Comments on: Night vision goggles ought to be fun

By: Frank Clarivu

Frank Clarivu — Mon, 28 Mar 2011 08:24:58 +0000

Where were these kind of toys when I was a kid? It’s a real shame that the field of vision is so small, but when you think about how this is practically science fiction technology to a 10 year old I suppose some limitations aren’t a problem!

By: youraloserXD

youraloserXD — Tue, 02 Nov 2010 17:08:08 +0000

wow O_o

By: Luis

Luis — Mon, 06 Sep 2010 00:27:00 +0000

Good article!thanks
http://espiamaestro.es

By: Imp

Imp — Mon, 14 Dec 2009 16:31:30 +0000

While Derek is right that far IR light is invisible to the human eye, but the eye does not shut off entirely at 650nm, so near infrared light is not completely invisible.

There are three factors:

1) The human eye can see up to ~725nm (I’m not positive where the cut off is or if it is the same for everyone, but I know can see 680nm, but I couldn’t see through a filter that cut out at 740nm). The rods which are more sensitive to light so take over in the dark don’t see in this range at all (they stop at ~650nm), so it is the less sensitive cones that you have to rely on. In addition to being less sensitive in general, the cones become less sensitive at longer wavelengths (at 650nm they need 10 times as much light to see as at 550nm it just gets worse at longer wavelengths). So out at 700nm, there needs to be a lot of light, but the eye can still see.

2) A CCD or CMOS sensor can work far into the infrared
(like the 8,000nm to 14,000nm that is needed for thermal imaging), but that requires special manufacturing, so the inexpensive ones normally work well around 650nm to 850nm.

3) IR LEDs can come in many different wavelengths, but inexpensive ones are 760nm, which aligns well with the peak sensitivity of the sensor. However, 760 is just the peak, the LED actually produces light from 710 to 810nm.

So with an LED that is producing some light at 710nm, and an eye that can see at 725nm, it is entirely possible to see the light from the IR LEDs.

I’ve also seen an 800nm IR flashlight that I could see in the dark, so I suspect that I’m being overly conservative in my estimates of the sensitivity of the eye and the range of light that an LED produces.

By: cheap night vision goggles

cheap night vision goggles — Mon, 07 Dec 2009 08:05:22 +0000

I had bookmarked your web site thanks

By: Zim

Zim — Thu, 01 Oct 2009 09:08:12 +0000

I recently purchased a pair of these for $50.00 from a well known retailer. They work pretty well for what they are and how cheap they are. The feild of vision is small yes but what are you going to be doing with night vision goggles anyways besides trying to impress your friends and sneaking up on them. The package itself says that your depth perception will be obstructed, oh well. So your not going to be doing any kind of special ops with these. But as a big kid who likes toys these rock. They didn’t have stuff like this when I was a kid at least not for kids.