Multifrequency dial sensing of the atmospheric gaseous constituents using the first and second harmonics of a tunable CO2 laser radiation

The results of field measurements of concentration of some gaseous components of the atmosphere along the paths, in Sofia, Bulgaria, using a gas analyzer based on the use of a CO2 laser radiation frequency-doubled with ZnGeP2 monocrystals are presented. The gas analyzer is a traditional long path absorption meter. Radiation from the tunable CO2 laser of low pressure and from an additional He-Ne laser is directed to a colliminating hundredfold Gregori telescope with a 300 mm diameter of the principal mirror. The dimensions of the mirrors of a retroreflector 500 x 500 mm and a receiving telescope allow one to totally intercept the beam passed through the atmospheric layer under study and back

The effect of volume inclusions of the ZnGeP2 single-crystal on the dispersion of the refraction index and the absorption coefficient in mid-IR and terahertz ranges of wavelengths

Volume filamentary inclusions in ZnGeP2 have been visualized using the digital holography method. The chemical composition of the filamentous volume inclusions Zn3P2 and Ge have been determined using the method of X-ray diffraction analysis. It is shown that the presence of volume inclusions in the ZnGeP2 singlecrystal leads to an increase in the reflection coefficient in the region of 12.5 μm. The dispersion dependences of the refractive index and the absorption coefficient of the studied ZnGeP2 samples at wavelengths of 300–1000 μm in the region of non-fundamental absorption have been obtained. It has been shown that the presence of volume inclusions in a single-crystal leads to an increase in the refractive index in the entire THz range under study by the value of Δnmax = 0,0008. The difference between absorption coefficients for the studied samples varies from Δα = 0.1 cm 1 to Δα = 0.15 cm 1 depending on the wavelength

Influence of post-post processing technology and laser radiation parameters on the optical breakdown threshold of a ZnGeP2 single crystal

The aim of this work is to determine the influence of the parameters of post-growth technological operations and experimental conditions on the threshold of optical breakdown of the surface of ZGP crystals under the action of laser radiation at a wavelength of 2091 nm

Digital holography methods for visualization and identification of ZnGeP2 bulk defects

The volumetric filamentous inclusions in ZnGeP2 were visualized by digital holography, their characteristic sizes were determined, and their location in the sample volume was determined. The chemical composition of filamentous bulk inclusions – Zn3P2 and Ge-was determined by X-ray diffraction analysis. The influence of the second-phase inclusions (Zn3P2 and Ge) on the quasi optical characteristics (refractive index and absorption coefficient) in the resonant absorption band (12–12.5 microns) is established. The presence of bulk inclusions in the ZnGeP2 single crystal leads to an increase in the reflection coefficient in the region of 12.5 microns. The dispersion dependences of the refractive index and the absorption coefficient of the studied ZnGeP2 samples at wavelengths of 300–1000 microns in the non fundamental absorption region were obtained. The obtained experimental results confirm the assumption of the determining role of free carriers in the formation of dielectric losses in the wavelength range of 100–1000 microns. The hypothesis that one of the main sources of free carriers in ZnGeP2 is the matrix medium / inclusion interface of the second phase is confirmed.В ст. ошибочно: A. S. Bolshako

Threshold of laser destruction of nonlinear GaSe and GaSe:in crystals when exposed to pulsed radiation at a wavelength of 2.1 microns

The aim of this work is to determine the optical breakdown threshold of a single crystal GaSe and GaSe:In when exposed to nanosecond radiation of the two micron range and determining the influence of the energy parameters of the testing radiation on the breakdown threshold. The Ho3+:YAG laser was used as the laser radiation source in this work. Pumping was carried out by a Thule fiber laser.В ст. ошибочно: E. V. Zhuravle

ПРИМЕНЕНИЕ МАТЕМАТИЧЕСКОЙ МОДЕЛИ ДЛЯ СОПРОВОЖДЕНИЯ ПРОЦЕССА ВЫРАЩИВАНИЯ КРИСТАЛЛОВ В МНОГОЗОННЫХ ТЕРМИЧЕСКИХ УСТАНОВКАХ

A system for control of crystal growth process in the multizone thermal installation with an integrated mathematical model is developed. Experimental information on both temperature distribution and powers of the heating elements as well as calculation data about the form of crystallization front have been used as input information for the control system. Consecutive correction of controller setpoints of multizone thermal installation during crystal growth process based on calculated data is aiming at deviation reduction between crystal growth rate and container moving rate.Разработана система управления технологическим процессом выращивания кристаллов в многозонной термической установке Бриджмена с интегрированной математической моделью. Описана процедура настройки параметров математической модели. Для работы системы управления использована экспериментальная информация о распределении температуры в установке, а также информация о скорости роста кристалла и положении фронта кристаллизации, полученная расчетным путем. Последовательная коррекция установок регуляторов многозонной термической установки в процессе выращивания кристалла на основе расчетной информации направлена на снижение отклонений осевой скорости роста кристалла от скорости перемещения ростового контейнера. Представлены результаты вычислительных экспериментов по применению математической модели в составе системы автоматического управления

Estimation of temperature sensor effect on temperature field of ring heating module

The computation experiments on investigation of temperature sensor effect on temperature field of ring heating module of multipoint heat-treatment installation have been carried out. The results of calculation show that the temperature sensors effect considerably the temperature distribution in heating module and its energy consumption

Investigation of the process of optical damage of ZnGeP2 crystals using digital holography

A method of visualization of the process of optical damage of a ZnGeP 2 single crystal using digital holography is suggested. The mechanism of the ZnGeP 2 single crystal damage is investigated at energy density ~0.3–0.6 J/cm ² . The temperature in the damage channel during its formation is estimated. The data obtained allow the conclusion on the thermal nature of ZnGeP 2 crystal damage to be made under the action of laser radiation with a wavelength of ~2.1 μm. © 2019, Springer Science+Business Media, LLC, part of Springer Nature