Path: utzoo!attcan!uunet!mailrus!tut.cis.ohio-state.edu!purdue!mentor.cc.purdue.edu!pur-ee!pur-phy!piner From: piner@pur-phy (Richard Piner) Newsgroups: sci.electronics Subject: Re: How do you aim a laser? (Watch where you point that, son!) Message-ID: <2837@pur-phy> Date: 2 Dec 89 20:38:02 GMT References: <6220003@hpcupt1.HP.COM> Reply-To: piner@newton.physics.purdue.edu.UUCP (Richard Piner) Organization: Purdue Univ. Physics Dept., W. Lafayette, IN Lines: 19 In article <6220003@hpcupt1.HP.COM> dclaar@hpcupt1.HP.COM (Doug Claar) writes: >This is probably a naive question, but how do you aim a laser beam? (I know, >very carefully!). But seriously, are there non-mechanical methods to aim >a beam, or must I rely on moving mirrors around? What do things like >handheld laser barcode scanners and heads-up displays do? Are they >mechanical?? Most laser scanners use spining mirrors and electro-mechanical shutters. Some use electo-optical shutters, like LCDs. However, for really high speed laser stering, the neatest trick I've heard of is an ultrasonic diffraction grating. An ultrasonic standing wave creates a density sine wave in air, water, or other material. By changing the frequence of the sound, the grating spacing changes and hence the angle of diffraction changes. Very high speed, low mass system. Of cousre, there is the old trick of a mylar mirror on a speaker cone. If the speed of electrical response of non-linear optical materials ever gets high enough, electronic gratings will be a big application. R. Piner Brought to you by Super Global Mega Corp .com