Microshutter arrays: high contrast programmable field masks for JWST NIRSpec
Publication date: 12 Jul 2008
Authors: Kutyrev, A.S. et al.
Journal: Proceedings of SPIE, the International Society for Optical Engineering
Copyright: SPIESpace Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter. Edited by Oschmann, Jacobus M., Jr.; de Graauw, Mattheus W.M.; MacEwen, Howard A. Proceedings of the SPIE, Volume 7010, pp. 70103D-70103D-10 (2008)
Microshutter arrays are one of the novel technologies developed for the James Webb Space Telescope (JWST). It will allow Near Infrared Spectrometer (NIRSpec) to acquire spectra of hundreds of objects simultaneously therefore increasing its efficiency tremendously. We have developed these programmable arrays that are based on Micro-Electro Mechanical Structures (MEMS) technology. The arrays are 2D addressable masks that can operate in cryogenic environment of JWST. Since the primary JWST science requires acquisition of spectra of extremely faint objects, it is important to provide very high contrast of the open to closed shutters. This high contrast is necessary to eliminate any possible contamination and confusion in the acquired spectra by unwanted objects. We have developed and built a test system for the microshutter array functional and optical characterization. This system is capable of measuring the contrast of the mciroshutter array both in visible and infrared light of the NIRSpec wavelength range while the arrays are in their working cryogenic environment. We have measured contrast ratio of several microshutter arrays and demonstrated that they satisfy and in many cases far exceed the NIRSpec contrast requirement value of 2000.