Compact focusing von Hamos spectrometer for quantitative x-ray spectroscopy

A compact focusing crystal spectrometer based on the von Hamos scheme is described. Cylindrically curved mica and graphite crystals with a radius of curvature of Rϭ20 mm are used in the spectrometer. A front illuminated charge-coupled device ͑CCD͒ linear array detector makes this spectrometer useful for real-time spectroscopy of laser-produced plasma x-ray sources within the wavelength range of ␭ϭ1.8– 10 Å. Calibration of crystals and the CCD linear array makes it possible to measure absolute photon fluxes. X-ray spectra in an absolute intensity scale were obtained from Mg, Ti, and Fe laser-produced plasmas, with a spectral resolution ␭/␦␭ ϭ800– 2000 for the mica and ␭/␦␭ϭ200– 300 for graphite crystal spectrometers. The spectrometer has high efficiency in a wide spectral range, it is compact ͑40 mm diam, 150 mm length͒, easy to align, and flexible. The spectrometer is promising for absolute spectral measurements of x-ray radiation of low-intensity sources ͑femtosecond laser-produced plasmas, micropinches, electron-beam–ion-trap sources, etc.͒.