A wide-field near-infrared camera and spectrograph for the Mt. Abu 1.2 m telescope

Boddapati Anandarao; Eric Harvey Richardson; Abhijit Chakraborty; Harland Epps

doi:10.1117/12.788246

14 July 2008 A wide-field near-infrared camera and spectrograph for the Mt. Abu 1.2 m telescope

Boddapati Anandarao, Eric Harvey Richardson, Abhijit Chakraborty, Harland Epps

Proceedings Volume 7014, Ground-based and Airborne Instrumentation for Astronomy II; 70142Y (2008) https://doi.org/10.1117/12.788246
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

Abstract

We describe the design and optimization of a wide-field near-infrared camera and spectrograph (NICAS) for Mt Abu 1.2 m, f/13 Cassegrain telescope of Physical Research Laboratory. The principal science goals include photometric mapping of star forming regions and medium resolution spectroscopy of Young Stellar Objects, evolved stars and transient sources. The design goals are to achieve seeing-limited angular resolution in an un-vignetted field of view of ~ 8'x8' with 0.5" per pixel (of 18.5 μm) on a HgCdTe 1024×1024 infrared array, requiring a two-fold Cassegrain focal reduction. In addition to the imaging, the instrument is required to have spectroscopic capability with a resolving power of 10³ in the 0.85 - 2.5 μm region, needing a dispersion of 1 nm per pixel. Finally, since our telescope has a moderate aperture, the throughput losses need to be minimized. The specifications are achieved by an optical design using 9 singlet lenses. Only those lens materials are chosen for which measured values are available for refractive indices at 77 K (detector operating temperature), changes of indices with temperature, and thermal coefficients of expansion. The design is optimized to give sharpest images at 77 K. The optical path is folded by 90° after collimation by a fold-mirror and re-imaged on the detector. The fold-mirror is replaced by a diffraction grating for spectrograph mode. In order to minimize the reflection losses, all the lenses will be anti-reflection coated for the full operating wavelength range. Details of the design are presented.

Citation Download Citation

Boddapati Anandarao, Eric Harvey Richardson, Abhijit Chakraborty, and Harland Epps "A wide-field near-infrared camera and spectrograph for the Mt. Abu 1.2 m telescope", Proc. SPIE 7014, Ground-based and Airborne Instrumentation for Astronomy II, 70142Y (14 July 2008); https://doi.org/10.1117/12.788246

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available