Abstract:
Spatial light modulator techniques for stage lighting. A first technique pieces together multiple spatial light modulator&#39;s or sectors within an existing spatial light modulator to form an overall area which is closer to being square. For example, to 16×9 spatial light modulators may be located next to one another to form, in effect, a 16×18 spatial light modulator. The same thing can be done within sectors of the spatial light modulator. New forms for the spatial light modulator are also disclosed including a ferroelectric liquid Crystal. The spatial light modulators can receive computer-generated holograms to form three-dimensional representations that are projected from a stage light.

Description:
BACKGROUND 
       [0001]    Stage lighting often includes projecting high-intensity beams of light in specified shapes, colors and with specified effects, onto a stage. The basic perimeter shape of such a beam is typically circular, although “gobos” can be used to shape the outer circumference of the shape to any desired single or multiple shape. 
         [0002]    Pixel-level controllable gobos have been implemented, including the so-called digital light. Digital lights use spatial light modulators such as digital mirror devices or grating light valves to control the projection of the light. These allow both video to be produced, but also allow shaping the outer perimeter of the beam. 
       SUMMARY  
       [0003]    The present application describes an improved digital light device and method, using a spatial light modulator technique which allows new effects. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is an illustration showing a light producing a light beam; 
           [0005]      FIG. 2  is a flowchart showing how the controller controls the spatial light modulators; 
           [0006]      FIG. 3  illustrates an embodiment where each spatial light modulator has its own light source; 
           [0007]      FIG. 4  illustrates an embodiment where a single spatial light modulator is logically divided into the first and second parts; and 
           [0008]      FIG. 5  shows an embodiment with a computer generated hologram. 
       
    
    
     DETAILED DESCRIPTION  
       [0009]    The general structure and techniques, and more specific embodiments which can be used to effect different ways of carrying out the more general goals, are described herein. 
         [0010]    According to one embodiment, two or more separate spatial light modulators are used to form different parts of a single projected beam. 
         [0011]    Digitally controlled spatial light modulators have recently found application for use in television applications. Accordingly, the chip manufacturers have tended to optimize the packaging and aspect ratio of the spatial light modulators for use in television. 
         [0012]    Unfortunately for the stage lighting industry, television has evolved towards screens with wider aspect ratios. The 4:3 aspect ratio of the 80&#39;s has evolved into a 16:9 aspect ratio, or even wider aspect ratios. Projection of light in a stage lighting environment, however, more often makes use of symmetrical perimeters such as circles and triangles. This means, therefore, that only a fraction of the rectangular aspect ratio chip has been used. 
         [0013]    Square or circular chips would be ideal for stage lighting, but the chip manufacturers are unlikely to make them in the future. Therefore only a very small part of the chip can be used. 
         [0014]    According to the present embodiment, the overall light beam to be modified and/or shaped by the spatial light modulator (“SLM”) is divided. The divided light beam is then shaped, and pieced back together. By dividing the light beam, the rectangular aspect ratio of the spatial light modulator can be used as a slice of the overall beam. The light beam is pieced together in slices edge to edge. Edge blending techniques are used on the edges of the pieced image to allow an edge blended image to be formed from two separate SLM&#39;s. For example, 2 16×9 SLM&#39;s can be used to each project half of a display—for an effective size of 16×18. 
         [0015]      FIG. 1  shows a first embodiment in which a light  100  produces a light beam  105 . In the embodiment, the system may be used in stage lighting, and therefore the light may be between 100 and 900 W, more preferably at least 300 W in illumination. The light beam  105  is first modified by preprocessing optical system  110 . The preprocessing optical system  110  may include a dichroic system which rejects certain parts of the infrared, and may also include certain kinds of coloration parts. In the embodiment, the entire light beam may be uniformly colored even though that uniformly colored light beam is being sent to multiple different spatial light modulators. The light beam is divided at  120  into a first light path  130  and a second light path  135 .  120  may simply be a prism or mirror assembly that divides the beam into two laterally divided beams. The beam  130  is sent to a first spatial light modulator  140 , and the beam  135  is sent to a second spatial light modulator  145 . According to the embodiment, the spatial light modulators may be mirror devices or DMD&#39;s. Alternatively, the spatial light modulators can be other devices, such as liquid crystals, ferroelectric liquid crystals, or other similar devices. Ferroelectric liquid crystals may be particularly interesting, because of their ability to switch light quickly and in interesting ways. 
         [0016]    Both of the spatial light modulators  140 ,  145  are connected to and controlled by a controller  150 . Controller  150  controls the spatial light modulators according to the flowchart of  FIG. 2 . The controller  150  may itself be controlled by a central controller  149 , that also controls other lights. According to this flowchart, an image is divided laterally into two parts, with a dividing point of the image corresponding to a dividing point between the two parts of the two spatial light modulators. Of course, more than two SLM&#39;s may be used, e.g., 3 or 4. It may be preferred that the SLM&#39;s form as close to a square as possible when laterally pieced together. Since different parts of the image are controlled by different parts of the spatial light modulator, an edge blending effect is also carried out to edge blend the pieces image. 
         [0017]    At  200 , the image or gobo which is going to be used by the spatial light modulators is obtained. This image or gobo may be a circle, or may be any desired shape.  201  shows this image as being a circle. This may be any shape, preferably a shape other than a rectangle. The image is divided laterally at  205 , so that the image is formed into two sub image parts with a dividing line between the two parts. This is shown in  205  as the left image part  210 , and right image part  215  with the dividing line between the two parts as  217 . At  220 , the images of the laterally divided images are edge blended. For example, the image part  210  has its edge  222  blended with the edge  224  of the other part  215 . These parts may be blended to be slightly overlapped, or to remove edge effects, using any known image blending technique. The edge blending changes the images in a way such that the images  210  and  215  can be displayed directly next to one another and look like a single image. Technology for modifying positions of the images in this way are well-known, for example, used in multiple DMD based devices. At  230 , the images are then combined. 
         [0018]    Note that both the images from the spatial light modulators  140  and  145  correspond to different parts of the same image at the same time. This compares with other multiple spatial light modulator devices where each spatial light modulator handles a separate part of the image, produced at different times, which are averaged together by persistence of vision. 
         [0019]    The image output  151  from light modulator  140  and the image output  152  from light modulator  145  form the two parts of the projected beam. Post optics  160  receive these projected beams, and may color the beam, and may also include lensing and other elements to more precisely register the two beam parts with one another. The output of the optics is the beam itself shown as  170 , which is an overall image as shaped by the two image parts, with an edge blended portion  175  as its pieced-together central portion. 
         [0020]    Different modifications of this basic concept are also contemplated.  FIG. 3  illustrates an embodiment where each spatial light modulator  140 ,  145  has its own light source,  200 ,  210  respectively associated therewith. This may allow more brightness out of the device, at a cost of more power consumption and a heavier and larger device. 
         [0021]      FIG. 4  illustrates an alternative embodiment, in which a single spatial light modulator  400  is logically divided into the first and second parts  405 ,  410 . Each of the parts corresponds to a division which is in a direction which tends to preserve more symmetry in the geometry of the spatial light modulator  400 . In this embodiment, the computer  420  divides the overall image into its two halves, and feeds those two halves respectively to portions of the single spatial light modulator. The light beam is shaped in this way, later processed by optics  430 , and used to form the final shape image  440 . As in the other embodiments, the area of overlap between the two partial images shown as  441 , is edge blended by the computer operation. Also, as in the other embodiments, the image may be divided into more than 2 parts, e.g., 3 or 4 parts 
         [0022]    According to another embodiment shown in  FIG. 5 , the spatial light modulator, such as a DMD or other device, is controlled by a computer  500  in order to form a computer-generated hologram. Computer-generated holography uses interference and diffraction to record and reconstruct optical waveforms, and may be used to manipulate light in ways that are not possible using pure lens and mirror systems. For example, the computer-generated holograph can be used to synthesize a three-dimensional image that has stereoscopic displays, and use that to form a hologram on the spatial light modulator  510  which is used for projection of an image. Grayscale images from the spatial light modulator can be formed from binary fringe patterns. This embodiment may also divide the images into multiple parts and edge blend them, as in the embodiments of  FIGS. 1-4 . This embodiment also may gobo the outer shape, so that the outer shape is something other than a rectangle. 
         [0023]    The general structure and techniques, and more specific embodiments which can be used to effect different ways of carrying out the more general goals are described herein. 
         [0024]    Although only a few embodiments have been disclosed in detail above, other embodiments are possible and the inventor intends these to be encompassed within this specification. The specification describes specific examples to accomplish a more general goal that may be accomplished in another way. This disclosure is intended to be exemplary, and the claims are intended to cover any modification or alternative which might be predictable to a person having ordinary skill in the art. For example, other divisions and other SLM&#39;s are possible. 
         [0025]    Also, the inventor intends that only those claims which use the words “means for” are intended to be interpreted under 35 USC 112, sixth paragraph. Moreover, no limitations from the specification are intended to be read into any claims, unless those limitations are expressly included in the claims. The computers described herein may be any kind of computer, either general purpose, or some specific purpose computer such as a workstation. The computer may be a Pentium class computer, running Windows XP or Linux, or may be a Macintosh computer. The computer may also be a handheld computer, such as a PDA, cellphone, or laptop. 
         [0026]    The programs may be written in C, or Java, Brew or any other programming language. The programs may be resident on a storage medium, e.g., magnetic or optical, e.g. the computer hard drive, a removable disk or media such as a memory stick or SD media, or other removable medium. The programs may also be run over a network, for example, with a server or other machine sending signals to the local machine, which allows the local machine to carry out the operations described herein.