High-speed acousto-optic shutter with no optical frequency shift

Acousto-optic modulators are widely used for rapid switching and shuttering of laser beams. In many applications, the concomitant frequency shift is undesirable and must be compensated for elsewhere in the system. Here we present a simple method of achieving rapid laser power switching without an accompanying laser frequency shift. The demonstrated acousto-optic shutter achieves a switching time of around 25 ns, an extinction ratio of 46 dB, and efficiency comparable to a conventional double-pass acousto-optical modulator configuration. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4746292]

The Meanings of Work for Older Workers

Several elements influence the meanings of work: the basic psychological processes of aging; the cohort or generation of the worker; the ecology of the work itself; and the larger social context of managing the risks of aging. This article discusses the meaning of work across the lifespan, and then reviews each of these elements to describe the meanings of work for older workers. The authors summarize data from multiple sources to answer several related questions: Why do older workers continue to work—beyond the solely monetary motivation? How do older workers' meanings of work vary by financial, health, job satisfaction, familial, or workplace concerns? What are the implications of these findings for employers and employees?