jay@npois.UUCP (Anton Winteroak) (03/05/85)
The largest atoms are about 0.3 nanometers in diameter, hydrogen (by far the most common) is about 0.1 nm. About the shortest wavelength of light that comes out of the sun in quantity is about 90 nanometers. Besides anything much higher energy than that would go through a micron of aluminum nearly untouched. Visable light is more like 300 to 700 nanometers. Clearly holes under a quarter wave length could work to reduce weight and drag, while not altering reflectiveness much. I have trouble imagining the process by which this stuff is made. How could a few square miles of this stuff be cheap ?
henry@utzoo.UUCP (Henry Spencer) (03/10/85)
> Clearly holes under a quarter wave length could work to reduce > weight and drag, while not altering reflectiveness much. I have trouble > imagining the process by which this stuff is made. How could a few square > miles of this stuff be cheap ? That's precisely the hard part. Ultrathin aluminum is not hard to make by vapor deposition in vacuum, but punching lots of submicroscopic holes in it isn't simple. Perhaps a photolithographic process like that used in ICs, using shortwave ultraviolet so the holes are small by visible-light standards? But how to make it fast and cheap...? -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry