| 摘要 |
A material has a reflective surface which bears a light diffracting pattern in the form of a series of well-defined grooves and ridges, wherein the transverse cross-section of the surface has a non-cyclical sequence of peaks and troughs. The pattern is produced by a method involving the interference of a first reference beam of coherent light with a second beam of coherent light, the second beam consisting of a bundle of divergent beams all of which illuminate the same area as the first beam. Apparatus for this method has a special lens system for producing the second beam.
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