Patent ID: 6574437
Filing Date: 2003-06-03
Classification: G03B

Abstract:
A focus detection apparatus comprising:a pupil dividing device that divides an exit pupil of an objective lens into separate areas, the objective lens defining an optical axis; a field mask located at a position substantially optically equivalent to an image forming position of the objective lens; a condenser lens, located in a vicinity of the field mask, that enables the exit pupil of the objective lens to conjugate with the pupil dividing device, the condenser lens comprising at least one movable lens element that is moveable along the optical axis in accordance with the position of the exit pupil of the objective lens; a light quantity distribution forming device that receives light transmitted through the separate areas and forms light quantity distribution portions, a relative position of the light quantity distribution portions varying in accordance with a focus state of the objective lens; and a plurality of photoelectric transducers that receives the light quantity distribution portions and enables detection of the focus state.