Patent ID: 6101044
Filing Date: 2000-08-08
Classification: G02B

Abstract:
A zoom lens system comprising from the object side,a first lens unit having a negative optical power and including at least one diffractive optical surface; anda second lens unit having a positive optical power and including at least one diffractive optical surface,wherein a distance between the first and second lens units varies during zooming operation, andwherein the diffractive optical surface of said lens units in the zoom lens system fulfills the following condition: ##EQU7## wherein .phi.d represents an optical power resulting from the diffractive effect of an individual lens unit, and.phi. represents an optical power of an individual lens unit, andthe following equations (a) and (b) describe .phi.d and .phi. respectively:.phi.d=-2mR2 (a).phi.=.phi.r+.phi.d (b)wherein,m represents a degree of diffraction,R2 represents a second order phase coefficient, and.phi.r represents an optical power resulting from the refractive effect of an individual lens unit.