A gated spectrometer has been designed for real-time, pulsed infrared (IR) studies at the National Synchrotron Light
Source at the Brookhaven National Laboratory. A pair of 90-degree, off-axis parabolic mirrors are used to relay the light
from an entrance slit to an output IR recording camera. With an initial wavelength range of 1500-4500 nm required,
gratings could not be used in the spectrometer because grating orders would overlap. A magnesium oxide prism, placed
between these parabolic mirrors, serves as the dispersion element. The spectrometer is doubly telecentric. With proper
choice of the air spacing between the prism and the second parabolic mirror, any spectral region of interest within the
InSb camera array's sensitivity region can be recorded. The wavelengths leaving the second parabolic mirror are
collimated, thereby relaxing the camera positioning tolerance. To set up the instrument, two different wavelength
(visible) lasers are introduced at the entrance slit and made collinear with the optical axis via flip mirrors. After
dispersion by the prism, these two laser beams are directed to tick marks located on the outside housing of the gated IR
camera. This provides first-order wavelength calibration for the instrument. Light that is reflected off the front prism
face is coupled into a high-speed detector to verify steady radiance during the gated spectral imaging. Alignment
features include tick marks on the prism and parabolic mirrors. This instrument was designed to complement singlepoint
pyrometry, which provides continuous time histories of a small collection of spots from shock-heated targets.
Wired array studies are being conducted at the SNL Z accelerator to maximize the x-ray generation for inertial
confinement fusion targets and high energy density physics experiments. An integral component of these studies is the
characterization of the time-resolved spectral content of the x-rays. Due to potential spatial anisotropy in the emitted
radiation, it is also critical to diagnose the time-evolved spectral content in a space-resolved manner. To accomplish
these two measurement goals, we developed an x-ray spectrometer using a set of high-speed detectors (silicon PIN
diodes) with a collimated field-of-view that converged on a 1-cm-diameter spot at the pinch axis. Spectral
discrimination is achieved by placing high Z absorbers in front of these detectors. We built two spectrometers to permit
simultaneous different angular views of the emitted radiation. Spectral data have been acquired from recent Z shots for
the radial and axial (polar) views. UNSPEC1 has been adapted to analyze and unfold the measured data to reconstruct
the x-ray spectrum. The unfold operator code, UFO2, is being adapted for a more comprehensive spectral unfolding
treatment.
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