FLATNESS MEASUREMENT:

Flatness:

A surface is said to be flat within a given range of measurement.

Flatness testing:

r anauto

If the test surface is large, then  it is tested  for flatness using  a sprit level o collimator.

Procedure to determine flatness:

A surface can be considered to be a collection of a large number of lines.

Flatness testing by interferometry:

Monochromatic light source and a set of optical flats are used.