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t@nn
2009-Jan-22, 12:56 PM
If you could see infrared light, and were standing outside on a perfectly clear night, how would the sky's appearance differ?

Hornblower
2009-Jan-22, 02:58 PM
If you could see infrared light, and were standing outside on a perfectly clear night, how would the sky's appearance differ?

That depends on how far into the infrared (IR) range of the spectrum you go, and whether or not you are looking through our atmosphere, which is opaque at some IR wavelengths. Let's start with a thought experiment out in space, to eliminate the complications of the latter.

K and M stars would be much brighter, because most of their radiation is in the near IR. If we go far enough into longer wavelengths, we would be able to see through the galactic dust that obscures many stars, including protostars immersed in dusty nebulae. Many of these nebulae would be bright in IR.

Some of these objects would be dimmed by absorption bands in our atmosphere. If we go to the longer wavelengths where IR snooperscopes can see warm bodies at night, the IR glow of the atmosphere itself would be the mother of all light pollution.

Tim Thompson
2009-Jan-22, 03:25 PM
Orion (http://en.wikipedia.org/wiki/Orion_(constellation)) is certainly a distinctive & easy constellation, and is well placed in the northern hemisphere evening sky now. There is a huge complex of molecular & dust clouds streaming through that region of the sly which makes a big difference between visible and infrared. See this page: Infrared Orion (http://www.ipac.caltech.edu/Outreach/Edu/animation.html). You can also find a lot of interesting stuff about infrared astronomy, and comparing visible and infrared on the Cool Cosmos (http://coolcosmos.ipac.caltech.edu/) website from Caltech's Infrared Processing and Analysis Center (http://www.ipac.caltech.edu/).

Chunky
2009-Jan-22, 04:44 PM
I've looked at a remote controls light at the top. While I was pushing buttons, I barely saw a red light. was i seeing part of the spectrum?
(i was really close and it was dark)

is this high jacking a thread?

swansont
2009-Jan-22, 05:19 PM
I've looked at a remote controls light at the top. While I was pushing buttons, I barely saw a red light. was i seeing part of the spectrum?
(i was really close and it was dark)

is this high jacking a thread?

We're actually discussing things like that in another thread.
http://www.bautforum.com/science-technology/83393-infra-ultravision.html

tdvance
2009-Jan-22, 09:53 PM
I don't know this, of course, but I suspect you'd see a lot more light pollution.

t@nn
2009-Jan-31, 02:28 PM
Thanks for the input.

Sorry for the delay in replying. I somehow forgot about this thread. :O

BigDon
2009-Jan-31, 11:01 PM
Oh yeah, and most clothes would have to be redesigned.

t@nn
2009-Feb-01, 07:04 AM
Oh yeah, and most clothes would have to be redesigned.

Why is that?

swansont
2009-Feb-01, 11:37 AM
Why is that?

If they are transparent to IR, then one of their functions has been lost.

eburacum45
2009-Feb-02, 04:08 AM
I'm just amazed at the spooky effects obtained in images taken of Earth landscapes in the near-infrared.

Vegetation in particular is very bright; this phenomenon, the so-called 'red edge', allows different types of vegetation and crops to be distinguished from space, and the effect is so strong that a planet with Earth-like vegetation in another solar system might stick out like a sore thumb in these wavelengths.
Take a look at this set of images, for instance; just chosen at random from the Interweb;
http://flickr.com/photos/giladbenari/sets/72157601963674503/
the light colours in these pictures are mostly vegetation seen in the red-edge wavelengths.

BigDon
2009-Feb-02, 02:39 PM
If they are transparent to IR, then one of their functions has been lost.

San Francisco Airport.

The Channel 7 news ran a story exactly twice before it was squashed about the IR cameras at the airports being used to search for weapons in crowds and the veiw through the camers had to have "black tape" censoring. That was before 9/11. Same with most non-thermal curtains.

The IR cameras used by PG&E, our power utitlity company, can see through the walls of your house. Another squashed expose'.

mugaliens
2009-Feb-02, 07:00 PM
If they are transparent to IR, then one of their functions has been lost.

That would depend on the frequency. Thermal IR is a much longer wavelength than near IR.

Fabrics such as rayon are transparent to thermal IR. :shhh:

Buttercup
2009-Feb-02, 07:04 PM
I guess I'd be wondering if someone had slipped LSD into my Diet Pepsi... :p

ryanmercer
2009-Feb-03, 11:46 AM
You can, just cough up a grand or twenty for the monocular/binoculars that show you how much you want to see of the IR spectrum.

RalofTyr
2009-Feb-04, 05:10 PM
If I could see in inferred, I'd be hunting special ops in Central American jungles...

Or be a mosquito.

BigDon
2009-Feb-04, 09:31 PM
If I could see in inferred, I'd be hunting special ops in Central American jungles...

Or be a mosquito.

Inferred red, is that like a dark pink?

DyerWolf
2009-Feb-09, 12:39 AM
I believe an inferred red is more like what color you presume the light to be when you see all those people stopped at the intersection...

Ara Pacis
2009-Feb-09, 09:44 AM
Near Infrared viewing devices aren't that hard to get ahold of. Any camcorder with night vision will do it easily for a couple hundred dollars. A cheaper digital camera or camcorder might do it too, put perhaps not as easily. but in either case, it might help to get some lens accessories.

timb
2009-Feb-09, 10:25 AM
Near Infrared viewing devices aren't that hard to get ahold of. Any camcorder with night vision will do it easily for a couple hundred dollars. A cheaper digital camera or camcorder might do it too, put perhaps not as easily. but in either case, it might help to get some lens accessories.

Standard digital camera CCDs are sensitive in the near IR. Almost alll mass market cameras these days include an IR filter. There are several tutorials online on how to convert your digital camera into an IR camera. Basically they tell you how to remove the filter and replace it with a piece of exposed 35mm negative which is transparent in the IR but opaque in the visible. Then you make an IR illuminator from IR LEDs and you're set to go around filming/photographing people unawares in the dark.

Ara Pacis
2009-Feb-10, 08:59 AM
Standard digital camera CCDs are sensitive in the near IR. Almost alll mass market cameras these days include an IR filter. There are several tutorials online on how to convert your digital camera into an IR camera. Basically they tell you how to remove the filter and replace it with a piece of exposed 35mm negative which is transparent in the IR but opaque in the visible. Then you make an IR illuminator from IR LEDs and you're set to go around filming/photographing people unawares in the dark.

Hence, the "not as easily" part. But I'd never heard of anyone replacing the ICF with an IPF in situ, though I suppose it should work, minus some focusing issues.

timb
2009-Feb-10, 09:33 AM
Hence, the "not as easily" part. But I'd never heard of anyone replacing the ICF with an IPF in situ, though I suppose it should work, minus some focusing issues.

I don't know what ICF or IPF stand for, so they probably require expansion, but GeekTechnique has instructions that follow (http://geektechnique.org/index.php?id=254)my outline.

swansont
2009-Feb-10, 05:11 PM
Standard digital camera CCDs are sensitive in the near IR. Almost alll mass market cameras these days include an IR filter. There are several tutorials online on how to convert your digital camera into an IR camera. Basically they tell you how to remove the filter and replace it with a piece of exposed 35mm negative which is transparent in the IR but opaque in the visible. Then you make an IR illuminator from IR LEDs and you're set to go around filming/photographing people unawares in the dark.

A cheaper alternative is to do this to a webcam, if you're willing to put up with the lower resolution. A drawback of modifying an autofocus digital camera is that you need to match the optical thickness of the filter you've removed, in order for the autofocus to work properly.

I did this and took a few snaps of some IR laser systems (http://blogs.scienceforums.net/swansont/archives/514). Didn't add the visible-light filter, though.

tracer
2009-Feb-11, 02:28 AM
I'd just like to point out that the Six Million Dollar Man could see in the Thermal Infrared range using his bionic eye.

Solfe
2009-Feb-11, 04:21 AM
I use a web cam to test infrared remotes at work. When they work, it shows up as a blue light on screen. Is that a function of how powerful the IR light is? Angle is another odd thing when using a web cam for this, if the IR source is turned too much, I cannot see it on screen.

Solfe

Sticks
2009-Feb-11, 05:57 AM
I use a web cam to test infrared remotes at work. When they work, it shows up as a blue light on screen. Is that a function of how powerful the IR light is? Angle is another odd thing when using a web cam for this, if the IR source is turned too much, I cannot see it on screen.

Solfe


This is more to do with the way the webcam is built to detect light. You can see the same effect with remote controls on digital cameras and camera phones