www.google.com.auhttp://www.google.com.au/patents/US3778548?utm_source=gb-gplus-sharePatent US3778548 - OPTICAL APPARATUS FOR COLLIMATION TO INFINITY OF TWO LUMINOUS IMAGES WHOSE FREQUENCIES FALL WITHIN DIFFERENT SPECTRAL BANDS
OPTICAL APPARATUS FOR COLLIMATION TO INFINITY OF TWO LUMINOUS IMAGES WHOSE ...
