Abstract: Optical multiplexer configurations are designed to minimize the volume of the multiplexer or minimize back focal distance of the lens of a multi-color projection system. The multiplexer employs three liquid crystal modulators under computer control to respectively and selectively transmit beams of three different colors for combination within the multiplexer which projects the combined modulated beams to a projection lens for focusing an image on a display screen. Optical light paths are chosen within the multiplexer by arrangement and configuation of mirrors and dichroic filters to direct the beams along folded paths within the multiplexer for combination and projection through a multiplexer exit window. For minimized volume of the multiplexer all beams are folded within the multiplexer, but two of the color beams are each folded twice in a single common plane which is perpendicular to a plane of folding of the third beam.

Abstract: A multifaceted aluminum scanwheel 11 mounted for rotation on a steel bearing assembly 19 is made less susceptible to thermally-induced stresses by the provision of a specially-configured web section 17 that extends between the hub 15 and facet ring portions 13 of the wheel 11. A circumferential, slotted jog section 45 provides the flexibility to relieve compressive forces in the web 17 which might distort either the bearing assembly 19 or the scanwheel facet ring 13, or both.

Abstract: A strain relieving channel 32 is provided between the hub 31 of a multifaceted scanwheel 15 and the bearing assembly 13 on which the hub 31 is mounted. Compression of the bearing assembly 13 and distortion of the scanwheel facets 29 due to thermally induced compression of the scanwheel web 33 are both reduced by bowing of the hub 31, made possible by the strain relieving channel 32.