Optical control for solar mirrors

Concentrated power on the receiver and homogeneity of irradiance distribution are optimised in the optical design of solar mirrors. However, the manufactured mirror may contain some fabrication defects, which alter the irradiance distribution on the receiver. Surface defects introduce aberrations that cause an enlarged spot on the receiver and the resulting energetic losses depend on the collection features of each solar plant. To minimise these losses, it is essential to control the surface curvature, especially on large solar reflectors like heliostats. Facility of application, low-cost equipment, and elaboration simplicity are the key advantages of the proposed optical control. Exploiting techniques of image analysis, it assesses the mirror surface quality comparing an acquired image with a reference image. The application requires only a photographic camera and a screen with a calibrated pattern. The surface defects of the reflecting surface appear as deformations in the image of the pattern. This optical measurement could be adapted to examine mirrors with various shapes and sizes. It is an optical control that can be applied during manufacturing of the mirrors or on the produced samples.