David Kirkpatrick

August 18, 2010

The world’s darkest material

I’ve previously blogged on a world’s darkest material in the past (couldn’t find the post in the archives, however) and it was nanotech-based as well so it’s possible this is the same stuff. Pretty cool either way.

From the link:

Harnessing darkness for practical use, researchers at the National Institute of Standards and Technology have developed a laser power detector coated with the world’s darkest material — a forest of carbon nanotubes that reflects almost no light across the visible and part of the infrared spectrum.

NIST will use the new ultra-dark detector, described in a new paper in ,* to make precision laser power measurements for advanced technologies such as optical communications, laser-based manufacturing, solar energy conversion, and industrial and satellite-borne sensors.

Inspired by a 2008 paper by Rensselaer Polytechnic Institute (RPI) on “the darkest man-made material ever,”** the NIST team used a sparse array of fine nanotubes as a coating for a thermal detector, a device used to measure . A co-author at Stony Brook University in New York grew the nanotube coating. The coating absorbs  and converts it to heat, which is registered in pyroelectric material (lithium tantalate in this case). The rise in temperature generates a current, which is measured to determine the power of the laser. The blacker the coating, the more efficiently it absorbs light instead of reflecting it, and the more accurate the measurements.

This is a colorized micrograph of the world’s darkest material — a sparse “forest” of fine carbon nanotubes — coating a NIST laser power detector. Image shows a region approximately 25 micrometers across. Credit: Aric Sanders, NIST