Research Of Laser Focus Discrimination System Based On MATLAB

With the rapid development of laser technology and lasers,lasers are widely used in various fields.According to the actual needs,sometimes several laser sources with different wavelength are required to be used in the same optical path,so the fiber coupled laser can meet the requirement.The position of the laser focusing spot is one of the important factors affecting the coupling efficiency of fiber-optic coupled lasers,and the accurate location is more conducive to improving the coupling efficiency.There are 632.8 nm and 355 nm laser sources are coupled into optical fibers.The original laser beam has large diameter,divergent angle and 355 nm wavelength laser is invisible.In order to couple laser beams into optical fibers better,A focusing combined lens group focusing laser beam is designed by ZEMAX,then CCD camera is used to collect the images of the front and back laser focusing spots,and the diameter of laser spot is calculated by MATLAB.The position of the minimum diameter is the focus position.The experimental results show that the position and size of the focus can be accurately measured to 0.001 mm.The relative errors between the actual and theoretical values of focal length are 0.59% and 0.73% respectively,and the coupling efficiency is above 30% and 40% respectively.The output laser power of the optical fibers meets the requirements of application.The design method is more superior in locating the focus of invisible wavelength accurately.The dual-wavelength fiber-coupled laser designed in this paper has been applied to large-aperture collimator system.In order to ensure the accuracy of the collimator and prevent defocusing,the collimator system needs real-time focusing.Similarly,CCD camera is used to collect real-time images at the focal plane of the collimator.The size of the focal spot is calculated by MATLAB,and the defocusing of the collimator is judged by comparing the size with the standard value of the spot.In addition,the defocusing correction method is described in detail.The results meet the requirements of digital and picture display for focal plane quality of collimator.The focus discrimination method based on MATLAB image processing designed in this paper is simple,low cost,automatic and accurate.what's more,It can meet the application requirements of practical projects.