Photo was removed on request of past employer who is still building this comparator for the government. In the late 1970's Perkin Elmer did a ray trace for McBain Instruments, but when I came on board I recalculated the optical track to include image rotators zoom and anamorphic optics. I designed almost all of the critical opto-mechanics that provided the capability to measure reconnaissance photos with with 0.1 micron accuracy.