Taking aim at missiles

In his memoir, How the Laser Happened, Nobel Laureate Charles Townes notes that, since their invention, lasers have provoked people to imagine them turned by the military into death rays and that a great deal of money has actually been spent trying to use lasers to destroy incoming missiles. Even before the laser's invention, death rays were an integral part of science fiction—dating back at least as early as Tolstoy's 1926 novel The Garin Death Ray, says Townes.

And while shooting down missiles with lasers may still be—for the most part—science fiction, other programs aimed at development of high-energy tactical laser weapons for the battlefield seem to be a little closer to reality. In fact, competing laboratory versions of these lasers are scheduled for demonstration in December of this year. Based on solid-state technology, the three prototype systems are expected to deliver approximately 25-kW average power from designs that can subsequently be scaled to much higher output (see p. 61). One of the lasers—from Lawrence Livermore National Laboratories—is featured on our cover.

Aside from the death-ray concept, of course, lasers have many other nonlethal applications both on and off the battlefield. The advent of miniature CO₂ lasers, for instance, has broadened their use in spectroscopy, while also delivering a portable source of infrared illumination for thermal imaging applications (see p. 89).

There are a number of solutions for imaging in low-light situations and two possible options are electron-multiplying CCDs and intensified CCDs. But which is the better of the two? A detailed look at the theoretical performance of both devices produces an answer that may surprise you (see p. 69). Meanwhile, advances in image sensors and associated processors are making machine vision much more accessible, so vision systems are increasingly apparent on the factory floor and elsewhere, providing automated inspection of everything from wood to biological cells (see p. 94).