Paper 13132-40
Paper 13132-40
Measured performance of the first automatic twisting heliostat: encircled energy vs angle of incidence
20 August 2024 • 1:40 PM - 2:00 PM PDT | Conv. Ctr. Room 18
Abstract
The first automatic twisting heliostat, with 8 m2 reflector, was completed and tested on-sun in January 2024. It was set up on a target-oriented dual-axis mount, with the target-axis aimed at a target 113 m to the west. The shape-twisting is then purely automatic, made by a mechanical cam coupling to the cross-axis, which turns as the angle of incidence of the sun’s rays on the reflector. Three unsaturated images taken at different times of day were recorded of the sun on the target, reflected at angles of incidence of 5°, 49° and 68°. The measured FWHM of three images is very similar, about 1.09 m or 9.5 mrad, only slightly larger than an ideal solar disc, indicating that the different twisted reflector shapes are close to the ideal biconics needed to image the sun. The encircled energy measured for all three images was similar, 87% within ~1.30 m diameter.
Presenter
Roger P. Angel
The Univ. of Arizona (United States)
Roger Angel is a Regents Professor at the University of Arizona’s Department of Astronomy and College of Optical Sciences. He is a member of the National Academy of Sciences, a Fellow of the Royal Society, and a recipient of a Kavli prize and a MacArthur Fellowship. He has brought about radical changes in telescope and optical technology for several decades. He founded and directs the Steward Observatory Caris Mirror Lab. His pioneering work in the use of optical fibers and adaptive optics in astronomy has led to the construction of some of the world’s largest optical telescopes and their instrumentation. In recent years Angel has worked also on solar energy technologies using concentrating optics, most recently on adjustable-shape heliostats to concentrate solar energy to the very high temperatures needed to make fuels and cement.