Research On The Resonator With Diffraction Optical Elements And Its Applications

Three parts (6 chapters) are included in this dissertation except the 1 st and 6th chapters.The first part (the 2nd, 3rd and 4th chapters) is the theory for analyzing and designing resonators with diffraction optical elements by use of a matrix eigenvalue method. The eigen modes and diffraction loss for a laser cavity have been obtained by this method. The cavity mirror can also be designed according to an objective function.The second part (the 5th chapter) is to introduce the concept of low diffraction beam and to illustrate the principle and method how to realize it. A low diffraction beam is obtained by reconstructing the existing optical resonator of a CO2 laser using a special diffraction phase plate. A theoretical model is provided to predict a laser ablated hole profile and the penetration depth. The theoretical results are in good agreement with the experimental measurements. Both the experimental and theoretical results show that the low diffraction beam has great advantages over the Gaussian beam in an ablation-dominated material removal processes.The third part (the 6th and 7th chapters) is for a practical application, in which hollow laser beams have been analyzed and designed in terms of the matrix eigenvalue method. The hollow optical beams have been analyzed theoretically, and have been realized experimentally by placinga diffraction optical element in the cavity. As two new models, high-order Bessel-Gaussian beams and hollow Gaussian beams are introduced to describe hollow beams. The results for high order Bessel-Gaussian beams and hollow Gaussian beams propagating through a free space and a focusing lens system are derived respectively in terms of Collins' integral formula. The experimental results are illustrated.The main work of this dissertation focuses on the analysis and design theory for a resonator with diffraction optical elements by using a matrix eigenvalue method. The principle and method how to realize a low diffraction beam have been described. Both the experimental and theoretical results show that the low diffraction beam has great advantages over the Gaussian beam in an ablation-dominated material removal processes. The hollow optical beams have been analyzed theoretically. They have been obtained experimentally. Two new models, high-order Bessel-Gaussian modes and hollow Gaussian beams, are used to describe hollow beams.