О допустимой интенсивности лазерного излучения в оптической системе и о технологии измерения коэффициента поглощения его мощностистатья
Статья опубликована в журнале из списка RSCI Web of Science
Статья опубликована в журнале из перечня ВАК
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 20 апреля 2022 г.
Аннотация:Laser damage to transparent solids is a major limiting factor output power of laser systems.For laser rangefinders, the most likely destruction cause of elements of the optical system (lenses, mirrors) actually,as a rule, somewhat dusty, is not an optical breakdown as a result of avalanche, but such a thermal effect on the dust speckdeposited on an element of the optical system (EOS), which leads to its ignition. It is the ignition of a speck of dust thatinitiates the process of EOS damage.The corresponding model of this process leading to the ignition of a speck of dust takes into account the nonlinearStefan –Boltzmann law of thermal radiation and the infinite thermal effect of periodic radiation on the EOS and the speck ofdust. This model is described by a nonlinear system of differential equations for two functions: the EOS temperature and thedust particle temperature. It is proved that due to the accumulating effect of periodic thermal action, the process of reachingthe dust speck ignition temperature occurs almost at any a priori possible changes in this process of the thermophysicalparameters of the EOS and the dust speck, as well as the heat exchange coefficients between them and the surroundingair. Averaging these parameters over the variables related to both the volume and the surfaces of the dust speck and theEOS is correct under the natural constraints specified in the paper. The entire really significant spectrum of thermophysicalparameters is covered thanks to the use of dimensionless units in the problem (including numerical results).A thorough mathematical study of the corresponding nonlinear system of differential equations made it possible forthe first time for the general case of thermophysical parameters and characteristics of the thermal effect of periodic laserradiation to find a formula for the value of the permissible radiation intensity that does not lead to the destruction of the EOSas a result of the ignition of a speck of dust deposited on the EOS. The theoretical value of the permissible intensity foundin the general case in the special case of the data from the Grasse laser ranging station (south of France) almost matches thatexperimentally observed in the observatory.In parallel with the solution of the main problem, we derive a formula for the power absorption coefficient of laserradiation by an EOS expressed in terms of four dimensionless parameters: the relative intensity of laser radiation, the relativeillumination of the EOS, the relative heat transfer coefficient from the EOS to the surrounding air, and the relative steady-statetemperature of the EOS.