High-accuracy parallelism measurement of coated cube by dual-autocollimators

Abstract

A simple, cost-effective and high-accuracy measurement of parallelism by dual autocollimators is proposed. A differential measurement was chosen to eliminate most of the environmental noises and systematic errors. The accuracy of parallelism measurement can reach the level of 1.6 µrad (1σ). This method can be widely used for parallelism measurements of components with reflective coating, such as glass blocks in metrology laboratories and test masses in the Gravitational Reference Sensor.