基于斩光取样与衰减技术的CO_(2)激光功率校准装置

Calibration Device for CO_(2) Laser Power Based on Chopper Sampling and Attenuation Technique

CO_(2)激光器输出功率的稳定性和调节能力较差,在激光功率校准中严重影响校准结果的重复性和校准功率范围。通过分光取样监测系统对CO_(2)激光功率进行实时监测,可改善校准的重复性。但对于波长为10.6μm的激光,常用的ZnSe镜片的监测比很不稳定,导致监测比的波动幅度过大。本文基于斩光原理,研制了斩光取样与衰减系统,衰减范围达到0.2%~50%。通过控制单元的优化设计,避免了同一束光路中两套斩光组件的相互干扰。对校准装置的监测比进行了测试,斩光取样系统的监测比不稳定度达到1.1%以内,显著优于CO_(2)激光功率的不稳定度(约5%)和ZnSe镜片的监测比不稳定度(8.6%)。利用该装置进行了CO_(2)激光功率校准测试,被测功率计修正因子的重复性(k=1)从无监测条件下的1.09%变为0.62%。本文提出的斩光取样与衰减系统,在CO_(2)激光功率校准中提高了校准结果的重复性,增大了功率调节范围。

The calibration repeatability of CO_(2)laser and the power range that can be calibrated are reduced by the laser's poor power stability and adjustability.The repeatability can be improved by monitoring the CO_(2)laser power in real time with a beam splitting system.But for 10.6μm laser,the reflectance of ZnSe beam splitters is very unstable,which leads to fluctuation of the monitor ratio.Based on the principle of chopper,a chopper sampling and attenuation system was developed.The attenuation range is 0.2%~50%.Through an optimization design of the control unit,the interference between two sets of choppers in the same beam was avoided.The monitor ratio of the calibration setup was tested,and the monitor ratio instability was less than 1.1%,which is significantly better than that of ZnSe beam splitters(8.6%).The repeatability(k=1)of the correction factor of the measured laser power meter improved from 1.09%(without a monitor)to 0.62%.The chopper sampling and attenuation system proposed in this paper improves the repeatability of calibration results and increases the power adjustment capability in CO_(2)laser power calibrations.