Agile Deflectometry

Abstract

Concentrating Solar Power (CSP) systems use mirorrs to focus light onto a receiver, and high optical slope accuracy is required to achieve high concentration. Deflectometry is a technique for measuring optical slope directly, at fine spatial resolution across a miror surface. In this paper we report techniques for making an existing deflectometry system, SOFAST, more flexible and easier to deploy across a wide range of application scenarios. Example applications include mirror prototype development, high-volume manufacturing, outdoor in situ heliostat inspection, and education. We report using the resulting system to measure mirrors ranging in diameter from 0.13 m to 9.3 m, a range of nearly two orders of magnitude. Hardware implementations vary from a simple laptop computer to a system combining a computer, projector, screen, and camera. These efforts pursue a goal of making deflectometry easier to use, applicable to a wider range of problems, and widely available to the CSP community.