Measuring large mirrors using SCOTS: the Software Configurable Optical Test System

Abstract

Large telescope mirrors are typically measured using interferometry, which can achieve measurement accuracy of a few nanometers. However, applications of interferometry can be limited by small dynamic range, sensitivity to environment, and high cost. We have developed a range of surface measurement solutions using SCOTS, the Software Configurable Optical Test System, which illuminates the surface under test with light modulated from a digital display or moving source. The reflected light is captured and used to determine the surface slope which is integrated to provide the shape. A range of systems is presented that measures nearly all spatial scales and supports all phases of processing for large telescope mirrors.