| 摘要 |
There is disclosed an electro-optical system for real time projection of very high brightness, full color pictorial images from television or other program sources onto a large display screen from a set of three reflection type AC driven field effect mode birefringent liquid crystal light valves each of which modulates a primary color component video image onto a collimated beam of polarized light of a given primary color by modulating the polarization state thereof. In order to achieve very high brightness without overheating the system it is necessary that none of the optical elements forming the projection beam optical system absorb light in carrying out their function. Hence all projection beam optical processes are non-absorptive to first order. The light valves are devices that receive and reflect projection light from an independent high power light source while modulating onto the reflected light video images derived from a low level light source such as a cathode ray tube. The modulation onto the projection beam is achieved by modulating the state of polarization thereof. One such device is used for the red portion of the video image, a second for the green portion and a third for the blue portion. The optical system derives light from a white projection light source, polarizes it, splits it into the three primary colors, directs the three colored beams to the three light valves respectively for image modulation, collects the light that has been modulated by the light valves, recombines the three beams, and projects them onto the screen with sufficient registration to create full color range for the full color image. The optical system uses only a single projection lens and a single polarizing/analyzing beam splitter/recombiner and suitable dichroic mirrors. There is thus provided a simple, compact low weight, high brightness and high efficiency full color light valve image projection system for the projection of high brightness, full color, real time dynamic or static imagery which may include provision for overlay legends or other information as well as possible steroscopic or three dimensional perception by the viewer.
|
