Manufacture of a hollow pentaprism using one autocollimator and a reference retroreflector

The pentaprism is widely used in optical measurement instruments; for example, an autocollimator and a scanning pentaprism system can be used to measure the shape of a large optical surface, and the quality of the pentaprism will influence the accuracy of these instruments. Bulk pentaprisms are commonly used in these instruments; however, their beam deviation is usually within 5^'' due to the limitation of processing. The hollow pentaprism, with lighter weight and lower beam deviation, can effectively replace the bulk pentaprisms in almost any situation. In this paper, we propose a new method, to the best of our knowledge, for hollow pentaprism manufacture using an autocollimator and a standard hollow cube corner retroreflector. The beam deviation of the achieved hollow pentaprisms reaches 0.1^'', as measured by the Zygo interferometer, which exceeds the highest accuracy of current commercial products. This method provides a simple and efficient way to manufacture hollow pentaprisms and can be widely used in situations for 45° angle measurement.