chen@uiucdcsb.UUCP (12/15/84)
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
herbie@watdcsu.UUCP (Herb Chong, Computing Services) (12/17/84)
how about just plain mirrors. Herb Chong... I'm user-friendly -- I don't byte, I nybble....
crandell@ut-sally.UUCP (12/18/84)
> 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. Don't forget directing the beam toward a rotating mirror. That's the way most laser printers do it. -- Jim Crandell, C. S. Dept., The University of Texas at Austin {ihnp4,seismo,ctvax}!ut-sally!crandell
gijs@vu44.UUCP (12/19/84)
In <10800014@uiucdcsb.UUCP> Kaihu Chen writes: > [] 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. [] They simply deflect the beam with a rotating or vibrating mirror. The same technique is used in a laser printer: the light of a stationary laser is deflected in the x direction by a rotating mirror and then projected on a rotating (light sensitive) drum. Gijs Mos Free University Dept. of Biology Amsterdam ..{seismo,philabs,decvax}!mcvax!vu44!gijs
eder@ssc-vax.UUCP (Dani Eder) (12/21/84)
> > 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.
dgary@ecsvax.UUCP (01/02/85)
<>
It is also possible to deflect laser light by running it through a
moving hologram. This is, I think, how supermarket UPC scanners
operate.
--
D Gary Grady
Duke University Computation Center, Durham, NC 27706
(919) 684-4146
USENET: {decvax,ihnp4,akgua,etc.}!mcnc!ecsvax!dgarywill@anasazi.UUCP (Will Fuller) (01/07/85)
> > 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 The map might be projected holographically. Perhaps a raster scan might be achieved using either the Kerr electro-optical, or the Voigt & Cotton-Mouton magneto-optical effects. The beam intensity could be modulated via a Pockel Cell. Every time I have seen someone scan something with a laser they've used some variant of a mirror on an air bearing, and a linear servo (yawn). William Fuller ..!terrak!anasazi!will
ross@dsd.UUCP (Evan Ross) (01/11/85)
One common means for single dimensional raster-scanning with a laser is to reflect it off the outside surface of a mirrored rotating polygon. The rotation causes the angle of intersection (an reflection) of the beam to constantly change. This can be applied to two polygons (of different speeds) to produce a two dimensional scan.