Abstract: In this paper, the lasers with wavelengths of 633nm and 1319nm are taken as examples to study the laser coupled confocal system. In order to satisfy the design requirement that the convergence angle of two kinds of wavelength laser beam after combined focusing is less than 10 degrees, two solutions are proposed in this paper: One is to use a mirror 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 microns and a numerical aperture (NA) of 0.14, design a coupling lens group based on fiber and laser parameters. 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 dual-wavelength laser combining, and the coupling efficiency is higher. The coupling efficiency of the system is greater than 40% when the input wavelength is 633nm, and the system coupling efficiency is greater than 30% when the input wavelength is 1319nm. The experimental results meet the design requirements and achieve the desired results.

Key words: laser technology, dual wavelength laser coupled confocal, lens coupling method, coupling efficiency, fiber combiner