The family of lasers: a survey

Operating over a frequency range from audio to ultraviolet, the modern laser may be the most widely applicable active device at the disposal of today's engineer, enabling him to generate, amplify, modulate, transmit, and detect signals at frequencies more than 10000 times higher than was previously possible. Yet despite the almost unlimited potential for new and exotic applications offered by these shorter wavelengths, innovations have not lived up to their rave notices. Reasons for this relative inertia vary according to the application intended but, in general, it can be predicted that progress in the laser art will accelerate with the improvement of laser efficiency, development of auxiliary systems, and an updating of engineering thinking in terms of finding the ``problems' that lasers can solve. This first article in a series deals with the laser devices themselves?their advantages and their deficiencies?and will summarize what is happening in the laser art today. Other parts, scheduled to appear in future issues of IEEE SPECTRUM, will cover applications in materials processing, instrumentation and measurement, optical communication, medicine, holography, data processing and storage, displays, and safety.     

Liquid chromatography — Particle beam mass spectrometry for identification of unknown pollutants in water

Summary Trace enrichment on a precolumn packed with copolymer material, coupled on-line with reversed-phase, column liquid chromatography-particle beammass spectrometry (RPLC-PB-MS) has been used for both target and non-target analysis of water samples. RPLC is carried out on a C-18-bonded silica column using a linear acetonitrile-0.1 M ammonium acetate gradient. Using optimised PB-MS conditions and 100–250 ml water samples, the detection limits for several phenylureas are in the 0.03–0.05 g l^–1 range using the full-scan mode; repeatability is good and the LC-PB-MS system is robust. Several surface and drinking water samples have been analysed and low levels of various environmental contaminants have been identified using electron impact mass spectra. Applying chemical ionisation with methane as reagent gas in both the positive and negative mode in conjunction with PB-MS provides relevant confirmatory information.     

X radiation from color television receivers

When black-and-white television receivers using cathode-ray tubes were introduced to the consumer public, measurements verified that, with the voltages and currects needed for satisfactory pictures, the externally emitted X radiation was indeed negligible. Color receivers, with much higher voltages and currents, led to a re-examination of the problem. Again, it was found that proper design could produce a bright picture with negligible radiation. In the past two years, however, some unusual events, reported experiments, and surveys involving color receivers have been widely publicized in the lay press?resulting in a major controversy with respect to the existence of radiation hazards. In an effort to free the subject from political overtones and from what has appeared to some as ``sensational journalism,' the National Center for Radiological Health joined the Electronic Industries Association in sponsoring a special measurements conference, reported herein, which represents a first step toward complete examination of the X-radiation problem.