Laser information-measurement thechnology

The main difference of lasers from other optical radiation sources is the high coherence of the radiation. For many applications, an important role is played by temporal coherence. These applications, most importantly, include measurement engineering and, to a great extent, information engineering. The lasers most widely used in the Twentieth Century in measurement engineering—He–Ne lasers—with no additional apparatus provided a relative reproducibility error of the radiation frequency (wavelength) of 10−5–10−6. This already made it possible to carry out measurements with greater accuracy than did sources of spontaneous radiation. For example, the first laser interferometers measured a length of 1 m to within about 1 μm, while interferometers with sources of spontaneous radiation made it possible to do this at a length of 20–30 cm. The appearance of frequency-stabilized lasers provided the possibility of measuring a length of 1 m to within 0.1 μm or better. The length that could be measured with this accuracy increased. The appearance of lasers stabilized using absorption in iodine and methane in the year in which the meter was newly defined (1983) already reduced the reproducibility error of the wavelength of radiation to 1–0.1 nm. This figure has now been appreciably improved. The number of wavelength standards have increased. The accuracy is not excessive. Although it is a brilliant example, this is not the only case that illustrates how the appearance of lasers has altered the situation in information-measurement technologies.
This special issue of Opticheskiı˘ Zhurnal is devoted to a wide spectrum of problems of laser information-measurement technologies. Familiarity with this issue’s articles will undoubtedly promote the influx of new efforts toward the solution of the indicated problems.