Patent ID: 6055107
Filing Date: 2000-04-25
Classification: G02B,G03F

Abstract:
A lens assembly comprising a substrate containing at least a lens material and an etching mask having a multi-homocentric pattern of mask areas wherein said etching mask comprises a multi-homecentric pattern of masked areas wherein said masked areas are divided into steps, with masked areas belonging to a same step having the same width, the widths of said masked areas are b.sub.n, the intervals between masked areas of a same step is a.sub.n, n is the sequence of step and the interval between the masked areas in the n.sup.th step and in the (n+1).sup.th step is a.sub.n+1 ; whereina.sub.n =a.sub.1 +(n-1)A and b.sub.n =b.sub.1- (n-1)B wherein ##EQU28## h is the height of each level, ##EQU29## and f.sub.100 is the etching rate of the (100) surface of the substrate, f.sub.1 is the etching rate in the lateral direction and R.sub.n -K.sub.n-1 is the width of the narrowest terrace; andk is the number of masked areas on the narrowest level wherein ##EQU30##