Patent ID: 6671104
Filing Date: 2003-12-30
Classification: G02B

Abstract:
A zoom lens comprising:a first lens system having an overall negative power and comprising at least two negative lens elements and at least one positive lens element; and a second lens unit, disposed behind the first lens system, having a positive power and comprising at least two positive lens elements and at least one negative lens element, wherein during zooming, at least the second lens unit is moved so that the space between the first lens system and the second lens unit is changed, and at least one of the first lens system and the second lens unit comprises a diffractive optical element, wherein the following conditions are satisfied: DaW>DaT and10500, where DaW and DaT represent the spaces between the first lens system and the second lens unit at a wide-angle end and at a telephoto end, respectively; fDOE represents the focal length only due to diffraction of the diffractive optical element; and ft represents the focal length of the entire system at the telephoto end, and wherein the following condition is satisfied: âˆ’25Â°where &thgr; represents an angle between a ray incident on a diffraction surface of the diffractive optical element and a normal of the diffraction surface, or it represents an angle between a ray emitted from a diffraction surface of the diffractive optical element and a normal of the diffraction surface.