[SS2S-Main] Re: Infrared webcam
- From: "Cliff Bates" <cliff@xxxxxxxxxxxxxx>
- To: <sugarshot@xxxxxxxxxxxxx>
- Date: Fri, 16 May 2014 03:33:06 -0700
Nicely done !! The quality of the image is surprising. I've seen a few
articles on doing this to a camera, but assumed the image quality would be to
poor for the effort applied. Not so.
Learn something every day. Thanks Mattias
Cliff
----- Original Message -----
From: Lampe, Mattias SLC CT PEK
To: sugarshot@xxxxxxxxxxxxx
Sent: Friday, May 16, 2014 12:22 AM
Subject: [SS2S-Main] Re: Infrared webcam
Hi all,
after some experimenting I have to correct my previous statement that a
modified webcam (after removal/exchange of the IR filter) is unsuitable for
thermal imaging.
Here are my learnings:
- Objects hotter than approx. 260 degrees centigrade (about 500
degrees Fahrenheit) seem to “light up” in the near infrared image. The hotter
the brighter, so at least a relative temperature comparison is possible, to
some extent. The tip of a hot soldering iron, for example, appears to shine
quite brightly when looking at it through a modified webcam.
- Hot combustion gases show up brightly in the IR image, even if
they are invisible to the naked eye. (Not sure if it’s the CO2 or some other
gas that causes the effect.
As a proof, here are some videos taken simultaneously with three cheap
webcams of the same brad and model. One had the IR blocking filter removed,
anouther one had the blocking filter replaced by a filter blocking visible
light (i.e. only letting IR pass to the sensor), and the third camera was not
modified at all.
The so-so quality of the videos is not due to the camera but due to the slow
computer used for recording and encoding. If the videos don’t play in your
browser, downloading them may help.
This is me frying an egg as seen by a normal webcam (visible light only):
https://onedrive.live.com/redir?resid=6838BE39B86A56AC!178&authkey=!AKrXza_7QKYre8s&ithint=video%2c.mp4
Please note the familiar short, blue gas flame.
Looking only at the IR componente with a modified webcam, the flame looks
totally different:
https://onedrive.live.com/redir?resid=6838BE39B86A56AC!176&authkey=!AOAS5uk5p0QffiA&ithint=video%2c.mp4
The hot gas moving upward is visible, and after shutting down the flame you
can see the metal frame “glowing” for quite a while. The frying pan itself does
not light up because it never really exceeds 200 degrees C.
Here is a post-processed version of the video with a so-called
gradient-mapping applied to the IR video:
https://onedrive.live.com/redir?resid=6838BE39B86A56AC!177&authkey=!AKwVxXkHqhw0Z_k&ithint=video%2c.mp4
The camera that only had the IR blocking filter removed but no blocking
filter for visible light installed took the following video:
https://onedrive.live.com/redir?resid=6838BE39B86A56AC!179&authkey=!AOZAg8XGkhGL0aQ&ithint=video%2c.mp4
(The videos were recorded simultaneously, and the lights in my kitchen are
fluorescent ones, containg very little IR. Things look quite a bit different
under incandescent lights.)
So after initial doubts I do see some value in using modified webcams for IR
imaging of rocket motor tests. Compared to low-end FLIR cameras the resolution
is higher and the cost is nearly negligible (less than 15$ for the cameras I
used). You can observe the flow of exhaust gases and see where things get
really hot (>260 degrees), and I could imagine that IR penetrates the smoke a
little bit better than visible light.
Absolute temperature measurements, however, would probably be impossible or
at least require quite a bit of calibration work.
Only a single egg was hurt in the process of recording the four videos ;-)
(The other 11 eggs from the same box will be hurt later.)
Hope it’s interesting. I’ll send the cameras to Vicente, who started this
thread.
Have a good day!
Mattias
From: sugarshot-bounce@xxxxxxxxxxxxx [mailto:sugarshot-bounce@xxxxxxxxxxxxx]
On Behalf Of Lampe, Mattias SLC CT PEK
Sent: Sunday, May 04, 2014 10:12 AM
To: sugarshot@xxxxxxxxxxxxx
Subject: [SS2S-Main] Re: Infrared webcam
Hi,
I think removing the internal IR filter works with most webcams, and if you
want to make sure you ONLY see the infrared but not the visible part of the
spectrum, you can add a filter that only lets infrared light pass. A piece of
overexposed and developed color negative film (like from the beginning of a
film roll) works quite well for that purpose. It blocks nearly all visible
light and is quite transparent for IR. If you know someone who still shoots
pictures on film or someone who did so in the past and kept the negatives, they
should be able to find a suitable piece of material.
Not sure how you want to use the IR camera, but you should be aware that it
will not be a thermal imaging device. It will be sensitive only to near
infrared, and in order to emit those wavelengths a body must be quite hot
already, i.e. close to glowing.
I have a few unused webcams at home and will check if they can be converted.
Have a great day!
Mattias
From: sugarshot-bounce@xxxxxxxxxxxxx [mailto:sugarshot-bounce@xxxxxxxxxxxxx]
On Behalf Of James Fackert
Sent: Saturday, May 03, 2014 1:18 AM
To: sUGAR sHOT TO SPACE LIST
Subject: [SS2S-Main] Re: Infrared webcam
here is one, $30.
http://www.adafruit.com/products/1567
On Fri, May 2, 2014 at 9:53 AM, Lyn Berry <lyn_berry@xxxxxxxxxxx> wrote:
Hi
I am no expert but if memory serves webcams contain an IR filter. If the
filter is simply removed the webcam becomes much more sensative to the IR part
of the spectrum.
QED
Regards,
Lyn Berry
On Friday, 2 May 2014, 12:52, Vicente Alvero Zambrano
<vicente_alvero_14@xxxxxxxxxxx> wrote:
Hi,
Does anyone know and is willing to turn a webcam into a webcam with infrared
vision for the series of motors VIC and to study the ablative materials?
Cheers
Vicente Alvero
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