommodate them. As with the other embodiments in this application, a sealant may be used to seal all spaces (not shown) between each of the optic devices  302 A,  302 B,  302 C and the surface of optic device  408  that is inside aperture  422 . 
         [0085]      FIG. 12  illustrates yet another embodiment of the invention having a plurality of short wavelength radiation sources. In  FIG. 12 , a single heat sink  500  is shown having three separate heat sink sections  502 ,  504 ,  506 . Each of the heat sink sections may have its own respective reflective surfaces forming reflective cups  508 ,  510 ,  512  and its own respective short wavelength radiation source identified as short wavelength radiation sources  514 ,  516 , and  520 . In this embodiment, respective optic devices  522 ,  524 , and  526  having respective down conversion materials  528 ,  530 ,  532  and respective apertures  534 ,  536 , and  538  may be used. As with all of the other embodiments disclosed in this application, none of the radiation sources  514 ,  516 , or  520  may have a dome. Instead, a sealant may be used in the spaces (not shown) between each of the respective radiation sources and the respective inside surfaces of respective apertures  534 ,  536 ,  538  of optic devices  522 ,  524 ,  526 . Although  FIG. 12  shows three radiation sources and other matching elements, it will be understood that two radiation sources may be used; or more than three radiation sources may be used. If the number of radiation sources is different than is shown in the embodiment illustrated in  FIG. 12 , the number of optic devices may also be different in order to match the number of radiation sources. 
         [0086]    It will also be understood that for all embodiments illustrated in this application, various configurations of lenses and various attachments of such lenses may the same as illustrated and explained with respect to the embodiments illustrated in  FIGS. 6 to 9 . 
         [0087]      FIG. 14  illustrates an exemplary embodiment of a method that may be used to manufacture any of the embodiments of the invention described in connection with  FIGS. 3-12 . The method may be used to manufacture a light emitting apparatus that has a radiation source for emitting short wavelength radiation, a down conversion material that receives at least some short wavelength radiation emitted by the radiation source, and an optic device configured to extract radiation back transferred from the down conversion material and/or radiation emitted from the short wavelength radiation source. As shown in Block  700 , the down conversion material is placed on a first portion of the optic device. As explained previously, the first portion of the optic device may be a first end of the optic device. As shown in Block  702 , an aperture is formed in a second portion of the optic device. The second portion of the optic device may be a second end of the optic device. It will be understood that the step of forming the aperture as shown in Block  702  may be performed before the step of placing the down conversion material as shown in Block  700 . Block  704  shows that a sealant is placed on a surface of the second portion of the optic device, where the surface is inside the aperture. After the sealant is placed on the inside surface of the aperture, Block  706  shows that the radiation source may be placed into the aperture. When the radiation source is placed into the aperture, at least one surface of the radiation source may contact the sealant. 
         [0088]    After the radiation source is placed into the aperture, at least first and second spaces between the optic device and the radiation source may be sealed, as shown in Blocks  708  and  710 . After the spaces between the radiation source and the inside of the aperture have been sealed, the optic device, with the radiation source inside the aperture, may be placed on a support, as indicated in Block  712 . The support may be a heat sink. It will be understood that the steps illustrated in Blocks  708  and  710  may be performed after the step illustrated in Block  712 . After spaces between the radiation source and the inside of the aperture have been sealed and the device placed upon the support, a lens may be placed adjacent the down conversion material, as indicated in Block  714 . 
         [0089]      FIG. 15  illustrates another method of manufacturing any of the embodiments of the invention described in connection with  FIGS. 3-12 . In this method, the steps shown in Blocks  800 ,  802 , and  804  are the same as the steps shown in Blocks  700 ,  702 , and  704 . After a sealant is placed on the inside surface of the aperture, the radiation source may be placed on the support, which may be a heat sink, as shown in Block  806 . It will be understood that the step of placing the radiation source on a support as shown in Block  806  may be performed before the steps illustrated in Blocks  800 ,  802 , and  804 . After the radiation source is placed on the support, the optic device, with the sealant on its surface inside the aperture, is placed onto the support and over the radiation source, as shown in Block  808 . When this step is completed, the optic device may be substantially surrounding the radiation source, also as shown in Block  808 . At this point, a plurality of spaces between the optic device and the radiation source may be sealed, as shown in Block  810 . Then, a lens may be placed adjacent the down conversion material, as shown in Block  812 . It will be understood that the step illustrated in Block  812  and the step illustrated in Block  714  may not be performed, for example, in manufacturing the embodiment shown in  FIG. 7 , where no such lens may be used. 
         [0090]      FIG. 13  illustrates still another embodiment of the invention, wherein a plurality of reflective surfaces are adjacent the radiation source and the optic device. A light emitting apparatus  600  is shown in  FIG. 13 . Light emitting apparatus  600  has an optic device  608  with a down conversion material  610  on a portion  616  of the optic device  608  that may be an end of optic device  608 . Apparatus  600  may also have a short wavelength radiation source  602  positioned on a heat sink  604 . As is the case with all of the other embodiments in this application, short wavelength radiation source  602  may not be encapsulated by a dome. Heat sink  604  may form two reflective cups having reflective surfaces  612  and  614 . The first reflective cup and surface  612  may be adjacent the second reflective cup and surface  614 . The radius of reflective surface  612  may be the same or different than the radius of reflective surface  614 . In addition, reflective surface  612  may be comprised of a plurality of surfaces each of which may have a different radius. The number of radii comprising reflective surface  612  may depend upon the height of optic device  608 . 
         [0091]    First reflective surface  612  may partially surround optic device  608  and down conversion material  610 . As discussed regarding other embodiments of this invention, reflective surface  612  may direct light extracted from optic device  608  in the direction of down conversion material  610  and in the direction of lens  640 . 
         [0092]    Radiation source  602  may be positioned at the bottom of heat sink  604  so that the radiation source  602  may be partially surrounded by the reflective surface  614 . First reflective surface  612  may be coupled to second reflective surface  614  at points illustrated by points  613 ,  615 . A distance from the bottom  605  of heat sink  604  to points  613  and  615  may be equal to or greater than the height of radiation source  602 . A diameter of end portion  618  of optic device  608  may be substantially equal to the distance between points  613  and  615 . 
         [0093]    In effect, radiation source  602  may be positioned in a well formed by the bottom  605  of heat sink  604  and the reflective cup formed by reflective surface  614 . Reflective surface may direct radiation emitted from the sides of radiation source  602  into optic device  608 . Some of the radiation reflected by reflective surface  614  may be transmitted into optic device  608  and may impinge on down conversion material  610 . Some of the radiation reflected by reflective surface  614  may be transmitted into optic device  608  and may leave optic device  608  through walls  620 ,  622  without impinging upon down conversion material  610 . Some of the radiation reflected by reflective surface  614  may be directed toward lens  640  without impinging on down conversion material  610 . 
         [0094]    In this embodiment of the invention, optic device  608  does not have an aperture in its end  618 . End  618  of optic device  608  may be placed on a top surface  603  of radiation source  602 . A sealant (not shown) may be placed in spaces  642 ,  644  between radiation source  602  and reflective surface  614  and in space  646  between radiation source  602  and end  618  of optic  608 . The sealant may have the same characteristics and may be used for the same purposes as described in connection with other embodiments of this invention. 
         [0095]    A method of manufacture will now be described for manufacturing the apparatus illustrated in  FIG. 13 .  FIG. 16  illustrates an exemplary embodiment of the method that may be used to manufacture the embodiment of the invention described in connection with  FIG. 13 . 
         [0096]    For this method of manufacturing a light emitting apparatus, there is a radiation source for emitting short wavelength radiation, a down conversion material that receives at least some short wavelength radiation emitted by the radiation source, an optic device configured to extract radiation back transferred from the down conversion material and/or radiation emitted from the short wavelength radiation source. There is also a first reflective cup and a second reflective cup. The second reflective cup is adjacent the first reflective cup and forms a well. 
         [0097]    As shown in Block  900 , the down conversion material is placed on a first portion of the optic device. As shown in Block  902 , a first surface of the radiation source may be placed on a first surface of the well. After this step is performed, the radiation source may be partially surrounded by the reflective cup forming the well. A first sealant may then be placed between at least a second surface of the radiation source and a second surface of the well, as shown in Block  904 . A second sealant may then be placed on a least a third surface of the radiation source, as shown in Block  906 . The same kind of material, or different kinds of materials, may be used for the first and second sealants. As shown in Block  908 , the optic device may then be placed within the first reflective cup so that the optic device is partially surrounded by the first reflective cup and in contact with the second sealant. A lens may then be placed adjacent the down conversion material, as shown in Block  910 . 
         [0098]    Another embodiment of the invention is illustrated in  FIGS. 17 and 18 .  FIG. 17  is a partial cross-section view of an alternative embodiment of an optic device that may be mounted over a radiation source and onto a reflector.  FIG. 17  shows optic device  1008  and down conversion material  1010  on an end  1016  of optic device  1008 .  FIG. 17  shows aperture  1020  in end  1018  of optic device  1008 . Although aperture  1020  is illustrated as having a curved shape, aperture  1020  may have another shape that may more closely approximate a shape of a radiation source. For example, aperture  1020  may have a trapezoidal shape.  FIG. 17  also illustrates a radiation source  1032  mounted on a heat sink  1034  having a reflective surface  1036  forming a reflective cup. The dimensions and characteristics of the optic device  1008 , the aperture  1020 , the down conversion material  1010 , the radiation source  1032 , the heat sink  1034  and the reflective surface  1036  may be the same as the dimensions and characteristics described in this application with respect to other embodiments of the invention. Radiation source  1032  has a height  1033 . The optic device may also be mounted over the radiation source  1032  and onto the heat sink in the same way as has been described with respect to other embodiments of the invention.  FIG. 18  illustrates optic device  1008  after it has been mounted over radiation source  1032  and onto heat sink  1034 . 
         [0099]    Referring to  FIGS. 17 and 18 , optic device  1008  may have side walls  1040  and  1042  between end  1016  and end  1018 . A first portion of the side walls  1040 ,  1042  may be substantially light transmissive and a second portion of the side walls  1040 ,  1042  may not be substantially light transmissive. A reflective material  1046 A may be applied to a portion of wall  1040  and a reflective material  1046 B may be applied to a portion of wall  1042 . Reflective materials  1046 A and  1046 B may be a highly reflective paint. In an exemplary embodiment, the paint may be made of barium-sulfate-based paint and may exhibit about 97% reflectivity. In an alternative embodiment, a vaporized aluminum coating, or a wavelength selective coating may be used instead of paint. 
         [0100]    As illustrated in  FIG. 18 , short wavelength radiation may be emitted not only from the top  1050  of radiation source  1032 , short wavelength radiation may also be emitted from the sides  1052  and  1054  of radiation source  1032 . Arrows  1056  and  1058  indicate exemplary short wavelength radiation rays being emitted from sides  1052  and  1054 , respectively, of short wavelength radiation source  1032 . It will be understood that short wavelength radiation rays in addition to exemplary radiation rays  1056  and  1058  may also be emitted from sides  1052  and  1054 . In the absence of reflective materials  1046 A and  1046 B, radiation rays from the sides  1052  and  1054  may be extracted through walls  1040  and  1042  of optic device  1008  and reflect off of reflective surfaces  1036 . Some of the radiation reflected from reflective surfaces  1036  may be directed so that they impinge on down conversion material  1010 . Other radiation reflected from reflective surfaces  1036  may not be directed. Instead, for example, some reflected radiation may be directed toward and through spaces  1060  and  1062  between down conversion material  1010  and reflective surfaces  1036 . Any radiation that is reflected toward and through spaces  1060  and  1062  will not be converted into white light by down conversion material  1010 . 
         [0101]    When reflective material  1046  is placed on the bottom portion of optic device  1008 , radiation emitted from sides  1052  and  1054  of radiation source  1032  may be directed toward, and impinge upon, down conversion material by reflective material  1046 .  FIG. 18  shows exemplary radiation rays  1070  and  1072  that may be reflected by reflective materials  1046 A,  1046 B when exemplary radiation rays  1056  and  1058  impinge on reflective materials  1046 A,  1046 B. It will be understood that short wavelength radiation rays, in addition to exemplary reflected radiation rays  1070  and  1072 , may be emitted from sides  1052  and  1054  and may be reflected by reflective materials  1046 A,  1046 B toward down conversion material  1010 . 
         [0102]    It will be understood that a thickness of reflective materials  1046 A,  1046 B has been exaggerated for purposes of illustration. In an exemplary embodiment, the thickness of reflective materials  1046 A,  1046 B may be much thinner relative to the other elements illustrated in  FIGS. 17 and 18 . In an exemplary embodiment, as illustrated in  FIGS. 17 and 18 , reflective materials  1046 A,  1046 B may be disposed along the outside of walls  1040  and  1042 , respectively. In an alternative embodiment, reflective materials  1046 A,  1046 B may be embedded within walls  1040  and  1042 , respectively. In another alternative embodiment, reflective materials  1046 A,  1046 B may be disposed along an inside surface of walls  1040  and  1042 , respectively. 
         [0103]    Referring to  FIGS. 17 and 18 , a length  1047  of reflective material  1046 A,  1046 B may be up to 90% of the length of walls  1040  and  1042 , respectively. As shown in  FIG. 18 , an exemplary embodiment of reflective materials  1046 A,  1046 B may extend from a point that is adjacent the bottom  1051  of radiation source  1032  to respective end points  1049 A,  1049 B of reflective materials  1046 A,  1046 B that are beyond the top  1050  of radiation source  1032  and below end  1016  of optic device  1008 . In an alternative embodiment, the length  1047  of reflective material  1046  may result in end points  1049 A,  1049 B of one or both of reflective materials  1046 A,  1046 B being equal to, beyond, or under the height  1033  of radiation source  1032  so that different amount of radiation emitted from sides  1052  and  1054  hits the down conversion material  1010  depending on the length  1047 . That is, lengths of reflective materials  1046 A and  1046 B may be the same or they may be different and the respective lengths of reflective materials  1046 A and  1046 B may be symmetric or not symmetric. 
         [0104]    In this embodiment, the first portion of walls  1040 ,  1042  between end points  1049 A,  1049 B of reflective materials  1046 A,  1046 B and end  1016  of optic device  1008  may be substantially light transmissive. Because of the presence of reflective materials  1046 A,  1046 B, the second portion of walls  1040 ,  1042  between the bottom  1051  of radiation source  1032  and end points  1049 A,  1049 B may not be substantially light transmissive. Instead, the second portion of walls  1040 ,  1042  may be substantially reflective. 
         [0105]    Another advantage of using reflective materials  1046 A,  1046 B may be a reduction of a cost to manufacture an optic device such as optic device  1008 . If walls  1040 ,  1042  of optic device  1008  are substantially light transmissive over their entire length, the walls  1040 ,  1042  may have to be highly polished along their entire length in order to use principles of TIR. When reflective materials  1046 A,  1046 B are applied to the bottom portion of the optic device, the cost of manufacturing optic device may be reduced because it may not be necessary to highly polish reflective walls  1040  and  1042  along their entire length. Instead, it may be necessary to highly polish only those portions of reflective walls  1040  and  1042  that do have reflective material  1046 A,  1046 B. Referring to  FIG. 18 , when reflective materials  1046 A,  1046 B are disposed on or in reflective walls  1040  and  1042 , it may be necessary to highly polish reflective walls  1040  and  1042  only from end points  1049 A,  1049 B of reflective materials  1046 A,  1046 B to end  1016  of optic device  1008 . The remainder of walls  1040  and  1042  that coincide with length  1047  of reflective materials  1046 A,  1046 B may have surfaces that are more rough than the surfaces between end points  1049 A,  1049 B and end  1016  of optic device  1008 . Reducing the amount of polishing that may be performed on optic device  1008  may substantially reduce the cost of manufacturing optic device  1008 . 
         [0106]    Still another embodiment of the invention is illustrated in  FIGS. 19 and 20 .  FIG. 19  is a partial cross-section view of this embodiment of the invention.  FIG. 20  is another partial cross-section view of this embodiment illustrating an optic device being coupled to the other elements of the embodiment. The embodiment illustrated in  FIGS. 19 and 20  is substantially the same as the embodiment that is illustrated in  FIGS. 17 and 18 . 
         [0107]    The embodiment illustrated in  FIGS. 19 and 20  may have an alternative embodiment of a heat sink  1034 . In  FIGS. 19 and 20 , an alternative form of an aperture  1022  is illustrated. As explained in an earlier part of this application, alternative shapes of the aperture may be used. In this embodiment, heat sink  1034  has a raised portion  1035 . The height  1085  of raised portion  1035  may be up to 50% of the height  1087  of heat sink  1034 . Radiation source  1032  may be disposed on top of raised portion  1035 .  FIG. 20  illustrates exemplary radiation rays  1056 ,  1058  emitted from the sides of radiation source  1032  and being reflected toward down conversion material  1010  by reflective materials  1046 A,  1046 B as exemplary reflected radiation rays  1070 ,  1072 . As explained previously, more or fewer radiation rays may be emitted from the sides of radiation source  1032  and reflected toward down conversion material  1010  by reflective materials  1046 A,  1046 B. 
         [0108]    In the embodiment illustrated in  FIG. 20 , the aperture may cover the entire radiation source  1032  and substantially all of the raised portion  1035  of heat sink  1034 . In addition, sides  1080 ,  1082  of raised portion  1035  may have reflective surfaces on them. The aperture may also cover reflective surfaces  1080 ,  1082 . In other words, radiation source  1032  may be fully immersed within the aperture and the raised portion  1035  may be at least partially immersed in the aperture. 
         [0109]    An advantage of the embodiment illustrated in  FIG. 20  is that it may reduce the amount of radiation that may be reflected back toward radiation source  1034  because there may be a greater volume of space between the sides of radiation source  1034  and the reflective materials  1046 A,  1046 B. 
         [0110]      FIGS. 21 and 22  illustrate exemplary and alternative embodiments of methods that may be used to manufacture the embodiments illustrated in  FIGS. 17-20 . The method illustrated in  FIG. 21  is the same method that has been illustrated in  FIG. 14  with the inclusion of an additional step shown in Block  701 . The step shown in Block  701  involves placing reflective material along, or embedded in, one or more walls of the optic device. As illustrated, the step in Block  701  may be performed after the step shown in Block  700  and before the step shown in Block  702 . However, it will be understood that the steps illustrated in Blocks  700 ,  701 , and  702  may be performed in any order. 
         [0111]    The method illustrated in  FIG. 22  is the same method that has been illustrated in  FIG. 15  with the inclusion of an additional step shown on Block  801 . The step shown in Block  801  involves placing reflective material along, or embedded in, one or more walls of the optic device. As illustrated, the step in Block  801  may be performed after the step shown in Block  800  and before the step shown in Block  802 . However, it will be understood that the steps illustrated in Blocks  800 ,  801 , and  802  may be performed in any order. 
         [0112]    In all of the methods of manufacture described in this application, it will be understood that the short wavelength radiation source used in each of the various manufacturing processes does not have a dome. In order to obtain a short wavelength radiation source without a dome, a user may purchase it without the dome or may purchase it with a dome and then remove the dome as an additional step in the manufacturing process. 
         [0113]    Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.