Method and system to determine surface shapes of heliostats using fully-sampled starlight images

Abstract

A method for measuring a shape of a reflector surface of a heliostat at night using a bright star at different elevation and azimuthal settings according to an embodiment of the current invention includes setting the heliostat in fixed orientation such that aberrated and overlapping star images formed are translated due to Earth's rotation in a translation direction across the heliostat array receiver; viewing images of the bright star using a fixed array of cameras placed at or near an array receiver of the heliostat, wherein each camera of the fixed array of cameras has a large aperture lens, and simultaneous exposures are made quickly enough and repeated for long enough, so that, as they translate past the cameras, the aberrated star image is fully sampled in two dimensions, and wherein every point on the reflector surface of the heliostat appears in one or more of the recorded images as being bright from reflected starlight; and processing the recorded images from the fixed array of cameras with a data processor to obtain the surface shape by integration of the surface slopes.