Optical, flat
A flat, transparent piece of glass, generally of fused quartz, with one or both principal surfaces polished to within a few millionths of an inch of a true plane. It is used in conjunction with a monochromatic light source to measure the flatness of precision finished surfaces, and to determine the distance and parallelism between precision finished surfaces by comparison with known standards. In operation the flat is superimposed, reference surface downward, on the parts under test and when illuminated by monochromatic light the rays reflected from the reference surface are either reinforced or neutralized by the rays reflected from the surface under test producing interference bands which reveal any variations in the thickness of the film of air between surface under test and the flat. Excludes optical parallels.
NSN 6135-01-100-3593
NSN 6645-01-554-2871
NSN 6110-00-934-7943
NSN 5965-00-879-7287
NSN 6135-01-246-0308
NSN 4140-01-400-3610
NSN 5998-01-361-4652
NSN 5855-00-129-6055
NSN 6320-01-261-2848
NSN 6685-01-058-5686
NSN 2925-00-816-8765
NSN 5920-00-709-1149