Pinhole-array x-ray spectrometer for laser-fusion experiments

A pinhole-array x-ray spectrometer for laser-fusion experiments is demonstrated. An array of approximately 300 pinholes is placed in front of a flat-crystal spectrometer, yielding target images at photon energies similar to 10 eV apart (for photon energies of similar to 4 to 5 keV). For wideband radiation the images are two dimensional, whereas when a single spectral line is used, the field of view in the direction of dispersion is limited. However, single spectral line images can have a field of view sufficient for imaging the compressed target core. We show the image at the Ti-K alpha-line fluorescence from a Ti-doped shell, which we show to be excited by continuum radiation from the compressed core. The K alpha image delineates the cold, compressed shell at peak compression, which can otherwise be obtained only through backlighting. In addition, the array provides spectra of high spectral resolution because of the reduction in the effective source size. (C) 1998 Optical Society of America.