Oct 25 2007
A small low-priced 3-D CMOS camera is set to capture the attention of the security technology market: It is equally suitable for blind-spot monitoring in cars and for controlling access to buildings. The camera's core component is a high-performance light sensor.
Modern vehicle electronics can prevent many a traffic accident, but the systems are still not perfect. Problems are caused particularly by traffic coming from the sides. Objects or pedestrians approaching rapidly from the side have so far been almost impossible to detect. A small, robust and above all low-priced camera could make all the difference. Developed at the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg, the device emits a rapid series of short laser flashes that are invisible to the human eye.
From the reflected light signals, the camera determines not only how far away an object is, but even its three-dimensional shape. Rays of light that encounter protruding areas are reflected back sooner than those that encounter lower-lying areas. Precision control of the camera aperture separates these light signals and subsequently uses them to create a 3-D image. The observation of lateral traffic is only one possible application scenario. The camera system can also be employed for robotic workplaces or for controlling access to buildings.
The researchers' goal was to develop a low-cost device from standard components - for instance by using off-the-shelf components for the camera lenses and the laser diodes. The core component of the camera is the CMOS chip developed by the researchers themselves, which transforms light signals into electrical impulses. The chip can be manufactured at low cost in a standard process. "The challenge we faced was to create a chip that would reliably interpret light signals in any situation," says project manager Werner Brockherde.
"For example, the electronics cuts out interfering background light from its calculation by opening the aperture for one millionth of a second and measuring the natural ambient light." Depending how far away an object is, a greater or lesser amount of reflected light enters the camera. The CMOS chip therefore has to be capable of analyzing extremely bright images as well as very dark ones. The researchers have developed special algorithms to achieve this high level of dynamic performance.