Design of the near infrared camera DIRAC for East Anatolia Observatory

Ross Zhelem; Robert Content; Vladimir Churilov; Yevgen Kripak; Lew Waller; Scott Case; Slavko Mali; Rolf Muller; Mario Gonzalez; David Adams; Nick Binos; Timothy Chin; Tony Farrell; Urs Klauser; Yuriy Kondrat; Nirmala Kunwar; Jon. Lawrence; Nuria Lorente; Summer Luo; Erica Mcdonald; Helen McGregor; Vijay Nichani; Naveen Pai; Minh Vuong; Jahanzeb Zahoor; Jessica Zheng; Barnaby Norris; Julia Bryant; Annino Vaccarella; Nick Herrald; James Gilbert; Cahit Yesilyaprak; Bulent Gucsav; Deniz Coker; Onur Keskin; Laurent Jolissaint

doi:10.1117/12.2629716

29 August 2022 Design of the near infrared camera DIRAC for East Anatolia Observatory

Ross Zhelem, Robert Content, Vladimir Churilov, Yevgen Kripak, Lew Waller, Scott Case, Slavko Mali, Rolf Muller, Mario Gonzalez, David Adams, Nick Binos, Timothy Chin, Tony Farrell, Urs Klauser, Yuriy Kondrat, Nirmala Kunwar, Jon. Lawrence, Nuria Lorente, Summer Luo, Erica Mcdonald, Helen McGregor, Vijay Nichani, Naveen Pai, Minh Vuong, Jahanzeb Zahoor, Jessica Zheng, Barnaby Norris, Julia Bryant, Annino Vaccarella, Nick Herrald, James Gilbert, Cahit Yesilyaprak, Bulent Gucsav, Deniz Coker, Onur Keskin, Laurent Jolissaint

Author Affiliations +

Proceedings Volume 12184, Ground-based and Airborne Instrumentation for Astronomy IX; 1218440 (2022) https://doi.org/10.1117/12.2629716
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

The 4m DAG telescope is under construction at East Anatolia Observatory in Turkey. DIRAC, the “DAG InfraRed Adaptive optics Camera”, is one of the facility instruments. This paper describes the design of the camera to meet the performance specifications. Adaptive and auxiliary optics relay the telescope F/14 input 1:1 into DIRAC. The camera has an all refractive design for the wavelength range 0.9 - 2.4 micron. Lenses reimage the telescope focal plane 33 x 33 as (9 x 9 mm) on a 1k x 1k focal plane array. With magnification of 2x, the plate scale on the detector is 33 mas/pixel. There are 4 standard filters (Y, J, H, K) and 4 narrowband continuum filters. A 12 position filter wheel allows installation of 2 extra customer filters for specific needs; the filter wheel also deploys a pupil viewer lens. Optical tolerancing is carried out to deliver the required image quality at polychromatic Strehl ratio of 90% with focus compensator. This reveals some challenges in the precision assembly of optics for cryogenic environments. We require cells capable of maintaining precision alignment and keeping lenses stress free. The goal is achieved by a combination of flexures with special bonding epoxy matching closely the CTE of the lens cells and crystalline materials. The camera design is very compact with object to image distance <220 mm and lens diameters <25 mm. A standalone cryostat is LN2 cooled for vibration free operation with the bench mounted adaptive optics module (TROIA) and coronagraph (PLACID) at the Nasmyth focus of the DAG telescope.

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Ross Zhelem, Robert Content, Vladimir Churilov, Yevgen Kripak, Lew Waller, Scott Case, Slavko Mali, Rolf Muller, Mario Gonzalez, David Adams, Nick Binos, Timothy Chin, Tony Farrell, Urs Klauser, Yuriy Kondrat, Nirmala Kunwar, Jon. Lawrence, Nuria Lorente, Summer Luo, Erica Mcdonald, Helen McGregor, Vijay Nichani, Naveen Pai, Minh Vuong, Jahanzeb Zahoor, Jessica Zheng, Barnaby Norris, Julia Bryant, Annino Vaccarella, Nick Herrald, James Gilbert, Cahit Yesilyaprak, Bulent Gucsav, Deniz Coker, Onur Keskin, and Laurent Jolissaint "Design of the near infrared camera DIRAC for East Anatolia Observatory", Proc. SPIE 12184, Ground-based and Airborne Instrumentation for Astronomy IX, 1218440 (29 August 2022); https://doi.org/10.1117/12.2629716

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