Laser information-measurement technology

Frequency-stabilized lasers are used in many measurement devices, from working measurement facilities to standards. Helium–neon lasers stabilized by saturated absorption in iodine and methane are used to control circuits for calibrating frequency and length units. However, frequency-unstabilized lasers are also widely used in information–measurement technologies. Remote-probing devices and systems (lidars) as a rule do not include feedback. However, they ensure that measurements of impurity concentration in the atmosphere at great distances have high sensitivity. Lidars are effective not only on the earth, but also when the atmosphere is probed from satellites. Stabilization of the radiation power of the lasers included in lidars naturally broadens the possibilities of the latter. Good results have been obtained from remote-sensing laser devices when the parameters of gaseous and liquid flows are being measured. Semiconductor lasers, whose radiation is less monochromatic than that of gas lasers, are successfully used in some measurement devices. Even LEDs are used in a number of devices. It has become necessary to do a comprehensive study of the requirements on the radiation sources in new devices intended both for scientific research and for production in order to find the optimum solutions.
Similar problems also appear in biology. The properties of laser radiation transmitted through biological materials are being studied. These results are used when creating medical and agrophysical devices, etc.
This special issue of Opticheskiı˘ Zhurnal is devoted to a wide range of questions that face specialists today in the area of laser information-measurement technologies. Some of these problems are being solved by the authors of the articles of this issue of the journal and, we hope, will attract readers and will help them in their work.