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YT2095

Infrared Fun! (with pictures)

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here`s a really cool experiment anyone can do that not only gives very interesting results (some of which I`ll present here) but won`t break the bank either,

I`ll only present some of the effects and results here as the potential hasn`t been fully explored yet by myself leaving Plenty of scope for others to join in.

 

you`ll need a cheap webcam, you can pick them up for pocket change nowadays.

the Best sort are the ones that you have to focus manually by turning the lens holder.

you`ll have to take this appart so that you can unscrew it entirely to see the CCD chip itself, although the CDD isn`t the bit you`r after, the bit you need to remove is 99.99% of the time in the Lens housing itself.

it`s the Infrared filter! :cool:

it`s often a small flat square piece of glass that has a Green color to it, I say Often as it can be circular too, but it always flat and has a green color.

depending on the design you`ll have to either remove tiny spots of glue at the edges to remove it, or cut some plastic away and let it drop out, eitherway a sharp box cutter blade is the ideal tool.

 

when you`v removed this IR filter, screw the lens housing back into place.

if you connect the Cam to the PC and switch it on during this, you can can also sharpen the focus as you`r doing it, you`ll know you`v got it right when your keyboard letters are all nice and sharp looking form about half a meter away.

 

you`ll not notice any strange effects at 1`st, until you shove the cam up the window to look at some trees or plants, here:

 

irnorm.jpg

 

still not all That bizzare but don`t the trees have a strange Whiteish color and not at all Green anymore, this is just the beginning!

 

here`s what it looks like with different colored plastic filters in front of the lens, I`ll start with Blue:

irb.jpg

 

 

green:

irg.jpg

 

Red:

irr.jpg

 

Now you can see the Plants have taken on a Very odd White color compared to everything else ;)

 

my story didn`t end there though, I wondered What would happen if I used all 3 of these filters together Red/Green and Blue?

well I made up the layers and couldn`t see a thing through it with my eyes, but tested it anyway...

 

irbw.jpg

 

irbw1.jpg

Yes! a Black and White filter for color cameras!

Now the Plants look really strange:cool:

 

 

and THIS is probably the Freakiest thing about this experiment:

irhand.jpg

all the Veins in my hand are perfectly visible now, and yet in "normal" vision you can`t see them.

 

 

I hope you all have fun with this and present Your results here as well as Ideas of things to try IR vision with.

 

Have Fun!

 

 

 

 

 

 

 

(Non of these pictures have been altered in Any way using any s/ware at all, they are ALL direct from the cam)

Edited by YT2095

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Sweet!

 

Cheap B&W surveillance cameras generally don't bother with the IR filter; we use these in the lab for detecting IR fluorescence — it's probably the only instance where we get to use the cheaper technology.

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Thanks ;)

 

it`s interesting to be able to read a book in a blacked out room using a Cig or a TV remote as well, the Bunsen burner looks Very bright and stays bright for some time time after turning it off as well.

it`s a long way off from True thermal imaging, but non the less it`s in that capture band and demonstrates it quite nicely.

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I think it's a lens flare but it might be a slight smudge I lent the filter to someone once and have not cleaned it since...

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OK, I went and did it. IR filter was on the back of the lens, so that was easy. The hard part was getting the software to talk to the camera properly.

 

One of the laser tables in the lab. The laser is 780 nm, and you can see the losses from two optical fibers on the right, and scattering from many pieces of optics.

Lasertable2 IR.jpg

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Sweet!

 

mine was on the back too, the closest thing to the actual CCD chip window, perhaps that`s the optimum place for it?

it would seem that for Your line of work, such a thing is an Ideal tool for optimizing :)

I`ll have to try with my near IR laser as well, that`s one thing I haven`t gotten around to yet.

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Sweet!

 

mine was on the back too, the closest thing to the actual CCD chip window, perhaps that`s the optimum place for it?

it would seem that for Your line of work, such a thing is an Ideal tool for optimizing :)

I`ll have to try with my near IR laser as well, that`s one thing I haven`t gotten around to yet.

 

I'm guessing it's easier to mount it there than on the circuit board, in front of the CCD or CMOS chip. I've got another couple of pics, and I'm going to build a blog post around them.

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LOL, a complete and utter piece of useless experimental info for you all that I just discovered, the IR cam can see clean through a pint of Guiness almost as if it wasn`t there!

 

I`d tested it with a Hoya R72 and Suntek 750 IR filter and it sees though those as it were plain glass.

 

but Guiness!!!

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mine was yeah, I drink all my beer at room temp or higher, my wifes was out the fridge so about 4c, both were no different.

 

the only effect was that of a neutral density filter on each, but quite transparent :)

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YT - great stuff. Why did the green trees not look green when the green filter was held in front of them? Just a simple question which probably has a simple answer.

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YT, hook up an old CD laser (and turn it on) - take a picture and see what you get :)

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Mag I went one better and took apart an old 50mW Green laser, the secondary crystal got fractured so it was no good anyway.

I used the IR pump diode and calibrated the colminating lens to suit the IR length, it works great!

 

anyway, I`v had a new digi-cam given to me (it`ll do 5 megapixel) and have converted that to purely IR also, but since this had a flash built in as well I thought I`d modify that too :cool:

basically all you do is get Red, Green and Blue acetate of a high density and layer them, but with 2 reds so you have R-G-B-R and then put that over the flash tube reflector inside the cam.

the acetate must be of a high enough density that you cannot see through it with your eyes at all, and when done correctly over the cam flash, you can fire it in a dark room and not see it (unless you look directly at it up close).

I`v tested this out and it takes perfect pictures even in pitch black, you could in effect walk right up to someone in the dark, take their picture and they wouldn`t even notice! >:D

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I`v tested this out and it takes perfect pictures even in pitch black, you could in effect walk right up to someone in the dark, take their picture and they wouldn`t even notice! >:D

 

haha, awesome!

 

Green laser huh? This intrigues me. :eyebrow:

 

Looking forward to some pics :)

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I have no idea?

but I imagine very hot but only for a tiny fraction of a second.

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YT - great stuff. Why did the green trees not look green when the green filter was held in front of them? Just a simple question which probably has a simple answer.

 

I found the answer to this question at last ;)

 

here:

 

The Short Answer

 

Based on several different lines of evidence, I've concluded that one must simultaneously consider what goes on in 2 functionally different NIR bands in order to understand the false colors seen in digital RGB images taken with IR filters:

 

  • 700-770 nm, hereafter referred to as shortwave NIR
  • 770-1100 nm, hereafter referred to as longwave NIR

Longwave NIR (770-1100 nm) stimulates all sensels equally because Bayer pattern filter dyes are uniformly transparent at those wavelengths for quantum mechanical reasons elaborated in the sidebar. Thus, longwave IR primarily affects false-color saturations.

Shortwave NIR (700-770 nm), on the other hand, stimulates red sensels quite a bit, green sensels a little and blue sensels minimally if at all. Shortwave NIR thus drives the false colors, especially with shallow filters like the R72 (50% cut-off at 720 nm). The red tinge typical of R72 skies bears this out: Shortwave NIR is heavily over-represented in what little NIR the atmosphere manages to scatter because scattering efficiency by air molecules falls off inversely with the 4th power of wavelength.

If you block most of the shortwave NIR with a deeper Wratten 87 IR filter (50% cut-off at 800 nm), you get a near-perfect grayscale image, as you'd expect with equal stimulation of all 3 sensel types by the remaining longwave NIR.

Things get even more interesting with the Wratten 87c (50% cut-off at 850 nm), which in many digital cameras produces blue monochromes rather than the grayscales one might expect. I believe that this reflects a slight blue bias built into most auto white balance algorithms to counter the anti-blue bias carried by NIR contamination in visible light digital images.

 

 

 

 

taken from: http://www.dpfwiw.com/ir.htm

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If you put the red filter only and then has software in the camera to remove anything with too much saturation or too much red then you would only get plants show up.

 

Why? How about animals?

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that wouldn`t work, a red filter would block green making it darker, to do a false IR you`d need a green filter and then develop as B&W.

but True IR has to have the hot mirror filter removed and then replaced by an IR pass filter that blocks all Visible light.

here`s one:

comp1.JPG

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