Studies On The High Power CO₂ Laser Thin Films By The Ion-assisted Deposition Technique

In the high power CO2 laser system, optical films?are usually important and unsubstantial. Under the high power density, the heat aberrance and the heat destroy of windows and reflectors are the key problems which restrict the increace of the laser power and the quality of the beam of light. In this paper,the designs of anti-reflecting films,part-reflection films and total reflection films and IAD technology are theoretically and experimentally studied. In this paper, we use the optimum design of Needle and Tunneling. Because we study the optical films in the high power system, we take electric-field intensity distribute into account. We reform the new evaluation function and realize the autodesign the best optimization structure of film and calculate the film sensitivity which instructs the actual deposition of the coating. From the ghermoconductivity, absorbability and coefficient of thermal expansion, we choose adequate substrate materials of reflectors and windows. Using the orthogonal intersection experimental method, we study the IAD technology, analyze the influences of the substrate temperature, screen pole voltage and beam density and find the suitable technology parameters. In the measure of refractive index of coating materials, we use elliptical polarization method and spectrophotometric method .Owing to their limitation,we employ optimization principle to calculate refractive index and extinction coefficient of YF3 and ZnSe. Using them, we inosculate the design curve with testing curve and compare it with the two methods mentioned above. This thesis makes a study on the accurately optical monitoring approaches of thin film. We put forward a reformative monitoring method which compounds crystal quiver monitor and optical monitor. The method can use overshoot monitor method when the crystal quiver monitor is ineffective. This method ensure the success of deposition and is more suitable for monitoring the deposition of the infrared optical films. This thesis completed lots of experiments on optical coating deposition and determined some optimum technological parameters.And we deposited the GaAs partial transmittion window,the ZnSe total transmittion window and the total reflection mirror. We put them into actual use and the effect is better.