Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site ssc-vax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!mhuxj!houxm!vax135!cornell!uw-beaver!ssc-vax!eder From: eder@ssc-vax.UUCP (Dani Eder) Newsgroups: net.physics Subject: Re: deflecting laser Message-ID: <290@ssc-vax.UUCP> Date: Thu, 20-Dec-84 16:02:22 EST Article-I.D.: ssc-vax.290 Posted: Thu Dec 20 16:02:22 1984 Date-Received: Fri, 21-Dec-84 04:25:09 EST References: <10800014@uiucdcsb.UUCP> Organization: Boeing Aerospace Co., Seattle, WA Lines: 29 > > I remember seeing the world map projected onto the silver dome > in monochrome laser in the EPCOT center, Florida. How did they do that? > They must have a way of deflecting the laser light to make it > does raster scanning. I can imagine only two ways to do this: > > 1) move the laser device mechanically. > 2) projects laser through some tansparent medium whose refractivity > is electronically controllable. > > The second one seems to be a more reasonable solution to me. Anyone > knowledgeable in the field care to comment on this? > > > Kaihu Chen > uiucdcs!chen There are additional ways to do it. One way is to mount a curved mirror on an audio speaker voice coil. As the voice coil moves in and out, the laser beam would strike different parts of the mirror, and hence would be reflected off in different directions. Two such mirrors could provide two axes of motion, with turning the laser on and off providing pixels. This is similar in principle to how CRT and TV tubes operate. Another method involves a rapidly spinning wheel with flat mirrors spaced around the rim. As a single mirror intercepts the beam, the reflection would scan in an arc. As you reach the edge between two mirrors, the beam would suddenly jump to the other side. This is the type of motion you want in raster scanning.