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.͒.

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The high transparency of carbon-containing materials in the spectral region of "carbon window" (lambda approximately 4.5-5nm) introduces new opportunities for various soft X-ray microscopy applications. The development of efficient multilayer coated X-ray optics operating at the wavelengths of about 4.5nm has stimulated a series of our imaging experiments to study thick biological and synthetic objects. Our experimental set-up consisted of a laser plasma X-ray source generated with the 2nd harmonics of Nd-glass laser, scandium-based thin-film filters, Co/C multilayer mirror and X-ray film UF-4. All soft X-ray images were produced with a single nanosecond exposure and demonstrated appropriate absorption contrast and detector-limited spatial resolution. A special attention was paid to the 3D imaging of thick low-density foam materials to be used in design of laser fusion targets.

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Abstract. The interaction of focused soft x-ray laser radiation with metallic targets was studied experimentally. The radiation of a capillary-discharge Ne-like Ar ion laser (A = 46.9 nm) with a repetition rate of I Hz was focused on the surface of metallic samples by using a spherical Sij Sc multilayer mirror. The radiation intensity at the target surface was far greater than the threshold for laser ablation of the materials in use -aluminium, brass, and stainless steel. A study of the shape of laser craters in relation to the position of the caustic of the focusing mirror, combined with computer ray-tracing simulations, made it possible to determine the radiation intensity distribution in the focal region of the mirror. The radiation energy density in the 2 urn central domain of the focal spot was 10 2 J ern-2, and the corresponding intensity was 1011 W em-2. The reflectivity of a SijSc multilayer mirror was measured as a function of the angle of incidence of the radiation.