Infrared detectors stay cool while they take the heat

July is a hot month in most of the northern hemisphere, forcing most of us to find ways to keep cool. This issue of Laser Focus World looks at technologies for sensing heat—or infrared radiation—with a collection of articles on thermal imaging cameras. Originally developed for military night-vision operations and surveillance, these devices have successfully been converted to viable commercial products—an example of dual-use technology.

Because infrared detectors sense heat, they must be kept cool to discern a signal from the vast thermal background of the world. Immersing a detector into a vat of liquid nitrogen at 77 K has given way to mechanical refrigeration techniques. Closed-cycle Stirling coolers have facilitated the development of lightweight, portable infrared cameras. Also, detector arrays, whether of platinum silicide, indium antimonide, indium gallium arsenide, or even mercury cadmium telluride, have been incorporated into staring focal-plane-array cameras that do not have the mechanical complexities of scanning systems. Array detectors have also boosted camera resolution, accelerating the growth of thermal imaging applications.

The photo on the cover and the article on p. 67 illustrate how engineers have adapted military thermal imaging technologies for the commercial market. In this month's Product Focus, associate editor Rick DeMeis explains the choices and trade-offs involved in selecting a thermal imaging camera (see p. 105). Still another article describes a portable thermal imaging camera and various industrial applications, including semiconductor manufacturing (see p. 150).

Moving on from thermal imaging, another article covers the use of surface scattering measurements in the semiconductor industry (see p. 99). Solid-state, gas, and liquid lasers are described in this month's Back to Basics (see p. 73). Then there is our second annual "Fiberoptic Components Handbook," which covers enabling devices for fiberoptic systems—diode lasers, isolators, splices and connectors, modulators, and photodetectors (see p. 113). Former senior editor Gene Jungbluth coordinated the handbook again this year, before moving on to another PennWell publication, Solid State Technology. His contributions to this project are greatly appreciated.