High-precision assembly and measurement of a hollow pentaprism utilizing dual autocollimators and double-sided...

The replacement of a bulk pentaprism with a hollow pentaprism (HPP) in an autocollimator-based scanning optical path is recognized as an effective strategy for improving the reliability of the surface slope measuring method. However, simultaneous monitoring and control of the wedge error (δ) and parallel error (ω) of the two mirrors of an HPP is still a challenge. To address these limitations, we propose a new assembly and measurement method, to our knowledge, which involves two double-sided mirrors and dual autocollimators. We provide a detailed theoretical derivation and error analysis with experimental verification. The result shows that the measurement uncertainty of the wedge error Δδ_M reaches the level of ±2.9µrad, and the parallel error uncertainty Δω_M reaches ±18.2µrad.