"DETERMINES POSITION OF FOCAL PLANE OF OPTICAL MODULE AND ESTABLISH THICKNESS OF SHIM REQD. TO BE FITTED AT INTERFACE BETWEEN OPTICAL MODULE AND DISPLAY CATHODE RAY TUBE ASSY;C/O OPTICALBENCH 84 IN. L, 6 IN. W, 8 IN. H;10 INPARABOLIC MIRROR ATTACHED TO ONE END OF BENCH W/ADAPTER ASSY MOUNTED AT OPPOSITE END;DRWG NAME FOCAL PLANE DETERMINATION TEST SET"