Performance of the first mechanically-coupled twisting heliostat: encircled energy vs angle of incidence, and closed loop tracking

A. Vagher; R. Angel; N. Didato; M. Rademacher

doi:10.1117/12.3027719

1 October 2024 Performance of the first mechanically-coupled twisting heliostat: encircled energy vs angle of incidence, and closed loop tracking

A. Vagher, R. Angel, N. Didato, M. Rademacher

Author Affiliations +

Proceedings Volume 13132, Nonimaging Optics: Efficient Design for Illumination and Concentration XIX; 131320F (2024) https://doi.org/10.1117/12.3027719
Event: Optical Engineering + Applications, 2024, San Diego, California, United States

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 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 approximately 1.30 m diameter. We report here also on a novel, tracking camera that employs a semitransparent beamsplitter fixed perpendicular to the mirror surface and to the plane of incidence. Over 2.5 hours of measurement of closed loop tracking, errors were ≤ 0.36 mrad rms, in both tracking axes.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

A. Vagher, R. Angel, N. Didato, and M. Rademacher "Performance of the first mechanically-coupled twisting heliostat: encircled energy vs angle of incidence, and closed loop tracking", Proc. SPIE 13132, Nonimaging Optics: Efficient Design for Illumination and Concentration XIX, 131320F (1 October 2024); https://doi.org/10.1117/12.3027719

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