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Black is the new black, according to UK scientists who have further developed their very low reflectance ultra-black materials using existing techniques originally developed in the US and Japan. The new coatings could be used to improve optical instruments, as well as boost the performance of ultra-violet, infra-red and visible spectrometers. The material could improve efficiency to such an extent that instruments used in radiometry, spectroscopy, optical metrology, and within the aerospace and defence industries will also benefit from a reduction in size and weight. Richard Brown, Senior Research Scientist at the National Physical Laboratory, in Teddington, Middlesex and colleagues Paul Brewer and Martin Milton have developed the blackest, lowest reflectance commercially available surfaces ever "seen". The performance of any optical instrument depends on the quality of materials used in its manufacture. For spectroscopic accuracy in the UV-vis and IR regions the optimal radiation detection is possible only if stray light is kept to a minimum. The NPL team investigated the different available methods for chemical etching of nickel-phosphorus with the aim of developing their well-known low reflectance materials still further into the black. Their improved understanding of the process by which black nickel-phosphorous coating can be produced is based on atomic force, and scanning electron, microscopy studies and has led to the development of NPL Super Black (or Ni-P Black). This material has a reflectance as low as 0.35% in the visible region. NPL has produced Super Black on a small scale at its laboratories for several years. The material is very efficient at detecting radiation and at reducing stray light in instruments. Now, the researchers at NPL have a new, improved grasp on what makes the coatings so effective, which they hope will allow them to improve these materials still further. Brown is enthusiastic about his team's results. "The improved understanding of the process means that NPL Super Black will be available to a wider range of users across many areas of science and technology, and its benefits are enormous," he says, "One of the advantages of this new black is that it can withstand cryogenic temperatures without cracking." It also does not age at the same rate as other low reflectance materials that are already used in instrumentation. The researchers say that NPL Super Black could be plated (using electroless techniques) on to a range of materials of different shapes and sizes, potentially including glass and ceramics. This will increase its range of possible applications as well as extending its suitability for different environmental conditions. The new understanding of the formation of these coatings is now allowing the NPL researchers to suggest requirements for developing larger-scale production methods without compromising quality. Related links: |
 An electron micrograph picture of the surface of an NPL Super Black (Credit: National Physical Laboratory)  NPL Super Black is blacker than black! (Credit: David Bradley, adapted from National Physical Laboratory image) |
