From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Make infrared goggles inexpensively (like $10!!!)
References: <email@example.com> <3D848F5E.91EC2A2F@xympatico.ca>
Date: Sun, 15 Sep 2002 20:04:25 GMT
NNTP-Posting-Date: Sun, 15 Sep 2002 13:04:25 PDT
John Larkin wrote:
> On Sun, 15 Sep 2002 09:47:10 -0400, Joseph Legris
> >Jonathan Kirwan wrote:
> >> On Sun, 15 Sep 2002 12:00:47 +0100, "Prai Jei"
> >> wrote:
> >> >No comprendo. If you can see it, it is (by definition) not IR.
> >> Yes. The only possibility I could imagine here was anti-Stokes
> >> fluorescence with up-conversion phosphors. Unlikely.
> >> I think his argument on principle is that "very loud" 30kHz can be
> >> heard. Which isn't anywhere close to a valid analogy, regardless.
> >> Jon
> >There are various definitions of the shortest wavelength boundary of
> >infrared (760, 770, 800 nm), and the human eye responds weakly beyond
> >760nm (some 6 order of magnitude down from the maximum sensitivity). I
> >have a reference that shows measurable response past 800 nm. Conclusion:
> >we can see IR, but not very well.
> I can see, very faintly, a 1 mw 850 nm VCSEL laser in a dark room. I
> guess it's possible that it's leaking a bit of non-laser emission at
> shorter wavelengths. But I wouldn't spend a lot of time staring at one
> of these.
Yes, I can see very distinctly a CD laser but I can't tell how bright it
is (it can be pretty dead and I will still see it). DVD lasers, however,
are "visible" and I can tell at a glance a good one from a bad one (a
totally dead one putting out 20 microwatts looks bright but I can tell
it from one putting out 200 microwatts but not so with CD lasers).
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons firstname.lastname@example.org