Part-reflecting surface coating in optics for filtering out light rays which are not axially parallel incorporates optical axis, filter, and lens

摘要

A flat-planed surface (4), such as filter or the next lens surface, at right angles to the optical axis (1) is placed behind the lens (5). The coating (7) lets through rays (8) striking at right angles, but reflects rays causing lack of definition. The rays are thrown against the blackened lens parts, and diffused light held back.