Image replication system having focusing means to receive reflected light through lightguide from spatial light modulator

Abstract

The present invention relates, in one aspect to an image replication system comprising a light guide ( 2 ), a light source ( 8 ) arranged to direct emitted light into the first end ( 2 a) of a light guide ( 2 ), a reflective spatial light modulator ( 6 ) and focussing means ( 16 ). In a preferred embodiment, the light guide ( 2 ) is in the form of an elongate glass rod having first and second parallel polygonal end faces ( 2 a, 2 b) which are parallel to the long axis of the rod, the rod having a uniform polygonal cross section along its length. The spatial light modulator ( 6 ) is optically coupled to the second end face ( 2 b) of the light guide ( 2 ) and the focussing means ( 16 ) is arranged to receive light reflected back through the rod from the spatial light modulator ( 6 ), whereby to form multiple images of said spatial light modulator in an image plane ( 18 ).

What is claimed is: 
     
       1. An image replication systems system comprising:
 (i) an elongate light guide having a polygonal cross section and parallel sides along its a length, of the light guide; 
 (ii) a light source arranged to direct emitted non-collimated light, in use, into the light guide at its a first end, of the light guide, wherein the light incident with the parallel sides is internally reflected through the light guide toward a second end of the light guide; 
 (iii) a reflective first spatial light modulator optically coupled to the second end of the light guide,; and 
 (v) focussing means arrangedfocusing means configured to receive light reflected through the light guide from the first spatial light modulator, said reflective light having exited wherein the reflected light exits the light guide through its the first end, and to form multiple images derived from said first the spatial light modulator in an image plane. 
 
     
     
       2. A system as claimed in The system of  claim 1 , wherein the light source is a source of non-polarised non-polarized light. 
     
     
       3. A system as claimed in The system of  claim 1 , wherein the light source is a source of polarised polarized light, and wherein further comprising means for converting polarised the polarized light to non-polerised non-polarized light are provided, and wherein the means for converting is located in the light path between the light source and the light guide. 
     
     
       4. A system as claimed in  claim 1 , wherein the light source is a source of collimated light and wherein a light spreading element is disposed in the light path between the light source and the light guide. 
     
     
       5. A system as claimed in The system of  claim 1 , wherein the light guide is in the form of a solid rod of optically transparent material, preferably glass, having first and second perpendicular polygonal end faces, said and wherein the first and second end faces being are parallel to the each other and perpendicular to a longitudinal axis of the rod. 
     
     
       6. A system as claimed in The system of  claim 5 , wherein the longitudinal edges of the light guide are beveled. 
     
     
       7. A system as claimed in The system of  claim 6 , wherein the bevel depth is about 1% or less of the distance between adjacent longitudinal edges. 
     
     
       8. A system as claimed in The system of  claim 1 , wherein the light guide is a hollow pipe, the internal surfaces of the pipe being light reflective. 
     
     
       9. A system as claimed in The system of  claim 8 , wherein the light guide is constructed from discrete reflecting elements. 
     
     
       10. A system as claimed in The system of  claim 8 , wherein the light guide is moulded molded from glass, plastics or metal. 
     
     
       11. A system as claimed in The system of  claim 8 , wherein the light guide is sealed at its the first end and at the second end by transparent end pieces. 
     
     
       12. A system as claimed in The system of  claim 11 , wherein the light guide is evacuated or gas or liquid filled. 
     
     
       13. A system as claimed in The system of  claim 1 , wherein the first spatial light modulator modulates the polarisation a polarization state of incident light. 
     
     
       14. A system as claimed in The system of  claim 13 , wherein the first spatial light modulator comprises a pixelated liquid crystal layer on a reflective silicon backing layer, switched pixels causing modulation of the polarisation polarization state of incident light, unswitched pixels causing no such modulation and/or absorption of light incident thereon. 
     
     
       15. A system as claimed in The system of  claim 13 , wherein the polariser is provided spatial light modulator is located in the light path between the light guide and the focussing focusing means, and is orientated such that only reflected modulated light passes therethrough to form an image in the image plane and/or a polariser polarizer is provided located between the light source and the light guide. 
     
     
       16. A system that is claimed in The system of  claim 13 , wherein a polariser polarizer is provided located between the light guide and first spatial light modulator, with wherein a fractional-wave plate being provided is located between the polariser polarizer and the first spatial light modulator, and wherein the fractional wave fractional-wave plate is chosen such that only light passing through the polariser polarizer and wave fractional-wave plate and incident on a switched pixel, passes back through the wave fractional-wave plate and polariser the polarizer upon reflection from the spatial light modulator. 
     
     
       17. A system claimed in The system of  claim 1 , wherein the first spatial light modulator modulates the reflectivity or angular deflection of incident light. 
     
     
       18. A system as claimed in The system of  claim 1 , wherein the light guide is provided with comprises an additional light source around its a periphery at of an end of the light guide which, in use, will be adjacent the first spatial light modulator. 
     
     
       19. A system as claimed in The system of  claim 18 , wherein said the additional light source comprises a plurality of optical fibres, and wherein a diffusing element is provided located between the optical fibres and the first spatial light modulator. 
     
     
       20. A system as claimed in The system of  claim 18 , wherein a light steering element is provided configured to direct light emitted from the additional light source towards edge regions of the first spatial light modulator. 
     
     
       21. A system as claimed in The system of  claim 1 , wherein further comprising an image screen is provided for viewing images formed located in the image plane. 
     
     
       22. A system as claimed in The system of  claim 1 , wherein a photosensitive material is provided located in an the image plane. 
     
     
       23. A system as claimed in The system of  claim 1 , wherein a second, an optically addressable, spatial light modulator is provided located in the image plane. 
     
     
       24. A system as claimed in The system of  claim 23 , wherein the optically addressable spatial light modulator is comprises a ferroelectric liquid crystal light modulator on a silicon backing. 
     
     
       25. A system as claimed in claims The system of claim  23 , wherein further comprising means are provided to selectably sensitise for selectively sensitizing a predetermined region of the second optically addressable spatial light modulator to incident light. 
     
     
       26. A system as claimed in The system of  claim 1 , wherein further comprising means are provided to produce for producing an image from light reflected from the first spatial light modulator in a predetermined region of the image plane. 
     
     
       27. A system as claimed in The system of  claim 26 , wherein said the means for producing comprises means to introduce an angular bias to light from the light source prior to entry into the light guide in conjunction with a narrow angle diffuser. 
     
     
       28. A system as claimed in The system of  claim 26 , wherein said the means for producing comprises an electro-optical or mechanical shutter. 
     
     
       29. A system as claimed in The system of  claim 1 , wherein further comprising means for guiding light from the light source to the light guide are provided. 
     
     
       30. A system as claimed in The system of  claim 29 , wherein said light the means for guiding means light comprises a beam splitter located between the light source and the light guide and an optical relay located between the light source and the beam splitter. 
     
     
       31. A system as claimed in The system of  claim 30 , wherein the optical relay comprises a pair of mutually spaced lenses with a variable aperture stop located therebetween. 
     
     
       32. A system as claimed in The system of  claim 31 , wherein further comprising an amplitude mask is provided located in the stop of the optical relay. 
     
     
       33. A system as claimed in The system of  claim 1 , further comprising a plurality of light guides. 
     
     
       34. A system as claimed in The system of  claim 33 , wherein said the plurality of light guides are arranged in an array such that adjacent light guides are mutually spaced. 
     
     
       35. An image replication method comprising providing a light source and modulating the light emitted therefrom using first spatial light modulator, the method characterised by:
 directing, in a first direction, light through an elongate light guide having a polygonal cross section and parallel sides along its a length of the light guide, wherein the elongated light guide is configured to direct the light by virtue of total internal reflection of the light within the polygonal cross section; 
 modulating said the light with the first spatial light modulator,; 
 reflecting said the modulated light in a direction opposite to said the first direction back through the light guide,; and 
 focussing saidfocusing the modulated light in an image plane. 
 
     
     
       36. The system of claim 1, wherein the elongated light guide comprises reflective surfaces configured to reflect the light, and wherein the reflective surfaces form the polygonal cross section of the elongated light tube. 
     
     
       37. The system of claim 36, wherein the elongated light guide is configured to reflect the light by virtue of total internal reflection of the light between the reflective surfaces. 
     
     
       38. The system of claim 1, wherein the light incident with the parallel sides is internally reflected from the parallel sides through the light guide. 
     
     
       39. The image replication method of claim 35, wherein the light directed through the elongated light guide is received from a non-collimated light source. 
     
     
       40. A method comprising:
 transmitting light received from a non-collimated light source through an elongated light guide comprising parallel sides along a length of the elongated light guide, wherein the light incident with the parallel sides is internally reflected from the parallel sides within the elongated light guide;   modulating the light transmitted through the elongated light guide; and   reflecting the modulated light back into the elongated light guide to form one or more replicated images.   
     
     
       41. The method of claim 40, further comprising:
 converting the light to non-polarized light prior to modulating the light.   
     
     
       42. The method of claim 40, wherein modulating the light comprises modulating a polarization state of the light. 
     
     
       43. The method of claim 40, wherein modulating the light comprises modulating an angular deflection of the light. 
     
     
       44. The method of claim 40, further comprising:
 modulating the reflected light prior to forming the one or more replicated images.   
     
     
       45. The method of claim 44, further comprising:
 focusing the reflected light in an image plane, wherein the reflected light is modulated in the image plane.   
     
     
       46. An apparatus comprising:
 a spatial light modulator (SLM); and   an elongated light guide configured to direct light received from a non-collimated light source onto the SLM, wherein the elongated light guide comprises parallel sides along a length of the elongated light guide, wherein the light incident with the parallel sides is internally reflected from the parallel sides within the elongated light guide toward the SLM, and wherein the SLM is configured to modulate the light such that a portion of the light is reflected back into the elongated light guide.   
     
     
       47. The apparatus of claim 46 wherein the SLM comprises switchable pixels configured to modulate reflectivity. 
     
     
       48. The apparatus of claim 47 wherein switched pixels reflect the portion of the light to an end of the elongated light guide opposite the SLM. 
     
     
       49. The apparatus of claim 46 wherein the SLM comprises switchable pixels configured to modulate angular deflection. 
     
     
       50. The apparatus of claim 49 wherein switched pixels are configured to reflect the modulated light to an end of the elongated light guide opposite the SLM. 
     
     
       51. The apparatus of claim 46, further comprising a focusing device that receives the modulated light, wherein the focusing device is configured to receive the modulated light from an end of the elongated light guide opposite the SLM. 
     
     
       52. The apparatus of claim 46, further comprising a light source configured to direct non-polarized light into the elongated light guide. 
     
     
       53. The apparatus of claim 46, wherein the elongated light guide comprises a polygonal cross section of the elongated light tube, and wherein the elongated light guide is configured to reflect the light by virtue of total internal reflection of the light within the polygonal cross section. 
     
     
       54. The apparatus of claim 46, wherein the elongated light guide is configured to reflect the light by virtue of total internal reflection of the light within the parallel sides. 
     
     
       55. An apparatus, comprising:
 means for transmitting light received from a non-collimated light source through an elongated light guide comprising parallel sides along a length of the elongated light guide, wherein the light incident to the parallel sides is internally reflected from the parallel sides within the elongated light guide;   means for modulating the transmitted light; and   means for reflecting the modulated light back into the elongated light guide to form one or more replicated images.   
     
     
       56. The apparatus of claim 55, wherein a portion of the modulated light is reflected to an end of the elongated light guide opposite a spatial light modulator. 
     
     
       57. The apparatus of claim 56, further comprising means for focusing the portion of the reflected light on an image plane, wherein the reflected light is modulated prior to forming the one or more replicated images on the image plane. 
     
     
       58. The apparatus of claim 55, wherein the means for modulating comprises means for modulating a polarization state of the light. 
     
     
       59. The apparatus of claim 55, wherein the light entering the elongated light guide comprises non-polarized light. 
     
     
       60. The apparatus of claim 55, wherein the elongated light guide comprises reflective surfaces that form a polygonal cross section of the elongated light guide, and wherein the elongated light guide is configured to reflect the light by virtue of total internal reflection of the light within the polygonal cross section. 
     
     
       61. The apparatus of claim 55, wherein the elongated light guide is configured to reflect the light by virtue of total internal reflection of the light within the parallel sides.