Optical system for ophthalmoscopic camera free from influx of detrimental light rays

Claim 1

AN OPTICAL INSTRUMENT COMPRISING A MAIN OPTICAL SYSTEM, A HALF-SILVERED MIRROR SURFACE AND AN OBJECTIVE LENS IN THE MAIN OPTICAL SYSTEM, THE HALF-SILVERED SURFACE BEING IN FRONT OF THE OBJECTIVE OBLIQUER OF THE MAIN OPTICAL SYSTEM, THE HALF-SILVERED SURFACE PROVIDING TWO OPTICAL AXES INTERSECTING EACH OTHER AT THE HALFSILVERED SURFACE CORRESPONDING RESPECTIVELY TO LIGHT INCIDENT ON SAID SURFACE WHICH IS REFLECTED BY, AND TRANSMITTED THROUGH, SAID SURFACE, AN ILLUMINATING OPTICAL SYSTEM OBLIQUELY IN FRONT OF THE HALF-SILVERED SURFACE AND SO POSITIONED THAT THE TWO OPTICAL AXES OF THE MAIN SYSTEM ALSO CONSTITUTE THE TWO OPTICAL AXES OF THE ILLUMINATING OPTICAL SYSTEM CORRESPONDING TO LIGHT IN THE ILLUMINATING OPTICAL SYSTEM INCIDENT ON THE HALF-SILVERED SURFACE TRANSMITTED THROUGH AND REFLECTED BY THE HALF-SILVERED SURFACE, AN APERTURE STOP IN AN IMAGE PLANE OF ONE OF THE AXES OF THE MAIN OPTICAL SYSTEM CONJUGATE WITH AN OBJECT PLANE THEREOF, AND A LIGHT INTERCEPTING MEANS IN THE OTHER AXIS OF THE MAIN OPTICAL SYSTEM SUBSTANTIALLY CONJUGATE IN SHAPE WITH THE APERTURE OF THE APERTURE STOP AND POSITIONED SUBSTANTIALLY IN A PLANE CONJUGATE WITH THAT OF THE APERTURE STOP.