Chapter 7: Navigating with Infrared Headlights · Page 235
Chapter 7: Navigating with Infrared Headlights
Today's hottest products seem to have one thing in common: wireless communication.
Personal organizers beam data into desktop computers, and wireless remotes let us
channel surf. Many remote controls and PDA’s use signals in the infrared frequency
range to communicate, below the visible light spectrum. With a few inexpensive and
widely available parts, the BASIC Stamp can also receive and transmit infrared light
signals.
USING INFRARED HEADLIGHTS TO SEE THE ROAD
Detecting objects without whiskers doesn’t require anything as sophisticated as machine
vision. Some robots use RADAR or SONAR (sometimes called SODAR when used in
air instead of water). An even simpler system is to use infrared light to illuminate the
robot’s path and determine when the light reflects off an object. Thanks to the
proliferation of infrared (IR) remote controls, IR illuminators and detectors are readily
available and inexpensive.
Infrared: Infra means below, so Infra-red is light (or electromagnetic radiation) that has
lower frequency, or longer wavelength than red light. Table 7-1 shows the wavelengths for
common colors along with the infrared spectrum. Our IR LED and detector work at 980 nm
(nanometers) which is considered near infrared. Night-vision goggles and IR temperature
sensing use far infrared wavelengths of 2000-10,000 nm, depending on the application.
Table 7-1 shows the wavelengths for common colors along with the infrared spectrum.
Table 7-1: Colors and Approximate Wavelengths
Color Wavelength Color Wavelength
Violet 400 Red 780
Blue 470 Near infrared 800-1000
Green 565 Infrared 1000-2000
Yellow 590 Far infrared 2000-10,000
Orange 630
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