SINGLE GRADED INDEX (GRIN) LENS FOR ACTIVE-OPTICAL TARGET DETECTION
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2002-Jan-09
A compact, active optical system, utilizing graded index (GRIN) rod lenses, was previously proposed for target detection applications. Referring to Figure la, that system concept comprised transmit fibers 1 separate from receive fibers 2, GRIN-rod lenses 3 and 4, a spherical collector/reflector 5, and a common window 6. Both fibers 1 and 2 would be cemented with index matching epoxy 7 to GRIN-rod lenses 3 and 4. Transmitter 8 employs a % pitch GRIN-rod lens 3 which colIiiates the light 9 emitting from fiber 1 and is aimed out the com- mon window 6 (common since both transmitted and received light energy passes through the same window). This transmitted light wave 30 becomes a reflected light wave 31 off target 10 and is collected by spherical reflec- tor 5 through common window 6. The light energy is focussed onto one side of a % pitch GRIN-rod lens 4, which translates the image to receive fiber 2 cemented to the lens's other side. The receiver GRIN-rod lens 4 is used to eliminate the need for fiber-end polishing, which is a high cost manufacturing procedure. Transmit signal 32 is sourced from a pulsed laser diode (not shown in the figure), coupled into transmit fiber 1. Receive fiber 2 guides the collected light energy 33 to an optical photodetector (also not shown).