Optical and optomechanical design of the WIYN High Resolution Infrared Camera

The WIYN High Resolution Infrared Camera (WHIRC) is being developed for use on the WIYN 3.5 m telescope at Kitt Peak. It will mount on a Nasmyth port behind the recently commissioned WIYN Tip-Tilt Module (WTTM). WTTM is expected to routinely deliver 0.25" FWHM images in the near infrared (0.8-2.5 μm), with occasional periods of 0.12" diffraction-limited performance in the K band. WHIRC will take advantage of this superb imaging capability, offering a plate scale of 0.09" per pixel and a 3'x3' field-of-view (FOV) with the planned 2K2 detector. Stringent moment loading requirements at the WTTM interface necessitate a compact, low mass design, which has been achieved using an all-refractive optical path. Tight centering tolerances on the lenses call for precision cryogenic lens assemblies. In this paper we present details of the optical and optomechanical designs, and engineering analyses completed to date.