Abstract

A reflective metallic foil is modified so that an incident laser beam is diffused into multiple beams to dissipate the energy of the incident beam. The surface can have protrusions that range from 0.3 to 10,000 microns high with an average diameter of from 1 to 1,000 microns and an average spacing between protrusions of from 0.2 to 5,000 microns. The surface of the metallic foil can be provided with a first type pattern consisting of protrusions and indentations having an optimum range of 0.3 to 20 microns deep having average optimum diameter of 2 to 40 microns with an average optimum spacing between protrusions of 1 to 100 microns or a second type pattern consisting of protrusions and indentations having an optimum range of 20 to 100 microns deep having an average optimum diameter of 20 to 100 microns with an average optimum spacing of from 20 to 200 microns. The second type pattern can be superimposed on patterns of the first type.