Using your mobile telephone, you can see infrared radiation – a unremarkably invisible part of the electromagnetic spectrum. Ken's Tech Tips looks at some of the physics of electromagnetic waves and explains how you lot tin come across this invisible world – and yous don't demand anything more than the mobile phone in your pocket.

What is infrared radiation?

Infrared is a course of electromagnetic radiation. Other forms of electromagnetic  radiation (EM radiation) include visible light, x-rays, microwaves (the EM waves that wi-fi networks utilise and likewise the waves that melt your nutrient in microwave ovens) and radio waves. The deviation between all these different forms of radiation are the wavelength of the EM wave. We can illustrate this electromagnetic spectrum (CC-licensed image from Wikipedia):

What is the deviation between visible light and infrared?

Visible lite and infrared are both forms of electromagnetic radiations but with different wavelengths. Visible calorie-free has a wavelength of betwixt 400nm and 700nm (a nanometer is then pocket-sized that we can fit ane,000,000,000 in just 1 meter). We tin can but "come across" the EM radiation in this range. At 700nm and longer, we enter the realm of infrared radiations.

Why tin can mobile phone cameras "meet" infrared?

Almost cameras are designed to capture an paradigm of what people can see. Hence a proficient camera would only detect EM radiation in the visible light spectrum (between 400nm and 700nm).

Still the charged couple devices used within cameras are typically manufactured to pick up EM radiations between 300nm and 1100nm. This means they are capable of detecting infrared light too (between 700nm and 1100nm is infrared).

To improve image quality, camera manufacturers typically add films and filters to block out infrared light and ensure but visible light reaches the CCD. If the infrared radiation was recorded past the camera and appeared in our photos, the photos would not be an accurate representation of what we can see – i.eastward. what we desire to photograph!

Mobile phone cameras tend to exist produced a lot cheaper than proper digital cameras and hence the vast majority of mobile phone cameras have a much thinner film/filter to block out infrared light. The lack of infrared filter is 1 reason photographs taken on mobile phones don't expect as expert as those taken on proper digital cameras but it likewise provides us with an opportunity to apply our mobiles to "meet" in infrared.

How can I harness this fact?

But betoken your mobile telephone camera towards a infrared calorie-free source and yous can begin to see this new invisible infrared world!

For instance, stick your phone photographic camera in front of a television receiver remote control and starting time pressing some buttons: yous'll see a few flashes of light (your remote uses invisible IR radiation to communicate with your Tv set – y'all wouldn't normally be able to run into this radiations every bit our optics are non sensitive to the infrared wavelengths used by the remote). If you've got a Nintendo Wii, betoken your telephone photographic camera at the sensor bar. Yous'll notice the sensor bar emits invisible IR radiation (this is how the Wiimotes track your movement).

Unfortunately, yous won't see the globe in true infrared. Your mobile telephone camera is sensitive to visible light as well – and fortunately (although unfortunately in our case) this always registers much brighter on the CCD and drowns out the infrared image. If yous're really serious nigh seeing the world in infrared, you tin pick up an infrared filter from Amazon. These filters will block out visible light and hence allow you to become a better prototype of the invisible infrared world.