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.     

Macroamylasemia in HIV infection

A case of macroamylasemia was seen in a 40-year-old HIV-positive bisexual male treated at the Fort Worth-Tarrant County Health Department (Ryan White Clinic). Macroamylasemia is a rare condition encountered sometimes in persons with HIV infection. Apart from the setting of HIV infection and acquired immunodeficiency syndrome, macroamylasemia is seen also in various conditions including liver disease, diabetes, cancer, malabsorption, and autoimmune disorders. Although this biochemical phenomenon requires no therapy, it should be considered in the differential diagnosis of patients who have persistently high levels of serum amylase and yet do not exhibit any clinical symptoms of pancreatitis or salivary gland inflammation.     

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.