Patent ID: 7295387
Filing Date: 2007-11-13
Classification: G02B

Abstract:
1. An optical system comprising: a cemented lens element, formed by cementing at least two constituent lens elements made of different optical materials together, and having a diffractive optical surface formed at a cementing interface between the two constituent lens elements, the two constituent lens elements having at their respective interfaces with air a radius of curvature different from a radius of curvature that they have at the cementing interface wherein the cemented lens element fulfills the following condition: where φp represents a refractive optical Dower of that one of the two constituent lens elements of the cemented lens element which has a refractive optical power of an opposite sign to a diffractive optical power of the cementing interface; νd represents an Abbe number of that one of the two constituent lens elements of the cemented lens element which has a refractive optical power of an opposite sign to the diffractive optical power of the cementing interface; φDOE represents the diffractive optical power of the cementing interface; and νDOE represents an Abbe-number-equivalent value of the cementing interface.