Dynamic optical tests of a high-speed polygon

A dynamic optical deformation test for a high-speed polygon is described in which a laser beam is reflected off a rotating polygon and is focused on a pair of Ronchi rulings at 45 degrees to each other. The astigmatism and defocus terms of the deformation are measured and mapped over any one of the polygon facets. The relatively simple and sensitive setup is also used for testing pyramidal error, facet-to-facet angle error, and axis-to-facet interval deviations.