Research On Calibration Techniques For Measuring Absorption Loss Of Optical Components By Laser Calorimetry

Modern high-power laser systems require the use of optical components with excellent thermophysical properties for construction,so to continue the development of high-power laser technology,the absorption loss of optical components needs to be further reduced to improve the performance of the whole laser system.Accurate measurement of optical components and their thin film properties is a prerequisite for improving the components,and among the many measurement methods,laser calorimetry is widely used as a method recommended by the International Organization for Standardization.In this paper,we focus on the two key topics of laser calorimetry and absorption loss,introduce the uniform temperature model and the accurate temperature model to describe the internal temperature gradient distribution of optical components,and propose an automatic adjustment fixture based on these two models;build a laser calorimetry measurement platform according to the actual experimental conditions,study the effect of the experimental system on the measurement of absorption loss of optical components made of quartz,and The laser calorimetric measurement platform is built according to the actual experimental conditions,the effect of the experimental system on the absorption loss of optical components of quartz materials is investigated,and some problems that need attention in the practical implementation of the laser calorimetric measurement experiment are analyzed.An exact temperature model is introduced to describe the exact temperature field distribution inside the component irradiated by the laser beam,which is taken into account the finite thermal conductivity,finite size,and heat exchange with the external environment of the optical component.A method for optimizing the optimal temperature detection location based on the thermal conductivity,size structure and laser irradiation time of the optical element is discussed by using the exact temperature model;and an improved sample holder for the optical element under test is proposed by this method to further reduce the error in the absorption loss values obtained in the actual measurement experiments.Starting from the basic structure of the laser calorimetry system,the construction process of the laser calorimetry measurement platform in the actual experiment is studied,and the operation methiod of adjusting the optical path in the optical path platform and reducing the influence of scattered light is proposed.Based on the Wheatstone bridge principle,the temperature measuring bridge required in the experimental system is designed,and the practical method of making temperature sensor and its assembly method in the measuring system are explained.Finally,the design ideas and functions of the measuring circuit used are introduced,as well as some design points of the computer-side data processing program.Based on the theoretical analysis and hardware implementation,a laser calorimetry platform is used to perform calorimetric experiments on transparent discs of quartz material at different laser powers and heating times.The operations that need to be handled for environmental effects before the experiments are analyzed,and the main points of operation that need to be paid attention to in the actual experiments are studied.The laser calorimetry system used in this paper showed poor measurement results on the optical components,which was analyzed to be due to the failure to build the temperature measurement platform completely,resulting in serious scattered light effects.