The quasi-optical design of the QUaD telescope

• Published in: Infrared physics & technology Vol. 51; no. 4; pp. 277 - 286
• Main Authors: O’Sullivan, C., Cahill, G., Murphy, J.A., Gear, W.K., Harris, J., Ade, P.A.R., Church, S.E., Thompson, K.L., Pryke, C., Bock, J., Bowden, M., Brown, M.L., Carlstrom, J.E., Castro, P.G., Culverhouse, T., Friedman, R.B., Ganga, K.M., Haynes, V., Hinderks, J.R., Kovak, J., Lange, A.E., Leitch, E.M., Mallie, O.E., Melhuish, S.J., Orlando, A., Piccirillo, L., Pisano, G., Rajguru, N., Rusholme, B.A., Schwarz, R., Taylor, A.N., Wu, E.Y.S., Zemcov, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2008; Elsevier
• Subjects: Astronomy; Astrophysics; Cosmic microwave background; Cosmology and Extra-Galactic Astrophysics; Earth, ocean, space; Exact sciences and technology; Feedhorn design; Fundamental areas of phenomenology (including applications); Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations; Gaussian beam modes; Geometrical optics; Historical astronomy and archaeoastronomy; and other topics in fundamental astronomy and astrophysics; instrumentation, techniques, and astronomical observations; Optical design; Optical system design; Optics; Physics; Quasioptics; Sciences of the Universe; Wave fronts and ray tracing; Quasioptics; Optical design; Cosmic microwave background; 84.40.Ba; 42.15.Eq; Gaussian beam modes; 95.85.Bh; 98.70.Vc; Feedhorn design; Performance evaluation; Microwave radiation; Cosmic background radiation; Measuring methods; Experimental study; South pole; Gaussian beam; Optical polarization; Free space propagation; Electromagnetic wave propagation; Quasioptics; Gaussian beam modes; Optical design; Feedhorn design; Cosmic microwave background; Optical method; Ray tracing; Telescopes; Optical design techniques; Mirrors; 42.15.Eq; 84.40.Ba; 95.85.Bh; 98.70.Vc; Background radiations; Radio; components and accessories; Optical system design; microwave; Antennas: theory
• ISSN: 1350-4495; 1879-0275
• DOI: 10.1016/j.infrared.2007.10.001

We describe the optical design and performance of ’QUEST and DASI’ or ’QUaD’, a ground-based high-resolution experiment designed to measure the polarisation properties of the cosmic microwave background radiation. QUaD uses bolometric detectors at 100 and 150GHz on a 2.6m Cassegrain telescope. The QUaD optics are designed to minimise systematic effects as well as to maximise sensitivity, and we report here on the comprehensive quasi-optical analysis used to achieve this design. We also present initial optical performance measurements achieved in operation, and discuss changes made to the optics to overcome some errors in the mechanical construction of the primary mirror. The QUaD experiment is now fully operational and taking world-leading data at the South Pole.