Temperature camera: The visible light that human eyes can see is red, orange, yellow, green, cyan, blue, and purple in order from longest to shortest wavelength. Light with a shorter wavelength than purple light is called ultraviolet light; light with a longer wavelength than red light is called infrared, which is invisible to the naked eye. Because the temperature camera can sense all light, the captured image is very different from the image produced when we see only visible light with our naked eyes.