I'm able to admit that I was too young to go and see the film Predator when it was released, but when I watched it as a VHS rental (you kids can stop laughing at the back there) I was captivated at how the Predator alien saw in infrared and how Arnold Schwarzenegger disappeared when he covered himself in cold, wet mud. Thirty years ago, then, seeing in infrared was something from a science fiction film and an alien technology. Thermal imaging has been used by various agencies including the military for many years but the technology has been too bulky and expensive for wide scale adoption. Now a company called Seek Thermal has released a consumer friendly thermal camera for under $200, which is available for iPhones and Android devices that support USB on the go.
The camera connects to the device via the MicroUSB port; your flavour of Android must support USB OTG (on the go), which rules out the stock Nexus 4 and Nexus 5. It works on many other devices, however, including most recent Samsung and Moto 'phones. The unit weighs less than half a pound and measures 70 by 21 by 21mm, so it's about as wide as many handsets but quite a bit thicker. The camera equipment uses a proprietary 12-micron sensor chip and customised software; there are just 32,000 pixels in the unit. This indicates that there are relatively few pixels but each one is large. The larger the pixel, the more light that is captured and the more sensitive the sensor. To put things into perspective, most smartphones use a pixel size of between 1.0 to 1.5 microns and HTC's Ultrapixel technology uses 2.0 micron pixel.
We must also consider that infrared is a longer wavelength than visible light, which means there's less resolution: we can't see as much detail. This is why infrared images tend to look pixelated and why only having a 0.03 MP camera is not quite the handicap that we thought. The Thermal camera software is able to self calibrate itself based on ambient air temperature. The sensor has a detection range of -40 to 330 degrees C and the colour production can be set by the user in the application. Seek's camera software allows you to use the normal smartphone camera in conjunction with the thermal unit, swiping between images with a slide to the side. You can take still images and videos using both units and there's a choice of nine overlays to apply to the screen to change how the image is displayed.
There are many potential uses for an infrared camera attachment for a smartphone such as DIY, security, cooking, motorsport and paranormal investigations. I also like the idea of making my cat less smug in the dark by being able to see him. Better yet, Seek are planning to release the SDK, software development kit, so that third party developers can create their own applications and integrate the thermal imaging camera. This is a useful addition, but I do need to direct your attention to the fact that the camera requires USB OTG, on the go; the stock Nexus 4 and Nexus 5 don't support USB OTG out of the box so if you have one of these handsets and a desire to use the Thermal camera, you'll need to download an application or modify your device first.