Detectors provide answers
Optical signals perform experiments, advance processes, and carry information; detectors recognize that the signals have arrived, done their work, or contain the requested data. Indeed, detectors are ubiquitous components in a multitude of electro-optical systems. Applications for detectors range from motion sensors, spectrometers, and blood analyzers to fiberoptic phone systems, electronic cameras, and more.
This Detector Handbook explains, in a general sense, what engineers and scientists do with detectors rather than what various kinds of detectors are like. Recently, our "Back to Basics" series covered the physics, principles, and characteristics of thermal detectors, semiconductor detectors, and solid-state imaging sensors (see, respectively, Laser Focus World, Oct. 1994, p. 93; Nov. 1994, p. 65; and Dec. 1994, p. 53). The articles here complement that series with expert advice on how to pick, use, and incorporate detector elements for a variety of instruments and systems.
For example, choosing a photosensor can be a daunting task. Hundreds of choices result from considering wavelength region, sensitivity, cost, complexity, and manufacturers` model numbers. Approaching the process logically will hel¥you define the proper photosensor, and Larry Godfrey guides the decision process. A particular application may demand a photomultiplier tube, and Earl Hergert describes how to choose from the dozens of offerings in this category.
In many visible-wavelength imaging applications, the sensor of choice is often a two-dimensional charge-coupled-device (CCD) camera. High light levels, low light levels, and high-speed events can be monitored with a CCD camera, and Lisa Merrill and Alan Lichty explain the parameters that determine optimum performance in these situations. Systems incorporating infrared detectors present special obstacles because the photosensor in these systems responds to heat as well as the infrared radiation being measured. Approaches to minimizing stray light in IR instrument design are described by Marija Scholl. Finally, characterizing and making measurements with high-speed detectors is discussed by Janis Valdmanis and J. Van Rudd, who define techniques used in the regime where the distinction between electrical and optical signals blurs.
