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National Stock Number:
5210-00-685-5545
Federal Supply Class:
5210
National Item Identification Number:
006855545
Description:
OPTICAL FLAT
Detail:
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.
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Manufacturer Information:
| MIL026901CLASS1SIZE11 | 81349 | MILITARY SPECIFICATIONS PROMULGATED BY MILITARY DEPARTMENTS/AGENCIES UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M |
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Techincal Specification:
| CASE | PROVIDED | | DESIGN TYPE | MASTER DOUBLE | | DIAMETER | 4.000 INCHES NOMINAL | | MATERIAL | QUARTZ | | NONDEFINITIVE SPEC/STD DATA | 1 CLASS AND 11 SIZE | | WORKING SURFACE FLATNESS ACCURACY | 0.00000200 INCHES NOMINAL | | THICKNESS | 0.750 INCHES NOMINAL |
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