Characterization of a polarization-resolved high spectral resolution UV-visible spectrometer.

To measure the degree of polarization of a plasma emission, a polarization-resolved UV-visible Czerny-Turner-type spectrometer was designed and constructed. For a high spectral resolution, F=1 m mirrors were used as a focusing and collimating mirrors and the incidence angles to the mirrors were determined to eliminate coma. The effect of astigmatism was reduced by designing the incidence angles to the mirrors to be as small as possible. The flat focal plane condition proposed by Reader [J. Opt. Soc. Am. 59, 1189 (1969)] was used to determine the grating position. The measured spatial resolution was 170 microm. To simultaneously measure the intensities with two perpendicular polarizations, a calcite crystal was placed after the entrance slit of the spectrometer. The change in the imaging property of the spectrometer due to the calcite crystal was measured and minimized. The spectral resolution was experimentally measured with a laser produced plasma to be 0.05 nm at 348 nm. The resolving power measured is 6600.