Imaging performance and modeling of the Infrared Multi-Object Spectrometer focal reducer

Connelly, Joseph A.; Ohl, Raymond G.; Saha, Timo T.; Hadjimichael, Theo; Mentzell, John Eric; Mink, Ronald G.; Hylan, Jason E.; Sparr, Leroy; Chambers, J.; Hagopian, John J; Greenhouse, Matthew A.; Winsor, Robert S.; MacKenty, John

doi:10.1117/12.458974

Cited by 5 publications

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“…11 Stage 1 results are presented in detail by Connelly et al (2002). 5 We use the Advanced Systems Analysis Program (ASAP) + to model the effects of surface error for stage 2 (OSAC is unable to model non-symmetric prescriptions). The periodic tool marks and surface errors of the optics are approximated as low-order gratings.…”

Section: Measured and Modeled Resultsmentioning

confidence: 99%

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Alignment and performance of the Infrared Multi-Object Spectrometer

et al. 2003

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'The Infrared Multi-Object Spectrometer (IRA408 is a principle investigator class instrument for the Kitt Peak National Observatory 4 and 2.1 m telescopes. IRA4OS is a near-IR (0.8 -2.5 pm) spectrometer with low-to mid-resolving power (R = 300 -3000). IRA4OS produces simultaneous spectra of -100 objects in its 2.8 x 2.0 arc-min field of view (4 m telescope) using a commercial Micro Electro-Mechanical Systems (MEMS) micro-mirror array (MMA) from Texas Instruments. The I W O S optical design consists of two imaging subsystems. The focal reducer images the focal plane of the telescope onto the MMA field stop, and the spectrograph images the MMA onto the detector. We describe ambient breadboard subsystem alignment and imaging pe~%ormance of each stage independently, and ambient imaging performance of the fully assembled instrument-Lnterferometric measurements of subsystem wavefront error serve as a qualitative alignment guide, and are accomplished using a commercial, modified Twyman-Green laser unequal path interferometer. Image testing provides verification of the optomechanical alignment method and a measurement of nearangle scattered light due to mirror small-scale surface error. Image testing is performed at multiple field points. A mercury-argon pencil lamp provides a spectral line at 546.1 nm, a blackbody source provides a line at 1550 nm, and a CCD camera and IR camera are used as detectors. We use commercial optical modeling sofiware to predict the pointspread function and its effect on inshument slit transmission and resolution. Our breadboard and instrument level test results validate this prediction. We conclude with an instrument performance prediction for cryogenic operation and first light in late 2003.

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Section: Measured and Modeled Resultsmentioning

confidence: 99%

“…This optomechanical alignment setup and procedure is shown schematically by and is similar to that developed for previous NASA/GSFC missions. 5 …”

Section: Breadboardingmentioning

confidence: 97%

Alignment and performance of the Infrared Multi-Object Spectrometer

et al. 2003

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“…Considerable effort was expended on stress relief of the optical components and extensive testing. 7,8,9,10 The IRMOS instrument is enclosed in a cryogenic dewar constructed by Janis Research Company (Wilmington, MA) * . Cooling is provided by a mechanical cryocooler.…”

Section: Major Componentsmentioning

confidence: 99%

Design and performance of a MEMS-based infrared multi-object spectrometer

et al. 2004

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The Infrared Multi-Object Spectrometer (IRMOS) is an innovative near-IR instrument employing an array of MEMS micro mirrors for focal plane target selection. IRMOS is a joint project of the Space Telescope Science Institute, the NASA James Webb Space Telescope, and the Kitt Peak National Observatory and will shortly become available to the community at Kitt Peak. IRMOS uses a Texas Instruments 848x600 element DMD as a micro mirror array to synthesize slits to obtain up to 100 simultaneous spectra. It provides R~300, 1000, and 3000 spectroscopy in the J, H, and K bands plus R~1000 in Z together with imaging in all bands. Designed for the KPNO 4 and 2.1-meter telescopes, IRMOS will provide 3x2 and 6x4 arc minute fields of view on these telescopes. We describe the design and status of IRMOS, summarize its expected performance, and present early test data from system level lab tests.

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“…4 For the mirrors, the fiducials consist of the following: 1. System-level alignment equipment and procedures are described by .…”

Section: Mechanical Designmentioning

confidence: 99%

Design and fabrication of diamond machined, aspheric mirrors for ground-based, near-IR astronomy

et al. 2003

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Challenges in fabrication and testing have historically limited the choice of surfaces available for the design of reflective optical instruments. Spherical and conic mirrors are common, but, for future science instruments, more degrees of freedom will be necessary to meet performance and packaging requirements. These instruments will be composed of surfaces of revolution located far off-axis with large spherical departure, and some designs will even require asymmetric surface profiles. We describe the design and diamond machining of seven aluminum mirrors: three rotationally symmetric, off-axis conic sections, one off-axis biconic, and three flat mirror designs. These mirrors are for the Infrared Multi-Object Spectrometer instrument, a facility instrument for the Kitt Peak National Observatory's Mayall Telescope (3.8 m) and a pathfinder for the future Next Generation Space Telescope multi-object spectrograph. The symmetric mirrors include convex and concave prolate and oblate ellipsoids, and range in aperture from 92 × 77 mm to 284 × 264 mm and in f-number from 0.9 to 2.4. The biconic mirror is concave and has a 94 × 76 mm aperture, R x = 377 mm, k x = 0.078, R y = 407 mm, and k y = 0.127 and is decentered by -2 mm in x and 227 mm in y. The mirrors have an aspect ratio of approximately 6:1. The fabrication tolerances for surface error are < 63.3 nm RMS figure error and < 10 nm RMS microroughness. The mirrors are attached to the instrument bench using semi-kinematic, integral flexure mounts and optomechanically aligned to the instrument coordinate system using fiducial marks and datum surfaces. We also describe in-process profilometry and optical testing.

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Imaging performance and modeling of the Infrared Multi-Object Spectrometer focal reducer

Cited by 5 publications

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Alignment and performance of the Infrared Multi-Object Spectrometer

Alignment and performance of the Infrared Multi-Object Spectrometer

Design and performance of a MEMS-based infrared multi-object spectrometer

Design and fabrication of diamond machined, aspheric mirrors for ground-based, near-IR astronomy

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