Two-wavelength laser focusing point positioning method based on CCD image processing

As the application requirements of fiber-coupled lasers continue to increase, the coupling efficiency requirements for optical fibers and lasers also increase. There are differences in the position of the focal point of different wavelength lasers. The position of the laser focusing point is one of the important factors affecting the coupling efficiency, and it has certain practicability for the precise positioning of the laser focusing point. A focused combined lens group is used to focus the laser beam. The CCD camera is used to collect the image of the laser focus point before and after the focus. The acquired image is processed by MATLAB software. The spot is fitted to the spot and the spot diameter is calculated. The smallest position of the diameter is the focus position. The results show that the laser focusing points of different wavelengths are different and the relative error of focal length is 0.59% and 0.73%, respectively. The measured focus position and size can be accurate to 0.001 mm. The method is simple in design, automatic and accurate, and the judgment of the invisible laser focus position is superior.