SWUIS Spectrograph

The telescope used in SWUIS is a custom 7-inch diameter Maksutov-Cassegrain design built by Questar Corporation and ruggedized for space flight use. It has a UV transmissive front end corrector lens made of fused silica and mirror optical coatings of aluminum overcoated with magnesium fluoride for enhanced sensitivity at UV, VIS, and IR wavelengths. The telescope also has a small finder telescope that allows the operator to make fine pointing adjustments. The telescope is hard-mounted to the side hatch window in the shuttle mid-deck area via a custom two-axis mounting bracket and has manual slow-motion controls for fine pointing.

The telescope optical coupling assembly is a mechanical interface between the telescope and the ICCD camera, designed to hold imaging filters and lenses. The effective focal length can be varied between 105 and 257 cm for a field-of-view range between 0.3 and 0.6 degrees (full cone). The electronics that control the intensified charged couple device (ICCD) camera were custom built at the Institute. The power interface box provides power conditioning from the space shuttle orbiter's video interface unit to the ICCD camera.

The new spectrograph, which is being designed and built at SwRI and which is slated for a shuttle flight in 1999, will have a wavelength coverage that spans the mid-UV from 200 nanometers (nm) out to NIR wavelengths beyond 1,100 nm, allowing the spectrum from astronomical targets with moderately high spectral resolution (approximately 0.1 to 0.5 nm) to be recorded. The spectrum will be recorded by the ICCD camera, which will attach to the focal plane end of the spectrograph. The detector will be able to sample approximately 23.0 nm of spectral bandpass during any single observation. The diffraction grating, which disperses light to create a spectrum, is being designed such that it can be manually rotated to change the bandpass anywhere within the 200- to 1,100- nm wavelength coverage of the instrument.

Out the Window Technics Summer 1998 Technology Today
SwRI Publications SwRI Home