Patent Publication Number: US-7583446-B2

Title: Electronic adjustable color filter device

Description:
RELATED MATERIALS 
     This divisional application claims the benefit of U.S. Nonprovisional application Ser. No. 11/240,875, filed on Sep. 30, 2005 now U.S. Pat. No. 7,298,558 which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to color filters. More particularly, this invention relates to an electronically adjustable color filter that selectively combines filtered elements of light to create color light. 
     BACKGROUND 
     Color lighting systems are found in a variety of entertainment facilities, to include theaters, auditoriums, concert halls and stadiums. Regardless the size of the venue, in almost all instances a color lighting system is required or desired. The quality of the entertainment provided is often dependent, in part, on the quality of the color lighting system. 
     Aside from professional and amateur entertainment venues, theme parks and other such attractions use color light to enhance the experience of their customers. Private and public facilities, such as churches and museums, also have a need for variable color lighting. Further, sales oriented facilities and events, to include shopping malls and trade shows, rely on color lighting to help market products. Also, there are many scientific/engineering applications where discriminating color light is important it is simply a fact of life that color lighting is part of almost every person&#39;s daily routine. 
     Typically, color light systems include a broad band, white light source, the output of which must be filtered to produce the desired color(s) of light. Often, the broadband light is unpolarized, and a portion of the light is reflected (“thrown away”) in a first, polarizing step. The loss of 50% or more of the incoming light at the onset reduces the intensity of the generated light, as well as the variations in color that may be achieved. 
     In many instances, color filtering includes the use of “color wheels”. Generally speaking, color wheels rely on the movement (rotation or otherwise) of color filters into and out of optical alignment with a transmitted white light. In many instances, the color filters are dichroic filters, which is to say they filter (reflect or absorb) light within one wavelength band and pass through all remaining light. The filters may be glass, gelatin, or other transparent/semitransparent materials. Often, the number of possible color combinations is limited by the number of color filters that can be mounted into the color wheel. Further, the clarity of colors is affected by filter movement, alignment, etc. 
     Absorption is the most prevalent means for filtering colored light. Unfortunately, absorbed light can generate significant quantities of heat which must be dissipated by the lighting system. Operational heating also limits the optical power of a system, as there is a direct correlation between optical power and absorbed heat. System cooling requirements typically require active (e.g. fans) or passive (e.g. cooling fans) cooling subsystems. In addition to heating concerns, standard color wheel systems include multiple moving, mechanical components. The process of changing colors is distracting to the audience. Also, moving parts impede or limit the response time/speed of a system, as well as reduce system reliability In most instances, the useful operational life of a system is severely limited by reliability issues. 
     Pixilated color lighting systems are yet another lighting option found in the prior art. Unlike color wheel systems which are subtractive (filtering) in nature, pixilated systems are additive. Stated differently, pixilated systems achieve desired color combinations by adding colors together at a level unresolved by the naked human eye. Red, green and blue pixels produce an image on a screen, or alternatively direct color light to a designated region. Fiber optics or other delivery methods carry the colored light from light sources to the pixilated surface. Although operationally cooler and void of multiple moving parts, pixilated systems are not without their limitations. A ⅔ decrease in light intensity results from the use of a broadband while light source and red, green and blue pixel elements. To obtain red, green and blue light from the broadband white light, the light must pass through a matrix of red, green and blue absorptive “dots”. On each dot or pixel, two of the three colors (i.e. green and blue on a red dot) are absorbed. Therefore, by converting the broadband white light to red, green, and blue, ⅔ of the light is lost in the conversion. This loss precedes any further losses associated with transmitting and mixing the light. 
     In addition to needing color light, venues such as theaters, theme parks and trade shows often desire to shape the color light to create various images. The methods used, e.g. gobos or reflective display devices, are often times separate from the color lighting system. Integration, therefore, of the color lighting system and the imaging generating device can be cumbersome and inefficient. 
     Hence, there is a need for a color filter device and color filter system that overcome one or more of the limitations discussed above. 
     SUMMARY 
     The electronic combinational color filter devices and color filter system herein disclosed advance the art and overcome problems articulated above by providing electronically adjustable wave plates and dichroic reflective filter elements to selectively generate light having a desired color. 
     In particular, and by way of example only, in one embodiment an electronic combinational color filter is provided including: a plurality of wave plates structured and arranged to alter a polarization state of incoming light; a first plurality of dichroic reflective filters, each filter optically aligned with a corresponding wave plate to reflect a first element of the incoming light having a predetermined wavelength; a second plurality of dichroic reflective filters, each filter optically aligned with a corresponding wave plate to reflect a second element of the incoming light having a predetermined wavelength; and a polarizing beam splitter/combiner, positioned to split the incoming light into the first element of light and the second element of light, and to combine light reflected from the first plurality of dichroic reflective filters and the second plurality of dichroic reflective filters, to generate color light. 
     In a another embodiment, an electronic combinational color lighting system is provided, including: a light source for generating light; a plurality of wave plates structured and arranged to alter a polarization state of the light; a first plurality of dichroic reflective filters, each filter optically aligned with a corresponding wave plate to reflect a first element of the light having a predetermined wavelength; a second plurality of dichroic reflective filters, each filter optically aligned with a corresponding wave plate to reflect a second element of the light having a predetermined wavelength; a polarizing beam splitter/combiner, positioned to split the light into the first element of light and the second element of light, and to combine light reflected from the first plurality and the second plurality of dichroic reflective filters, to generate color light; and a chromaticity monitor for measuring a chromaticity of the color light. 
     In still yet another embodiment, a method for generating color light is provided, including: receiving incoming light into a polarizing beam splitter/combines; splitting the incoming light into a first element of light having a first polarization state and a second element of light having a second polarization state; selectively passing the first element of light through a first plurality of wave plates to alter the polarization state of the first element of light; selectively reflecting the first element of light off a first plurality of dichroic reflective filters, each filter reflecting a portion of the first element of light having a predetermined wavelength; selectively passing the second element of light through a second plurality of wave plates to alter the polarization state of the second element of light; selectively reflecting the second element of light off a second plurality of dichroic reflective filters, each filter reflecting a portion of the second element of light having a predetermined wavelength; and combining, in the polarizing beam splitter/combines, reflected portions of the first element of light and reflected portions of the second element of light, to generate color light. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of an electronic combinational color filter device having wave plate-dichroic reflective filter pairs, according to an embodiment; 
         FIG. 2  is a plan view of an electronic combinational color filter device having one set of wave plates and two sets of dichroic reflective filters, according to an embodiment; 
         FIG. 3  is plan view of an electronic combinational color filter device having a single mirror, according to an embodiment; 
         FIG. 4  is a schematic of an electronic combinational color lighting system, according to an embodiment; 
         FIG. 5  is a perspective view of a gobo device for creating color images, according to an embodiment; and 
         FIG. 6  is a perspective view of a reflective display device integrated with an electronic combinational color filter device, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Before proceeding with the detailed description, it should be noted that the present teaching is by way of example, not by limitation. The concepts herein are not limited to use or application with one specific type of electronic combinational color filter device in a specific environment. Thus, although the instrumentalities described herein are for the convenience of explanation, shown and described with respect to exemplary embodiments, the principles herein may be equally applied in other types of electronic combinational color filter devices in a variety of different settings. 
       FIG. 1  illustrates an electronic combinational color filter device  100  according to the present disclosure. Color filter device  100  is a multi-color device, which is to say it filters several colors, at varying levels, to create a desired transmitted or output color light  102 . It can be appreciated by those skilled in the art, however, that color filter device  100 , as well as the electronic combinational color filter devices disclosed below, may be used to filter a single color. Further, device  100  may be used for polarization spectrum control, which may include polarization spectrum control as a function of color. The primary advantages of the electronic combinational color filter devices disclosed herein, which include maximum light efficiency/use of light, independent color control, thermal stability, etc. are recognized regardless the number of separate colors and polarizations addressed by the filter. 
     Continuing with  FIG. 1 , a polarizing beam splitter/combiner  104  is positioned to receive light  106  from a light source (not shown) In one embodiment, light  106  is broadband, white light, however, light  106  may be any type of light to include laser light, etc. Light  106  is subsequently split into a two light elements  108 ,  110  by polarizing beam splitter/combiner  104 , each element having a known polarization state. Specifically, light  106  is split into “s” polarized light  108 , which is reflected by polarizing beam splitter/combiner  104 , and “p” polarized light  110 , which is transmitted by polarizing beam splitter/combiner  104 . 
     As shown, a plurality of wave plates, of which wave plates  112 ,  114  and  116  are exemplary, are optically aligned with light element  108 . The wave plates  112 - 116  may be controlled to alter the polarization state of light element  108 , therefore the wave plates may be referred to as “tunable”. Wave plates  112 - 116  may be any of a type well known in the art, to include but not limited to electro-optically tunable wave plates and/or mechanically rotated crystalline wave plates. By altering the voltage applied to a wave plate (e.g. wave plate  112 ) the polarization of element  108  may be altered. 
     Positioned adjacent to, and sequentially following, each wave plate  112 - 116  is a dichroic reflective filter, e.g. filters  118 ,  120  and  122 . In general, dichroic reflective filters reflect light in a select wavelength band. In one embodiment, dichroic reflective filters  118 - 122  are cholesteric films, which is to say they reflect light having a wavelength in a select wavelength band and a discrete polarization state (e.g. left-hand polarized). As represented in  FIG. 1 , color filter device  100  may include multiple filters to filter a variety of colors, for example blue, green and red. Additional dichroic reflective filters, such as a yellow or a cyan filter, may be included in color filter device  100 , or alternatively they may be substituted for the filters  118 - 122  depicted in  FIG. 1 . 
     As shown in  FIG. 1 , two or more “wave plate-dichroic reflective filter” pairs may be “stacked” or positioned such that each pair is optically aligned with, and contacting, at least one other pair. As is discussed in greater detail below, it is not required, however, that the wave plates and dichroic reflective filters be in contact to be effective. Optical alignment and coupling, which may include the use of optical mirrors to redirect light, is a relevant factor, as further amplified in  FIGS. 22 and 3 . 
     A second set of wave plates  124 ,  126  and  128  are optically coupled with light element  110 . As discussed above, light element  110  has an initial polarization state different from that of element  108 , i.e. a “p” polarization. Similar to wave plates  112 - 116 , wave plates  124 - 128  are structured and arranged to electronically alter the polarization state of light element  110 . Varying the voltage applied to one or more of the wave plates  124 - 128  will modify or alter the polarization state of element  110 . The degree to which the polarization state is altered, and the manner in which it is altered, depends on the type of wave plate and the voltage applied. As with wave plates  112 - 116 , wave plates  124 - 128  may be any of a type well known in the art, to include but not limited to, twisted nematic, dual frequency, cholesteric, and mechanically rotated crystal quartz wave plates. 
     Positioned adjacent to, and sequentially following, each wave plate  124 - 128  is a dichroic reflective filter, e.g. filters  130 ,  132  and  134 . In one embodiment, dichroic reflective filters  130 - 134  are cholesteric films. As with filters  118 - 122 , color filter device  100  may include multiple filters  130 - 134  addressing a variety of colors. In one embodiment, filters  130 - 134  address the same colors as filters  118 - 122 . In yet another embodiment, one or more of the filters  130 - 134  address a color not addressed by filters  118 - 122 . 
     In operation, electronic combinational color filter device  100  receives light  106  from a light source (not shown) which may, or may not, be part of a color filter system. Polarizing beam splitter/combiner  104  splits beam  106  into two elements, each element having a known polarization state, i.e. “s” and “p” polarization. In particular, a percentage of light  106  is split into light element  108 , wherein light element  108  is “s” polarized. The remaining percentage of light  106  is transmitted as light element  110 , wherein light element  110  is “p” polarized. 
     As light element  108  strikes wave plate  112 , a voltage is applied to wave plate  112 . The polarization state of light element  108  is subsequently altered. The degree of alteration depends on the voltage applied to wave plate  112 . In this way, wave plate  112  controls the polarization state or states of light element  108  For example, as “s” polarized light element  108  contacts wave plate  112 , some portion of the polarization state of light element  108  is altered. In particular, some portion of light element  108  may be converted to a right or left-hand polarization. 
     Light element  108  subsequently passes through wave plate  112  and contacts dichroic reflective filter  118 . Dichroic reflective filter  118  is positioned to reflect that portion of light element  108  having a wavelength within a known wavelength band. The predetermined wavelength corresponds to the wavelength of a single color, which is a wavelength of light in the visible, NIR, MWIR, etc ranges of the Electromagnetic Spectrum (the “EM Spectrum”). If, for example, dichroic reflective filter  118  is intended to filter and control the color red, the wavelength of concern would be in the range of approximately 622-780 nanometers. If the color to filter is blue, the wavelength would be in the range of approximately 455-492 nanometers, and if it is green, the wavelength would be approximately 492-577 nanometers. All other light of element  108 , i.e. light having a different wavelength, is transmitted through dichroic reflective filter  118 . 
     As one part of light element  108  reflects off of filter  118 , for example all “blue” light, the “handness” of the reflected light changes, e.g. from right-hand polarized to left-hand polarized. As the reflected blue light, which is part of reflected light  123 , passes back through polarizing beam splitter/combiner  104 , that portion which is “p” polarized is transmitted through polarizing beam splitter/combiner  104 . The light becomes part of the color light  102  ultimately transmitted by color filter device  100 . All “s” polarized light is reflected in polarizing beam splitter/combiner  104 , and becomes part of the light  136  discarded by the device  100 .″ 
     After passing through dichroic reflective filter  118 , the remaining light of element  108  subsequently passes through wave plate  114 . Similar to wave plate  112 , the polarization state of the light passing through wave plate  114  is altered. In this manner, wave plate  114  acts to control the polarization state(s) of the remaining light of light element  108 . Once again, the percentage of light altered depends upon the voltage applied to wave plate  114 . The remaining light of light element  108  then contacts dichroic reflective filter  120 , and that portion of light element  108  having a predetermined wavelength, is reflected. In this instance, dichroic reflective filter  120  operates to reflect light having a different wavelength of the EM spectrum than the light reflected by dichroic reflective filter  118 , for example green light. The polarization state of the reflected green light is “flipped” and all “p” polarized green light passing back through polarizing beam splitter/combiner  104  is transmitted, while all “s” polarized green light is reflected. 
     The process of first passing a remaining portion of light of element  108  through a wave plate  116  to alter the polarization state, and then reflecting a portion of the modified light element  108  off a dichroic reflective filter  122 , repeats for a third time. The predetermined operational wavelength of dichroic reflective filter  122  is different than the wavelength of filter  118  and filter  120 , which is to say dichroic reflective filter  122  reflects light of a different color, for example the color red. As with the blue and the green light, the “red” portion of reflected light  123  having a “p” polarization state is transmitted and becomes part of the output light  102 . All “s” polarized light is reflected in the polarizing beam splitter/combiner  104  to become part of discarded light  136 . The light reflected by dichroic reflective filters  118 ,  120  and  122  combines with other light, as described in detail below, to form the transmitted, output light  102 . 
     Concurrent with the selective modification of light element  108 , light element  110  travels along a different path toward a series of “wave plate dichroic reflective filter” pairs. Initially, light element  110  is “p” polarized, however, the polarization state of the light element  110  changes in the operation of device  100 . The sequencing of the wave plates  124 ,  126 ,  128 , and the dichroic reflective filters  130 ,  132 ,  134 , optically aligned with light element  110  is substantially the same as that described for light element  108 . Stated differently, in at least one embodiment, dichroic reflective filter  130  operates to reflect light in the same wavelength band as dichroic reflective filter  118 . Similarly, dichroic reflective filters  132  and  134  reflect light in the same wavelength bands as dichroic reflective filters  120  and  122  respectively. 
     The reflected color light  135  of light element  110  ultimately consists of “s” and “p” polarized blue, green and red light. The “p” polarized light exits the polarizing beam splitter/combiner  104  in the direction of the source of light  106 , wherein it becomes part of the light  136  discarded by the system and converted to heat. The “s” polarized light is reflected to become part of the color light  102  transmitted from electronic combinational color filter device  100 . The color of light  102  may be constantly modified by altering the voltages applied to various wave plates  112 - 116  and  124 - 128 . Furthermore, by separately controlling wave plates  112 ,  116  and  124 - 128 , the output light  102  can be made to have a controllable polarization state, as described below. 
     In addition to controlling the color of output light  102 , the polarization can be tailored as well. For example, by controlling wave plates  112 - 116  such that all of the reflected light  123  is “p” polarized, all of light  123  passes through polarizing beam splitter/combiner  104  and becomes part of output light  102 . Further, by controlling wave plates  124 - 128  such that all of reflected light  135  is “p” polarized, all of light  135  passes through polarizing beam splitter/combiner  104  as part of discarded light  136 . In this manner, output light  102  can be tailored to have only a “p” polarization. Alternatively, light  102  may be tailored to only have a “s” polarization state. 
     Considering this embodiment further, it is possible, for example, to tailor individual colors such that all of the blue light in output light  102  is “p” polarized, all of the red light in output light  102  is “s” polarized, and the green light in output light  102  is a combination of “s” and “p” polarized light. Depending on the integration of color filter device  100  with other systems and subsystems, this tailoring of color and polarization can be advantageous. It can be appreciated that the examples presented herein are for illustration purposes only, and other combinations of color and/or color-based polarization may be achieved by device  100 . 
     In yet another embodiment, filters  118 - 122  and  130 - 134  may be cholesteric filters or films. In this embodiment, all light within a specific wavelength band (e.g. all “red” light), having a predetermined polarization state (e.g. right-hand polarized), will be reflected by the cholesteric filters corresponding to that wavelength band (e.g. filters  122  and  134  for the color red). As shown in phantom in  FIG. 1 , all other light in the wavelength band of interest passes through color filter device  104 . The same may be said for the “blue” and “green” color light, such that the light exiting device  104 , along the same paths as light elements  108  and  110  (light  38  and  140  respectively), is a combination of all three colors. In this embodiment, the light  136  discarded by device  100  and converted into heat may therefore be reduced. 
     Referring now to  FIG. 2 , yet another embodiment of the present disclosure is depicted. Electronic combinational color filter device  200  includes a polarizing beam splitter/combiner  202  optically aligned with incoming light  204 , In at least one embodiment, light  204  is broadband, white light. Light  204  is in subsequently split into two light elements  206 ,  208 , each having a known polarization state, i.e. a “s” polarization and a “p” polarization, respectively. 
     Optically aligned with light element  206  is a plurality of dichroic reflective filters  210 ,  212  and  214  Likewise, a plurality of dichroic reflective filters  216 ,  218  and  220  are optically aligned with light element  208 . As shown, dichroic reflective filters  216 - 220  are also oriented substantially parallel to dichroic reflective filters  210 - 214 . Of note, in the embodiment presented in  FIG. 2 , the sequencing of dichroic reflective filters  210 - 214  is identical to that of dichroic reflective filters  216 ,  220  respectively. For example, if the dichroic reflective filter  210 , aligned with light element  206 , reflects blue light (light having a wavelength in the band of approximately 455-492 nanometers), then the dichroic reflective filter  216 , aligned with light element  208 , will also reflect light in this wavelength band. Further, if dichroic reflective filter  212  reflects light falling within the wavelength band of 492-577 nanometers (green light), dichroic reflective filter  218  will also operate to reflect green light. Finally, if dichroic reflective filter  214  (aligned with light element  206 ) reflects red light (622-780 nanometers), dichroic reflective filter  220  (aligned with light element  208 ) also reflects red light. 
     As shown in  FIG. 2 , an electronically controllable wave plate, e.g. wave plate  222 , is optically coupled to a “pair” of dichroic reflective filters operating over a specified wavelength band (e.g. filters  210  and  216  which operate to reflect blue light). In addition to wave plate  222 , wave plate  224  is optically coupled to filters  212  and  218 , and wave plate  226  is optically coupled to filters  214  and  220 . In this manner, the wave plates  222 - 226  axe structured and arranged to alter the polarization state of both the first element of light  206  and the second element of light  208 . Each dichroic reflective filter  210 - 220  also operates on both elements of light  206 ,  208 , to reflect all or some portion of each element  206 ,  208  having a wavelength corresponding to the operational wavelength band of a given filter. 
     In particular, in the operation of color filter device  200 , incoming light  204  is split by polarizing beam sputter/combiner  202  into the first element of light  206  having a “s” polarization, and the second element of light  208  having a “p” polarization. The first element of light  206  is reflected toward a first dichroic reflective filter  210 , wherein light having a wavelength within a specified wavelength band (e.g. approximately 455-492 nanometers or “blue” light) is reflected toward wave plate  222 . All other light of element  206  passes through filter  210 . The reflected blue light  228  strikes and passes through wave plate  222 . In doing so, the polarization state of all or a portion of light  228  is altered or modified. All of light  228  reflects off a mirror  230  positioned on the back side of wave plate  222 , and is directed toward dichroic reflective filter  216 . Dichroic reflective filter  216  also reflects light having a wavelength within a specified wavelength band (e.g. a wavelength in the wave band corresponding to blue light). The reflected light  232  is directed toward polarizing beam splitter/combiner  202 , wherein that portion of light  232  having a “s” polarization is reflected to become part of output light  234 . The portion of light  232  which is “p” polarized, by virtue of the alteration induced by wave plate  222 , transmits through polarizing beam splitter/combiner  202 . 
     The remaining light  236 , passing through dichroic reflective filter  210 , contacts a second dichroic reflective filter  212 , wherein light having a wavelength in the wave band 492-577 nanometers (“green” light) is reflected toward a second wave plate  224 . Reflected green light  238  strikes and passes through wave plate  224 . In doing so, the polarization state of light  238  is altered or modified. All of light  238  reflects off a mirror  240  positioned on the back side of wave plate  224 , and is directed toward dichroic reflective filter  218 . Dichroic reflective filter  218  reflects light having a wavelength within a specified wavelength bard (e.g. green light). The reflected light  242  is directed toward polarizing beam splitter/combiner  202 , wherein that portion of light  242  having a “s” polarization is reflected to become part of output light  234 . The portion of light  242  which is “p” polarized, by virtue of the alteration induced by wave plate  224 , transmits through polarizing beam splitter/combiner  202 . 
     The process disclosed above repeats for a third time. The remaining light  244 , passing through dichroic reflective filter  212 , contacts a third dichroic reflective filter  214 , wherein light having a wavelength in the wave band of approximately 622-780 nanometers, i.e. “red” light, is reflected toward a third wave plate  226 . Reflected red light  246  strikes and passes through wave plate  226 . In doing so, the polarization state of light  246  is altered or modified. All of light  246  reflects off a mirror  248  positioned on the back side of wave plate  226 , and is directed toward dichroic reflective filter  220 . Dichroic reflective filter  220  reflects light having a wavelength within a specified wavelength band (e.g. red light). The reflected light  250  is directed toward polarizing beam splitter/combiner  202 , wherein that portion of light  250  having an “s” polarization is reflected to become part of output light  234 . The portion of light  250  which is “p” polarized, by virtue of the alteration induced by wave plate  226 , transmits through polarizing beam splitter/combiner  202 . As can be appreciated, all of the “p” polarized light, of what was initially light element  206 , passes through polarizing beam splitter  202  and is part of discarded light  251 . 
     A similar process occurs with light element  208 . Initially, the “red” light portion  252  of light element  208  is reflected by dichroic reflective filters  220  and  214 , and the polarization state is altered by wave plate  226 . The resultant red light  254  enters polarizing beam splitter/combiner  202 , wherein that portion which is “p” polarized is transmitted to become part of output light  234 , and that portion which is “s” polarized is reflected to become part of discarded light  251 . Similarly, the “green” light portion  256  of light element  208  is reflected by dichroic reflective filters  218  and  212 , as well as altered by wave plate  224 . The resultant green light  258  enters polarizing beam splitter/combiner  202  wherein that portion which is “p” polarized is transmitted to become part of output light  234 , and that portion which is “s” polarized is reflected to become part of discarded light  251 . Further, the “blue” light  260  of light element  208  interacts with dichroic reflective filters  216  and  210 , and is altered by wave plate  222 , the end result of which is a blue light  262 . Light  262  enters polarizing beam splitter/combiner  202  wherein that portion which is “p” polarized is transmitted to become part of output light  234 , and that portion which is “s” polarized is reflected to become part of discarded light  251 . 
     As a result of the alteration of light elements  206  and  208 , output light  234  is a combination of both “s” and “p” polarized light. The discarded light  251  is also a combination of both polarization states and is typically directed back toward the light source (not shown), wherein light  251  is ultimately converted to heat that must be dissipated. 
     It can be appreciated that the colors of blue, green and red disclosed in  FIG. 22  are exemplary. Others colors, such as yellow and cyan, may replace or be added to the embodiment of  FIG. 2  without departing from the intent of the disclosure. It can further be appreciated that each wave plate  222 - 226  may be individually addressed with a desired voltage. In this way, the amount of blue, green and red light resulting from light element  206 , as well as the amount of color light resulting from light element  208 , may be individually tailored and controlled for each color. 
     Referring now to  FIG. 3 , an embodiment similar to that of  FIG. 2  is presented. As such, the operation of electronic combinational color filter device  300  is similar to that of color filter device  200  as well. As shown, color filter device  300  includes a plurality of wave plates, i.e. wave plates  302 ,  304  and  306 . Unlike the embodiment of  FIG. 2 , however, each wave plate  302 - 306  is coupled to the same, single mirror  308  positioned to reflect all of the light exiting from all wave plates  302 ,  306  (e.g. blue light  310 ), as well as to reflect all light toward all wave plates  302 - 306  (e.g. blue light  312 ). 
     Further, a set  314  of dichroic reflective filters includes a “blue” light filter  316 , a “green” light filter  318 , and a “red” light filter  320 . Similarly, a set  322  of dichroic reflective filters includes filters for the color&#39;s blue (filter  324 ), green (filter  326 ) and red (filter  328 ). In at least one embodiment, the dichroic reflective filters  316 - 320  and  324 - 328  are twisted nematic cells or films. In yet another embodiment, the filters  316 - 320  and  324 - 328  are cholesteric filters. A polarizing beam splitter/combiner  330  is positioned to receive incoming light  332 , which may be a broadband light, and split the light  332  into a first element  334  and a second element  336 . Similar, to  FIG. 2 , element  334  is “s” polarized, and element  336  is “p” polarized. 
     Operationally, color filter device  300  functions in much the same way as color filter, device  200 . Blue, green and red light from two light elements ( 334  and  336 ) is reflected by dichroic reflective filters ( 316 - 320  and  324 - 328  respectively), altered by wave plates ( 302 - 306 ), reflected by a mirror ( 308 ), and reflected once again by the dichroic reflective filters ( 324 - 328  and  316 - 320  respectively). As the altered light (e.g. blue light  338  and blue light  340 ) enters polarizing beam splitter  330 , that portion of each color of altered light which is “s” polarized is reflected, and that portion which is “p” polarized is transmitted. As a result of the operation of color filter device  300 , color light  342 , transmitted by color filter device  300 , is a controlled combination of “s” and “p” polarizations, as well as a combination of blue, green and red light. Discarded light  344  is typically directed back toward the light source (not shown). As with color filter device  200 , wave plates  302 - 306  are driven by an applied voltage to ultimately control the amount of blue, green, and red light combined to make color light  342 . 
     In at least one embodiment, filters  316 - 320  and  324 - 328  may be cholesteric filters. As such, the filters  316 - 320  and  324 - 328  will reflect light that is within a specific wavelength band, and that has a specific polarization state, e.g. either right or left-hand polarization. Stated differently, filters  316 - 320  and  324 - 328  may be “mirrors” for one polarization state (e.g. right-hand polarization) and “windows” for the other polarization state (e.g. left-hand polarization). In this embodiment, therefore, not all light is discarded in the direction of light  344 . 
     As shown in  FIG. 4 , an electronic combinational color filter device may be part of an overall system for delivering color light, e.g. system  400 . System  400  may include a light source  402 . An electronic combinational color filter device  404  is optically aligned with light source  402 . Color filter device  404  may be any of several embodiments, the specific details of which are encompassed in the present disclosure and depicted in  FIGS. 1-3 . A chromaticity monitor or color detector  406  is oriented to measure the chromaticity of a light  408  ultimately transmitted by system  400 . The chromaticity of the transmitted light  408  is communicated to a controller  410 , via an electrical wire  412 , for further processing and use. Alternatively, chromaticity monitor  406  may simply record the characteristics of the transmitted light  408 , and communicate the recorded data to controller  410 , wherein the chromaticity of light  408  can be calculated. Of note, chromaticity monitor  406  may be employed with any or all of the embodiments disclosed in the present application. Also, chromaticity monitor  406  may include a polarizing beam splitter and two color sensors, such that color monitoring is also accomplished on the basis of polarization. 
     Chromaticity data is used to determine what adjustments, if any, should be made to the wave plates of the color filter device  404  by controller  410 . Adjustments, in the form of varying voltages selectively applied to the wave plates, are used to tune or modify the color of transmitted light  408 . The electrical current applied to the wave plates is carried via electrical lines, e.g. lines  414  and  416 . All of the components (e.g. light source  402 , color filter  404 , etc.) may be contained within a housing  418 . Alternatively, depending on the operational use of system  400 , some components may be mounted outside housing  418 . 
     A color lighting system, such as system  400 , may include one or more spatial light modulators for creating a tailored color image. Referring now to  FIGS. 5 and 6 , one such modulator is a gobo  500 . As shown in  FIG. 5 , the gobo  500  may be used to block a portion (not shown) of transmitted color light  502 , while allowing other portions ( 504 ,  506  and  508 ) of color light  502  to pass through. The creative tailoring of gobo  500  allows color images having structure and form to be transmitted by system  400 . It can be appreciated that gobo  500  is exemplary of gobo devices well known in the art, and that the specific shape, structure and design of a gobo will vary with each desired image. 
     Yet another modulator for creating a tailored color image having structure and/or shape is a reflective display device  600 . A reflective display device, such as device  600 , is a pixilated device. Each pixel, e.g. pixel  602 , can either reflect or not reflect light striking the pixel  602 , depending on an electronic signal sent to the pixel by a controller, e.g. controller  410  ( FIG. 4 ). The reflectivity of a pixel  602  may be constantly changed to vary the image ultimately displayed by the reflective display device  600 . As shown in  FIG. 6 , certain pixels may reflect light  604  transmitted by a electronic combinational color filter device  606 , e.g. reflected light  608  and  610 , while the reflectivity of other pixels (e.g. pixel  602 ) is set to zero. In one embodiment, reflective display device  600  is a digital light processor having a plurality of mirrored pixels. In at least one other embodiment, reflective display device  600  includes a plurality of “liquid crystal-on-silicon” pixels. 
     A reflective display device  600  may, therefore, actively create any color image that can be created using a gobo. Further, device  600  can quickly and efficiently change the projected image without having to physically (mechanically) move components, i.e. the gobo. The gobo and reflective display device presented in  FIGS. 5 and 6  respectively, are simplified for understanding. It can be appreciated that actual modulators may be more complex, with many more smaller, pixels, more intricate details, etc. 
     Changes may be made in the above methods, devices and structures without departing from the scope hereof. It should thus be noted that the matter contained in the above description and/or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method, device and structure, which, as a matter of language, might be said to fall there between.