An often-unfortunate fact of life is that personal safety is taken for granted by most of us most of the time. The short-term inconvenience of sensible and routine precautions-wearing automobile seat belts, for example-frequently leads individuals to cut corners; the problem is compounded by the "it can't happen to me" syndrome and the convenient justification that "everybody does it." These human characteristics notwithstanding, though, few of us who work in photonics would argue with the need to treat laser emissions with a great deal of respect, hopefully avoiding accidental "contact" with the beams at all times. And while the considerable damage that can be inflicted by high-output lasers used for working metal is inherently obvious from their effect on the metals, the impact of emissions in other situations may not be so obvious.
In the case of optical networks, for example, laser emissions are routed all over the world through optical fiber, but the light is contained. The network is essentially a closed system so the emissions do not normally emerge into free space. Of course, in the real world, the fiber may rupture, optical connections are made and broken, and active components must be tested, so hazardous conditions do occur in the field and must be taken into account by network designers and safety standards organizations. In fact, the escalating optical power within communications networks makes the related safety engineering even more important (see p. 161). The American National Standards Institute (ANSI) also addresses this challenge in its standard entitled "Safe use of optical fiber communication systems utilizing laser diode and LED sources" (ANSI Z136.2), which is available from the Laser Institute of America (see www.laserinstitute.org).
While laser emissions typically are a hazard, optoelectronics technology is playing an increasingly significant role in maintaining personal safety. Sophisticated solutions that involve many aspects of our lives are emerging. Image recognition and thermal imaging, for example, can enhance security in high-risk environments such as airports and banks, while wind-shear detectors can make flying on commercial aircraft safer by helping pilots avoid unsafe flying conditions. On the roads, a combination of technologies focuses on making personal transportation safer. Automated guidance and collision avoidance systems for cars and buses, some just beginning to appear on the consumer market, may eventually eliminate the need for that "inconvenient" seat belt by eliminating accidents altogether.