Take a TV remote control and look at its front end and press a button. Can you see anything? No.

 

Now do the same but look at it through a camera phone. You can see it flickering!

 

Amazing huh.

not really, camera phones have crap IR filters and the CCD has some sensitivity in the near IR range.

not really, camera phones have crap IR filters and the CCD has some sensitivity in the near IR range.

 

As do CMOS chips which your phone is FAR more likely to have...

oh is that what it is. i didn't know that. i thought CMOS were just for transistors.

oh is that what it is. i didn't know that. i thought CMOS were just for transistors.

 

Nope, you can build photodetectors out of them too... My SLR has a CMOS in it. They work in a similar manor to CCD's but the charge collection is completely different...

not really, camera phones have crap IR filters and the CCD has some sensitivity in the near IR range.

 

Actually quite a bit of sensitivity — their peak response is typically in the red or near-IR

 

http://68.4.248.85:800/observatory/ccdfltr/ccdfiltr.html

http://www2.edmundoptics.com/techsup/reform/CCDfinal.gif

I found this trick very useful a few years ago when I was building an IR R/C circuit, I could check the remote was working using my phone!

If you have a Wii console, you can use two remotes as the Sensor bar (in the Wii the sensor bar does not actually "sense" anything, it is just an emitter for the sensor in the remotes to detect). All you need to do is make sure that the buttons on the remotes are held down (I did it with heavy books when I tried this). The main problem is that you will go through the batteries in your remotes fast if you do this (so it is only really worth while as a party trick ).

You can also use your phone to detect IR night vision equipment such as night vision CCTV. You can see if the police have set up a watch on your favourite night hangout!

You can also use your phone to detect IR night vision equipment such as night vision CCTV. You can see if the police have set up a watch on your favourite night hangout!

 

Depends on the type of night vision. The detectors that sense in the near-IR are probably silicon, and that cuts off at ~1.1 microns, which is fine for the CCTV's that use that. But if it's a system that senses thermal emissions, those are out at ~10 microns, and you won't pick those up.