RECONFIGURABLE SPATIAL LIGHT MODULATORS
This invention relates to reconfigurable spatial light modulators (SLM) incorporating a scatter plate. Computer generated diffraction patterns or holograms may be loaded on the (SLM) either as a single frame or as a series of frames for observation by an observer. In a preferred embodiment both an electrically addressable spatial light modulator (EASLM) and an optically addressable spatial light modulator (OASLM) are used. The (OASLM) may be formed of several smaller (OASLMs) arranged in a matrix format. The faster (EASLM) forms a light pattern on the sub-areas of the large (OASLM) in turn to give a large display. The scatter plate is arranged at the output of the (SLM) nearest an observer. This scatter plate has a known characteristic and serves to increase the field of view and/or reduce the number of pixels required to give a holographic or two dimensional displays. Prior to producing a display, the diffraction patterns, holograms, or image in the computer is modified to take account of the properties of the scatter plate; a modified computer generated diffraction pattern, hologram, or image is then displayed to an observer. The system may also be used for optical switching.
1 . A method comprising:
generating a hologram pattern of a holographic image to compensate for known characteristics of a light scattering plate;
transmitting incident light from a light source to a hologram device including a spatial light modulator and the light scattering plate;
controlling a transmission of the incident light through the spatial light modulator having a number of addressable pixels;
modulating the incident light to replicate the hologram pattern; and
presenting the holographic image.
2 . The method of claim 1 including modifying an allowable range of diffraction angles of the incident light through the light scattering plate.
3 . The method of claim 1 wherein the allowable range of diffraction angles is increased by the light scattering plate.
4 . The method of claim 1 wherein the available range of diffraction angles is proportional to a ratio of a pixel spatial frequency of the light scattering plate to a pixel spatial frequency of the spatial light modulator
5 . The method of claim 1 wherein the compensated pattern is calculated using a direct binary search algorithm.
6 . The method of claim 1 wherein the hologram pattern further compensates for the holographic image presented to a receiver.
7 . The method of claim 1 including storing an electronic copy of both the hologram pattern and the holographic image.
8 . A method comprising:
storing a computer generated pattern of a diffractive structure to be displayed;
controlling a transmission of incident light through a spatial light modulator having a number of pixels;
modulating the incident light according to the computer generated pattern to compensate for a diffractive effect of the incident light through the spatial light modulator including a scattering plate; and
displaying the diffractive structure as an enlarged image compared to an image displayed as a result of a transmission of incident light through the spatial light modulator without a scattering plate.
9 . The method of claim 8 including compensating for the diffractive effect according to a known surface characteristic of the scatter plate.
10 . The method of claim 9 wherein the known surface characteristic includes a number of pixels of the scatter plate.
11 . The method of claim 9 wherein the known surface characteristic includes an electric field distribution.
12 . The method of claim 9 wherein a size of the enlarge image may be increased without increasing the number of pixels in the spatial light modulator.
13 . The method of claim 8 including storing an electronic copy of the diffractive structure.
14 . A system comprising:
a holographic engine capable of storing a hologram pattern of an image;
one or more spatial light modulators having a number of addressable pixels capable of passing light under the control of the engine;
a light scattering plate capable of modifying the light that passes through the one or more spatial light modulators; and
a processor configured to control at least one of the one or more spatial light modulators to compensate for a scattering effect of the light scattering plate in order to replicate the hologram pattern.
15 . The system of claim 14 wherein the light scattering plate has a number of surface features greater than the number of addressable pixels of the one or more spatial light modulator.
16 . The system of claim 14 including displaying the image, wherein the image displayed is larger than an image generated by a system including the one or more spatial light modulators without the light scattering plate.
17 . The system of claim 14 wherein the hologram pattern compensates for a scattering effect of the light scattering plate and further compensates for a known optical aberration of one or more components of the system.
18 . The system of claim 14 wherein the holographic engine is a computer with storage and means for calculating both a computer generated hologram image and a compensated hologram pattern for each image to be displayed.
19 . The display system of claim 14 including an electrically addressable liquid crystal spatial light modulator (EASLM).
20 . The system of claim 19 wherein the system comprises at least two spatial light modulators arranged such that light from the EASLM is directed towards an optically addressable spatial light modulator.