FIBER OPTIC FACEPLATE COUPLER FOR IMAGE BAR APPLICATION - LIQUID CRYSTAL IMAGE BAR PROJECT
Original Publication Date: 1987-Oct-31
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
The design of shutter or gate-array type image bars which incorporate Lambertian sources is usually complicated by the conflicting requirements of high radiant coupling efficiency between the light source and the gate-array and thermal isolation of the hot source from the gate-array. In order to obtain maximum irradiance at the gate-array image plane, one would like to place the lamp as close as possible to the gate-array. On the other hand, the proximity of the lamp to the array many times results in degraded performance characteristics of the array due to the elevated lamp temperature. One possible solution that has been used in the past is to employ a "critical illumination" scheme whereby a lens is used to image the source onto the gate-array. In the case of an extended linear source and gate-array, both linear SELFOC lenses, and cylinder lenses have been proposed. Although these methods work, there are drawbacks such as expense, difficulty in proper alignment, insufficient numerical aperture (hence low coupling efficiency), Fresnel loss problems, or "bow-tie" blurring effects (i.e., in the case of the cylinder lens).