Seeing in Infrared

The infrared portion of the electromagnetic spectrum has a frequency just below visible light so our eyes are not able to perceive it directly. It is possible, however, to use specialized equipment to image in this range and allow us to "see in infrared". In this short blog post, I want to share two ways that I try to turn this into a hands-on investigation in my classroom

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Infrared Remote

Many old remotes use infrared LEDs to transmit data in flashes that are invisible to the human eye. This light is in the Near Infrared part of the spectrum so not the range that is associated with thermal energy like the infrared camera below. Since this frequency is so close to visible light, some camera sensors actually pick this up.

Specifically, I have found that most android phone cameras pick up this infrared signal and shift it to a visible color (usually light purple) when you look at the display. When you look at the end of the remote through the phone screen and hold a button, you should be able to see the infrared LED flashing out instructions for the receiver.

This also works to show how my kids' baby monitor uses infrared LEDs to "light up" a dark room in infrared to see in dark without visible light.

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Infrared Thermal Camera

Using infrared to visualize radiant heat energy is a really cool application of electromagnetic waves. I've loved playing around with my FLIR infrared camera but I've struggled finding ways to make the experience more student lead. Recently, I've assembled a demonstration stations activity and used the infrared camera as one of the stations with questions for students to investigated. My favorite two investigations are:

What can infrared light pass through? Try putting your hand in an opaque plastic bag
What blocks infrared light? Take a selfie with someone wearing glasses

FLIR ONE Infrared Camera (Amazon)

This camera add on for a smart phone or iPad is a little pricey but it's a great way to turn a screen that you already have into an infrared camera. Pay attention to the connector option that you choose to make sure that it's compatible with your device

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