Abstract:
An apparatus and method for flexible configuring of optical fibers to illuminate digital projectors. The optical fibers are attached to various positions of a configurable back plane assembly and a condensing assembly condenses the light beams prior to launch into the projector. Horizontal and vertical launch symmetries are maintained for any number of optical fibers between 1 and 9.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Laser light sources may be coupled into digital projection systems using various components such as optical fibers, lenses, diffusers, and mixing rods. It is challenging to maintain brightness and color uniformity when different numbers of laser light sources are used in different projection systems. For example, a high-output projection system may require  5  green lasers and a low-output projection system may require  2  green lasers. Conventional optical designs require different launch assemblies designed for each case to maintain uniformity. 
       SUMMARY OF THE INVENTION 
       [0002]    In general, in one aspect, an optical apparatus that includes an optical fiber, a configurable back plane assembly, and a condensing assembly. The optical fiber attaches to a position of the configurable back plane assembly. The optical fiber illuminates the condensing assembly. 
         [0003]    Implementations may include one or more of the following features. There may be a mixing rod illuminated by the condensing assembly. There may be a digital projector illuminated by the mixing rod. There may be a multiplicity of optical fibers attached to positions of the configurable back plane and illuminating the condensing assembly. The pattern of spots formed by the condensing assembly on the mixing rod may depend on the positions of the optical fibers. The pattern of spots may be symmetrical in the x and y directions of the mixing rod. The long axis of the pattern of spots may be oriented to extend across the short axis of the mixing rod. The pattern of spots may include two to nine spots. 
         [0004]    In general, in one aspect, an optical coupling method that includes the steps of generating light and transmitting it over an optical fiber, generating another light and transmitting it over another optical fiber, holding both optical fibers in a configurable back plane assembly, and condensing the light from the optical fibers with a condensing assembly. 
         [0005]    Implementations may include one or more of the following features. The output of the condensing assembly may be coupled to a mixing rod. The output of the mixing rod may be coupled to a digital projector. The pattern of spots from the condensing assembly may depend on the positions of the fibers. The pattern of spots may be symmetrical in the x and y directions. The long axis of the pattern of spots may be oriented to extend across the short axis of the mixing rod. The pattern of spots may include two to nine spots. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0006]      FIG. 1  is a block diagram of a configurable optical coupling in a projection system; 
           [0007]      FIG. 2A  is a top view of a configurable back plane assembly; 
           [0008]      FIG. 2B  is a front view of a configurable back plane assembly; 
           [0009]      FIG. 3A  is a top view of a condensing assembly; 
           [0010]      FIG. 3B  is a front view of a condensing assembly; 
           [0011]      FIG. 4  is a front view of one spot on a mixing rod; 
           [0012]      FIG. 5  is a front view of two spots on a mixing rod; 
           [0013]      FIG. 6  is a front view of three spots on a mixing rod; 
           [0014]      FIG. 7  is a front view of four spots on a mixing rod; 
           [0015]      FIG. 8  is a front view of five spots on a mixing rod; 
           [0016]      FIG. 9  is a front view of six spots on a mixing rod; 
           [0017]      FIG. 10  is a front view of seven spots on a mixing rod; 
           [0018]      FIG. 11  is a front view of eight spots on a mixing rod; 
           [0019]      FIG. 12  is a front view of nine spots on a mixing rod; and 
           [0020]      FIG. 13  is a flowchart of a configurable optical coupling method. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Laser projection systems require optical coupling between the lasers and the projector. For cinema systems, there are often advantages for separating the lasers from the projector, thus the light may be transmitted from the laser to the projector through fiber optics. This allows the lasers to be located a distance away from the projector. A small number of fibers, in the range of one to nine for each color, is a low-cost and practical way to carry light when each laser has output power in the range of approximately 10 to 200 W. If the lasers are significantly less than 10 W each, a number of small lasers may be aggregated per optical fiber to reach the range of 10 to 200 W per optical fiber. 
         [0022]    Projectors that use digital light processing (DLP) light valves typically couple light into the projector with mixing rods (also called integrating rods). The mixing rod uses multiple bounces inside a rectangular rod of glass to help make the light uniform and achieve sufficient uniformity on the projection screen in both brightness and color. Although longer mixing rods can achieve better uniformity, there are limitations on the length that will fit in projection systems which have an overall maximum length defined by the overall size of the projector. There has been a long-standing need in the laser-projection industry to improve uniformity when a small number of optical fibers are used for coupling. 
         [0023]      FIG. 1  shows a block diagram of a configurable optical coupling in a projection system. First laser  100  illuminates first optical fiber  102 . First optical fiber is attached to and held by configurable back plane assembly  104 . Configurable back plane assembly  104  is attached to condensing assembly  106 . Condensing assembly  106  form first beam  108 . First beam  108  illuminates coupling lens  108 . Coupling lens  108  form second beam  110 . Second beam  110  illuminates mixing rod  112 . Mixing rod  112  forms third beam  114 . Third beam  114  illuminates projector  116 . Second laser  118  illuminates second optical fiber  120 . Second optical fiber  120  is attached to and held by configurable back plane assembly  104 . Third laser  122  illuminates third optical fiber  124 . Third optical fiber  124  is attached to and held by configurable back plane assembly  104 . In this example, three lasers and three optical fibers are shown attached to the configurable back plane assembly, but any number of lasers and fibers may be attached. Coupling optics between lasers and optical fibers are not shown in  FIG. 1 . Coupling lens  108  may be replaced by any combination of lenses, diffusers, or other optical elements that are able to appropriately illuminate mixing rod  112 . Mixing rod  112  may be incorporated into projector  116 . 
         [0024]      FIG. 2A  shows a top view of a configurable back plane assembly.  FIG. 2B  shows a front view of the same configurable back plane assembly. The configurable back plane assembly holds from one to nine optical fibers in the proper position for illuminating a condensing assembly. Plate  200  holds nine optical fiber receptacles  202 ,  204 ,  206 ,  208 ,  210 ,  212 ,  214 ,  216 , and  218 . The optical fiber receptacles have holes  220 ,  222 ,  224 ,  226 ,  228 ,  230 ,  232 ,  234 , and  236 . Optical fibers (not shown) may be attached to the optical fiber receptacles and the light emitted from the optical fibers passes through the holes and illuminates a condensing assembly. 
         [0025]      FIG. 3A  shows a top view of a condensing assembly.  FIG. 3B  shows a front view of the same condensing assembly. First optical fiber  301  generates first beam  302 . First beam  302  illuminates first collimating lens  303 . First collimating lens  303  generates second beam  304 . Second beam  304  reflects from first minor  305 . First minor  305  generates third beam  306 . Second optical fiber  307  generates fourth beam  308 . Fourth beam  308  illuminates second collimating lens  309 . Second collimating lens  309  generates fifth beam  310 . Fifth beam  310  reflects from second minor  311 . Second minor  311  generates sixth beam  312 . Third optical fiber  313  generates seventh beam  314 . Seventh beam  314  illuminates third collimating lens  315 . Third collimating lens  315  generates eighth beam  316 . Eighth beam  316  reflects from third minor  317 . Third minor  317  generates ninth beam  318 . Fourth optical fiber  319  generates tenth beam  320 . Tenth beam  320  illuminates fourth collimating lens  321 . Fourth collimating lens  321  generates eleventh beam  322 . Eleventh beam  322  reflects from fourth mirror  323 . Fourth mirror  323  generates twelfth beam  324 . Fifth optical fiber  325  generates thirteenth beam  326 . Thirteenth beam  326  illuminates fifth collimating lens  327 . Fifth collimating lens  327  generates fourteenth beam  328 . Fourteenth beam  328  reflects from fifth minor  329 . Fifth minor  329  generates fifteenth beam  330 . Sixth optical fiber  331  generates sixteenth beam  332 . Sixteenth beam  332  illuminates sixth collimating lens  333 . Sixth collimating lens  333  generates seventeenth beam  334 . Seventeenth beam  334  reflects from fifth minor  335 . Fifth mirror  335  generates eighteenth beam  336 . Seventh optical fiber  337  generates nineteenth beam  338 . Nineteenth beam  338  illuminates seventh collimating lens  339 . Seventh collimating lens  339  generates twentieth beam  340 . Twentieth beam  340  reflects from seventh minor  341 . Seventh mirror  341  generates twenty first beam  342 . Eighth optical fiber  343  generates twenty second beam  344 . Twenty second beam  344  illuminates eighth collimating lens  345 . Eighth collimating lens  345  generates twenty third beam  346 . Twenty third beam  346  reflects from eighth minor  347 . Eighth minor  347  generates twenty fourth beam  348 . Ninth optical fiber  349  generates twenty fifth beam  350 . Twenty fifth beam  350  illuminates ninth collimating lens  351 . Ninth collimating lens  351  generates twenty sixth beam  352 . Twenty sixth beam  352  reflects from ninth mirror  353 . Ninth mirror  353  generates twenty seventh beam  354 . A configurable back plane may be utilized to hold the optical fibers in the proper position for launch into the condensing assembly. The configurable back plane separates the optical fibers in the horizontal direction for easy attachment to the fiber receptacles and separates the optical fibers in the vertical direction at the proper spacing to achieve closely packed output beams in the vertical direction. First mirror  305 , second minor  311 , third mirror  317 , fourth mirror  323 , fifth minor  329 , sixth mirror  335 , seventh minor  341 , eighth mirror  347 , and ninth mirror  353  are used to condense the beams to achieve closely packed output beams in the horizontal direction. 
         [0026]      FIG. 4  shows a front view of one spot on a mixing rod. The output beams from the condensing assembly form a closely packed pattern with spots that depend on which optical fibers are attached to the configurable back plane assembly. In the case of a very low power projection system, only one optical fiber is attached. In the case of a very high power projection system, all nine optical fibers are attached. Power levels in between those two extremes are achieved with various numbers of optical fibers attached.  FIG. 4  shows the illumination of the input face of a mixing rod with one optical fiber attached. Mixing rod  400  is illuminated by fifth spot  414 . The illumination pattern is symmetrical about horizontal axis  402  and symmetrical about vertical axis  404 . First spot  406 , second spot  408 , third spot,  410 , fourth spot  412 , sixth spot  416 , seventh spot  418 , eighth spot  420 , and ninth spot  422  (shown with dashed circles) are not used in this pattern of spots. 
         [0027]      FIG. 5  shows a front view of two spots on a mixing rod. Mixing rod  500  is illuminated by fourth spot  512  and sixth spot  516 . The illumination pattern is symmetrical about horizontal axis  502  and symmetrical about vertical axis  504 . First spot  506 , second spot  508 , third spot,  510 , fifth spot  514 , seventh spot  518 , eighth spot  520 , and ninth spot  522  (shown with dashed circles) are not used in this pattern of spots. 
         [0028]      FIG. 6  shows a front view of three spots on a mixing rod. Mixing rod  600  is illuminated by fourth spot  612 , fifth spot  614 , and sixth spot  616 . The illumination pattern is symmetrical about horizontal axis  602  and symmetrical about vertical axis  604 . First spot  606 , second spot  608 , third spot,  610 , seventh spot  618 , eighth spot  620 , and ninth spot  622  (shown with dashed circles) are not used in this pattern of spots. 
         [0029]      FIG. 7  shows a front view of four spots on a mixing rod. Mixing rod  700  is illuminated by second spot  708 , fourth spot  712 , sixth spot  716 , and eighth spot  720 . The illumination pattern is symmetrical about horizontal axis  702  and symmetrical about vertical axis  704 . First spot  706 , third spot  710 , fifth spot  714 , seventh spot  718 , and ninth spot  722  (shown with dashed circles) are not used in this pattern of spots. 
         [0030]      FIG. 8  shows a front view of five spots on a mixing rod. Mixing rod  800  is illuminated by second spot  808 , fourth spot  812 , fifth spot  814 , sixth spot  816 , and eighth spot  820 . The illumination pattern is symmetrical about horizontal axis  802  and symmetrical about vertical axis  804 . First spot  806 , third spot  810 , seventh spot  818 , and ninth spot  822  (shown with dashed circles) are not used in this pattern of spots. 
         [0031]      FIG. 9  shows a front view of six spots on a mixing rod. Mixing rod  900  is illuminated by first spot  906 , second spot  908 , third spot  910 , seventh spot  918 , eighth spot  920 , and ninth spot  922 . The illumination pattern is symmetrical about horizontal axis  902  and symmetrical about vertical axis  904 . Third spot  912 , fourth spot  914 , and fifth spot  916  (shown with dashed circles) are not used in this pattern of spots. 
         [0032]      FIG. 10  shows a front view of seven spots on a mixing rod. Mixing rod  1000  is illuminated by first spot  1006 , second spot  1008 , third spot  1010 , fifth spot  1014 , seventh spot  1018 , eighth spot  1020 , and ninth spot  1022 . The illumination pattern is symmetrical about horizontal axis  1002  and symmetrical about vertical axis  1004 . Third spot  1012  and fifth spot  1016  (shown with dashed circles) are not used in this pattern of spots. 
         [0033]      FIG. 11  shows a front view of eight spots on a mixing rod. Mixing rod  1100  is illuminated by first spot  1106 , second spot  1108 , third spot  1110 , fourth spot  1112 , sixth spot  1116 , seventh spot  1118 , eighth spot  1120 , and ninth spot  1122 . The illumination pattern is symmetrical about horizontal axis  1102  and symmetrical about vertical axis  1104 . Fifth spot  1114  (shown with a dashed circle) is not used in this pattern of spots. 
         [0034]      FIG. 12  shows a front view of nine spots on a mixing rod. Mixing rod  1200  is illuminated by first spot  1206 , second spot  1208 , third spot  1210 , fourth spot  1212 , fifth spot  1214 , sixth spot  1216 , seventh spot  1218 , eighth spot  1220 , and ninth spot  1222 . The illumination pattern is symmetrical about horizontal axis  1202  and symmetrical about vertical axis  1204 . 
         [0035]      FIG. 13  shows a flowchart of a configurable optical coupling method. In step  1300 , light is generated. In step  1302 , the light is transmitted over an optical fiber. In step,  1304  the optical fiber is held in a configurable back plane. In step  1312 , a second light is generated. In step  1314 , the second light is transmitted over a second optical fiber. In step  1304 , the second optical fiber is also held in the configurable back plane. In step  1306 , the light from both optical fibers is combined and condensed. In step  1308 , the condensed light is coupled to a mixing rod. In step  1310 , the light from the mixing rod is coupled to a projector. In a similar way, more than two lights and fibers can be combined, condensed, and coupled to the projector. 
         [0036]    Orthogonal symmetry in x and y axes across the orthogonal directions of the input face of a mixing rod are helpful to achieve excellent projection uniformity in both color and brightness. One possible configuration is to utilize a separate configurable back plane for each color. A typical full-color projection system would require three configurable back planes for red, green, and blue. In this case, conventional dichroic beamsplitters may be used to combine the three colors and then couple the light to the mixing rod. In another example, blue light may be carried by some of the optical fibers and a combination of green and red light may be carried in each of the other optical fibers. Two configurable back planes would then be sufficient. 
         [0037]    It is preferable to arrange the long axis of the spot pattern (if any) to extend across the short axis of the mixing rod. This results in more bounces through the rod and improved uniformity. For example, in  FIG. 6 , fourth spot  612 , fifth spot  614 , and sixth spot,  616  are extended along the short axis of the mixing rod and this configuration is preferable to utilizing second spot  608 , fifth spot  614 , and eighth spot  620  which would be extended along the long axis of the mixing rod. 
         [0038]    Other implementations are also within the scope of the following claims.