A look at the content of this month's issue brings to mind the long-running television science-fiction series Star Trek. Essential to the ongoing survival of the star ships is their ability to remotely sense distant environments to assess the risks the space crusaders may face from an unknown planet or space vessel. Although these abilities seemed rather far-fetched during the earliest days of this program in 1966, remote sensing technology has subsequently evolved to become a lot more fact and a lot less fiction. This month's cover, for example, highlights plans by researchers at NASA's Jet Propulsion Laboratory to establish a virtual presence throughout the Solar System using a web of integrated optoelectronic sensing devices for environmental monitoring (see p. 15). The US space agency also is involved with efforts to remotely monitor the health of plant life using laser-induced fluorescence combined with multispectral imaging (see p. 46).
Remote sensing in its various forms requires a host of different detector technologies that range from relatively simple photosensors to complex imaging arrays working in tandem with high-capacity computers. Novel designs are constantly being explored to improve performance factors such as the wavelength range or response speed of these devices—and in its broadest sense, environmental monitoring also encompasses sophisticated detectors designed specifically for astronomy. The Optoelectronics World supplement included with this issue, together with the Understanding Detectors feature on page 147, highlights just a few of these activities. Doubtless, others also will be highlighted at Aerosense (Orlando, FL) this month.
Light-based measurement techniques are another form of sensing and have been around for a very long time. Some of the earliest recorded examples might include Stonehenge and the shadow clock, which date back to about 2900 and 3500 BCE respectively. More recent examples are spectroscopy and interferometry. For instance, pulsed tunable laser sources make possible detection of gases at trace levels (see p. 141), and speckle interferometry is being applied to the study of mechanical stresses on the human body (see p. 95).
Cool sources
This month brings the return of our acclaimed Back to Basics feature series. Contributing editor Stephen J. Matthews will spend the next 12 months delving into the details behind various sources, opening with a close look at light-emitting diodes (LEDs). These devices have recently gained relative prominence due to the advent of high-brightness devices, whichhave the potential to replace some conventional lighting as well as to enable novel applications such as entire walls that light up and change color (see p. 133). These might even be worthy of a star ship!