TITLE: Pond Machine II
MATERIALS: Tinted PPMA sheet, servos, distributed computer
DIMENSIONS: 16ft x 4ft
DATE: 2003

DESCRIPTION
A wall-sized plastic mirror. The mirror is sliced into thin vertical strips maybe 2" wide, maybe 100 of them, each strip attached at the top to a moving-coil galvanometer (galvo) and hanging downwards. Each galvo can deflect its mirror strip slightly. It's like a venetian blind, but with the plastic strips running vertically. When turned off, all the plastic strips are hand-aligned to be flat, so it looks like a huge flat mirror. Or, if rendered in dark plexiglas, it just looks like a shiny black wall.

A PC outputs 100 analog channels, one to each galvo, and each galvo deflects its mirror strip. So essentially the computer dynamically sculpts the mirror array into a rippled surface with moving waves by independantly controlling each galvo (and each mirror-strip angle). Broad waves and tiny ripples can interpenetrate and march across the array with different speeds and different directions. We can create standing waves; bathtub-slosh effects or "chop." Invisible winds can blow, riffling the "water surface." The system can simulate a falling stone or a raindrop hitting the "water", and a correct ripple-pattern will spread outwards from a point. (Of course the spreading ripples will be long parallel waves, not the expanding circles of a real pond.)

Aside from the software, this is a very simple device, but nobody in their right mind would ever consider building one. Laser-control galvos NORMALLY COST $300 EACH WHEN NEW. $30,000 for a hundred of them…

CONTACT
William J. Beaty
Seattle, WA
http://www.eskimo.com/~billb/weird.html