US 5,710,667 A · Focus detecting optical system

Abstract

A focus detecting optical system for detecting a focus condition of an image of an object to be picked-up by an image forming lens including a condenser lens arranged in a vicinity of a predetermined focal plane of the image forming lens, aperture stop having a plurality of apertures, a plurality of image reforming lenses and a plurality of light receiving element arrays. At least one diffractive optical element having a lens function due to a diffraction is provided on a surface of the condenser lens or image reforming lenses. The diffractive optical element may be formed by kinoform or binary optical element having a step-wise configuration. The diffractive optical element may be formed in a surface of an infrared cut filter.

Claims18

Dependent claims

A focus detecting optical system for detecting a focus condition of an image of an object, said focus detecting optical system comprising:

a focus detecting optical means for reforming an image of an object formed on a first predetermined focal plane by an image forming optical system on a second focal plane;
and
a diffractive optical means having at least one optical function and arranged between said first predetermined focal plane and said second predetermined focal plane, said diffractive optical means comprising a surface having a diffraction grating whose pitch is continuously changed in an area in which a light flux having an optical axis is made incident.

Dependencies are inferred from the claim text.

Focus detecting optical system

Life of this patent

Focus detecting optical system

Life of this patent

Abstract

Claims18