space@mit-mc (03/09/85)
From: Richard M. King <DKING@KESTREL.ARPA> A hexagonal array of holes is exactly the interference pattern of three mutually coherent light sources an infinite distance away from the surface and located at the corners of an equilateral triangle. The holes do not have to be accurately placed so there is no need for the light sources to be an infinite distance away. The wavelenght of the light throwing the interference pattern does have to be no larger than comparable to the desired holes, however. We should use an Eximer UV laser as a pilot beam to keep three more coherent, and fire a very short, high energy trio of beams onto the surface. The power has to be enough to vaporize the surface exactly where we have triply constructuve interference, and the beam has to be a short pulse for two reasons; to stop the various parts from moving during the blast, and to prevent heat from the holes from spreading. The pulse length constraint probably makes it impossible to do a large area at one time. I haven't worked any numbers, but a 1-meter diameter area seems about right to be able to deliver enough energy, to be able to have a short enough pulse, and to have the transmission apparatus a reasonable size. It is possible to "expose" lots of separate areas. Unexposed areas between the exposed ones do little harm. Dick -------