27 June 2006 Performance of large chemically etched silicon grisms for infrared spectroscopy
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FORCAST is a mid/far-IR camera for use on NASA's SOFIA airborne observatory. We are fabricating monolithic silicon grisms to retrofit a spectroscopic capability for this facility-class instrument without affecting the imaging optics. The grisms will operate in the 5-8, 17-28, and 28-37 μm wavelength ranges. We will cover the 5-8 μm range in one exposure at a resolving power R=1200 with a 2 arcsecond slit using two grisms with one serving as a cross-disperser. For the 17-28 and 28-37 μm ranges, the resolving powers are R~140, 250 when used in low order with a slit of 3 arcseconds. We illustrate aspects of fabrication and testing during the grism development, and summarize the performance of the gratings at near- and mid-IR wavelengths. These gratings rely on procedures that can be used for modest sized (~10 cm) silicon pieces, thereby providing dispersive elements with good optical performance and large slit width-resolving power products from 1.2-8.1 μm and beyond 17 μm.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. J. Mar, J. P. Marsh, D. T. Jaffe, L. D. Keller, K. A. Ennico, "Performance of large chemically etched silicon grisms for infrared spectroscopy", Proc. SPIE 6269, Ground-based and Airborne Instrumentation for Astronomy, 62695R (27 June 2006); doi: 10.1117/12.671728; https://doi.org/10.1117/12.671728

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