Abstract:
An optical device for coupling the luminous output of a light-emitting diode (LED) to a predominantly spherical pattern comprises a transfer section that receives the LED&#39;s light within it and an ejector positioned adjacent the transfer section to receive light from the transfer section and spread the light generally spherically. A base of the transfer section is optically aligned and/or coupled to the LED so that the LED&#39;s light enters the transfer section. The transfer section can comprises a compound elliptic concentrator operating via total internal reflection. The ejector section can have a variety of shapes, and can have diffusive features on its surface as well, including a phosphor coating. The transfer section can in some implementations be polygonal, V-grooved, faceted and other configurations.

Description:
PRIORITY CLAIM 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 11/970,462, filed Jan. 1, 2008 to Chaves et al., entitled OPTICAL DEVICE FOR LED-BASED LAMP, which is a Divisional application of U.S. patent application Ser. No. 10/816,228, filed Mar. 31, 2004, to Chaves et al., entitled OPTICAL DEVICE FOR LED BASED LAMP, now U.S. Pat. No. 7,329,029, which is a continuation-in-part of:
       U.S. patent application Ser. No. 10/814,598, filed Mar. 30, 2004, to Chaves et al., entitled OPTICAL DEVICE FOR LED-BASED LAMP, which claims the benefit under 35 U.S.C. §119(e) of both provisional Application No. 60/470,691, filed May 13, 2003, to Minano, titled OPTICAL DEVICE FOR LED-BASED LIGHT-BULB SUBSTITUTE, and provisional Application No. 60/520,951, filed Nov. 17, 2003, to Falicoff et al., titled COLOR-MIXING COLLIMATOR, each of provisional Application Nos. 60/470,691 and 60/520,951 are incorporated herein by reference in their entirety; and   U.S. patent application Ser. No. 10/461,557, filed Jun. 12, 2003, to Minano, et al., entitled OPTICAL DEVICE FOR LED-BASED LIGHT-BULB SUBSTITUTE, now U.S. Pat. No. 7,021,797, which claims the benefit under 35 U.S.C. §119(e) of provisional Application No. 60/470,691, filed May 13, 2003, to Minano, titled OPTICAL DEVICE FOR LED-BASED LIGHT-BULB SUBSTITUTE, each of U.S. patent application Ser. Nos. 11/970,462, 10/816,228, 10/814,598 and 10/461,557, and provisional Application No. 60/470,691 are incorporated herein by reference in their entirety;       
 
         [0004]    this application is a continuation-in-part of U.S. patent application Ser. No. 11/890,601, filed Aug. 6, 2007 to Chaves et al., entitled OPTICAL MANIFOLD FOR LIGHT-EMITTING DIODES, incorporated herein by reference in its entirety, which is a Divisional of U.S. patent application Ser. No. 11/115,055, filed Apr. 25, 2005 to Chaves et al., now U.S. Pat. No. 7,286,296, entitled OPTICAL MANIFOLD FOR LIGHT-EMITTING DIODES, incorporated herein by reference in its entirety, which claims the benefit under 35 U.S.C. §119(e) of: provisional Application No. 60/658,713, filed Mar. 3, 2005, entitled OPTICAL MANIFOLDS FOR LIGHT-EMITTING DIODES, incorporated herein by reference in its entirety; provisional Application No. 60/614,565, filed Sep. 29, 2004, entitled OPTICAL MANIFOLDS FOR LIGHT-EMITTING DIODES, incorporated herein by reference in their entirety; provisional Application No. 60/612,558, filed Sep. 22, 2004, entitled OPTICAL MANIFOLDS FOR LIGHT-EMITTING DIODES, incorporated herein by reference in their entirety; and provisional Application No. 60/564,847, filed Apr. 23, 2004, entitled OPTICAL MANIFOLDS FOR LIGHT-EMITTING DIODES, incorporated herein by reference in their entirety; 
         [0005]    this application claims the benefit under 35 U.S.C. §119(e) of U.S. provisional Applications 61/066,528, filed Feb. 21, 2008, titled SPHERICALLY EMITTING REMOTE PHOSPHOR, which is incorporated herein by reference in its entirety; and 
         [0006]    this application claims the benefit under 35 U.S.C. §119(e) of U.S. provisional Applications 61/125,844, filed Apr. 29, 2008, titled SPHERICALLY EMITTING REMOTE PHOSPHOR, which is incorporated herein by reference in its entirety. 
         [0007]    The present embodiments may be further understood and/or can also be utilized with the embodiments described in U.S. patent application Ser. No. 10/461,557, filed Jun. 12, 2003, to Minano et al., titled OPTICAL DEVICE FOR LED-BASED LIGHT-BULB SUBSTITUTE, which is incorporated herein by reference in its entirety; U.S. provisional Application No. 61/066,528, filed Feb. 21, 2008, titled SPHERICALLY EMITTING REMOTE PHOSPHOR; and U.S. provisional Application No. 61/125,844, filed Apr. 29, 2008, titled SPHERICALLY EMITTING REMOTE PHOSPHOR, both of which are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0008]    The present invention relates to light-emitting diodes (LEDs), particularly optical means for producing various far-field light intensity distributions for LEDs. 
         [0009]    Conventional incandescent lamps of less than 100 lumens output can be matched by the latest white LEDs, albeit at a higher price. At this low end of the lumen range, the majority of incandescent applications are battery-powered. It is desirable to have an LED suitable for direct installation in the place of a burnt-out flashlight bulb. 
         [0010]    LED&#39;s can offer superior luminous efficacy over the conventional incandescent lamps used in battery-operated flashlights. Moreover, LEDs are far more tolerant of shock, vibration, and crush-stress. Although they currently cost more to produce than the incandescents, their lifetimes are ten thousand times longer. For the sake of efficacy flashlight bulbs are run hot so they typically last only a few hours until filament failure. Also, the prices of LEDs continue to fall, along with those of the control-electronics to handle variations in battery voltage. 
         [0011]    Indeed, LED flashlights are commercially available already, but their optics have to be adapted to the geometry of light-emitting diodes, which only emit into a hemisphere. Conventional LED lamps are unsuitable for direct installation into conventional flashlights, both electrically and optically. LED lamps are electrically unsuitable because they are current-driven devices, whereas batteries are voltage sources. Typical variations in the voltage of fresh batteries are enough to exceed an LED&#39;s tolerable operating-voltage range. This causes such high currents that the Ohmic heating within the die exceeds the ability of thermal conduction to remove it, causing a runaway temperature-rise that destroys the die. Therefore, a current-control device must accompany the lamp. 
         [0012]    Conventional LED lamps are optically unsuitable for direct installation into the parabolic reflectors of flashlights. This is because their bullet-lens configuration forms a narrow beam that would completely miss a nearby parabola. Using instead a hemispherically emitting non-directional dome, centered on the luminous die, gives the maximum spread commercially available, a Lambertian pattern, with a sin 2  θ dependence of encircled flux on angle θ from the lamp axis. Since θ for a typical parabolic flashlight reflector extends from 45° to 135°, an LED with a hemispheric pattern is mismatched because it&#39;s emission falls to zero at only θ=90°. This would result in a beam that was brightest on the outside and completely dark halfway in. Worse yet, even this inferior beam pattern from a hemispheric LED would require that it be held up at the parabola&#39;s focal point, several millimeters above the socket wherein a conventional incandescent bulb is installed. 
         [0013]    Another type of battery-powered lamp utilizes cylindrical fluorescent lamps. Although LEDs do not yet offer better luminous efficacy, fluorescent lamps nonetheless are relatively fragile and require unsafely high voltages. A low-voltage, cylindrical LED-based lamp could advantageously provide the same luminous output as a fluorescent lamp. 
         [0014]    Addressing the needs above, U.S. patent application Ser. No. 10/461,557, OPTICAL DEVICE FOR LED-BASED LIGHT-BULB SUBSTITUTE, filed Jun. 12, 2003, which is hereby incorporated by reference in its entirety, discloses such LED-based lamps with which current fluorescent and incandescent bulb flashlights can be retrofitted. It often desirable, however, for LED lamps such as those described in U.S. patent application Ser. No. 10/461,557 to have other far-field intensity distributions of interest. Also, U.S. patent application Ser. No. 10/461,557 touched on the function of color mixing, to make the different wavelengths of chips 23, 24, and 25 of FIG. 2 of U.S. patent application Ser. No. 10/461,557 have the same relative strengths throughout the light coming out of ejector section  12 . This assures that viewers will see only the intended metameric hue and not any colors of the individual chips. Previously, rectangular mixing rods have been used to transform the round focal spot of an ellipsoidal lamp into a uniformly illuminated rectangle, typically in cinema projectors. Generally, polygonal mixing rods worked best with an even number of sides, particularly four and six. With color mixing for LEDs, however, such rods are inefficient because half of an LED&#39;s Lambertian emission will escape from the base of the rod. 
         [0015]    There is thus a need in the art for effective and optically suitable LED lamps with various far-field intensity distributions and have proper shaping of their transfer sections enabling polygonal cross-sections to be used. 
       SUMMARY OF THE INVENTION 
       [0016]    The present invention advantageously addresses the needs above as well as other needs by providing an optical device for LED-based lamps with configurations for various far-field intensity distributions. 
         [0017]    In some embodiments, an optical device for use in distributing radiant emission of a light emitter is provided. The optical device can comprise a lower transfer section, and an upper ejector section situated upon the lower transfer section. The lower transfer section is operable for placement upon the light emitter and further operable to transfer the radiant emission to said upper ejector section. The upper ejector section can be shaped such that the emission is redistributed externally into a substantial solid angle. In some preferred embodiments, the transfer section is a solid of revolution having a profile in the shape of an equiangular spiral displaced laterally from an axis of said solid of revolution so as to place a center of the equiangular spiral on an opposite side of the axis therefrom. 
         [0018]    In some embodiments, an optical device for distributing the radiant emission of a light emitter is provided. The optical device can comprise a lower transfer section, and an upper ejector section situated upon the lower transfer section. The lower transfer section can be operable for placement upon the light emitter and operable to transfer the radiant emission to the upper ejector section. The upper ejector section can be shaped such that the emission is redistributed externally into a substantial solid angle. The ejector section can further comprise lower and connecting upper portions. 
         [0019]    Some preferred embodiments provide an optical device for distributing radiant emissions of a light emitter. The optical device can comprise a transfer section, and an ejector section situated upon the transfer section. The transfer section is operable for placement adjacent with a light emitter and operable to transfer radiant emission from the light emitter to the ejector section. The ejector section is shaped such that the emission is redistributed externally into a substantial solid angle. In some embodiments, the ejector section has an upper surface with a profile of an equiangular spiral with a center at an upper edge of said transfer section. Some embodiments further provide for the ejector section to include a surface comprised of a radial array of V-grooves. Still further embodiments provide that a surface of said transfer section is comprised of an array of V-grooves. Further, the transfer section can be a polygonal, can be faceted and/or have other configurations. 
         [0020]    In one embodiment, the invention can be characterized as an optical device for distributing radiant emission of a light emitter comprising a lower transfer section and an upper ejector section situated upon the lower transfer section. The lower transfer section is operable for placement upon the light emitter and operable to transfer the radiant emission to the upper ejector section. The upper ejector section is shaped such that the light within it is redistributed out an external surface of the upper ejector section into a solid angle substantially greater than a hemisphere, and approximating that of an incandescent flashlight bulb. The ejector section is positioned at the same height as the glowing filament of the light bulb it replaces. It is easier to optically move this emission point, using the transfer section, than to put the LED itself at such a height, which would make heat transfer difficult, among other problems that the present invention advantageously addresses. 
         [0021]    In another embodiment, this invention comprises a multiplicity of such transfer sections joined end-to-end, with two LED sources at opposite ends of this line-up. These transfer sections have slightly roughened surfaces to promote diffuse emission, so that the entire device acts as a cylindrical emitter, and approximating the luminous characteristics of a fluorescent flashlight bulb. 
         [0022]    Other embodiments comprise a compound elliptical concentrator transfer section and an ejector section with a photostimulative layer, for example a coating of a photostimulative phosphor, on its external surface. The light source for the transfer section can comprise an array of blue LEDs, at a wavelength that stimulates the phosphor to emit yellow light, which combines with the blue light to produce a white output. The ejector section can be spherical, for spherical emission, conical, for partially spherical emission, or other relevant configurations. A thickness of the phosphor coating can be selected in accordance with a color temperature of the output white light. 
         [0023]    Other embodiments provide optical devices that distribute radiant emissions of light. These embodiments comprise a lower transfer section; and an upper ejector section situated upon the lower transfer section, said lower transfer section operable for placement upon a light emitter and operable to transfer through total internal reflection radiant emission to said upper ejector section, said upper ejector section shaped such that the emission is redistributed externally into a substantial solid angle. 
         [0024]    Still other embodiments provide optical device in distributing radiant emissions, where the optical device comprises a lower transfer section comprising an expanding portion and an contracting section; and an upper ejector section optically cooperated with the expanding portion of the lower transfer section, said lower transfer section operable for placement upon a light emitter and operable to transfer radiant emission to said upper ejector section, said upper ejector section comprising a photostimulative layer extending about the ejector section, where the photostimulative layer comprises a photostimulative component. 
         [0025]    Some embodiments provide optical devices for use in distributing radiant emission. At least some of these devices comprise a transfer section optically configured to receive radiant emission; and an ejector section situated adjacent and optically coupled with the transfer section, said transfer section configured to transfer the radiant emission to said ejector section, said ejector section comprising a sphere. 
         [0026]    Still other embodiments provide optical devices for use in distributing radiant emission that comprise a transfer section optically configured to receive radiant emission; and an ejector section situated adjacent and optically coupled with the transfer section, said transfer section configured to transfer the radiant emission to said ejector section, said ejector section comprising a cone extending from an interface of the transfer section and the ejector section. 
         [0027]    A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description of the invention and accompanying drawings, which set forth an illustrative embodiment in which the principles of the invention are utilized. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
           [0029]      FIGS. 1   a  through  38   b  are cross sectional views of LED lamps having various configurations of transfer and ejector lens sections (hereafter called virtual filaments) according to the present invention, with each cross sectional view accompanied, respectively, by the individual configuration&#39;s far field pattern. 
           [0030]      FIG. 39  is a perspective view of a linear array of V-grooves. 
           [0031]      FIG. 40  is a diagram of the angles reflected by a linear V-groove array. 
           [0032]      FIG. 41  is a perspective view of a radial array of V-grooves. 
           [0033]      FIG. 42   a  is a perspective view of the configuration of  FIG. 37   a  according to the present invention. 
           [0034]      FIG. 42   b  is a perspective view showing the vector triad on the configuration of  FIG. 42   a  according to the present invention. 
           [0035]      FIG. 43  is a perspective view of the construction of a V-groove on a curved surface according to the present invention. 
           [0036]      FIG. 44  is a perspective view of a virtual filament with a curved radial V-groove array on top according to the present invention. 
           [0037]      FIG. 45  is a perspective view of a virtual filament with a linear V-groove array on its transfer section according to the present invention. 
           [0038]      FIG. 46  is a perspective view of a six-sided barrel-shaped virtual filament according to the present invention. 
           [0039]      FIGS. 47   a  and  47   b  is a side and perspective view, respectively, of a sixteen-sided virtual filament according to the present invention. 
           [0040]      FIG. 47   c - e  show blue (465 nanometers), green (520 nanometers) and red (620 nanometers) emission patterns, respectively, of the embodiments of  FIGS. 47   a - b , at the various cylindrical azimuths. 
           [0041]      FIGS. 48   a  and  48   b  is a side and perspective view, respectively, of another sixteen-sided virtual filament, with a slotted ejector section according to the present invention. 
           [0042]      FIG. 48   c  depicts a 300° emission pattern produced by the collar of  FIG. 48   a.    
           [0043]      FIGS. 49   a  and  49   b  is a side and perspective view, respectively, of a faceted virtual filament that mixes the disparate wavelengths of a tricolor LED according to the present invention. 
           [0044]      FIG. 50  depicts a side view of the faceted virtual filament of  FIGS. 49   a  and  49   b  and a rectangularly cut collimating totally internally reflecting (TIR) lens focused on its output section. 
           [0045]      FIGS. 51-53  depicts perspective views of the faceted virtual filament and the rectangularly cut collimating TIR lens of  FIG. 50  as seen from three different angles. 
           [0046]      FIG. 54  shows a perspective view of a plurality of the faceted virtual filament and collimating TIR lenses of  FIG. 50  cooperated in a row. 
           [0047]      FIG. 55  shows a luminaire for a row shown in  FIG. 54 . 
           [0048]      FIG. 56  shows an alternative virtual filament cooperated with a TIR lens. 
           [0049]      FIG. 57A  show a virtual filament light source with a phosphor ball. 
           [0050]      FIG. 57B  shows a partially cut-away view of the virtual filament light source with the phosphor ball of  FIG. 57A . 
           [0051]      FIG. 58  shows a simplified block diagram depiction of a geometry of a phosphor ball. 
           [0052]      FIG. 59  is a graphical representation of the performance improvement due to the use of a phosphor ball, such as a phosphor ball of  FIGS. 57A  and/or  58 B. 
           [0053]      FIG. 60A  is a perspective view of a virtual filament light source. 
           [0054]      FIG. 60B  is an exploded view of the virtual filament light source of  FIG. 60A . 
           [0055]      FIG. 61  is a graph of far-field intensity provided through the virtual filament light source of  FIG. 60A . 
       
    
    
       [0056]    Corresponding reference characters indicate corresponding components throughout the several views of the drawings, especially the explicit label in  FIG. 1   a  of LED package  20  being implied throughout  FIG. 2   a  to  FIG. 38   a.    
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0057]    The following description of the presently contemplated best mode of practicing the invention is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be determined with reference to the claims. 
         [0058]    The present embodiments provide light sources with predefined far-field intensities. The present embodiments can be utilized in numerous applications. For example, in some applications, the embodiments can be utilized to replace and/or substitute for other types of light sources, such as compact light sources, incandescent light sources, florescent light sources and other light sources. As a further example, the present embodiments can be utilized in replacing incandescent light sources in flight lights and other devices using incandescent light sources. 
         [0059]    The present embodiments can also be utilized with the embodiments described in co-pending U.S. Provisional Patent application No. 60/520,951, filed Nov. 17, 2003, incorporated herein by reference in its entirety. The surface faceting configuration presented herein in  FIG. 49A  and  FIG. 49B , and in co-pending U.S. Provisional Patent Application No. 60/520,951, filed Nov. 17, 2003, can be employed in variations of all of the non-faceted embodiments shown herein in order to achieve the color mixing and other benefits thereof. 
         [0060]    The present embodiments can further be utilized with the embodiments of and in the applications described in U.S. Provisional Patent Application No. 60/470,691, filed May 13, 2003, and U.S. patent application Ser. No. 10/461,557, filed Jun. 12, 2003, incorporated herein by reference in their entirety. For example, the present embodiments can be utilized in the light sources described in U.S. Provisional Patent Application No. 60/470,691, filed May 13, 2003, and U.S. patent application Ser. No. 10/461,557, filed Jun. 12, 2003. 
         [0061]    Still further, LED white-light sources can be utilized, according to some embodiments, with similar spherical type of emission as conventional light bulbs. Some of these embodiments comprise a remote phosphor (e.g., with blue LEDs separated from the yellow phosphor they stimulate), and some embodiments further employ highly efficient blue-delivery optics as described below. 
         [0062]      FIGS. 1   a  through  38   b  are cross sectional views of LED lamps having various configurations of transfer and ejector lens sections (hereafter called virtual filaments) according to some present embodiments, with each cross sectional view accompanied, respectively, by the individual configuration&#39;s far field pattern. 
         [0063]    Only  FIG. 1   b  has the labels that are implicit in all the output patterns of the preferred embodiments in the figures that follow: semicircular polar plot  2700  shows normalized far-field distribution  2701  on semi-circular angular scale  2702 , with off-axis angle, with zero denoting the on-axis direction, and 180° the opposite direction, totally backward. This is possible for those preferred embodiments having some sideways extension so that 180° is unimpeded by the source. 
         [0064]    In  FIG. 1   a  only, the light source is designated as LED package  20  with LED chips  22 ,  23 , and  24 , but the same package-outline is depicted without labels in all subsequent figures of virtual filaments. This LED package represents but one possible way for the present invention to utilize multiple light emitters. Such multiple chips can have identical or different wavelengths. For example, the different wavelengths can be red, green, and blue wavelengths that span a chromaticity gamut for human color vision, or amber, red, and infrared wavelengths for night-vision devices, or other combinations of different wavelengths. 
         [0065]    Similarly in  FIG. 1   a  only, the position of the focus of ellipse segment  271  is shown by star  271   f . In all subsequent figures, the focus of the profile of the transfer section is also near the bottom point of the same curve on an opposite side of a central axis. 
         [0066]      FIG. 1   a  shows virtual filament  270  comprising compound elliptical concentrator (hereinafter CEC) transfer section  271 , and an ejector section comprising outward slanting lower cone  272  and inward slanting upper cone  273 .  FIG. 1   b  shows that the far-field distribution of this preferred embodiment peaks in the forward direction with a ±20° extent. 
         [0067]      FIG. 2   a  shows virtual filament  280  comprising CEC transfer section  281 , multiple stacked toroids  282 , and ejector section  283 , shaped as an equiangular spiral with origin at point  283   f .  FIG. 2   b  shows that the maximum far-field intensity of this preferred embodiment lies on angles from about 50° to 60° off-axis, a so-called bat-wing distribution. 
         [0068]      FIG. 3   a  shows virtual filament  290 , comprising CEC transfer section  291 , cones  292  and  293 , and equiangular spirals  294  and  295 . Predominantly horizontal equiangular spiral  294  has its center at central point  294   f . Equiangular spiral profile  295  has oppositely situated center  295   f .  FIG. 3   b  shows the far-field distribution of this preferred embodiment, peaking at 40° off-axis and mostly confined to the range of 10-70°, also with a secondary lobe from 150-170°. 
         [0069]      FIG. 4   a  shows virtual filament  300  comprising CEC section  301 , flat  302 , sideways equiangular spiral  303  with center at point  303   f , and top equiangular spiral  304  with center at point  304   f .  FIG. 4   b  shows a subtle tuning of the far-field resulting from the noticeable profile-modification, as shown in  FIG. 4   a , of the preferred embodiment shown in  FIG. 3   a .  FIG. 4   b  shows that the far-field distribution of this preferred embodiment has a primary maximum on a main lobe between 40° and 60° off-axis, and a secondary maximum on a secondary rear lobe extending between 160° and 170°, nearly backwards. The next preferred embodiment is a modification of this one. 
         [0070]      FIG. 5   a  shows virtual filament  310  with CEC transfer section  311 , planar annulus  312 , equiangular spiral  313  with center at axial point  313   f , and upper equiangular spiral  314  with center at opposite point  314   f . In addition to elements in correspondence with those of  FIG. 4   a  are inward slanting steep cone  315 , upward slanting shallow cone  316 , and upper flat circle  317 . The normalized far-field pattern of this preferred embodiment differs significantly from the previous, as shown in  FIG. 5   b , with a fluctuating forward lobe and a half-strength rear lobe. 
         [0071]    Delving further on the theme of minor modifications,  FIG. 6   a  shows virtual filament  320  comprising CEC transfer section  321 , planar annulus  322 , equiangular spiral  323  with axial position of its center as shown by star  323   f , upper equiangular spiral  324  with center at opposite point  324   f , and a new element—central upper equiangular spiral  327 , also with center at  324   f . In similarity to  FIG. 5   a , virtual filament  320  also comprises inwardly slanting steep cone  325  and upward shallow cone  326 . The normalized far-field pattern of the preferred embodiment of  FIG. 6   a  is shown by  FIG. 6   b  to be mainly between 30° and 50° off axis, with a rear lobe from 120° to 170°, with reduced forward emission as compared to  FIG. 5   b.    
         [0072]      FIG. 7   a  depicts a preferred embodiment that is the result of small modifications of virtual filament  320  of  FIG. 6   a .  FIG. 7   a  is a cross-section of virtual filament  330 , comprising CEC transfer section  331 , slanting conical section  332 , horizontal equiangular spiral  333  with center at axial point  333   f , steep conic edge  335 , vertical equiangular spiral  334  with oppositely situated center  334   f , and central cone  336 .  FIG. 7   b  shows its far-field intensity concentrated in a forward lobe within ±20° of the axis, with a strong rearward lobe peaking at 150°. 
         [0073]    Continuing the theme of component modifications,  FIG. 8   a  depicts virtual filament  340  comprising CEC transfer section  341 , planar annulus  342 , inwardly slanting steep cone  335 , downward slanting shallow cone  346 , outer edge  348 , horizontal equiangular spiral  343  with center at off-axis point  343   f , vertical equiangular spiral  344  with center at opposite point  344   f , and upper equiangular spiral  347 , also with center at opposite point  344   f .  FIG. 8   b  shows that its far field pattern has a collimated anti-axial beam and a broader ±30° forward beam. 
         [0074]      FIG. 9   a  depicts virtual filament  350  comprising CEC transfer section  351 , dual conical flanges  352 , and upper conic indentation  353 .  FIG. 9   b  shows that its far-field pattern has strong forward and rear lobs, but some side emission. 
         [0075]      FIG. 10   a  depicts virtual filament  360  comprising CEC transfer section  361 , conical flange  362 , upper equiangular spiral indentation  363  with center at proximal point  363   f , and cylindrical flange  364 .  FIG. 10   b  shows how the rearward emission of  FIG. 9   b  has been eliminated. 
         [0076]      FIG. 11   a  depicts another variation of  FIG. 10   a . Virtual filament  370  comprises CEC transfer section  371 , dual conic flanges  372 , central conic indentation  373 , set into central cylinder  374 . The far field pattern of  FIG. 11   b  shows a forward ±30° main lobe and a small secondary lobe at 125°. 
         [0077]      FIG. 12   a  depicts a variation of component proportions in the preferred embodiment of  FIG. 11   a . Virtual filament  380  comprises CEC transfer section  381 , dual conic flanges  382 , and central conic indentation  383 . The far field intensity pattern of  FIG. 12   b  shows the same overall forward and backward emphasis of  FIG. 9   b , with differing details. 
         [0078]      FIG. 13   a  depicts virtual filament  390  comprising CEC transfer section  391 , spheric section  392 , and central conic indentation  393 . In similarity to spheric ejector section  72  of FIG. 7 of U.S. patent application Ser. No. 10/461,557, both surfaces  392  and  393  are diffusing, in that rays from within and going through them are scattered diffusely into air.  FIG. 13   b  shows a strong forward lobe of ±40° superimposed on a weaker emission that is nearly omnidirectional. 
         [0079]      FIG. 14   a  depicts virtual filament  400  comprising CEC transfer section  401 , steeply slanting cone  402 , outer equiangular spiral  403  with axially located center  403   f , and inner equiangular spiral  404  with center at proximal point  404   f . As shown in  FIG. 14   b , its far field intensity pattern has no rearward energy, and somewhat approximates a Lambertian pattern. 
         [0080]    In a variant of the previous figure,  FIG. 15   a  depicts virtual filament  410  comprising CEC transfer section  411 , cylindrical stack  412  of multiple toroidal sections  412   t , inner equiangular spiral  414  with center at proximal point  414   f , and upper curve  413  tailored to refract rays coming from  414   f  and being reflected at  414  and direct them tangent to  413 .  FIG. 15   b  shows the resultant far-field pattern to be mostly forward, within ±30°. 
         [0081]      FIG. 16   a  depicts virtual filament  420 , comprising CEC transfer section  421 , cylinder  422 , conical indentation  423  in shallower top cone  424 .  FIG. 16   b  shows its far-field pattern is mostly between 10° and 20° off axis. 
         [0082]      FIG. 17   a  depicts virtual filament  430 , comprising CEC transfer section  431 , outer cone  432 , and inner conical indentation  433 . In spite of the small differences from  FIG. 16   a , the far-field pattern of  FIG. 17   b  is considerably different from that of  FIG. 16   b.    
         [0083]      FIG. 18   a  depicts virtual filament  440 , comprising CEC transfer section  441 , outer cone  442 , and inner conical indentation  443 . In spite of the small differences of this preferred embodiment from that of from  FIG. 17   a , the far-field pattern of  FIG. 18   b  is narrower than that of  FIG. 17   b.    
         [0084]      FIG. 19   a  depicts virtual filament  450  comprising CEC transfer section  451 , spline curve  452 , central equiangular spiral  453  with center at proximal point  453   f , and surrounding top conic indentation  454 .  FIG. 19   b  shows its far-field pattern is predominantly forward, with ±20° at the half-power point. 
         [0085]      FIG. 20   a  depicts virtual filament  460  comprising CEC transfer section  461 , spheric section  462  with radius  462   r  that equals 0.38 times the height of section  461 , and central equiangular spiral  463  with center at proximal point  463   f .  FIG. 20   b  shows its far-field pattern to lie between 10° and 60° off axis. 
         [0086]      FIG. 21   a  depicts another similar configuration, virtual filament  470  comprising CEC transfer section  471 , spheric section  472  with radius  472   r  that is 0.7 times the height of section  471 , and central equiangular spiral  473  with center at proximal point  473   f .  FIG. 21   b  shows that the far-field pattern has significantly narrowed from the previous one. 
         [0087]      FIG. 22   a  depicts another similar configuration, virtual filament  480  comprising CEC transfer section  481 , spheric section  482  with radius  482   r  that is 0.8 times the height of section  481 , and central equiangular spiral  483  with center at proximal point  483   f . Spheric section  482  is partially covered with multiple convex toroidal lenslets  482   t .  FIG. 22   b  shows that the far-field pattern undergoes only minor change from the previous one, with narrowing of the central beam compared to that seen in  FIG. 21   b.    
         [0088]      FIG. 23   a  depicts virtual filament  490  comprising CEC transfer section  491 , spheric section  492  with radius  492   r  that is 0.62 times the height of section  491 , section  492  being fully surfaced by multiple toroidal lenslets  492   t , and central equiangular spiral  493  with center at proximal point  493   f .  FIG. 23   b  shows how these lenslets greatly broaden the far-field pattern over that of  FIG. 22   b.    
         [0089]      FIG. 24   a  depicts virtual filament  500  comprising CEC transfer section  501 , spheric section  502  with radius  502   r  that is 0.76 times the height of section  501 , section  502  being surfaced by multiple convex toroidal lenslets  502   t , and central equiangular spiral  503  with center at proximal point  503   f .  FIG. 24   b  shows that the far field pattern is not greatly changed from that of  FIG. 23   b , by section  502  having a somewhat larger radius than that of section  492  of  FIG. 23   a.    
         [0090]      FIG. 25   a  depicts virtual filament  510  comprising CEC transfer section  511 , spheric section  512  with radius  512   r  that is equal to the height of section  511 , section  512  surfaced by multiple convex toroidal lenslets  512   t , and central equiangular spiral  513  with center at proximal point  513   f .  FIG. 25   b  shows that the far field pattern is now considerably changed from that of  FIG. 24   b , due to the larger radius of section  512  than that of section  502  of  FIG. 24   a.    
         [0091]      FIG. 26   a  depicts virtual filament  520  comprising CEC transfer section  521 , lower spline section  522 , central equiangular spiral  523  with center at proximal point  523   f , and outer cylindrical section  524  covered with multiple convex toroidal lenslets  524   t .  FIG. 26   b  shows a very broad pattern that does not vary much until 130° and is only reduced by half at 180°. 
         [0092]      FIG. 27   a  depicts virtual filament  530  comprising CEC transfer section  531 , conical section  532 , central equiangular spiral  533  with center at proximal point  533   f , and cylindrical stack  534  surfaced by multiple convex toroidal lenslets  534   t .  FIG. 27   b  shows that this substitution of a cone for a tailored spline causes the far-field pattern to drop in the near-axis angles, as compared to  FIG. 26   b . In the following FIGURE there are no such lenslets. 
         [0093]      FIG. 28   a  depicts virtual filament  540  comprising CEC transfer section  541 , conic section  542 , central equiangular spiral  543  with center at proximal point  543   f , and outer cylinder  544 .  FIG. 28   b  shows that the far-field pattern of this preferred embodiment is much narrower without the lenslets  534   t  of  FIG. 27   a.    
         [0094]      FIG. 29   a  depicts virtual filament  550  comprising CEC transfer section  551 , shallow upward cone  552 , central equiangular spiral  553  with center at proximal point  553   f , and outer concave spline  554 .  FIG. 29   b  shows its far-field pattern, with substantial axial emission. 
         [0095]      FIG. 30   a  depicts virtual filament  560  comprising CEC transfer section  561 , planar annulus  562 , central equiangular spiral  563  with center at proximal point  563   f , and outer cylinder  564 .  FIG. 30   b  shows its far-field pattern 
         [0096]      FIG. 31   a  depicts virtual filament  570  comprising CEC transfer section  571 , planar annulus  572 , central equiangular spiral  573  with center at proximal point  573   f , and outer conical edge  574 .  FIG. 31   b  shows that far-field emission is predominantly forward. 
         [0097]      FIG. 32   a  depicts virtual filament  580  comprising CEC transfer section  581 , planar annulus  582 , upper equiangular spiral  583  with center at proximal point  583   f , outer cylinder  584  surfaced with concave toroidal lenslets  584   t , and central upper cone  585 .  FIG. 32   b  shows that its far-field pattern is predominantly forward, with full intensity within ±30°. 
         [0098]      FIG. 33   a  depicts virtual filament  590  comprising equiangular-spiral transfer section  591  with center at opposite point  591   f , outward cone  592 , central indentation  593  shaped as a higher-order polynomial, and steep outer cone  594 , and surfaces  595 ,  596 , and  597  forming a slot. Its far-field pattern is shown in  FIG. 33   b , with a sharp cutoff at 150° off-axis and only 2:1 variation from uniform intensity at lesser angles. 
         [0099]      FIG. 34   a  depicts virtual filament  600  comprising equiangular-spiral transfer section  601  with center on opposite point  601   f , protruding cubic spline  602 , and central equiangular spiral  603  with center at proximal point  603   f . Its far field pattern is shown in  FIG. 34   b , and is to be compared with those of the following two preferred embodiments, in which the cubic spline protrudes more. 
         [0100]      FIG. 35   a  depicts virtual filament  610  comprising equiangular-spiral transfer section  611  with center at opposite point  611   f , protruding cubic spline  612 , and central equiangular spiral  613  with center at proximal point  613   f .  FIG. 35   b  shows that its far field pattern has reduced on-axis intensity compared with  FIG. 34   b.    
         [0101]      FIG. 36   a  depicts virtual filament  620  comprising equiangular-spiral transfer section  621  with center at opposite point  621   f , protruding cubic spline  622 , and central equiangular spiral  623  with center at proximal point  623   f .  FIG. 36   b  shows that its far field pattern has reduced on-axis intensity compared with  FIG. 35   b.    
         [0102]      FIG. 37   a  depicts virtual filament  630  comprising equiangular-spiral transfer section  631  with center at opposite point  631   f , planar annulus  632 , central equiangular spiral  633  with center at proximal point  633   f , and outer cylinder  634 .  FIG. 37   b  shows that its far field pattern has no on-axis intensity.  FIG. 37   b  can be compared with  FIG. 30   b , given the similarity of  FIG. 37   a  to  FIG. 30   a.    
         [0103]      FIG. 38   a  depicts virtual filament  640  comprising equiangular-spiral transfer section  641  with center at opposite point  641   f , lower conical section  642 , upper conical section  643 , and outer spline curve  644 .  FIG. 38   b  shows the far-field pattern. Cone  642  is a white diffuse reflector with Lambertian scattering, so that unlike the diffuse transmissive surface  392  of  FIG. 13   a , it only reflects light falling on it. 
         [0104]    Previous embodiments have complete circular symmetry, since they are formed by a 360° cylindrical profile-sweep. Thus they have no azimuthal shape variation, only the radial variation of the profile. This is because real-world 360° output patterns do not call for azimuthal variation. There is one type of azimuthal shape variation, however, having no azimuthal intensity variations in its light output. This is the V-groove. 
         [0105]    The geometry of a linear array of V-grooves is shown in  FIG. 39 . Reflective 90° V-groove array  650  is bordered by x-z plane  651  and y-z plane  652 . Incoming ray  653  is reflected at first groove wall  650   a  become bounce ray  654 , then reflected at second groove wall  650   b  to become outgoing ray  655 . Incoming ray  653  has projection  653   yz  on border plane  652  and projection  653   xz  on border plane  651 . Bounce ray  654  has projection  654   yz  on border plane  652  and projection  654   xz  on border plane  651 . Outgoing ray  655  has projection  655   yz  on border plane  652  and projection  655   xz  on border plane  651 . 
         [0106]      FIG. 39  also shows macrosurface normal N lying perpendicular to the plane of V-groove array  650 , which in the case of  FIG. 39  is the xy plane. The directions of projected rays  653   xz  and  655   xz  obey the law of reflection from a planar mirror with the same surface normal. But on yz plane  652 , outgoing projection  655   yz  has the opposite direction of incoming projection  653   yz , which has in-plane incidence angle Ψ. Thus linear V-groove array  650  acts as a combination of retroreflector and conventional reflector. That is, when incoming ray  653  has direction vector (p,q,r), then outgoing ray  655  has direction vector (p,−q,−r). This condition, however, only holds for those rays undergoing two reflections. Of all possible input-ray directions, the fraction that is reflected twice is 1−tan(Ψ). 
         [0107]    The configuration pertinent to the present invention is when surface  650  is the interface between a transparent dielectric, such as acrylic or polycarbonate, lying above the surface (i.e. positive z) and air below it. The particular case shown in  FIG. 39  is also valid for total internal reflection, which occurs whenever the incidence angle θ of a ray on the dielectric-air interface exceeds the local critical angle 
         [0000]      θ c =arcsin(1/ n ) for refractive index n. 
         [0000]    Since the unitary normal vectors on the 2 sides of the grooves are (0,√0.5,√0.5) and (0,√0.5,√0.5), the condition for total internal reflection can be vectorially expressed as 
         [0000]      ( p,q,r )·(0,√0.5,√0.5)&lt;cos θ c    
         [0000]    which can be rearranged to yield 
         [0000]      | q |+√(1− p   2   −q   2 )&lt;√[2(1−1/ n   2 )]. 
         [0108]      FIG. 40  shows contour graph  660  with abscissa p and ordinate q. Legend  661  shows the fraction of rays that are retroreflected by total internal reflection. For p=0, the maximum q value for which there is total internal reflection for the 2 reflections is 
         [0000]      |cos −1    q|&lt; 45°−θ c    
         [0000]    which amounts to a vertical width of ±2.8° for acrylic (n=1.492) and ±6° for polycarbonate (n=1.585). These small angles are how much such incoming rays are not in plane  651 . 
         [0109]    More pertinent to the present invention is radial V-groove array  670  shown in  FIG. 41 . Crest-lines  671  and trough-lines  672  are the boundaries of planar triangles  673 , which meet at the crest-lines and trough-lines with 90° included angles  674 . 
         [0110]    In  FIG. 37   a , the genatrix curve of upper surface  633  has the form of an equiangular spiral. It is possible to impose a radial V-groove array on such a surface, so that crest-lines  671  of  FIG. 41  would become curved downward, depressing the center point. 
         [0111]      FIG. 42   a  is a perspective view of the preferred embodiment of  FIG. 37   a . Virtual filament  680  comprises equiangular-spiral transfer section  681 , equiangular-spiral top surface  683 , and cylindrical side surface  684 , the apparently polygonal shape of which is a pictorial artifact. Crest curves  683   c  are shown as twelve in number, to correspond with crest-lines  671  of  FIG. 41 . 
         [0112]      FIG. 42   b  is another perspective view of the same preferred embodiment, but with surfaces  683  and  684  of  FIG. 42   a  removed. Twelve crest-curves  683   c  are shown, one shown with tangent vector t, normal vector n, and their vector product the binormal vector b=t×n. If a crest-curve were the path followed at uniform speed by a particle, then its velocity vector lies along tangent vector t and its acceleration vector is the negative the normal vector n. The latter is so that it will coincide with the surface normal of the surface. Because each crest-curve lies in a plane, binormal vector b is constant, meaning the crest-curves have zero torsion. 
         [0113]      FIG. 43  is a perspective view of the construction of a V-groove on a curved surface according to the present invention. 
         [0114]    In modifying surface  683  of  FIG. 42   a  to become like radial-groove array  670  of  FIG. 41 , the curvature of the crest-lines would make the groove surfaces become non-planar. In fact, such surfaces would be the envelopes of elemental planes coming off each point on the curve at a 45° angle, as shown in  FIG. 43 . Incompletely swept equiangular spiral surface  690  is identical to surface  683  of  FIG. 42   a . Part of the sweep is unfinished so that crest-curve  691  can be clearly seen. Tangent to it are three elemental planar ridges  692  with 90° interior angles. Let a crest curve be specified by the parametric function P(t), where t is the path-length along said crest-curve, with normal vector n(t) and binormal vector b(t). Any point X on a 45° plane touching the crest-curve at P(t) is specified by 
         [0000]      ( X−P ( t ))·( n ( t )± b ( t ))=0  (1) 
         [0000]    with the ‘±’ referring to there being two such 45° planes corresponding to the walls of a 90 V-groove. Varying t gives a family of such planes. In order to calculate the envelope surface to this family of planes, differentiate Equation (1) with respect to parameter t, giving 
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         [0000]    The orthogonal vector triad formed by the parametrically specified unit vectors t(t), n(t), and b(t) is called the Frenet frame of the curve it follows as t varies. Each of these three vectors has a definition based on various derivatives of the equation for P(t). Differentiating these definitions with respect to t gives the Frenet equations, well-known in differential geometry. A laborious combination of the Frenet equations with Equation (2), and eliminating t, finally yields 
         [0000]      ( X−P ( t ))· t ( t )=0  (3) 
         [0000]    Equation (3) and Equation (1) must be fulfilled simultaneously for each point X of the envelope surface. Equation (3) establishes that the same vector X−P is normal to tangent vector t, while Equation (1) implies that the vector X−P is normal to n±b. Thus X−P, for a point satisfying equations (1) and (3), must be in the direction n−b, because n and b are orthogonal unit vectors so that (n−b)·(n+b)=0, i.e., 
         [0000]        X−P ( t )= s (− n ( t )± b ( t ))  (4) 
         [0000]    This is the parametric equation of the two envelope surfaces of the ridge. The radial parameter is t and transverse parameter is s, with one ridge for +b(t) and the other for −b(t). Curves  683   c  of  FIG. 42   b  will be crest curves if we take s&gt;0 for both ridges (with s=0 for the crest curves) and they will be trough curves if s&lt;0 (with s=0 for the trough curves in this case). More pertinently, 
         [0000]        X ( t,s )= P ( t )+ s (− n ( t )± b ( t ))  (5) 
         [0000]    is the equation of the envelope surface as a function of the crest equation P(t), and its normal and binormal vectors. The parameter s extends to the value of s that at the bottom of the groove, where it meets the corresponding point on the next ridge. 
         [0115]    The upshot of this differential-geometry proof is that each of the planes of  FIG. 43  contributes thick lines  693  to the envelope surface of the curved V-groove. Thick lines  693  of  FIG. 43  in fact represent the second term in Equation (5). If successive lines  693  cross as they issue from closely neighbouring points, then the resultant envelope surface may have ripples or even caustics (which are physically unrealisable). In the present invention, any such mathematical anomalies would be too far from the crest curve to be of relevance. 
         [0116]      FIG. 44  is a perspective view of virtual filament  700 , comprising equiangular-spiral transfer section  701 , radial V-grooves  702 , and cylindrical sidewall  703 . Only twelve V-grooves are shown, for the sake of clarity, but an actual device may have many more. The utility of such grooves is that they enable the designer to avoid the use of a coated reflector. 
         [0117]      FIG. 45  shows virtual filament  710 , comprising transfer section  711  with longitudinal V-grooves, and ejector section  703 . As shown in  FIG. 45 , V-grooves can also be used on the transfer section of the present invention, enabling a cylindrical shape to be used. 
         [0118]    The discussion of FIG. 2 of U.S. patent application Ser. No. 10/461,557 touched on the function of color mixing, to make different wavelengths from chips  23 ,  24 , and  25  have the same relative strengths throughout the light coming out of ejector section  12 . This assures that viewers will see only the intended metameric hue and not any colors of the individual chips. Previously, rectangular mixing rods have been used to transform the round focal spot of an ellipsoidal lamp into a uniformly illuminated rectangle, typically in cinema projectors. Generally, polygonal mixing rods worked best with an even number of sides, particularly four and six. With color mixing for LEDs, however, such rods are inefficient because half of an LED&#39;s Lambertian emission will escape from the base of the rod. 
         [0119]    The following preferred embodiments of the present invention remedy this deficit by proper shaping of its transfer section. This shaping enables polygonal cross-sections to be used in the present invention. 
         [0120]      FIG. 46  depicts virtual filament  720 , comprising hexagonal transfer section  721  and hemispheric ejector section  722 . Within package  723  are red LED chip  723   r , green chip  723   g , and blue chip  723   b . Transfer section  721  comprises expanding bottom section  721   b , mid-section  721   m  with constant cross-section, and contracting upper section  721   u . The shape of sections  721   b  and  721   u  acts to prevent the escape of rays that a constant cross section would allow if it extended the entire length of transfer section  721 . Similar to the grooves of  FIG. 44  and  FIG. 45 , a polygonal transfer section would constitute a departure from complete rotational symmetry. 
         [0121]      FIG. 47   a  is a side view of virtual filament  730  comprising sixteen-sided off-axis ellipsoid  731 , conical ejector section  732 , and mounting feet  734 .  FIG. 47   b  is a perspective view of the same preferred embodiment, also showing spline top surface  733 .  FIG. 47   c  shows the blue (465 nanometers) emission pattern of this preferred embodiment, at the various cylindrical azimuths, 0° azimuth indicated by reference numeral  735 , 45° azimuth indicated by reference numeral  736 , 90° azimuth indicated by reference numeral  737 , and 135° azimuth indicated by reference numeral  738 , and as indicated in the legend at upper right.  FIG. 47   d  shows the green (520 nanometers) emission pattern of this preferred embodiment, at the various cylindrical azimuths  735 - 738  and as indicated in the legend at upper right.  FIG. 47E  shows the red (620 nanometers) emission pattern of this preferred embodiment, at the various cylindrical azimuths  735 - 738  and as indicated in the legend at upper right. 
         [0122]      FIG. 48   a  is a side view of virtual filament  740  comprising sixteen-sided off-axis ellipsoid  741 , conical ejector section  742 , conical collar  744 , and cylindrical connector  745 .  FIG. 48   b  is a perspective view of the same preferred embodiment  743 . The purpose of the narrowing by collar  744  is to produce the 300° emission pattern  747  shown in  FIG. 48   c.    
         [0123]      FIG. 49   a  is an exploded side view of faceted virtual filament  750  and tricolor LED package  755  being inserted into and optically coupled to the filament  750 . Beyond polygonally-shaped transfer sections are more complex departures from circular symmetry. Virtual filament  750  comprises an output section spanned by arrow  751 , transfer section  752 , and mounting feet  753 . Faceted virtual filament  750  is a single piece of plastic, such as acrylic, the surface of which is covered by planar facets  754 . The two mounting feet  753  are designed to be proximate to the outer surfaces of LED package  755 , to aid in alignment and bonding of virtual filament  750  to package  755 . In one embodiment of the invention, adhesive is applied to the inner sidewalls of feet  753  for bonding to LED package  755 . In this instance the inner sidewall of each leg  753  has a surface that is substantially parallel to the proximate edge surface of LED package  755 . Optical coupling of the bottom of virtual filament  750  to the top surface of LED package  755  can be achieved by several means, such as use of optical adhesives, non-curing and curing optical gels (such as available from Nye Optical Products of Fairhaven, Ma) or index matching liquids (such as available from Cargille Laboratories of Cedar Grove, N.J.). 
         [0124]      FIG. 49   b  is an exploded-part perspective view showing rectangular LED package  755  as removed from virtual filament  750 . Within reflector cup  757  are red chip  758   r , green chip  758   g , and blue chip  758   b . Cup  757  is filled with transparent epoxy (not shown) up to top  756  of package  755 . Top  756  is optically bonded to the bottom of faceted virtual filament  750 . This three-chip configuration is an example of the present invention incorporating multiple light sources. The three chips shown could also be amber, red, and infrared, suitable for illuminators compatible with night-vision devices, and other combinations. 
         [0125]    Typically the base of a mixing virtual filament is larger than the emitting surface of the RGB LED illuminating it. In one preferred embodiment the inner diameter of the sixteen-sided polygonal shaped base of the mixing optic  750  is 20% larger than the diameter of the circular exit aperture of the RGB LED  755 . In the case where the RGB LED  755  has a non-circular exit aperture, the base of the virtual filament is made sufficiently large to completely cover the exit aperture of the LED. 
         [0126]      FIG. 50  is a side view showing TIR lens  5030  with its focus at output section  751  of faceted virtual filament  750 . 
         [0127]      FIG. 51  is a view from below also showing faceted virtual filament  750 , LED package  755 , and TIR lens  5030 , the latter comprising facets  5031  and flat cut-out planes  5032 . 
         [0128]      FIG. 52  shows the rectangular shape of TIR lens  5030 , positioned above faceted virtual filament  750 . Also shown is LED package  755  coupled to the bottom of virtual filament  750 . There are four mounting feet  5013 , somewhat smaller than the two shown in  FIG. 49A , so as not to leak a greater amount of light from LED  755 . 
         [0129]      FIG. 53  is a perspective view from above showing virtual filament  750  and LED package  755 . Rectangularly cut TIR lens  5030  has planar side walls  5032  and slightly indented upper surface  5033 . 
         [0130]      FIG. 54  shows lens  5040  comprising a row of rectangular TIR lenses  5030 , and endmost virtual filament  750 . 
         [0131]      FIG. 55  shows endmost virtual filament  750  and circuit board  5050  upon which it is mounted. Sidewalls  5055  hold row lens  5040 , flat holographic diffuser  5060  just above it, and outer cover  5070 , which is optionally a holographic diffuser. Transverse arrow  5061  shows the long axis of the elliptical pattern of holographic diffuser  5060 . Longitudinal arrow  5071  shows the long axis of the elliptical pattern of a holographic diffuser deployed on cover  5070 . These diffusers cause a distant viewer to see a narrow line of light on cover  5070 . It will have the color of the metameric resultant of the component colors mixed by faceted virtual filament  750 . 
         [0132]      FIG. 56  shows an alternative virtual filament configuration. Reflector cup  5061  is analogous to reflector cup  21  of  FIG. 49B , in that it contains the system&#39;s light-emitting chips. Six-fold compound parabolic concentrator (CPC) section  5062  widens to hexagonal rod  5063 . This CPC section can alternatively be a combination of an equiangular and a parabolic curve, hereinafter referred to as an equiangular-spiral concentrator, to avoid leakage. At the top of rod  5063 , another parabolic (or equiangular spiral) section  5064  narrows the rod again. This widens the angular swath of light from the range of guided angles, about ±48°, to about the full ±90° of LED package  755 . Other even-polygon cross sections for the rod can also be used. Connected to rod  5063  is hemispheric lens  5065 , positioned just under rectangular TIR lens  5066  and delivering light thereinto. Sections  5062 ,  5063 ,  5064  and  5065  can, in some embodiments, be formed all of one piece of transparent plastic, such as acrylic or polycarbonate. Light received into section  5062  is mixed by section  5063  and emitted out section  5065  into collimating lens  5066 . 
         [0133]    At least some of the above described embodiments, when used with multiple LEDs, can well-mix different colors into a single calorimetric resultant. In other embodiments, however, a phosphor-conversion white LED could be used, or an array thereof. Still other embodiments include a generally spherical ejector section extending form a transfer section. A base of the transfer section can be optically bonded to an array of LEDs, such as an array of blue LEDs, in a cup reflector, rather than a multi-colored array. Additionally, the upper generally spherical ejector section, positioned distant from the array of LEDs, can be coated with a photostimulative component, such as a photostimulative phosphor, which in some embodiments can be similar in composition to that already in use in conventional white LEDs. 
         [0134]      FIG. 57A  shows an external perspective view of light source  5700  according to some embodiments, comprising LED package  5710 , compound elliptical concentrator  5720 , and upper ejector section that comprises a sphere or portion of a sphere  5730 . 
         [0135]      FIG. 57B  shows a cutaway perspective view of the light source  5700  of  FIG. 57A , further showing that LED package  5710  comprises an array of blue LEDs  5711 , reflective surface  5712  surrounding the LEDs  5711 , and conical reflector  5713 . The top of reflector  5713  is generally even, in some implementations, with the transparent top surface (not shown) of package  5710 , to which the bottom surface (not shown) of concentrator  5720  is optically bonded, and in some instances optically bonded to eliminate air gaps. Blue light from LEDs  5711  shines into concentrator  5720 , where it is maintained through total internal reflection and transferred to spherical portion  5730 . The blue light proceeds into sphere  5730 , striking an external surface of the sphere  5730 , upon which is placed phosphor coating  5731 . Light source  5700  can thus be classified as a remote phosphor system. 
         [0136]    With the phosphor incorporated on an exterior surface of the spherical or other ejector section the heat generated, due at least to Stokes losses, does not exceed the operating temperature of the ejector section, including ejector sections constructed of plastic and glass. In some instances, as demonstrated through actual testing, light having more than 5 Watts directed into an ejector section having an exterior layer of phosphor generates heat; however, this heat only results in a maximum temperature in the material of the operating device of less than 70° C., which is well below the operating temperature of plastics, including PMMA. Additionally, even higher Wattages can be handled by increasing the size and/or surface area of the ejector section. 
         [0137]    The spherical deployment of the remote phosphor material increases its area relative to that of the exit aperture of concentrator  5720 .  FIG. 58  shows a simplified close-up diagram of a generic spherical phosphor configuration according to some embodiments, with the lower part of the profile of concentrator  5801  terminating at aperture  5802 , of radius r. Radius r subtends the angle θ from the center of spherical surface  5803 , of radius R, so that r=R sin θ, and the output area of the concentrator is A 0 =πr 2 . The remote phosphor (actually too thin to be visibly depicted in  FIG. 58 ) coats the outside of spherical surface  5803 , and thereby receives the light that concentrator  5801  sends through aperture  5802 . One of the properties of the sphere, in accordance with at least some embodiments, is that an elemental Lambertian radiator on its inside surface will generate uniform irradiance on the rest of the inside surface, because the change in the viewing angle exactly compensates for the distance to the radiator from any viewpoint. Therefore if concentrator  5801  produces uniform illumination upon aperture  5802  then spherical surface  5803  will be uniformly illuminated as well. Reinforcing this uniformity is the fact that both the blue light scattered by the phosphor and the yellow light stimulated by its absorption will divide between outwards emission and return emission back into the concentrator. The ratio of this outward white emission to the blue light delivered by the concentrator is termed P T . The fraction returned to concentrator  5801  is (1−P T ). Much of this will be recovered by reflection off of the LEDs themselves ( 5711  in  FIG. 57 ), as well as the material surrounding them ( 5712  in  FIG. 57 ). The spherical phosphor acts to greatly increase P T . 
         [0138]    A flat remote phosphor across exit aperture  5802  will typically send somewhat more back into concentrator  5801  than outwards. A phosphor on the outside of spherical surface  5802  has strong back emission as well, but most of it shines elsewhere on the phosphor, acting as a kind of recycling. The fraction of this that goes back into aperture  5802  equals the ratio of exit area A O  to phosphor sphere area A S , as given by 
         [0000]    
       
         
           
             
               
                 A 
                 O 
               
               
                 A 
                 P 
               
             
             = 
             
               
                 
                   sin 
                   2 
                 
                  
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                 2 
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                     ( 
                     
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         [0000]    In  FIG. 58 , this fraction is only about 11%, considerably less than the 50% of a hemisphere. Further, the increased area of surface  5803  over exit aperture  5802  causes the phosphor luminance to be reduced by this amount as well, but at least some of the benefits provide better spherical emission and increased efficiency. 
         [0139]      FIG. 58  shows that a glowing phosphor on surface  5803  will have substantially the same intensity from the on-axis direction represented by rays  5804  to the off-axis angle β=90−θ, represented by rays  5805 . At greater off-axis angles intensity falls off slowly, and only until nearly downward angles does it go under half. This is substantially similar to the nearly spherical emission of a conventional light bulb, enabling at least reasonable functional substitution. The small amount of radiation from the outside of surface  5803  that is re-entering concentrator  5801  from the outside will mostly pass through it, merely adding a gleam to its appearance. 
         [0140]    The deployment of a remote phosphor on a spherical surface will also increase its emission efficiency P T  over that of a flat one deployed on the concentrator exit plane. The P T  of a flat remote phosphor is a complicated function of its thickness and the scattering coefficient of the phosphor layer, as well as the absorptivity, quantum efficiency, and Stokes&#39; shift of the phosphor&#39;s photoluminescent component. The absorptivity is proportional to the concentration of the photoluminescent component and can thus be slightly altered, while the last two factors are generally fixed for given phosphor formulations. This leaves layer thickness and scattering coefficient that can be tailored to a specific situation, but they too are constrained by the color-balance requirement that about one quarter of the output light be blue, with the rest converted to yellow. An additional parameter for at least some remote phosphor systems, according to some embodiments, is the fraction P T  of the blue input that is output, as blue or yellow light, without recycling. For a typical flat remote phosphor that produces white light, this fraction is typically between about 0.15 and 0.3, which in most applications is impractically low. The phosphor ball can greatly increase this output fraction. 
         [0141]    The light output of the phosphor ball is: 
         [0000]    
       
         
           
             
               P 
               TB 
             
             = 
             
               
                 
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         [0142]    The light returned to the optic by the phosphor ball is: 
         [0000]    
       
         
           
             
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         [0143]      FIG. 59  shows graph  5900  with abscissa  5901  for the ratio of area A S , over a flat one of area A P , and ordinate  5902  for the P TB  of the spherical remote phosphor given the P T  value a flat phosphor would have across the exit aperture, with the same phosphor material and thickness. Operating point  5903  is at the ⅓ point, lying between curve  5904  for P T =0.3 and  5905  for P T =0.35. At an abscissa of 9, corresponding to the configuration of  FIGS. 57A-B , moves the system to operating point  5906 , for about P T =80%. Of the 20% that is sent back down into the concentrator, generally over 70% will be returned by the LEDs and surrounding surfaces, making overall efficiency relatively high. 
         [0144]    Numerous phosphor formulations can be utilized with the subject embodiments to achieve the yellow light emittance. For example, phosphors from the Internatix Corporation, with headquarters located in Fremont, Calif., produces a variety of families of phosphors for different LED lighting applications that can be utilized. For example, the SY phosphors from the Internatix Corporation can be used, at least in some applications, for general illumination, with the SY450-B phosphor formulation being applicable, at least, in targeting high-CRI applications. The EY4254 phosphors can used, in some implementations, for high brightness general illumination, and the OG450-30 phosphors can be used to target, at least, warm (i.e., lower) color temperature applications. 
         [0145]    Mixtures of at least the above identified phosphors were applied and tested in the prototype development of the spherical remote phosphor light sources. In at least some of these implementations, the phosphors were each mixed with a clear UV-curable epoxy, UV15-7 from Master Bond, Inc., which has an index of refraction of 1.55. Each of the phosphors were mixed using a phosphor-to-epoxy, weight-to-weight ratio of about 15:100. The spheres were coated with the UV-curable slurry, with repeated very thin applications to control thickness. The various phosphor materials were tested for both color temperature and color-rendering index. 
         [0146]    A further consideration in the selection of one or more phosphor materials and thicknesses, which goes beyond the usual specification of color temperature, is that the longest visual wavelengths (red) are the least efficient for a phosphor to generate, which is due to the Stokes loss in the photonic conversion of blue to the less energetic red, with the difference becoming heat. This Stokes loss is generally less for green light, which also has advantageously high efficacy. Although a phosphor with a greenish spectrum, such as EY4254, would by itself typically have inadequate color rendering, its light can be supplemented by that of a red LED, which can be included in the array  5712  of  FIGS. 57A-B . Further, some embodiments provide for redundancy, mixing at least in the spherical portion or other extraction feature providing an output that is substantially uniform, and in some instances allows different thinning of the LEDs and allows changing color temperature by varying LEDs. Still further, the redundancy and/or mixing additionally allows one or more of the LEDs and/or one or more arrays of LEDs to operate as needed, to achieve a desired output illumination and still achieve high uniformity. Similarly, LEDs can be adjusted and/or ratios of LEDs can be adjusted to provide different color temperatures. For example, different colored LEDs can be activated in various cooperations to achieve a desired output, including for example having blue LEDs of varying wavelengths to achieve a desired output having differing wavelengths. Additionally, one or more LEDs can be operated independently or arrays of LEDs can be operated independently to allow varying intensities of the output, which in some applications allows for at least the appearance of dimming of a light source. The control of the intensity can be achieved, for example, by incorporating multiple dies that are activated independently, and/or varying current supplied to independent LEDs or banks of LEDs. 
         [0147]    The generally spherical geometry of the surface to be phosphor-coated may exclude, in some instances, or make difficult some methods of applying the coating. For example, a particularly low-cost phosphor-coating application method can include a thin film, such as silicon or other suitable materials, with the phosphor embedded within the film and/or on the film, and the film is readily cut into pieces able to be adhered to a developable surface. Some alternative embodiments, however, can employ the thin film coated with a phosphor formulation.  FIG. 60A , for example, discloses light source  6000 , comprising basal LED package  6010 , with an immersed array of blue LEDs (not shown, but can be similar to the array of LEDs  5711  as described above with reference to  FIG. 57B ), intermediate transfer section  6020  in the shape, for example, of a totally internally reflecting compound elliptical concentrator optically coupled to the LED package, and upper conical ejector section  6030  receiving blue light from the transfer section. 
         [0148]    Conical ejector section  6030  is a solid body with an external surface comprising bottom surface  6031  and an external lateral surface  6032 . Bottom surface, which in some implementations is generally planar, is positioned adjacent an exit surface of transfer section  6020 , and lateral surface  6032  extends from a perimeter of the bottom surface  6031  to an apex of conical ejector section  6030 . The conical ejector section  6030  has a height that is about n times its basal radius R B  (here shown twice the radius of the exit surface of transfer section  6020 ), making its triangular laterally-projected area about equal to its circularly-axial projected area πR B   2 . This provides isotropic intensity over substantially an entire forward hemisphere of directions, when as the luminance of the conical surface is uniform. This uniform luminance in turn is assured by the relatively small area A e  of the exit aperture of transfer section  6020  when compared to the lateral surface area A c  of conical ejector section  6030 . As much as half of the phosphor emission may be directed back into conical ejector section  6030 , but little of that escapes into the transfer section  6020  (which escaped light does, however, have a 70% or more chance of being returned). As this light ‘rattles around’ inside conical ejector section  6030 , it can aid in smoothing out illumination artifacts that section  6020  may have produced, for example, due to imperfections therein or in the light output of the LED array. In some embodiments, planar annular reflector  6033  is glued to the otherwise exposed planar bottom  6031  of ejector section  6030 , with a highly reflective film for reflecting light back inside the conical ejector section  6030 . 
         [0149]      FIG. 60B  is an exploded view of light source  6000  of  FIG. 60A , showing LED package  6010  already optically cooperated, for example glued, with transfer section  6020 . In turn the transfer section  6020  is optically cooperated, for example glued, to basal surface  6031  of ejector  6030 . Annular reflector  6033  is secured, for example glued, with the base1 surface  6031  around the transfer section  6020  at the interface with the base1 surface  6031 . Upon lateral conic surface  6032  is secured, for example glued, a flat phosphor-coated thin film  6034 , shown cut out into the requisite portion of a circle, of radius 
         [0000]        F=R   B √(1+π 2 )=3.297 R   B . 
         [0000]    Thin film  6034  wraps around the circumference 2π R B  of basal surface  6031 . The interior angle of this in radians is then 
         [0000]      θ=2π/√(1+π 2 )=109.2° 
         [0000]    as shown in  FIG. 60B . Since this is less than a third of a circle, three such pieces can be cut out of a square, minimizing waste. In some embodiments, the film includes an adhesive-backed carrier that bears the phosphor. 
         [0150]    The projected cross section of this shape of cone is substantially constant from 0 to 90°, then declines to zero at 162.35°. Thus the intensity will follow the same dependence upon angle. 
         [0151]    Both the spherical and the conical versions of the remote-phosphor ejector section produce quite similar far-field intensity patterns, as illustrated by  FIG. 61 , showing radial plot  6100 , comprising azimuthal off-axis angle scale  6110  and radial scale  6120 . Relative intensity graph  6130  shows substantial uniformity all the way to shadow region  6135 . 
         [0152]    While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention as set forth in the claims.