Spring 2010

Letter

Diffraction Gratings on Diamond Surfaces

In the article by A. Gilbertson et al. describing a combination of microlithography and plasma etching to improve dispersion in diamonds (Winter 2009 G&G, pp. 260–270), the authors describe some technological developments at the California Institute of Technology. Your readers may be interested to know that two of the coauthors were part of a team that recently published a patent application relating to the process described (G. Maltezos, A. Scherer, and J. Witzens, Enhancing the Optical Characteristics of a Gemstone, U.S. Patent Application 2007/0157667A1, July 12, 2007, and International Patent Application WO2007/067696A1, June 14, 2007). The patent documents provide schematic drawings of the various steps used to create the diffraction grating patterns. Further improvements on the techniques are discussed in a later application by Maltezos and Scherer (Gemstones and Methods for Controlling the Appearance Thereof, U.S. Patent Application 2009/0126402A1, May 21, 2009; International Patent Application WO2009/073576A2, June 11, 2009).

The 2007 Maltezos et al. application was mentioned in a review summarizing patent documents about various surface treatments of gemstones (K. Schmetzer, “Surface treatment of gemstones, especially topaz—An update of recent patent literature,” Journal of Gemmology, Vol. 31, No. 1/2, 2008, pp. 7–13), which also provides additional information for the interested reader. A recently published patent application by G. L. W. Cross, W. McKenzie, and J. B. Pethica (Process and System for Fabrication of Patterns on a Surface, International Patent Application WO2010/003600A1, January 14, 2010, and European Patent Application EP 2 144 117 A1, January 13, 2010) describes further developments in the surface treatment of diamonds. Well-defined periodical patterns were prepared by treatment of the diamond’s surface with a focused ion beam and subsequent plasma etching. These publications also present a general review of the technical literature dealing with surface patterning and nanostructuring.

Karl Schmetzer
Petershausen, Germany