See Heat

Look at yourself in infrared.  The camera uses heat waves instead of light so the varying temperatures of your skin and clothes are shown as different colours on the screen.  With this camera, you see pictures of yourself in infrared light.  The camera lens is made of germanium and is not transparent to ordinary light.  However, infrared light - the heat radiation from your body - will pass through quite well. The infrared image falls on a screen of about 20,000 pixels which detect the infrared light.  Electrical signals from each pixel provide the information for producing the picture on the screen.  The screen uses 'false colours' to show which areas are hot, and which are cooler.  By creating friction you can alter the temperature of your hands or body.