Validation of two Optical Measurement Methods for the Qualification of the Shape Accuracy of Mirror Panels for Concentrating Solar Systems

Abstract

Photogrammetry and deflectometry are two optical measurement methods that are typically used to measure the shape accuracy of mirror panels used in CSP applications. They have been compared and validated by measuring a typical mirror panel under optimal conditions. Furthermore, as an absolute reference object a flat water surface has been measured by deflectometry. The remaining deviations between the results of both methods and to the reference object are discussed and possible sources of errors during the measurement are identified. A detailed error analysis is conducted for both methods and compared to the experimental findings. The results show that both methods, when used correctly, show acceptable measurement uncertainties for the measurement of presently achievable accuracies of CSP applications, although, deflectometry exhibits advantages in speed, measurement accuracy and spatial resolution.