National Item Identification Number

00-030-3426
000303426
5210-00-030-3426
5210000303426

National Stock Number

Item Name

OPTICAL FLAT

Federal Supply Class

5210

Description

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.

Commercial and Government Entity Code (Supplier Data)

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Reference Numbers (Part Numbers)

Required Categories

DESIGN TYPE
MATERIAL
WORKING SURFACE FLATNESS ACCURACY
DIAMETER
THICKNESS
C

Required Description

WORKING DOUBLE
QUARTZ, FUSED
0.00000300 INCHES NOMINAL
4.000 INCHES NOMINAL;