The Canarias InfraRed Camera Experiment (CIRCE): Progress of the Opto- and Cryo- mechanical Design and Manufacture M. L. Edwards a , S. S. Eikenberry a , M. Charcos-Llorens a , A. Marin-Franch b N. Lassoa, S. N. Raines a , J. Julian a , K. Hanna a , C. Packham a , M. Rodgers c , R. M. Bandyopadhyay a a University of Florida, Department of Astronomy, 211 Bryant Space Science Center, Gainesville, FL, 32611 b Instituto de Astrofsica de Canarias, Via Lactea s/n, E-38200 La Laguna,Spain c Optical Research Associates, 3280 East Foothill Boulevard, Suite 300 Pasadena, California 91107-3103 ABSTRACT We present the current status of the Canarias InfraRed Camera Experiment (CIRCE) an all-reflective near-IR, imager, spectrograph, and polarimeter for the 10.4-meter Gran Telescopio Canarias (GTC). In particular, we review the progress of the opto- and cryo- mechanical design and manufacture, focusing on the custom filter, lyot, and grism wheels, lightweight optics, and mirror brackets. We also outline our progress with the optical bench. Finally, we discuss a number of CIRCE’s features that both complement and augment the planned suite of GTC facility instruments. Keywords: instrumentation:miscellaneous, infrared:general 1. INTRODUCTION The Canarias Infrared Camera Experiment (CIRCE) is a near-infrared (1 - 2.5 micron) visitor instrument for the 10.4-meter Gran Telescopio Canarias (GTC). Located on the island of La Palma in the Canary Islands, the telescope is a joint venture between Spain, Mexico, and the University of Florida (UF). While the final suite of GTC instruments will sample all crucial optical and infrared regimes, the first- generation of facility instruments do not include a NIR camera. CIRCE fills the crucial gap between the tele- scope’s inception and the commissioning of the second-generation NIR facility instrument EMIR. Envisioned as a “workhorse” camera, capable of filling the NIR needs of the GTC community, CIRCE will have three basic modes, imaging, low- to moderate- resolution spectroscopy, and imaging and spectro- polarimetry. Additional features like high-speed imaging photometry, further complement and augment the GTC’s capabilities. In this paper, we review an analysis of the CIRCE optical layout. We then discuss our progress on the opto- and cryo- mechanical design. 2. OPTICAL DESIGN While CIRCE’s basic collimator/camera layout is similar to many modern NIR cameras, the all-reflective aspheric design is more novel. Significant advances in the manufacture of diamond-turned optics have made them a viable alternative to lenses, especially since they often offer better throughput and image quality than all-refractive systems. Figure 1 shows the CIRCE optical layout, as designed by M. Rodgers at Optical Research Associates (ORA). Incoming light will pass through the cryostat entrance window (1) to the telescope focal plane (2) where a slit wheel will house an imaging field stop, a long slit for grism spectroscopy, and a partial-field imaging stop for polarimetry. Two fold mirrors aft of the telescope focal plane will direct the light to a two mirror collimator (Send correspondence to M.L.E – E-mail: edwards@astro.ufl.edu, Telephone: 1-352-392-2052 ext. 253) Ground-based and Airborne Instrumentation for Astronomy II, edited by Ian S. McLean, Mark M. Casali, Proc. of SPIE Vol. 7014, 70142L, (2008) · 0277-786X/08/$18 · doi: 10.1117/12.788424 Proc. of SPIE Vol. 7014 70142L-1 Downloaded from SPIE Digital Library on 28 Apr 2010 to 128.227.184.43. Terms of Use: http://spiedl.org/terms