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 (1 σ ). 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.