Patent ID: 6382799
Filing Date: 2002-05-07
Classification: G03B

Abstract:
A projection optical apparatus comprising:a light source for radiating light; an illumination optical system for emitting as illumination light the light radiated from the light source; a Digital Micromirror Deviceâ„¢, having a plurality of micromirrors, for separating the illumination light into signal light and unnecessary light by varying, in accordance with a signal, angles at which the individual micromirrors reflect the illumination light shone thereon; a total internal reflection prism composed of a first prism for totally reflecting and thereby directing the illumination light exiting from the illumination optical system to the Digital Micromirror Deviceâ„¢ and a second prism for transmitting the signal light reflected from the Digital Micromirror Deviceâ„¢; and a projection optical system for projecting the signal light transmitted through the second prism onto a projection surface, wherein the following condition is fulfilled: L/[tan{&thgr;Dâˆ’sinâˆ’1(1/(2Â·Fa))}]&lE;xa&lE;L/tan(&thgr;Dâˆ’0.87 &thgr;D) whereFa represents an f/number of the illumination optical system on a Digital Micromirror Deviceâ„¢ side thereof, which falls within a range 1/{2 sin(0.85 &thgr;D)}&lE;Fa&lE;1/{2 sin(0.3 &thgr;D)}; xa represents a distance from the Digital Micromirror Deviceâ„¢ to a Digital Micromirror Deviceâ„¢ side pupil of the illumination optical system; L represents a distance from an optical axis position of the Digital Micromirror Deviceâ„¢ to a most off-axial position thereof; and &thgr;D represents a rotation angle of the micromirrors constituting the Digital Micromirror Deviceâ„¢.