Simple IR Detector
My nickname by a couple of friends is “Mr. Science” not unlike “Bill Nye, the Science Guy” and while I prefer “Dan, Dan, the Science Man” the Mr. Science seems to stick. While I remember building a lizard submarine and sending a captured lizard on increasingly longer “voyages” of up to 15 minutes, electricity and electronics always have been the most fascinating to me. I’ll show you how to use your iPhone 4/4S as a simple IR detector.
I’ve had a knack for fixing things and you can see examples here whether it is appliances, automobiles or whatever… Having five kids means I get lots of opportunities to make repairs. I always take every opportunity to make the kids think things through, “How would you do it? What would you try?”
I have gotten this question more than once. Dad, the remote for “X” doesn’t work, can you fix it? They’re all old enough now that they know the first question will be about the batteries so they often continue with, “I’ve put fresh batteries in it” If they do give me the second sentence then where do I start? Since I usually have my phone with me, I pick it up turn on the camera and see if the remote is transmitting infra-red (IR). I was an “early adopter” of the Palm(R) Treo 650 back in 2004. While the camera in it is crude by today’s standards, it works fine as a simple IR detector. It served me well over the years in many capacities, storing passwords, being a simple IR detector and yes, even making phone calls!
My Christmas gift in December of 2011 was an iPhone 4S (32GB). Just the other day I had my first opportunity to try the iPhone as a simple IR detector. So when my daughter said she had replaced the batteries in the remote and that it wouldn’t work, I was disappointed to find our that the iPhone couldn’t see IR. Apple must have some type of IR filter over the camera lens. 
I used our 3MP digital camera to trouble shoot and re-arrange the batteries to return the remote to functionality… Still I was bummed that the iPhone couldn’t see IR. A day later I was talking to my son on FaceTime (an Apple video chat application that uses WiFi) when I realized (remembered) that the phone has two cameras. I had only checked the hi resolution, rear-facing, camera. I grabbed a remote and checked the front facing, low resolution, camera it works as a simple IR detector! So I can continue to use my apple iPhone as an IR detector.
In both sets of photos, you can see the remote is activated as they have a visible LED that is activated at the same time as the IR LEDs.
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| Rear Facing | Front Facing |
|---|---|
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I hope this helps someone else wanting to use their iphone as a simple (go/no-go) IR detector.
Below are some photos of an IR remote as viewed on the iPhone cameras. If anyone can verify what cameras on what iPhones do or don’t detect IR please post a comment below.
John August 12, 2012 at 4:08 am
tnx for the info. nice to know my iPhone will do the same don’t know when it would have dawned on me to try the front camera…
Camera detector September 6, 2012 at 4:32 am
Now a days, many security equipments are used.Some are big in size.It is very pleased to know that these will be available with I phone.I think camera detectors are also available in tiny forms and these are really helpful.
best earphones for iphone February 10, 2013 at 11:15 pm
Oh! This is great. It is a very good experiment to use iPhone as IR detector. Experiments are the best way to learn and good experiments like this could be very helpful to make or design something very innovative.
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Andrew Ewers February 14, 2013 at 7:52 am
I have read the same thing on several sites now but my iPhone 4s doesn’t see IR with either camera. Maybe there were multiple runs of the same model some with and others without the IR filter.
Dan February 16, 2013 at 8:54 am
The other thing it might be is a screen protector. I don’t know of any that hype or advertise the ability to screen out IR or UV light but there might be. The other thing would be, as you suggest, a change to the spec and therefor the production run. When did you purchase yours and was it new or refurb?
Dan February 16, 2013 at 11:53 am
I’m not sure what it might be. My daughter has an iP4S that is a year newer than mine, no issues. Also the iP has an IR emitter on the face, in the slot above the speaker which it probably uses for proximity control? it needs to “see” IR energy