is known as interference, and nearly all instruments that make use of it are called Interferometers. The most common use for Interferometers is to determine the degree of flatness... of polished surfaces such as Gage Blocks, Optical Flats, Mirrors, etc. The reason interference is not normally observed is that it can only occur if the interacting light waves come... is the reference surface of known flatness and is the surface to which each test piece will be compared. In order to understand how interference is created, the path...

surfaces. Specifications: Prism Material: BK-7 Glass 90 degree Angle: 1 arc sec Porro Angle: 3 arc sec Flatness: /10 on all 3 surfaces Surface Quality: 80/50 per MIL-O-13830...