Recent announcement by NASA of nanotube ultrablack absorber is predated by other work, says independent researcher
Ashland, MA--A carbon-nanotube (CNT)-based optical absorber that absorbs 98% to 99.5% of incident radiation within the UV to far-IR band, unveiled by NASA in November, 2011, is not actually the first of its kind, according to Robert Crowley, president of Soundwave Research Laboratories. On Soundwave's blog site, Crowley notes that the NASA absorber is similar to a CNT ultrablack surface that Crowley himself invented and received several patents on, including one with a priority date of January 16, 1997.
NASA's absorber consists of a forest of vertical CNTs grown on a substrate such as silicon, silicon nitride, titanium, or stainless steel, creating an almost perfect blackbody absorber or emitter over a large wavelength range. Astronomy and spacecraft optical sytems are just two of the applications for the coating.
Crowley's 1997 patent contains the claim: "An electromagnetic energy absorbing structure device comprising: a substrate for supporting an aligned array of electromagnetic energy modifying nanotubes thereon; an array of nanotubes on said substrate arranged for the receipt of electromagnetic energy, wherein the electromagnetic energy received by the nanotubes arranged on the substrate is selected from the group consisting of: electromagnetic energy in the visible range, electromagnetic energy in the ultraviolet range or electromagnetic energy in the infrared range."
In his blog, Crowley mentions the use of his ultrablack surface for solar thermal absorbers, as well as for coating the insides of optical systems to get rid of internal reflections. In a private communication, he notes that he and his colleagues offered the absorber to ARPA-E, as the technology is a "game-changer in solar thermal applications."
"We do not begrudge our colleagues who still only rely on scientific papers for their research, but respectfully suggest that if they want to know what preceded, they should also be citing patents," says Crowley. "Forward-thinking academics are coming around to the idea that patents are at least as well peer-reviewed as some journal articles, and also stand the test of novelty, utility, and nonobviousness."
John Wallace | Senior Technical Editor (1998-2022)
John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.