Back to the IR light source concept...

Don Bruder · 2004-07-31T20:43:22+00:00

This message crossed over into RPEM as an "in case anybody is interested in my progress" update. Primarily aimed at the sci.electronics groups, since the start of the whole thing was there, and appears to have generated some interest there.Some of you may recall my post a few weeks ago asking about IR LEDs, filters, and other yakkety-yak about cheap ways to fab a light source that puts out either pure IR, or "close enough to it", with little or no visible component, for use in what boils down to a homebrew "Night Vision" system designed around a video camera that has a well-demonstrated sensitivity to IR in the same region of the spectrum that TV remotes use. After some false starts, I've managed what I think would count as a reasonable "first cut" at the problem. As those who are a bit more "techno-geeky" than the average Joe are aware, the base material used in CDs *MUST* be IR transparent if the CD is going to be readable by the (IR) laser in the player/reader. Regardless of what color (blue, silver, gold, whatever) the reflective material appears to be, or what color the base plastic shows up as in visible light, the plastic that it gets coated onto has to be clear (or close enough) to IR - A fact which permits such weirdness as the "black" PlayStation CDs, odd-colored CD-R/CD-RW media, and so on. Which got me thinking...If one were to remove the reflective layer from, for instance, one of the black PlayStation CDs, or the black CD-Rs that can be had, it would stand to reason that one would then have a chunk of plastic that's (at least reasonably) opaque to visible light, but transparent to IR.After spending some time looking for, and a grand total of 8 dollars acquiring, a few of these "black" CDs, I went to work on taking my idea from the realm of theory to reality. And I'm pleased to say "it works!"Preliminary testing, using a 3-cell Mag-Lite and a chunk of black CD material with the reflective coating removed (with steel wool, as a first attempt - I'm...

Jul 31, 2004 22 Replies

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John Fields 21 years ago

Cyro makes the stuff, and sells it through distribution, so you may want to check with one of your local plasic suppliers to see if they can help you out. Also, Cyro has a list of their distributors on their web site, so you may want to check that out.

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Don Bruder 21 years ago

We might just get something going, though it will likely be cash, since I wouldn't know a decent chardonnay from vinegar if it walked up and introduced itself to me. :) I'm basically a teetotaller - the "non preaching" kind - mainly due to lack of any interest. By my own personal drinking habits, buying a six-pack of Guinness, or, in a pinch, Bud long-necks, and killing it off inside of six months qualifies as a "major bender". :)

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Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004. Short form: I'm trashing EVERY E-mail that doesn't contain a password in the subject unless it comes from a "whitelisted" (pre-approved by me) address. See for full details.

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Chris Hodges 21 years ago

He was probably chucking approx 0.5-2kW at the gel, which was transmitting

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