Patent ID: 6713770
Filing Date: 2004-03-30
Classification: G01J

Abstract:
A high resolution spectral measurement device having a very narrow slit function and a relatively large spectral range for monitoring spectra of laser beam, said device comprising:A) an etalon optical unit configured to monitor a beam of narrow band ultraviolet light and to produce interference fringes, said etalon optical unit comprising: 1) a diffuser positioned to diffuse said light into a very large number of directions to produce a diffuse beam; 2) an etalon positioned in the path of said diffuse beam; 3) a first slit aperture; and 4) a lens unit positioned to collect light passing through said etalon and to focus a portion of the passing light through said first slit aperture, B) a grating spectrometer unit comprising: 1) a collimating optical unit positioned to collect light passing through said first slit aperture, 2) a grating positioned in an approximately Littrow configuration to reflect said collimated light back through said collimating optical unit so that spectral components of reflected light are focused by said collimating optical unit at positions dependent on wavelength of said spectral components, 3) a detector means, 4) a mirror positioned to reflect to said detector means a portion of said light passing back through said collimating optic, and C) a scanning means for scanning said laser beam so as to permit collection of sufficient spectral data by said detector means to permit precise determination said spectra of said laser beam.