This picture shows a hole in a section of the coating that's about 1/30th of an inch across.
If you want to look at tiny dim objects in deep space, you can't have a lot of stray light bleeding into your view, so NASA has developed a special blacker than black coating that absorbs almost all light that hits it.
The coating is made from carbon nanotubes, and is actually grown onto the surface you want to make light absorbent. Jet black paint absorbs about 90 percent of whatever light hits it, but this stuff makes black paint look like a mirror. Through the visible spectrum it absorbs about 99.5 percent of what hits it, and even at the ultraviolet and infrared ends it still sucks up 98 percent.
In the picture you can see a section of the coating that's about 1/30th of an inch across, with a hole cut in it to show the structure with the nanotubes.
NASA says they're exploring possible uses for the material, including ways to leverage its heat absorbing properties. I'm wondering whether I can cover my car with it, and never get another speeding ticket again.