NASA Jet Propulsion Laboratory, California Institute of Technology

A new imaging sensor -- virtually a camera on a chip -- is in development for NASA's space program and under consideration by several major companies for licensing.

The technology makes possible an imaging system that is smaller and cheaper than current state-of-the-art electronic imaging systems but comparable in performance, according to Dr. Eric Fossum, who led the team to develop the Active Pixel Sensor at NASA's Jet Propulsion Laboratory, Pasadena, CA.

Fossum said the new technology is a considerable leap beyond the current state of the art electronic sensors -- charge-coupled devices or CCDs. "It is a second generation solid state imaging technology," he said.

JPL has signed a technology cooperation agreement with AT&T Bell Laboratories. Several other companies, both large and small, are seeking licensing agreements to commercialize the technology.

Charge-coupled devices were developed by the Bell Laboratories in the early 1970s and have been used mostly in video camcorders and in spacecraft. The solid-state devices led to relatively low-cost, compact imaging systems compared to Vidicons and other tube technology. The charge-coupled devices have also advanced as the microelectronics industry has improved its quality and fabrication techniques.

Charge-coupled devices with a million pixels, or picture elements, are expensive to make, costing about $1,000 per million pixels when made for low-volume applications. Active Pixel Sensors, by contrast, are made within mainstream microelectronics technology -- which can potentially reduce the cost to under $200 per million pixels, according to Fossum.

The technology used to develop the Active Pixel Sensor is called complementary metal-oxide semiconductors, or CMOS. That technology, according to Fossum, is backed by an enormous worldwide research and development work force and large amounts of capital investment. CMOS is used for nearly all microprocessors and memory chips. The cost of manufacturing a CMOS image sensor is currently about three times less than that of a CCD image sensor.

The CMOS Active Pixel Sensor was developed at JPL's Center for Space Microelectronic Technology for space applications in which it has several advantages over CCDs, including a requirement for less power and less susceptibility to radiation damage in space.

Other applications, Fossum said, include personal computer visual communications, high-definition television, electronic still cameras, laboratory-based cameras, medical instruments, nuclear instruments, toys, automotive applications and space-based surveillance systems.

The use of complementary metal-oxide semiconductors for the new sensors presents an additional opportunity for reducing imaging costs, power and size and improving reliability. The Active Pixel Image Sensor can be a single-chip camera system. It can communicate directly with a microprocessor or computer and allows for reduced component count.

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