Optical system for turning picture through right angle uses directly adjoining pechan prisms straddled by identical lenses of glass having partial dispersion

摘要

The two Pechan prisms directly adjoin one another without interposed lenses, using a lens system composed of two lenses (6,7) set either side of the prisms, giving a telecentric beam between them (6,7). The two prisms (8,9) form an intermediate image (10) between them (8,9), both prisms being mirror-identically arranged. The pair of lenses are also identical and mirror-symmetric to one another and are made of glass having abnormal partial dispersion.