The WIYN One Degree Imager Optical Design

摘要

The main advantage of the WIYN One Degree Imager (ODI) over other wide-field imagers will be its exceptional image quality. The fine pixel scale (0.11') provides uncompromised sampling of stellar PSFs under most conditions (seeing >0.3'). The telescope routinely delivers the site seeing (median ～ 0.7') which is often below 0.5' FWHM, and can be as low as 0.25'. The ODI specifications require the optics to maintain native high quality images. A two-element, fused silica, corrector meets the geometric error budget of 0.10' images, but the first element requires a mildly aspheric surface. The other element serves as the dewar window. A pair of cemented prisms (fused silica plus PBL6Y) serve as an ADC, which is essential to meet the image quality requirements for many observing programs. We describe the optical design details and its performance, the tolerances required, and the trade-offs considered for anti-reflection coatings. This paper is an update to a preliminary three-element design.