Abstract:
A system for testing a display device is disclosed. A base has a surface with at least four holes in it. The display device has two layers and a surface. The first layer is a semiconductor substrate. The second layer is a transparent material. The surface of the display device is coupled to the surface of the base at each of the at least four apertures. The holes are positioned relative to the display device such that gravitational forces on the display device are optimally counterbalanced.

Description:
RELATED APPLICATION  
       [0001]    Pursuant to 35 USC §119(e), Applicants claim priority to Provisional Patent Application No. 60/267,443, filed Feb. 8, 2001, entitled “Micro Display Optical Systems”. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to preparation of liquid crystal display devices, and more particularly to a micro display manual tester and methods of its operation.  
         BACKGROUND OF THE INVENTION  
         [0003]    Liquid crystal displays (LCDs) are commonly used in devices such as portable televisions, portable computers, control displays, and cellular phones to display information to a user. LCDs act in effect as a light valve, i.e., they allow transmission of light in one state, block the transmission of light in a second state, and some include several intermediate stages for partial transmission. When used as a high resolution information display, LCDs are typically arranged in a matrix configuration with independently controlled pixels. Each individual pixel is signaled to selectively transmit or block light from a backlight (transmission mode), from a reflector (reflective mode), or from a combination of the two (transflective mode).  
           [0004]    An LCD pixel can control the transference for different wavelengths of light. For example, an LCD can have pixels that control the amount of transmission of red, green, and blue light independently. In some LCDS, voltages are applied to different portions of a pixel to control light passing through several portions of dyed glass. In other LCDs, different colors are projected onto the pixel sequentially in time. If the voltage is also changed sequentially in time, different intensities of different colors of light result. If the micro display quickly changes the wavelength of light to which the pixel is exposed, an observer will see the combination of colors rather than sequential discrete colors. Several monochrome LCDs can also result in a color display. For example, a monochrome red LCD can project its image onto a screen. If a monochrome green and monochrome blue LCD are projected in alignment with the red, the combination will be full color.  
           [0005]    Methods of manufacturing micro displays, LCDs having relatively small size pixels, often produce a number of usable devices and some unusable devices. For example, some devices may have a number of pixels that are not connected to the voltage actuation and therefore cannot be adjusted in light transference characteristics. As another example, the liquid crystal itself may not be properly oriented such that even when voltages are applied, the correct transference characteristics do not result. Therefore, it is important to test micro displays to determine whether their pixels will operate to display video images in accordance with voltages that correspond to an input signal.  
           [0006]    Many micro displays are manufactured with a substrate layer and a transparent layer. The substrate layer includes circuitry for applying voltages to particular portions, i.e., pixels, of the transparent layer. Testing of micro displays can include optical analysis of the transparent layer while voltages are applied through the circuitry of the substrate layer. The small size of micro displays can complicate both of these operations. Focussing light on and receiving light from a pixel of a micro display involves targeting a very small area. Some micro displays include over two million pixels in an area of less than one square inch. Electrically connecting successive micro displays to be tested such that the connection is made rapidly and accurately can also be a challenge.  
           [0007]    The small size and delicate nature of some micro displays formed of a transparent layer mounted on a substrate can also be taken into account. The characteristics of a micro display may not be accurately determined if the micro display is subject to physical forces while being optically analyzed. For example, the physical devices holding the micro display in place can affect the outcome of the testing if the pixels experience physical forces such as tension. Even worse, excessive amounts of such forces can damage pixels or the circuitry needed to actuate those pixels. In such a situation the testing method and apparatus would be counterproductive. Holding the micro display in a position relative to the tester is important however, both for purposes of accurately establishing electrical connection with the display and for accurately targeting particular pixels for optical analysis.  
         SUMMARY OF THE INVENTION  
         [0008]    The embodiments of the present application are directed to a system and method of testing a display device. In one embodiment, a base has a surface with at least four holes in it. The display device has two layers and a surface. The first layer is a semiconductor substrate. The second layer is a transparent material. The surface of the display device is coupled to the surface of the base at each of the at least four apertures. The holes are positioned relative to the display device such that gravitational forces on the display device are optimally counterbalanced.  
           [0009]    In another embodiment, a vacuum box includes a first surface. The display device includes two layers. The first layer is a silicon substrate and the second layer is a transparent material. The silicon substrate side of the display device is coupled to the first surface of the vacuum box.  
           [0010]    In another embodiment, a base includes a surface. The display device has a first surface and one or more electrical connectors. The first surface of the display device is mounted on the surface of the base. An electrical probe is mounted on a frame that is coupled to the base. A cam assembly is coupled to the frame. The electrical probe can be positioned by the cam assembly relative to the display device.  
           [0011]    In another embodiment, performing a method orients a display device for testing. A first surface of the display device is positioned proximate to a surface of a base. The base surface includes four apertures. The pressure within the base is reduced relative to the pressure on a second surface of the display device. The base is sealed by blocking the four apertures with the first surface of the display device, such that the display device is held to the base at the four apertures by a pressure differential that optimally counterbalances gravitational forces on the display device.  
           [0012]    In another embodiment, performing a method couples a display device to an electrical probe. The display device is mounted on a base. The display device includes a transparent layer. The electrical probe is mounted on a frame that is coupled to the base. A cam assembly that is coupled to the frame is actuated to move the electrical probe relative to the display device along a first axis. The first axis is perpendicular to the transparent layer of the display device.  
           [0013]    One technical advantage of the invention is preparing a display device for testing. Another technical advantage of the invention is positioning a display device while optimally reducing tension forces experienced by the display device. Another technical advantage of the invention is positioning the invention relative to an electrical probe to power the display device. Another technical advantage of the invention is positioning the display device along two axes to permit accurate corner and edge alignment capabilities. Those alignment capabilities are relevant to many detector types including human, CCD camera, and photodetector. Another technical advantage is improved of defect resolution and enhanced contrast as a result of the rotation capability of the system. Another technical advantage is the ability to oversample the imager when pixelated detectors (for example cameras) are used, as a result of the rotation and two axes positioning capabilities of the system. Other technical advantages of the present disclosure will be readily apparent to one skilled in the art from the following figures, descriptions, and claims. Various embodiments of the present application obtain only a subset of the advantages set forth. For example, one embodiment of the present invention could only prepare the display device for testing, while another embodiment could achieve several advantages. No one advantage is critical to the disclosure.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    A more complete understanding of the present disclosure and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:  
         [0015]    [0015]FIG. 1 is a side elevation of one embodiment of a structure for testing display devices;  
         [0016]    [0016]FIG. 1A is a top view of a system base;  
         [0017]    [0017]FIG. 2A is a top view of a stage locating base;  
         [0018]    [0018]FIG. 2B is a side view of a stage locating base;  
         [0019]    [0019]FIG. 3 is a top view of a positioning stage base;  
         [0020]    [0020]FIG. 4 is a top view of a pressure plate;  
         [0021]    FIGS.  5 A-C are a top view, side view, and end view of a vacuum block;  
         [0022]    [0022]FIG. 6 is a top view of a vacuum block cover;  
         [0023]    FIGS.  7 A-B are top and side views of a weight stop;  
         [0024]    FIGS.  8 A-C are top, side and end views of a cam anchor plate;  
         [0025]    FIGS.  9 A-C are top, side and end views of a cam linkage;  
         [0026]    [0026]FIG. 10 is a side view of an L cam;  
         [0027]    FIGS.  11 A-B are side and end views of a cam adjustment knob;  
         [0028]    [0028]FIG. 12 is a top view of a spring guide;  
         [0029]    FIGS.  13 A-B are top and side views of an adjustment block;  
         [0030]    [0030]FIG. 14 is a side view of a guide;  
         [0031]    FIGS.  15 A-B are end and side views of a Y-adjustment knob;  
         [0032]    [0032]FIG. 16 is a top view of a cable clamp;  
         [0033]    [0033]FIG. 17 is a side view of one embodiment of micro display optical system;  
         [0034]    FIGS.  18 A-B are top and end views of a beam splitter module;  
         [0035]    [0035]FIG. 19 is a side view of a beam splitter module spacer;  
         [0036]    [0036]FIG. 20 is a top view of a system cover;  
         [0037]    [0037]FIG. 21 is a top view of a cube holder assembly;  
         [0038]    [0038]FIG. 22 is a top view of an optical system base;  
         [0039]    [0039]FIG. 23 is a front view of an optics bracket;  
         [0040]    [0040]FIG. 24 is a side view of a mirror rail;  
         [0041]    [0041]FIG. 25 is a side view of a spacer-mirror;  
         [0042]    [0042]FIG. 26 is a side view of a stop bracket;  
         [0043]    [0043]FIG. 27 is a top view of a guide rail;  
         [0044]    [0044]FIG. 28 is a top view of a guide skid;  
         [0045]    [0045]FIG. 29 is a top view of a spacer block;  
         [0046]    [0046]FIG. 30 is a side view of a fiber-optic lamp bracket; and  
         [0047]    [0047]FIG. 31 is a top view of a projector lens adapter.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0048]    Turning to the drawings, exemplary embodiments of the present application will now be described. Referring to FIG. 1, a side elevation of a structure for testing display devices is provided. The system base  10  includes shaft apertures  16  in each of the four corners of the system base  10 . The shaft apertures  16  are oriented upward. Each of four shafts  14  has an end mounted in one of the shaft apertures  16  of the system base  10 . In one embodiment, the system base  10  is constructed of one-half inch thick aluminum. In one embodiment, the shafts  14  are made by McMaster with product number 6061K11. Apertures  12  in opposite sides of the system base  10  are perpendicular to and extend to the shaft apertures  16 . Set screws can be mounted in the apertures  12  to apply force to the shafts  14  located in the shaft apertures  16  and lock them in place.  
         [0049]    A stage locating base  30  is located on top of the system base  10 . The stage locating base  30  is coupled to the system base  10  by fasteners  24  that are fixed to the stage locating base  30  at apertures  34  and positioned in slots  18  of the system base  10 . The slots  18  include a wider portion  20  and a narrower portion  22  to accommodate the head and body of the fastener  24  respectively. The fastener  24  has limited movement along the Y-axis, i.e., left and right in FIG. 1, with respect to the system base  10 , e.g., the length of the slots  18 . The stage locating base  30  therefore has the same limited Y-axis movement with respect to the system base  10 , because it is attached to the fasteners  24 . The stage locating base  30  is longer than the system base  10  along the Y-axis, but is shorter along the X axis, i.e., into and out of the face of FIG. 1. The stage locating base  30  fits between the four shafts  14  and the weight stops  70  that surround the shafts  14  near the system base  10 .  
         [0050]    Two guides  32  are mounted to the sides of the stage locating base  30  and extend above the stage locating base  30 . A positioning stage base  40  is located on top of the stage locating base  30  and is constrained from movement along the X-axis by the guides  32 . The positioning stage base  40  has the same dimensions along the X-axis as the stage locating base  30 , but is shorter along the Y-axis. Slots  41  in the positioning stage base  40  accommodate fasteners  52 ,  54  in sliding engagement. The fasteners  52 ,  54  are fixed to the stage locating base  30  at apertures  36 . The positioning stage base  40  can therefore move relative to the stage locating base  30  to the extent that the fasteners  52 ,  54  can move in the slots  41 . A spring guide  42  includes a horizontal shaft  44  that extends into an aperture  43  in the positioning stage base  40 . A spring  46  is mounted on the horizontal shaft  44  and biases the positioning stage base  40  to the left relative to the stage locating base  30  to which the spring guide  42  is attached. A Y-adjustment knob  48  includes a threaded shaft  49  that is threadedly engaged with an adjustment block  50  and contacts the positioning stage base  40 . The bias of the spring  46  holds the positioning stage base  40  against the threaded shaft  49 . The position of the threaded shaft  49  can be adjusted along the Y-axis by rotation of the Y-adjustment knob  48  around the Y-axis, which causes the threads of the shaft  49  to move within the adjustment block  50  along the Y-axis.  
         [0051]    The positioning stage base  40  includes four apertures  45  for coupling to the stage  60 . In one embodiment, the stage  60  is a Model 4575 Daedal Combination Linear/Rotary Stage. The top surface of the stage is coupled to a vacuum box that includes a vacuum block  62  and a vacuum block cover  64 . The stage  60  is adjustable to rotate the vacuum block  62  relative to the positioning stage base  40  around a Z-axis, i.e., the vertical axis in FIG. 1. The stage  60  is also adjustable to move the vacuum block  62  along the X-axis relative to the positioning stage base  40 . As a combination, the stage  60 , positioning stage base  40 , stage locating base  30 , and system base  10  are able to position the vacuum block  62  linearly in two perpendicular directions, the X-axis and the Y-axis, relative to the system base  10  and rotationally around the Z-axis relative to the system base  10 . Those positioning options yield advantages for testing of devices coupled to the vacuum block cover  64 .  
         [0052]    A two layer device  152  is mounted on the vacuum block cover  64 . The mounting structure is discussed in more detail with regard to FIG. 6. In one embodiment, the device  152  is a micro display that has a silicon substrate layer and a transparent glass layer. The top layer of the device  152  is the transparent layer as can be seen from FIG. 17 which shows the optical targeting occurring from the top. The bottom layer is therefore the silicon substrate for a micro display. The bottom layer of the device  152  is the layer which has a bottom surface coupled to the vacuum block cover  64  as can be seen from FIG. 1. Using the combination discussed above, the device  152  can be moved in the X-axis, the Y-axis, and the rotational +-axis relative to the system base  10  and thus also to the shafts  14  rigidly attached to the system base  10 .  
         [0053]    The weight stops  70  that surround the shafts  14  near the system base  10  are each cylindrical and define an interior shoulder  74  that supports a spring  72 . The four springs  72  bias four bearings  78 ,  80  upward. Each of the four bearings has a wider top portion  92 . Each of the four bearings is attached to a pressure plate  90 . The pressure plate supports an electrical probe  150  that can couple with the device  152  to provide electrical power and communications.  
         [0054]    A cam assembly is provided to counterbalance along the Z-axis the biasing force of the springs  72  exerted through the bearings  78 ,  80  on the pressure plate  90 . The cam assembly includes four L cams  110 , a cam anchor plate  100 , a cam linkage  120 , and a cam knob  130 . The cam anchor plate  100  is fixed to each of the four shafts  14  at a particular position along the Z-axis by fasteners  102 . The cam anchor plate  100  supports an adjustment block  140  that is threadedly engaged with a threaded shaft  132  of the cam knob  130 . The cam linkage  120  includes slots  122  through which it is coupled to the two leftmost shafts  14  allowing for movement along the Y-axis relative to the shafts  14 . The L cams  110  are each rotatably coupled around the X-axis to the cam linkage  120  via fasteners mounted in apertures  114 . The L cams  110  are each also rotatably coupled around the X-axis to the cam anchor plate  100  via fasteners mounted in apertures  112 . When the cam knob  130  is rotated around the Y-axis, the threaded shaft  132  moves along the Y-axis relative to the adjustment block  140  and attached cam anchor plate  100  and pushes against the cam linkage  120 . When the cam linkage  120  is moved along the Y-axis relative to the cam anchor plate  100 , the L cams  110  rotate clockwise around the x-axis. The bottoms of the L cams  110  each press against the tops of the bearings  92  as a result of the rotation and move the pressure plate  90  downward, while counterbalancing the resulting upward force of the springs  72 . The cam assembly, through this mechanic, positions the electrical probe  150  relative to the device  152  along the Z-axis.  
         [0055]    By operation of the previously-described structure the electrical probe  150  and the display device  152  can be moved relative to each other along the X-axis, the Y-axis, and the Z-axis. In addition, the electrical probe and the display device can be moved relative to each other in the φ-axis of rotation around the Z-axis.  
         [0056]    [0056]FIG. 1A illustrates a top view of the system base  10 . The shaft apertures  12  in each corner intercept apertures  16  used for set screws that anchor the shafts  14 . Slots  18  contains fasteners  24  that slidingly engage the system base  10  to the stage locating base  30 . Additional apertures are provided for coupling the system base  10  to another surface.  
         [0057]    [0057]FIG. 2A illustrates a top view of the stage locating base  30 . Apertures  34  are defined for receiving fasteners  24  that slidingly engage the system base  10  to the stage locating base  30 . Apertures  36  are defined for receiving fasteners  52 ,  54  that slidingly engage the positioning stage base  40  to the stage locating base  30 . Apertures  37  are defined for receiving fasteners coupling the adjustment block  50  to the stage locating base  30 . Apertures  38  are defined for receiving fasteners coupling the spring guide  42  to the stage locating base  30 . FIG. 2B illustrates a side view of the stage locating base  30 . Apertures  33  are defined for receiving fasteners coupling a guide  32  to each side of the stage locating base  30 .  
         [0058]    [0058]FIG. 3 illustrates a top view of the positioning stage base  40 . Slots  41  contains fasteners  52 ,  54  that are coupled to the stage locating base  30 . Apertures  45  are provided to fixedly couple the positioning stage base  40  to the bottom surface of the stage  60 . Aperture  43  extends horizontally into the end of the positioning stage base  40  to receive the shaft  44  of the spring guide  42 .  
         [0059]    [0059]FIG. 4 illustrates a top view of the pressure plate  90 . The pressure plate  90  includes apertures  96  for receiving the bearings  78 ,  80  therethrough. Additional apertures  98  are defined to receive fasteners attaching the bearings  78 ,  80  to the pressure plate  90 . Apertures  93 ,  95 ,  97  are used to attach to the pressure plate  90  devices that are to be moved relative to the display device  152 , one example being the electrical probe  150 . Another example is a cable clamp as shown in FIG. 16.  
         [0060]    FIGS.  5 A-C illustrate a top view, side view, and end view of a vacuum block  62 . The vacuum block  62  includes apertures  65  in its bottom plate for sealed coupling to the stage  60 . The vacuum block  62  also includes apertures  66  in each corner for coupling the vacuum block cover  64 . An aperture  68  defined in a side wall of the vacuum block  62  allows a connection for evacuating the vacuum block  62  to lower the internal pressure relative to the external pressure.  
         [0061]    [0061]FIG. 6 illustrates a vacuum block cover  64 . The cover  64  includes four apertures  66  for receiving fasteners that attach the cover  64  to the vacuum block  62 . The cover also includes  4  apertures  63  arranged at the vertices of a rectangle. The apertures  63  are arranged in two pairs with the distance between each aperture in a pair being one sixth of the distance between the pairs. The position of the apertures  63  has been found to lower the stress on a micro display  152  coupled to the vacuum block cover  64  by a pressure differential between the apertures  63  and pressure on the other surfaces of the micro display  152 . In another embodiment, the pairs of apertures are separated by a distance at least five times the distance between apertures in a pair in order to reduce physical stresses on the display device  152 .  
         [0062]    FIGS.  7 A-B illustrate top and side views of one of the four weight stops  70 . Each weight stop  70  includes a cavity throughout its length with sufficient diameter to enclose a shaft  14 . The cavity in the upper portion of the weight stop  70  has greater diameter than the cavity in the lower portion of the weight stop  70 . An internal shoulder  74  is formed at the change in diameter. The internal shoulder  74  of each weight stop  70  supports a spring  72  that surrounds the shaft  14 .  
         [0063]    FIGS.  8 A-C illustrate top, side and end views of the cam anchor plate  100 . Two horizontal apertures  102  are provided around a socket for each shaft  14  for fixing the cam anchor plate  100  to each shaft  14  along the Z-axis. An adjustment block  140  is attached to the top of one end of the cam anchor plate  100  by fasteners  144 . The adjustment block  140  includes a threaded aperture  142  for receiving the threaded shaft  132  of the cam adjustment knob  130 . The side view shows apertures  112  for attaching the L cams  110  in a rotational relationship with the cam anchor plate  100 . An L cam  110  in attached proximate to each of the four shafts  14 .  
         [0064]    FIGS.  9 A-C illustrate top, side and end views of the cam linkage  120 . The cam linkage  120  includes slots  122  for receiving two of the four shafts  14 . One end of the cam linkage  120  includes a plate  124  attached with fasteners  126 . The plate  124  receives force from the end of the threaded shaft  132  when the cam adjustment knob  130  is actuated sufficiently to position the end of the threaded shaft  132  against the plate  124 . The side view shows apertures  114  for attaching the L cams  110  in a rotational relationship with the cam linkage  120 . An L cam  110  in attached proximate to each of the four shafts  14 .  
         [0065]    [0065]FIG. 10 illustrates a side view of an L cam  110 . Each L cam  110  includes an aperture  114  at the top for rotational engagement with the cam linkage  120 . Each L cam  110  also includes an aperture  112  in the corner of the L cam  110  for rotational engagement with the cam anchor plate  100 . The end of the L cam  110  that does not include an aperture applies pressure to the head  92  of one of the bearings  78 ,  80 , when the L cam  110  rotates.  
         [0066]    FIGS.  11 A-B illustrate side and end views of a cam adjustment knob  130 . The cam adjustment knob  130  includes a threaded shaft  132  for threadedly engaging the adjustment block  140 . The end of the threaded shaft  132  applies horizontal force to the plate  124  of the cam linkage  120 , when it is in an extended position. An aperture  134  in the cam adjustment knob  130  is provided. That aperture  134  can be used to attach further adjustment devices.  
         [0067]    [0067]FIG. 12 illustrates a top view of a spring guide  42 . The spring guide  42  includes a horizontal shaft  44  for mounting the spring  46  and apertures  38  for attaching the spring guide  42  to the stage locating base  30 .  
         [0068]    FIGS.  13 A-B illustrate top and side views of the adjustment block  50 . Apertures  37  are provided for attaching the adjustment block  50  to the stage locating base  30 . A threaded aperture  56  is provided through the entire length of the adjustment block  50  for threaded engagement with the threaded shaft  49  of Y-adjustment knob  48 .  
         [0069]    [0069]FIG. 14 illustrates a side view of a guide  32  including apertures  33  for attaching the guide  32  to the stage locating base  30 .  
         [0070]    FIGS.  15 A-B illustrate end and side views of a Y-adjustment knob  48 . The Y-adjustment knob  48  includes a threaded shaft  49  for threadedly engaging the adjustment block  50 . The end of the threaded shaft  49  applies horizontal force to the positioning stage base  40 , when it is in an extended position. An aperture  47  in the Y-adjustment knob  48  is provided. That aperture  47  can be used to attach further adjustment devices. FIG. 16 illustrates a top view of a cable clamp  154  that can be attached to the pressure plate  90  at apertures  97 .  
         [0071]    [0071]FIG. 17 illustrates one embodiment of micro display optical system  200  using an embodiment of a micro display manual tester. An optical system base  202  is supported by feet  204 . Guide rails  208  and guide skids  210  are mounted on the optical system base  202  for guiding the micro display manual tester in and out of position. A stop bracket  212  limits the manual tester from moving into contact with the fiber-optic lamp bracket  214 , which is attached to the optical system base by a fastener  216 . A fiber optic high intensity lamp  218  is mounted on the fiber-optic lamp bracket  214  so as to illuminate a lens  220 . The light then enters a beam splitter module  222  that contains a cube holder assembly  224  attached to the interior thereof. A system cover  206  is attached to the optical system base  202  and supports a projector lens adapter  226 . In another embodiment the system cover  206  supports a projection lens.  
         [0072]    An optics bracket  228  includes a beam splitter module spacer  227  and one or more spacer blocks  227 . The optics bracket  228  supports a mirror assembly  230  that includes mirror rails and a spacer mirror that can be adjusted in height by attachment to one of the several apertures defined by the optics bracket  228 . The light resulting from the fiber optic high intensity lamp  218  that has been targeted at the device  152  is reflected off the mirror assembly  230  for analysis.  
         [0073]    FIGS.  18 A-B illustrate top and end views of the beam splitter module  222 . The module  222  includes a top aperture  223  and a side aperture  221 . Light from the fiber optic high intensity lamp  218  enters the module  22  through the side aperture  221  and can leave through both the bottom and the top of the module  222 .  
         [0074]    [0074]FIG. 19 illustrates a side view of a beam splitter module spacer  227  that can be used to support the beam splitter module  222  with respect to the system cover  206 . FIG. 20 illustrates a top view of the system cover  206  showing the extended half circle which can be lined up with the top aperture  223  of the beam splitter module  222  to allow light to reach the mirror assembly  230  supported between the optics brackets  228 .  
         [0075]    [0075]FIG. 21 illustrates a top view of a cube holder assembly  224 . The cube holder assembly  224  can be used to support an optical device that receives light from the fiber optic high intensity lamp  218  and reflects it downward to the display device  152 .  
         [0076]    [0076]FIG. 22 illustrates a top view of the optical system base  202 . The optical system base  202  includes several apertures for attaching the guide rails  208 , guide skids  210 , stop bracket  212 , feet  204 , and fiber-optic lamp bracket  214 .  
         [0077]    [0077]FIG. 23 illustrates a front view of an optics bracket  228 . The optics bracket  228  has a low, wide portion and a high, narrow portion. The two apertures in the low portion allow fasteners to support the optics bracket  228  relative to the optical system base  202 . The seven apertures in the high portion of the optics bracket  228  allow the mirror assembly  230  to be attached at a variety of heights.  
         [0078]    [0078]FIG. 24 illustrates a mirror rail  230  that can be attached at the central aperture to one of the optics brackets  228 . The central groove of the mirror rail  230  that runs its length can be used in association with another mirror rail  230  mounted on the other optics bracket  228  to hold a mirror. FIG. 25 illustrates a spacer-mirror.  
         [0079]    [0079]FIG. 26 illustrates a side view of the stop bracket  212 , which is attached to the optical system base  202  by fasteners placed in the two apertures shown in dotted lines. FIG. 27 illustrates a guide rail  210 . FIG. 28 illustrates a guide skid  208 . Both the guide rail  210  and the guide skid  208  are fixed to the optical system base  202 .  
         [0080]    [0080]FIG. 29 illustrates a top view of a spacer block  227  that can be used in conjunction with a beam splitter module spacer  227  to support components relative to the optical system cover  206 . FIG. 30 illustrates a side view of a fiber-optic lamp bracket  214  including the apertures by which a fiber optic high intensity lamp  218  can be mounted. FIG. 31 illustrates a top view of a projector lens adapter  226 . The projector lens adapter can be mounted in the light path of the top aperture  223  of the beam splitter module  222 .  
         [0081]    While the present embodiments are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.