Color diffractive subtractive filter master recording comprising a plurality of superposed two-level relief patterns on the surface of a substrate

Claim 1

A color diffractive subtractive filter master recording for use in forming a stamper that simultaneously embosses preselected ones of all combination of three subtractive primary colors on a single surface of a transparent sheet of plastic in the fabrication of color diffractive subtractive filters, said master recording including: a substrate having a diffractive structure comprised of three angularly-displaced diffraction-grating two-level relief patterns on the surface of said substrate, said substrate surface including at least first and second regions, said three two-level relief patterns being arranged so that within said first region all three of said two-level relief patterns are superposed to provide a relief pattern having eight different levels and within said second region at least one but less than all three of said relief patterns are disposed to provide a relief pattern having at least two and no more than four different levels, wherein a first of said three two-level relief patterns has a first given depth corresponding substantially to a null for a first of said three primary colors of zero-order diffraction light, wherein a second of said three two-level relief patterns has a second given depth corresponding substantially to a null for a second of said three primary colors of zero-order diffraction, and wherein a third of said three two-level relief patterns has a third given depth corresponding substantially to a null for a third of said three primary colors of zero-order diffractive light.