Apparatus for detecting the focus adjusted state of an objective optical system

摘要

A focus detecting apparatus is provided with a plurality of pattern forming lenses for forming light patterns whose relative positional relation varies in conformity with the focus adjusted state of an objective optical system from lights passed through different areas on the pupil of the objective optical a sensing device is included for sensing the light patterns and producing a signal regarding the relative positional relation between the light patterns. A light divider is inclined along an optical path passing through the areas on the pupil and has a light-transmitting area through which light is refracted and transmitted. The light divider is disposed between the objective optical system and the pattern forming lenses. The pattern forming lenses are different in shape and are formed asymmetrically with respect to the optic axis of the objective optical system to correct the destruction of the light patterns caused by the light divider.