Charles M. Hanson

Uncooled thermal imaging at Texas Instruments

Texas Instruments is active in productizing uncooled thermal imaging systems for commercial and military products. The technology is based on the field-enhanced pyroelectric effect in ferroelectric barium-strontium titanate. The detector is mated to a readout IC (ROIC) via bump-bonding, and the single output from the ROIC is processed serially to provide both 8-bit digital and NTSC video outputs. Overall system cost is minimized and the electronics are simplified by using a scene-averaging chopper and operating the detector in its inherently ac- coupled mode. The past two years have been devoted to improving producibility, primarily of the uncooled focal plane array (UFPA) and its package. The result is a detector process that is 95% compatible with standard silicon processing. Although explicit performance improvement has been a secondary priority, the producibility improvements have led to a factor of two improvement in sensitivity. Recently demonstrated NETD is 0.047 degree(s)C with f/1 optics.

Uncooled thermal imaging with thin-film ferroelectric detectors

Uncooled infrared imaging as a viable technology began in earnest when ferroelectric detectors based on bulk ceramic barium strontium titanate (BST) demonstrated NETDs less than 100mK at prices sufficiently low for commercial and consumer applications. Although the image quality generated by this technology remains unsurpassed, it has been largely supplanted by microbolometer technology, which is capable of being fabricated in substantially smaller pixel sizes, leading to smaller systems, and which is a monolithic device, resulting in a simpler fabrication process than the hybrid BST device.

Chapter 4 Hybrid Pyroelectric-Ferroelectric Bolometer Arrays

Publisher Summary This chapter discusses the hybrid pyroelectric approach pioneered by Texas Instruments. The relatively poor thermal isolation of the bump-bonded, hybrid pyroelectric structure is offset by the high thermal response of the ferroelectric material. This approach has also achieved system noise equivalent temperature differences (NETDs) of less than 40mK for 328 x 245 arrays with f / l optics. The chapter explores the physics and applications of a class of uncooled infrared (IR) detectors distinguished by two features: They employ in some manner the pyroelectric properties of ferroelectric materials, and they comprise separate detection and electronic read-out means that are bonded together toward the end of the fabrication process. Hybrid pyroelectric-ferroelectric technology has matured greatly during its 20 years. Thermal isolation structure improvements and reduced detector thicknesses have evolved together to yield performance levels unsurpassed even by detectors having thermal isolation orders of magnitude greater. This highlights the superiority of the pyroelectric-ferroelectric detection mechanism.

Uncooled pyroelectric thermal imaging

Texas Instruments has been developing uncooled thermal imaging technology for the past 18 years with the promise that it would provide a low-cost solution to high-volume night vision applications. That promise is now being realized. Using technology developed for military applications with support from the U.S. Army Night Vision and Electronic Sensors Directorate (NVESD), the Advanced Research Projects Agency (ARPA), and the Balanced Technology initiative (BTI), TI has teamed with Hughes Aircraft to provide a thermal imaging capability for police cruisers. The night vision kits include a thermal sensor, a pan and tilt head, mounting hardware, a display and a control center. The price of the introductory product is approximately

Thermal imaging system with a monolithic focal plane array and method

6000.