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IR test equipment on your pocket

Ever need to know if the IR LEDs in your UniFi Camera are operating?   How about seeing if the SFP is putting out light or not?   Or if you're getting light transmitted down the fiber you just installed LC connectors on?    Turns out the piece of test equipment you need is probably in your pocket right now...


The camera in your smart phone is actually sensitive to Infrared light (just like the G3 camera above).   But unlike a full-fledged camera, most Smartphones don't have an IR cut filter - not enough space and it's really not needed.   This means it can see infrared which your eye can not.   So just point your camera at the IR source and see if it shows up


This is a photo of an SFP module plugged into a switch - an 850nm MM one in this case.   And again the IR clearly shows up as a red dot.   And this works with nore than just MM units:


Here is a SingleMode 1310nm SFP - smaller red dot, but it's clearly there.   Much smaller because this is single mode, but still clearly visible.


Works at the fiber end too - the camera picks it right up.   No more guessing if the cable is good or if there's light getting all the way to your end - you can clearly see it.   And this works with any IR device you have - want to see if the TV remote is working?


A general warning - never look directly into the SFP port with the naked eye, especially single mode ones - the IR level can damage your eye.   But with the camera that issue goes away.   I wouldn't shove the fiber end right into the camera lens, but leaving a few inches allows enough dispersion that it's safe.





on ‎09-13-2017 07:34 AM

Great idea Jim! This would definitely work in the field as a quick check. I never thought of using a camera from a phone to check.


However, since working in the Government, we can't have phones in the secure areas. Therefore, we use something like this: http://www.fiberinstrumentsales.com/fis-infrared-detection-card.html It's a quick enough check to see if the fiber pair is active or not. It's small enough to carry in a wallet too.

on ‎09-13-2017 07:36 AM

Very nice - and a lot smaller than hauling a power meter around...


on ‎09-13-2017 08:21 AM

Excellent tip! 


Be warned, iPhones have an IR cut filter and this solution will not work with them. 







on ‎09-13-2017 08:28 AM

Justin showed me that trick the first day I met him. We were in a McDonalds and the TV was too loud and he pointed his phone at TV and turned off the volume then he pointed his phone at my phone's camera and you couild see bright purple flashes. I said that is spooky, why are you so spooky, he say because no one else has the skills sets like he does to be spooky like him.

on ‎09-13-2017 10:46 AM

Good call @eejimm A trick I have used for years, started when I wanted to check an infra red on a TV remote and grabbed an early digi camera to test.

on ‎09-13-2017 11:50 AM

eejimm wrote:

A general warning - never look directly into the SFP port with the naked eye, especially single mode ones - do not look into SFP port with remaining eye.




FTFY Man Happy

on ‎09-13-2017 11:56 AM

Don't know what iPhone 7tigers has, but this works great on my iPhone 7 Plus, so obviously no IR cut filter.

on ‎09-13-2017 01:05 PM

@WPDAdmin Interesting, the iPhone 5/6 Series couldn't see IR but the Androids could... I'll retest that theory then...

on ‎09-14-2017 03:27 AM

Excuse my ignorance here but...I thought SFPs/fiber optic networks used lasers, not IR?


Either way - just a general warning: IR is fine and won't damage a camera sensor but be very careful with any kind of laser light - that can damage a sensor if you point a laser directly at it. I've seen quite a few reports of people who've used a DSLR for stuff like nightclub photography, and had their cameras damaged by the laser lighting effects. I'd imagine it'll do the same to a cell phone camera too.

on ‎09-14-2017 04:47 AM

@WilliamTM IR is a wavelength.

You are right, lasers are able to damage image sensors, even IR lasers.


Other kinds of IR sources (eg leds) is not really dangerous.