3. Surface finishes

We successively study the effects of typical local defects and roughness on the image of a point, the image of a low-contrast test pattern, and then the image of a test pattern when a bright source, such as the sun, illuminates the pupil.

Although highly efficient, optical polishing never produces absolutely perfect surfaces. There are always a few local defects, due to the raw material, impacts, surfacing operations, as well as micro-roundness called roughness.

The study is limited to the case of defects located in the plane of the pupil of the instrument, assumed to be stigmatic.