Patent ID: 7188961

Claim:
A method of making a master substrate, the method comprising the steps of: preparing a corner cube array master that has a surface defining a two-dimensional arrangement of unit elements, wherein the unit elements are arranged at a pitch of 200 μm or less, each said unit element has a peak point and a bottom point as viewed in a direction from which incoming light is coming, and a peak portion, including the peak point, and/or a bottom portion, including the bottom point, have an excessive portion and/or a missing portion as compared with an ideal peak portion or an ideal bottom portion of an ideal corner cube array; making a first transfer by transferring the surface of the corner cube array master; and obtaining a k th transfer as the master substrate by sequentially making an (n+1) th transfer from an n th transfer with n incremented one by one from 1 to k−1, where k and n are both integers, n≧1, and k≧2, wherein in the corner cube array master, k is an odd number if an average level difference h 1 between the level of the peak point and that of an ideal peak point of the ideal corner cube is greater than an average level difference h 2 between the level of the bottom point and that of the ideal bottom point of the ideal corner cube, but k is an even number if the average level difference h 1 is smaller than the average level difference h 2 .