Infrared Night Vision Expands What Drivers Can “See”
- Friday, 01 June 2007
The U.S. military has employed infrared vision technology for years. But it has only been the past several years that thermal imaging, or infrared, technology has been made commonly available by automakers. With the introduction of Night Vision on the 2000 Cadillac DeVille, General Motors (GM) became the first automaker to bring the safety benefits of extended night vision to drivers. Today, Night Vision is available on Cadillac’s current models.
Having improved night vision while driving is important in reducing pedestrian fatalities as well. Also, collisions with deer and other animals could be avoided if drivers had more time to react to the hazard in front of them at night.
GM’s Night Vision does not replace a driver’s view out of the windshield, but it does provide drivers with visual information beyond what they can see, enabling them to detect potentially dangerous situations that lie beyond the normal range of their headlights. The vision extends the range of low-beam headlights from three to five times, and doubles the range of high-beam headlights. At 60 miles per hour, regular headlights provide a driver with approximately 3.5 seconds to react to an object ahead. With Night Vision, the driver has up to 15 seconds to react. Also, drivers are able to see beyond the glare of headlights from oncoming vehicles.
The Cadillac Night Vision system is based on technology that was developed by Raytheon Systems, and uses thermal, or infrared, imaging to create pictures based on heat energy emitted by objects in the viewed scene. Humans, animals, and other moving vehicles emit enough heat energy to contrast sharply with their surroundings when they are viewed with Night Vision.
Cadillac’s Night Vision uses a refractive optical lens system to gather infrared energy. A camera mounted on the car’s grille views the road ahead through an infrared-transparent window that measures about 3" in diameter. Behind the window, refractive optics focus the infrared energy on a 1"-square detector. Information from the detector is passed on to sensor electronics that translate the data into a monochromatic image.
The image resembles a black and white photographic negative, so hotter objects appear white and cooler objects are black. People, animals, and cars stand out from the black nighttime background.
The virtual image is projected by a head-up display (HUD) rather than on a flat screen mounted in the car. This lets drivers keep their eyes on the road. The image is projected close to the front edge of the car’s hood, in the peripheral vision of the driver, and does not obstruct the driver’s view of the road.
The image has a horizontal field of view of 11 degrees and a vertical field of view of 4 degrees. Objects in the image are the same size as objects in the road scene, so the driver can relate the image to the road scene and judge the distance to the object.
The Night Vision system turns on when the key is in the “on” position, when the “twilight” photo cell indicates that it is dark, and if the headlights are on. Drivers can also turn the system on and off from a switch in the instrument panel, and can adjust the intensity of the image and the image vertical position.
For more information on General Motors’ Night Vision system, visit http://info.hotims.com/10970-140.