Desert Storm Comes to the Family Garage

CARMEL, CA - I recently sat behind the wheel of a 2000 Cadillac DeVille staring into the dark night, unable to see beyond the glaring headlights of a bus deliberately parked about 50 yds. (46 m) ahead. Then a General Motors Corp. engineer flicked a switch to turn on a new, infrared (IR) night-vision system. A head-up display (HUD) projected ahead of the windshield.

With the HUD image, I now could easily see another GM engineer standing beside the bus. Without the vision-enhancing system, he was completely obscured by the bus's headlight glare.

Cadillac General Manager John F. Smith says the 2000 DeVille will be the industry's first vehicle to get the IR system that has been 10 years in development. "With night vision, Cadillac will bring Desert Storm technology into the family garage," the GM vice president adds.

All objects emit some heat, but people, animals and moving vehicles create more "visible" images to the system because of their high thermal contrast with the background. The hotter the object, the whiter it appears in the display.

The sensor uses uncooled IR technology to detect the heat energy of objects invisible to the human eye. The thermal energy is focused on the detector with optics designed to pass IR wavelengths.

In turn, the energy is absorbed by a grid of detector elements. Each element responds with a change in capacitance. The changes are processed electronically to compose a black-and-white scene on the HUD.

IR imaging uses the thermal energy ranges of three to five microns and eight to 14 microns - because in these two bands IR photons are least absorbed by water molecules in the air.

The night vision sensor optics focus IR energy onto a 1-in. (2.5-cm) detector, similar to the way a camcorder images light. Then the IR energy is focused on an uncooled focal plane array detector that is 320 IR sensing elements wide by 240 IR sensing elements tall. Each element is a temperature-dependent capacitor that changes capacitance depending on how much IR it is receiving.

A chopper disc rotating in phase with the detector's readout-circuitry timing modulates the scene's energy by allowing the pixels to view the scene and then an absence of scene. Each pixel of the UFPA detector "stares" out into space contiguously as the scene is modulated. A circuit under each element regularly samples capacitance, and the electronic scans are converted into the black-and-white video signal that's sent to the HUD. Herb Shuldiner