optical system for a hilfsbildes fade in a beobachtungsstrahlengang to overlap with a main image

摘要

Optical system for directing an auxiliary image towards an observer so as to be superimposed on to a main image. The optical system comprises a pentagonal prism having a first surface for intercepting the auxiliary image and directing an auxiliary image beam toward an opposing second surface so as to be internally reflected by the second surface towards a third surface so as to be internally reflected by the third surface and propagated out of the pentagonal prism through a fourth surface opposite the third surface towards the observer. At least one of the surfaces of the pentagonal prism is aspeheric and a directing optics constituted by a wedge proximate and external to the third surface directs a main image beam derived from the main image through the third surface into the pentagonal prism and out of the fourth surface thereof towards the observer.