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S. Satyapal (STScI), M. Greenhouse, R. Barry, R. Barclay, D. Amato, B. Arritt, V. Harvey, C. Holt, J. Kuhn (Goddard Space Flight Center), N. Fonneland (Northrop Grumman Corporation), L. Lesyna (Lockheed Martin Corporation)
Tunable filters will enhance the spectral resolution, sensitivity, and field of view capabilities of a number of potential science instruments on NGST. They will : 1) provide flexibility in wavelength and bandwidth choice compared with a fixed inventory of filters in convential cameras, 2) improve the sensitivity of Fourier Transform Spectrometers when full wavelength coverage imaging is not needed, and 3) provide a greater multiplex advantage to multiobject spectrographs when limited spectral coverage is desired. We display work in progress on a near-infrared tunable bandpass filter for the wide field camera of the Next Generation Space Telescope (NGST) Integrated Science Instrument Module (ISIM). This Demonstration Unit for Low Order Cryogenic Etalon (DULCE), is designed to demonstrate a high efficiency scanning Fabry-Perot etalon operating in interference orders 1-4 at 30 K with a high stability DSP based servo control system. DULCE is currently the only available tunable filter for low order cryogenic operation in the near-infrared. In this application, scanning etalons will illuminate the focal plane arrays with a single order of interference to enable wide field low resolution (50 < R < 200) hyperspectral imaging over a wide range of redshifts.