Patent ID: 6509970
Filing Date: 2003-01-21
Classification: G01J

Abstract:
A wavelength monitoring apparatus for laser light for semiconductor exposure, comprising:an entrance-side optical system for making the laser light for semiconductor exposure and reference light incident on different areas of a single etalon in a form of diverging light, converging light or diffused light in such a manner that respective center axes of the laser light and the reference light are displaced relative to each other; two focusing optical systems provided in approximately coaxial relation to the respective center axes of said laser light and reference light passing through said etalon; and a one-dimensional array optical sensor placed in a plane coincident with back focal planes of said focusing optical systems to receive interference fringes produced by said laser light and reference light; wherein positions of the interference fringes on said one-dimensional array optical sensor are detected to calculate a wavelength of said laser light for semiconductor exposure.