DOUBLE PASS LIGHT MODULATOR

摘要

A double pass modulator (10) , which can be used to modulate the intensity of light in a projection system, includes a reflective polarizer (12) adapted to pass light having a predetermined polarization state (P) therethrough and to reflect substantially all other light, a quarter wave plat (14) positioned to receive and pass light from the reflective polarizer (12) , the quarter wave plate (14) being arranged at 45 degrees with respect to the direction of the polarization transmitted through the reflective polarizer (12) , so as to induce a relative phase shift of 90 degrees between the two components of the incident polarization along and perpeudicular to the optical axis of the plate (14) , a reflector (120,122) that receives light from the quarter wave plate (14) and a modulator (116) that modulates at least a portion of the light incident thereon in intensity and/or wavelength; the modulator can be realized as a micro-electro mechanical actuator.