optical flat

Date: circa 1946

Inventory Number: 2003-1-0152

Classification: Optical Flat

Subject:

optics, metrology,

Maker: American ?

Cultural Region:

United States,

Dimensions:

glass: 2.1 × 7.5 × 7.5 cm (13/16 × 2 15/16 × 2 15/16 in.)

case: 6 × 15.5 × 15.8 cm (2 3/8 × 6 1/8 × 6 1/4 in.)

Material:

pyrex, mahogany,

Accessories: case

Description:

Clear Pyrex cylindrical optical flat in mahogany case. There is a note in the case that says: "#2, 2-3 micro (?) M.C.N. 7-16-46". The corrected side of the test plate is opposite the N.G.F. marking on the plate." Good side of plate is heavily scratched.

Signedunsigned

FunctionThis disk is used to determine optically the flatness of a surface. It is itself made to be extremely flat (within a few millionths of a inch). When put on a surface and monochromatic light is shone on the flat, interference patterns will form. Their analysis determine the flatness of the surface.