Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!ames!uhccux!galileo!ressler From: ressler@galileo.ifa.hawaii.edu (Mike "IR" Ressler) Newsgroups: sci.electronics Subject: Re: I/R remotes Message-ID: <10028@uhccux.uhcc.Hawaii.Edu> Date: 26 Oct 90 00:30:11 GMT References: <972@qucis.queensu.CA> <1606@gold.GVG.TEK.COM> Sender: news@uhccux.uhcc.Hawaii.Edu Distribution: na Organization: UH Inst. for Astronomy and NASA Infrared Telescope Facility Lines: 32 In article hemstree@handel.CS.Colostate.Edu (charles he hemstreet) writes: >In article <1606@gold.GVG.TEK.COM> grege@gold.GVG.TEK.COM (Greg Ebert) writes: > I/R remote trivia: > > You can reflect I/R beams off lightly colored (ie white) surfaces. I got my > TV & VCR to respond around corners -- not just line-of-sight. No luck with > double reflections. > >Imagine my surprise when I turned 180 degrees from my TV to my >roommate to pretend to turn him off, pointed at my roommates face, hit >the off button, and turned off the tv instead! There were no mirrors >behind him, so I suppose the beam reflected off his eyes, or teeth. :-) Ah, young Jedi. You underestimate the power of the dark side. Or at least the IR side. Or at the very least, the reflectivities of various objects at 880 nm (maybe 950 nm, I'm not sure which LED they use). If your VCR is sufficiently sensitive, the walls and/or your roommate's body and clothing can reflect well enough to do the job, even if things look dark in the visible. Black is not necessarily black in the very-near infrared! If you want to have fun sometime, find someone who can take a picture of you in the near-infrared between 1 and 2 microns (1000 - 2000 nm for those who don't like archaic wavelength units). It looks kind of like a normal black and white picture, but things are a little out of kilter because reflectivities aren't the same as at 500 nm. If you want to get REALLY bizarre, try 4 microns where your body is emitting photons as well as reflecting them. Too much fun ... -- Mike Ressler - Infrared Photon Jockey ressler@galileo.ifa.hawaii.edu If at first you don't succeed, get a bigger sledgehammer.