Study on a quasi-CW Nd:YAG frequency-doubled laser at 660nm
A QCW Nd:YAG intracavity frequency doubled red laser was made. Using a flat—flat laser cavity, 2 Kr-lamps, KTP crystal and an AO Q-switch, 2 W output power at 660 nm was obtained. The relationship between laser cavity length and output power is analyzed.
Methods and experiments for dealing with the solid state laser beam with lower order mixing modes by Gaussian-like distribution
For solid state lasers with lower order mixing modes in which TEM00 mode is dominant and a few lower order modes are included, a method of dealing with the beam based on Gaussian-like distribution is presented. The beam of lower order mixing modes may be regarded as a fundamental mode Gassian beam expanded K times. (K is the multimode coefficient). Firstly, from the calculation of intensities and spot sizes of the mixing modes and the fundamental mode, the justification of this assumption is indicated. Then the calculating formulae for the beam characteristics of the mixing modes are given. By Gaussian-like method, a typical continuous wave YAG laser is analysed and the region of the optimum cavity length is found. After that, the experimental method of measuring the value of K is recounted. Finally, the coupling of the laser output beam with a fiber is discussed, the necessary parameters for the practical application are obtained.
Computer-Aided System of Virtual Testing of Gas Turbine Engines
The article describes the concept of a virtual lab that includes subsystem of gas turbine engine simulation, subsystem of experiment planning, subsystem of measurement errors simulation, subsystem of simulator identification and others. The basis for virtual lab development is the computer-aided system of thermogasdynamic research and analysis “ASTRA”. The features of gas turbine engine transient modes simulator are described. The principal difference between the simulators of transient and stationary modes of gas turbine engines is that the energy balance of the compressor and turbine becomes not applicable. The computer-aided system of virtual gas turbine engine testing was created using the developed transient modes simulator. This system solves the tasks of operational (throttling, speed, climatic, altitude) characteristics calculation, analysis of transient dynamics and selection of optimal control laws. Besides, the system of virtual gas turbine engine testing is a clear demonstration of gas turbine engine working process and the regularities of engine elements collaboration. The interface of the system of virtual gas turbine engine testing is described in the article and some screenshots of the interface elements are provided. The developed system of virtual gas turbine engine testing provides means for reducing the laboriousness of gas turbine engines testing. Besides, the implementation of this system in the learning process allows the diversification of lab works and therefore improve the quality of training.