IR Flashlight Safety?

[Kayaker530]

A friend purchased a consumer grade Night Vision Monocular that had a very weak IR Illuminator. I purchased a Convoy C8+ IR 850 NM flashlight so we could experiment outdoors. We were very careful to not get direct exposure to our eyes and we were careful about near reflections. What other measures do we need to do with a light of this intensity? Simon is working on an IR driver that will allow for lower levels of output. At 100 percent power we were able to view objects that were over 300 yards away and shadowed from the moonlight.

I reached out to some friends with formal training in NVG from military and LE. Their training is that anything that they were issued was eye safe. They did not know about any dangers from a LED emitting IR at high power.

Any and all information, links, is appreciated.
Steve

 

[letschat7]

I thought it is UV that is dangerous?

 

[Kayaker530]

I thought it is UV that is dangerous?

UV is Dangerous. IR is also dangerous. I just don't know how dangerous and under what conditions.

 

[LEDphile]

More information than you probably wanted is available at https://ehs.lbl.gov/resource/docume...izing-radiation/light-and-infrared-radiation/ and https://www.cdc.gov/niosh/docs/82-109/default.html

The summary is that IR radiation is similar to visible radiation in its damaging effects, and the concerns are mostly thermal in nature. I'd avoid staring into the beam, especially if it feels hot, but otherwise wouldn't worry too much about it.

 

[letschat7]

Are we talking about the same IR used in television remotes?

 

[PhotonWrangler]

Are we talking about the same IR used in television remotes?

TV remotes use 940nm. The OP mentioned 850nm. They're both in the near-IR neighborhood so I suspect the thermal effects are similar. The human eye has a little bit of sensitivity to 850nm light but none at 940nm.

 

[alpg88]

There is nothing dangerous about 850nm, I have 10W 850ir light, when it is on, it barely glows, there is no heat that you can feel.

 

[Kayaker530]

Are we talking about the same IR used in television remotes?

The flashlight in question consumes 1.5 amps of current at 3.7 volts. And it illuminates beyond 300 yards when viewed with an 'inexpensive' consumer grade NVD. Similar light frequency; but maybe like comparing a kayak to a Cigarette Racing boat....

 

[Kayaker530]

This is hard to get actionable information on. My friends in LE and Military tell me that they were simply told that everything that they were issued is eye safe. For the most part they don't know about non-issued IR gear. One friend who does low light training is concerned about the imported IR lights that may not be eye safe. A friend who used to work in an eye doctor's office said that she is very concerned about IR radiation from her time in the doctor's office. I can probably manage the dangers outside under controlled conditions. Don't look into the beam, be mindful of close reflections, don't blast people in the face. But I do worry about indoor work with the IR illuminator. Lots of reflections and common eyewear doesn't protect.

 

[PhotonWrangler]

The sun has loads of broad spectrum IR content. The difference is that the visible light that accompanies it causes the pupils to contract. Invisible radiation by itself doesn't do this, which is the concern for either IR or UV. There have been studies on IR laser safety for fiber optics networks but some of those operate at much longer wavelengths so the comparison to near-IR susceptibility isn't very solid.

 

[LEDphile]

There is actionable information in the Lawrence Berkley Labs link provided up thread - that link goes to their Environmental Health and Safety office, which sets the safety requirements for the lab (generally based on an 8-hour exposure), based on current scientific understanding. For the IR source in question, it's noted as an 850nm source with 5.5W of input power. If we assume 50% of that input electrical power comes out as photons (this is likely optimistic), we're talking 3W of radiometric power out the front.

The limits presented by LBL are 0.1W/cm^2 of energy at the eye to be of concern for causing cataracts, with the limit for preventing thermal damage to the retina being somewhat higher. For your 3W source, that means that the total output of the source needs to be concentrated into a 30 cm^2 area to be cause for concern, which is a circle about 2.5 inches in diameter. And this is for a constant exposure of at least 17 minutes.