US Patent 7293886 Stray-light reducing device for an optical system

A device is part of an optical system (1) that works with an intermediate image and comprises stop(5) with associated aperture (6). The device comprises a light-reducing or light-absorbing arrangement (12) located at the side of the aperture. The arrangement is arranged to reduce considerably or eliminate completely light (11) incident to the side of the aperture, and thereby considerably reduce beam reflections. In this way, there is less likelihood of the optical system being detected when this is in use.