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Subsystem Imaging Performance and Modeling of the Infrared Multi-Object SpectrographThe Infrared Multi-Object Spectrograph (IRMOS) is a facility instrument for the Kitt Peak National Observatory Mayall Telescope (3.8 meter). IRMOS is a near-IR (0.8 - 2.5 micron) spectrograph with low to mid resolution (R=lambda/delta, lambda = 300 - 3800). The IRMOS spectrograph produces simultaneous spectra of - 100 objects in its 2.8 x 2.0 arc-min field of view using a commercial MEMS multi-mirror array device (MMA). The IRMOS optical design consists of two imaging systems, or "stages." The focal reducer, stage one, images the focal plane of the telescope onto the MMA. The spectrograph, stage two, images the MMA onto the detector. We describe the breadboard alignment method and imaging and scattered light performance for both the focal reducer and spectrograph. This testing provides verification of the optomechanical alignment method, and a measurement of the contribution of scattered light in the system due to mirror small scale surface error. After the stage I and 2 optics are integrated with the instrument, our test results will make it possible to distinguish between scattered light from the mirrors and the MMA. Image testing will be done at four wavelengths in the visible and near-IR. A mercury-argon pencil lamp will provide spectral lines at 546.1 and 1012 nm, and a blackbody radiation source lines at 1600 and 2200 nm. A CCD camera will be used as a detector for the visible wavelengths, and an IR photodiode will be used for the IR wavelengths. We compare our data with a theoretical analysis using a commercial software package. Mirror surface error is modeled by treating each surface as a superposition of various gratings (e.g., diamond turning tool marks, features due to the impurities of Al 6061, and periodic mid-frequency errors due to drift during machining).
Document ID
20020039849
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Connelly, Joseph A.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Tveekrem, June L.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Ohl, Raymond G.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Mink, Ronald
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Chambers, V. John
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Mentzell, J. Eric
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Greenhouse, Matthew A.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
MacKenty, John W.
(Space Telescope Science Inst. Baltimore, MD United States)
Krebs, Carolyn
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Optics
Meeting Information
Meeting: SPIE Conference
Location: Kona, HI
Country: United States
Start Date: August 22, 2002
End Date: August 28, 2002
Sponsors: International Society for Optical Engineering
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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