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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 ‎09-14-2017 04:47 AM

@WilliamTM the word laser says nothing about the wave length of the light. Laser is just light that is focused in a path. For all I know it can be IR, visible light, gamma rays. Now typically they can make lasers in certain wave lengths because its easier/cheaper to manufacture, but nothing stops you from making a laser of any wavelength.


Also those lasers at night clubs aren't really lasers. They may have a laser effect but they do expand.


As for the fiber I don't think it needs a proper laser to work since any light that comes at a certain angle into the fibre optics will follow the fiber path, so a "normal" led right close to the fiber would do it. But fiber optics is not my strong suit yet so I could be wrong. Man Happy

on ‎09-14-2017 05:18 AM

Thanks for explaining - I sortof understand a bit better now but I will admit, fibre is somewhat of a dark art to me! Ack2 Lol

on ‎09-14-2017 06:29 AM

There is still a permanent IR filter on phone cameras because the sensors are very sensitive to IR, but it's usually with the color layer (so that the otherwise monochrome sensor can determine colors)

This works though because while it filters IR, very bright sources will still get through as no filter is 100% effective.  Because of that, different phones will have different levels of effectiveness depending on the IR frequency and how selective all the filters are.


Digital cameras are also handy to check if a IR remote is still working.


IR cut filters usually refers to a IR filter that can be mechanically moved out of the sensor FOV, so that night vision works properly.  If you've ever had a CAM with one broken, day views look much different.  (Trees become very bright from all the reflected IR)


‎09-14-2017 12:44 PM - edited ‎09-14-2017 12:55 PM

Laser damage to camera




"Also those lasers at night clubs aren't really lasers. They may have a laser effect but they do expand."

No, they really are lasers.

No, they don't "expand", there are mirrors that scan the beam and make it appear the beam is expanded.


Edited to add quotation marks and italics.


on ‎09-14-2017 01:19 PM

If the laser is powerful enough and if it's collimated (focused in a tight beam) then it can indeed harm your eye or the camera sensor.   If you look closely at the picture of the LC connectors where I'm holding it you can actually see in the upper left hand side the beam hitting the lens of the camera - this was connected to a 10Gb SFP+ (therefore a laser not a LED) and it's fairly well collimated.   But even then it's spread out enough by the distance from the polished fiber end (the LC ceramic ferrule) that it's not going to harm the camera.   If the beam stayed at 9microns, it definately could, but it spreads out pretty quickly so there's not much chance of damage...


on ‎09-14-2017 02:18 PM

Kind of amazes me how many people don't know that little tidbit.  I use the camera on my phone all the time to "see" IR things.

on ‎09-14-2017 03:43 PM
Who uses IR remotes when you have Bluetooth? #2017yall
on ‎09-15-2017 10:37 PM


Apart from usinhg IR for wireless communication, it is also used for discreet illumination. For the surveillance cameras, it's all very bright and nice - without disturbing the neighbourhood at night.


And, knowing that, you can now check for IR floodlights before sneaking into a dark corner at your workplace's basement. It might not be dark for the security cameras...

on ‎09-17-2017 01:09 PM

Iphones have IR Filters since iPhone 4s i think. But only on the backcamera. The frontcam can still see IR. Im now on Iphone 7 and tested it with all non-Plus models since 4s when checking remotes for dead batteries.

on ‎09-18-2017 10:02 AM