双波长激光耦合共焦系统研究

Research on dual-wavelength laser coupling confocal system

以波长分别为633 nm和1319 nm的激光为例研究了激光耦合共焦系统。为满足两种波长的激光合束聚焦后的会聚角小于10°的设计要求,提出了两种解决思路:一是用反射镜和二向色镜使双波长激光实现共光路,然后经离轴抛物面反射实现共焦;二是用透镜组耦合的方法把双波长激光分别耦合进二合一合束器,合束器采用单模光纤,其芯径为9μm,数值孔径(NA)为0.14,根据光纤和激光器参数设计耦合透镜组。综合考虑采用第二种方法进行实验,给出实验方法及测量结果,并计算出两种波长激光各自的耦合效率。实验结果表明:光纤耦合器耦合法能实现双波长激光合束,并且耦合效率较高,输入波长为633 nm、1319 nm时系统的耦合效率分别大于40%、30%,实验结果满足设计要求,达到了预期效果。

The lasers with wavelengths of 633 nm and 1319 nm are taken as examples to investigate the laser coupled confocal system.In order to satisfy the design requirement that the convergence angle of two wavelength laser beams is less than 10° after focusing,two solutions are proposed.One is to use a reflector and a dichroic mirror to achieve a common optical path for the double wavelength lasers,and then to achieve confocal via off-axis parabolic reflection.The other is to use a combination lens to couple the dual-wavelength laser into a two-in-one combiner,which uses a single-mode fiber with a core of 9 μm and a numerical aperture(NA)of 0.14.A coupling lens group based on fiber and laser parameters is designed.Considering the second method,the experimental method and measurement results are given,and the coupling efficiencies of the two wavelength lasers are calculated.The experimental results show that the combined lens coupling method can achieve two-wavelength lasers combining with high coupling efficiency.The coupling efficiencies of the system are greater than 40%,30% respectively when the input wavelength are 633 nm,1319 nm.The experimental results meet the design requirements and achieve the desired results.