Patent ID: 6178000
Filing Date: 2001-01-23
Classification: G03F

Abstract:
An interferometer, comprising:a first prism portion having a semi-transparent surface, a beam incident surface receiving an incident light beam at a selected point of incidence on the beam incident surface, a surface having a plurality of faces, and a beam emerging surface, the beam incident surface, the surface having the plurality of faces and the beam emerging surface each being different from the semi-transparent surface, and the incident light beam having a wavelength of .lambda.; anda second prism portion having a surface corresponding to the semi-transparent surface of the first prism portion, a surface having a plurality of faces corresponding to the surface having the plurality of faces of the first prism portion, and a beam emerging surface corresponding to the beam emerging surface of the first prism portion,the first and second prism portions being disposed with respect to each other so that the semi-transparent surface of the first prism portion and the surface of the second prism portion corresponding to the semi-transparent surface is between the first and second prism portions, andthe semi-transparent surface of the first prism portion splitting the incident light beam into first and second light beams, the first light beam being reflected at the semi-transparent surface and the second light beam passing through the semi-transparent surface and entering the second prism portion, the first light beam following a first beam path through the first prism portion to a selected face of the surface having the plurality of faces, the selected face corresponding to the selected point of incidence on the beam incident surface, the second light beam following a second beam path through the second prism portion corresponding to the first beam path, the first and second light beams respectively emerging from the beam emerging surfaces of the first and second prism portions to form an interference pattern on a surface, the interference pattern having a variable periodicity .LAMBDA. that is a function of the selected point of incidence of the incident light beam on the beam incident surface and the selected face of the surface having the plurality of faces.