The null-screen method has been used to test aspheric surfaces, among them the surface of a parabolic trough solar collector (PTSC). This geometrical method measures the slope of the test surface and by a numerical integration procedure the shape of the test surface can be obtained. In this work, through some numerical simulations sinusoidal deformations with different amplitudes and spatial periods are introduced on PTSC surfaces. Then, an analysis of the deformations of the reflected images of a null-screen by the PTSC surface due to defects on the surface is performed. This procedure allows to validate the kind and magnitude of the surface deformations that can be measured with the proposed method. Also, an analysis of the advantages and limitations of the null-screen testing method will be discussed.

Date Published: 24 September 2015
PDF: 7 pages
Proc. SPIE 9628, Optical Systems Design 2015: Optical Fabrication, Testing, and Metrology V, 96281E (24 September 2015); doi: 10.1117/12.2192136

Published in SPIE Proceedings Vol. 9628:
Optical Systems Design 2015: Optical Fabrication, Testing, and Metrology V
Angela Duparré; Roland Geyl, Editor(s)