Physical description

Part of a series entitled “Optical Munitions - School of Natural Philosophy, 1942-1945”. Black and white photo showing close up of glass optical flat in case. Photographed label reads: “Glass optical flat. Made by Natural Philosophy Laboratory. Melbourne University. Certificate Number 18. Accuracy of surface, flat within .000,001 (unmarked surface). Accuracy of surface, within .000,002 inch (marked) “use other side”. A photograh in Cd red light of the interference fringes of this flat when placed on a standard glass flat is shown above. Initials: [signature]. Tests made by: [VDH signature]. Certificate issued by T.H.L. Date: Feb 19th 1941.

Inscriptions & markings

In ink on lower left hand corner : “17”.