How to Test an Infrared Diode
If you’re working on a project that uses an infrared (IR) light-emitting diode (LED) and want to test it, or if you have a remote control you think might be bad, there’s an easy way to “see” infrared light. The charge-coupled device (CCD) elements used by some digital and cell phone cameras are sensitive to infrared light. To test your LED or remote, view it with a digital camera in a dark room.
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Instructions
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Darken the room in which you’re doing the test. In particular, block out sunlight and incandescent sources (light bulbs) that have a lot of infrared; any visible light will also interfere with the test.
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Turn the digital camera on so it’s in viewfinder mode, ready to take a picture. Hold the camera 12 to 18 inches from your LED device. You don’t need to press the picture button.
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Aim the LED or remote directly at the camera and turn it on. Make sure that the camera lens is lined up with the LED and not pointed in a stray direction. If the LED is working, you should see ghostly, blue-gray flashes in the camera monitor. These flashes will not be bright, but they’ll be perfectly visible. The camera sensors have been optimized to respond strongly to visible light. Infrared light response is a secondary effect.
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Tips & Warnings
This technique will probably work best with low-end digital cameras. More expensive cameras may have an IR-blocking filter meant to improve the quality of normal pictures. If your camera has this filter, it won’t see infrared.
References
- Photo Credit Stockbyte/Stockbyte/Getty Images
