what is ment by wedge interfrometer?

Answer 1

A multi-pass wedge interferometer is used to produce multiple-beam reflected fringes of increased spatial frequency by means of either modulating the phases of the interfering beams or observing the fringes on multi-pass planes. These techniques permit the control of the phases of the interfering beams, such that a phase multiplication takes place. The theory of fringe formation and intensity distribution is presented and demonstrated. It has been found that an interferometer with m passes gives fringes of spatial frequency m times greater than that of a single-pass.

Answer 2

First, I want to make sure you know what an interferometer is. This is simply a device that separates a beam of light into two ray beams, usually by means of reflection through a square shaped prism, and brings the rays together to produce interference. It is used to measure wavelength, index of refraction, and astronomical distances.

A wedge interferometer does the same thing in reverse, because the prism is in the shape of a right triangle. It takes two beams of light and combines them into a single ray beam. You can see a picture of the physics here:

http://journals.iucr.org/a/issues/2001/02/00/ay0010/ay0010fig1.html