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 6685-01-420-7407
NSN 6145-00-793-7816
NSN 6685-01-497-4698
NSN 6150-01-486-1948
NSN 6240-01-017-8281
NSN 7035-01-378-5074
NSN 5910-00-518-1009
NSN 5998-00-147-3205
NSN 6685-01-084-6432
NSN 6620-01-486-2555
NSN 5990-00-886-3685
NSN 6150-01-053-4134