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Optical Engineering

Design of a single flat null-screen for testing a parabolic trough solar collector
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Paper Abstract

We present a null-screen design for testing the shape quality of the reflecting surface of a parabolic trough solar collector (PTSC). This technique is inexpensive, the whole surface is tested at once, and it is easy to implement. For this, we propose the design of a flat null-screen perpendicular to the optical axis of the PTSC in such a way that it allows testing of the full aperture; we compute the caustic associated with the reflected light rays on the desired surface and analyze the parameters that determine the null-screen dimensions. Additionally, we perform a numerical simulation to analyze the accuracy of the method by introducing random displacement errors into the measured data. Accuracies >0.35  mrad were found to evaluate the quality of surfaces with this method. The errors in the determination of the coordinates of the centroids of the reflected images must be measured with an accuracy >0.5  pixels, and the errors in the coordinates of the spots of the null-screen must be <0.5  mm.

Paper Details

Date Published: 20 November 2014
PDF: 11 pages
Opt. Eng. 53(11) 114108 doi: 10.1117/1.OE.53.11.114108
Published in: Optical Engineering Volume 53, Issue 11
Show Author Affiliations
Víctor Iván Moreno-Oliva, Univ. del Istmo (México)
Manuel Campos-García, Univ. Nacional Autónoma de México (México)
Edwin Román-Hernández, Univ. del Istmo (México)
Agustín Santiago-Alvarado, Univ. Tecnológica de la Mixteca (México)

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