sidaphale
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NoIR Camera for Infrared Emissions

Tue Apr 12, 2016 3:30 am

Hi,

I am trying to image flames and blackbody radiations using NoIR camera of Raspberry Pi. I would like to know if the NoIR camera is capable of capturing the infrared emissions from hot bodies which are at temperatures above 500C.
The blackbody I am using becomes visible to naked eye once it is heated beyond 700C. However, I want to see the illumination below 700C. Can a NoIR camera be used for this purpose?

Thanks!

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jbeale
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Re: NoIR Camera for Infrared Emissions

Wed Apr 13, 2016 12:12 am

I think it might work. The Pi NoIR camera is a regular CMOS silicon sensor and the cutoff is around 950 or 1000 nm. I seem to recall that it can see a hot soldering iron, which is not visibly red-hot, although I can't find the picture right now.

Taking the spectrum chart below at face value, it looks like extending your vision from 700 nm to 1000 nm should move the temperature visibility threshold down by at least 200 degrees C.
Image

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jbeale
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Re: NoIR Camera for Infrared Emissions

Wed Apr 13, 2016 2:55 am

I used a different camera (Sony Digital8: TRV720 "Nightshot" mode) that might be somewhat similar to the RPi camera, in that it also uses a normal silicon sensor, and was able to see a faint glow in the darkness from a soldering iron that a thermocouple says is at 420 C.

Image
Image

sidaphale
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Re: NoIR Camera for Infrared Emissions

Sun Apr 17, 2016 3:58 am

Thanks for your reply jbeale. I tried capturing the images of the blackbody source I have. I capture time lapsed images with ISO 100, drc mode high and shutter speed of 1000 ms. But the images I obtained are weird. I tried imaging the source from 600 C to 800 C in a step of 40 C. The images obtained vary in color. Some images are red (actual color visible to naked eye) while some are in green and gray shades. I have attached some samples I clicked for 800 C.
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BerryPicker
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Re: NoIR Camera for Infrared Emissions

Sun Apr 17, 2016 8:25 am

Is the wierdness due to white balance? See:
viewtopic.php?p=939794#p939794

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Re: NoIR Camera for Infrared Emissions

Sun Apr 17, 2016 8:52 am

You haven't said you're using manual white balance, and this isn't a situation that an automatic algo is going to expect as it isn't a natural scene.
Berrypicker has pointed out that drc is incompatible with manual white balance, and it's unlikely to give you any significant image quality improvement as it is mainly a post processing step.

Please remember that the NoIR is NOT an ir sensor - it is a colour sensor with no IR filter fitted.
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jbeale
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Re: NoIR Camera for Infrared Emissions

Mon Apr 18, 2016 6:19 pm

I've found the color from NoIR modules will always be strange, unless you use manual white balance. Real IR cameras are usually black-and-white (or false-color map), you might as well just force output to B/W.
At any rate it looks like you have a decent amount of signal to work with, I don't know your requirements but looks to me that the RPi NoIR camera can be useful in this temperature range.

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