Patent ID: 8553331

Claim:
A selective diffractive optical element, comprising: a first diffractive region on a first surface of a substrate, the first diffractive region having a first design; and a second diffractive region, separate from the first diffractive region and on the first surface of the substrate, the second diffractive region having a second design, the first and second designs being different, but complementary respective to a desired balanced output of the selective diffractive optical element, wherein, by altering a position of a cross-section of an illumination beam, the selective diffractive optical element outputs a beam having a desired proportion of the first and second diffractive regions aligned along an optical axis of the illumination beam, the desired proportion being realized from a combination of the first and second diffractive regions and, when the position of the cross-section of the illumination beam is in a predetermined region including both the first and second diffractive regions, the output beam is balanced.