Patent ID: 6069750
Filing Date: 2000-05-30
Classification: G02B

Abstract:
A wide-field eyepiece comprising, in order from the side of a viewed object:a first lens group of negative refractive power, which consists of a single, biconcave lens element;a second lens group of positive refractive power,a third lens group of positive refractive power which includes a lens element of positive refractive power and a lens element of negative refractive power that are cemented together; and,a fourth lens group of positive refractive power which includes a lens element of positive refractive power having opposite surfaces of different radii of curvature, with the surface of larger radius of curvature lying on the side of an observer's eye position,wherein an air space separates each said lens group from an adjacent lens group, and said wide-field eyepiece has a field of view greater than 55 degrees.