Patent ID: 6219190
Filing Date: 2001-04-17
Classification: G02B

Abstract:
A zoom lens comprising:a plurality of lens units,said plurality of lens units including a movable lens unit having a negative refractive power lying closest to an image side, said movable lens unit having, in order from an object side, a first diffractive optical element and a second diffractive optical element,wherein, where C.sub.2a is a phase coefficient in the second order in an equation for phase shape of said first diffractive optical element and C.sub.2b is a phase coefficient in the second order in an equation for phase shape of said second diffractive optical element, the following condition is satisfied:0.7<.vertline.C.sub.2b.vertline./.vertline.C.sub.2a <3.0,andwherein said equation for phase shape is expressed by.phi.(h)=(2.pi./.lambda.)(C.sub.2.multidot.h.sup.2 +C.sub.4.multidot.h.sup.4 + . . . +C.sub.n.multidot.h.sup.n)where h is a height from an optical axis, .lambda. is a reference wavelength, C.sub.n is a phase coefficient in the n-th order, and .phi.(h) is the phase shape.