What Effect Does IR Illumination Have On Thermal Cameras?

940nm or 850nm.

Little or none?

If some, does it hurt or help?


FLIR .... None with ours. Shouldn't affect any.

Thanks, Greg. No effect from the standard IR LED of security cameras...

I do remember reading something about IR illuminators with much longer wavelengths (> 4um) being used with thermal cameras but can't locate it. Have you heard of anything like that?

How does any spectrum of light effect thermal cameras?

Do you consider IR light?

IR is on the light spectrum. Please don't detrail the thread.

Brian, I'm not trying to derail my own thread, it's unclear what is meant by the question:

How does any spectrum of light effect thermal cameras?

If 2 considers IR to be light then the answer is simply

"They are affected. Thermal cameras are sensitive to IR"

If, however you consider light to be visible illumination only, then the answer is

"They are not affected. Thermal cameras are not sensitive to visible light"

They (850 / 940 IR and thermal) are different wavelengths so they do not interfere.

It's like saying what impact does listening to 95.5 FM have on another radio next to it playing 100.3 FM. None.

I believe this marked up chart roughly represents the difference:

Thanks for the chart! It's infrared breakout is good.

FWIW, "Conbmotor Waves" surely is a mistake. Terahertz or Tetrahertz waves go there. Where did the chart come from?

Minor quibble, this analogy needs a little help

It's like saying what impact does listening to 95.5 FM have on another radio next to it playing 100.3 FM. None.

since we are not talking about the impact of one receiver on another receiver, which obviously is nil. A better example would be listening to 95.3 while working at the 100.3 radio tower, no?

I grabbed that chart off the Internet. I was focused on showing the IR cam vs thermal cam difference.

Sure, on the analogy.

We have a genius who wrote a book on what aliens would see if they saw in every spectrum. I could ask him. In general, anything your eyes can see thermal cameras don't. Is there a specific reason?

The reason is that I bought this dang FLIR handheld a while back, and for no defensible reason, I just point it at different things around the house randomly.

When I pointed it at an IR bullet at night I noticed it was picked up noticeably on the FLIR. Of course the camera is radiating all sorts of 'light' as heat so it was hard to tell how much, if any, was due to the IR LED's. So then I instead tried to pickup the IR reflected from an object directly in front of the bullet. I could definitely see an effect on the FLIR as I repointed the IR.

But, again this was most probably due to reflection of the LW-IR ambient 'light' of the camera electronics, not to the SW-IR 'light' of its LED's.

Taking a pictures head on seem to confirm this; left from the FLIR, thermal, right taken from a SNB-5004 in night mode with 1/2500 SS and aperture almost closed, (causing a slight bokeh effect).

Note how, on the FLIR, the IR LED's are actually showing cooler than the ring. Leading me to believe that any effect the IR could even theoretically have would be less than that of just the heat generated by the rest of the camera.

But because I couldn't be sure, I thought I'd ask if there were any known effects.

Thanks for your time.

Best of both worlds?

I'll clarify as much as I can. 850/950nm is used in CCTV and is not visible other than the heat the actual unit generates in the LWIR and MWIR ranges. This emitter functions specifically in the LWIR/MWIR range and would be unusable in a CCTV application.

Correct me if I am wrong, but this IR illuminator would have an effect on thermal security cameras (like the FLIR F-Series), even though it would not affect the standard NIR CCTV cam.

Your example is not a CCTV illuminator. It is used by combat troops to 'paint' a target for smartbombs. It is an example even beyond edge case.

Your example is not a CCTV illuminator.

Strawman.

I never called it a CCTV illuminator.

Nor was I suggesting it for any use, edge or otherwise, though it is a real product used with thermal cameras.

Maybe somebody reading this, who is using thermal cameras already, can think of an novel security application, perhaps as a long range beacon of some sort.

That's how innovation works.

Edit: I was following up on my initial comment to Greg above where I said:

I do remember reading something about IR illuminators with much longer wavelengths (> 4um) being used with thermal cameras but can't locate it.

The FLIR F/FC series operates in 7.5-13.5 μm, so that illuminator would be out of the spectral range.

4.5 μm is in the MWIR range, so you'd need an HRC (or I think the Ranger?) if you're looking at FLIR cameras, and that's a very large thermal package in the six figure price range.

Cortina, correct me if I'm wrong.

The FLIR F/FC series operates in 7.5-13.5 μm, so that illuminator would be out of the spectral range

From my link:

The compact PoyntIR quantum cascade laser (QCL) system emits at wavelengths of 4.6 microns or 9.6 microns...

Ah, I just looked at the spec sheet. It's just a footnote on there.

This technology isn't that new, but it's use has been specifically military to date. What I was attempting to clarify is that it's not an "illuminator" like you would have with a light bulb or LED's of whatever spectrum in security. Brian is very correct in one purpose for these type of laser and other illuminators or beacons.

Understood. Thanks for your insights.