MEMS-based camera makes debut

24 Apr 2003

The world's first uncooled MEMS-based infrared camera to boast 320 x 240 pixels goes on show in the US.

The world's first uncooled 320 x 240 MEMS-based IR camera has been unveiled in the US. The prototype camera exploits 76 800 heat-sensitive microscopic cantilevers and is said to have a sensitivity an order of magnitude higher than other uncooled IR technologies.

Sarcon Microsystems and its parent company Sarnoff, both of the US, developed the detector and expect to ship commercial samples in the first quarter of 2004. Initial uses are likely to include fire-fighting as well as military and security applications.

"We've shown the commercial viability of a technology that can deliver much high sensitivity at a lower cost than competing approaches to uncooled IR sensing," said Don Perrine, president of Sarcon. "Our new IR detector engine demonstrates that it's possible to fabricate MEMS-based IR imagers at 320 x 240 pixels, the benchmark resolution for most commercial applications."

The detector consists of an array of miniature cantilevers, each of which acts as a light-sensitive pixel. The array is fabricated on the surface of a silicon chip. One end of each cantilever is attached to a fixed support while the other end is able to bend.

Each cantilever is effectively a tiny bimetallic strip, made up of a thin-film coating that efficiently absorbs IR light and a thin metal layer that expands when heated. As the cantilever heats up it bends and generates an electrical signal that is proportional to the intensity of the infrared radiation absorbed. The current chip has a sensitivity of 3 milliKelvin and a dynamic range in excess of 10⁵.

Sarcon and Sarnoff say the chip can be produced in standard CMOS foundries with conventional processing techniques. "As the process matures and we increase the leverage in the MEMS structure, we'll get progressively better uncooled IR sensitivity, perhaps 10 or 20 times that of the typical IR sensor," said Frank Pantuso, vice president at Sarnoff. "We believe this MEMS IR technology will replace the current uncooled sensors available today."

The camera, and initial images, are on show at the AeroSense conference running in Orlando, Florida this week.

Author
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.