Studies On Mode Control Of TEA CO₂ Laser And Beam Propagation Characteristics

High energy laser is the most important area of laser technology and it has wide application on industry, aerospace, military and so on. TEA CO2 laser which is characterized by high efficiency, good beam quality and high average power takes an important position in high energy laser. It is considered as the most favorable laser for the application of laser propulsion which is increasingly studied recently. Beam mode is a key factor that has significant influence on this kind of energy transportation application. The thesis mainly focuses on the control of beam mode of TEA CO2 laser and its propagation characteristics.First, the methods how to evaluate the beam quality of high power laser were summarized. Then we calculated and measured different cavities in laboratory including plano-plano cavity, plano-concave cavity and unstable cavity, then we made theoretical analysis. Theβfactor of unstable cavity of TEA CO2 laser with M=4 is between 2～3, and with single pulse energy of 12 Joules. Besides transverse mode, spectrum and longitude of the beam are important parameters of a laser, however TEA CO2 laser usually has a long resonator, and work on multi longitudinal mode. Single longitudinal mode operation can be realized in locking injection with traverse and longitudinal matching. The experimental results show that under injection locking the pulse appeared in advance, the temporal of laser pulse prolongs, and its peak power lowers. And we did primary high power pulsed laser transition experiments, the pulsed energy propagated to 25m and 50m with energy efficiency of 85% and 55% in conditions of high humidity and powder, and theoretical analysis agreed with the experimental results.The above results are useful for studying high quality of high power pulsed CO2 laser and make primary preparation for its long range applications.