Working with Infrared
In This Chapter
Transmitting information with infrared light
Spotting infrared light
Making infrared light
Building proximity detector projects
In this chapter, we describe working with circuits that produce and detect the invisible light that’s commonly called infrared.
Infrared light has all sorts of applications for wireless communication, the most common of which is the remote control for your television. Other uses for infrared include night-vision goggles and cameras as well as temperature detection.
Introducing Infrared Light
Infrared light is light whose frequency is just below the range of visible red light. Specifically, infrared is light whose frequency falls between 1 and 400 THz (1 THz is 1 trillion cycles per second). The infrared spectrum falls right between microwaves and visible light.
As we discuss in Chapter 1 of this minibook, an inverse relationship exists between frequency and wavelength: the lower the frequency, the longer the wavelength. If you describe infrared in terms of its wavelength rather than its frequency, ...