Design Of Laser Auto-focus Precision System

The auto-focus technology has greatly improved the working efficiency of the optical system.Nowadays,the application of auto-focus technology is widely used in optical imaging,spectrum detection,microscopic measurement and machine vision,etc.,however,high precision focusing is always the focus of auto focus technology.In view of the requirement of high precision focus in the field of spectrum detection,this paper proposes a bichromatic laser phase focusing method.The position of the positive and negative out of focus is judged by the relative position of the red and blue spot,and then the focus plane search is done by the high precision actuator.In this paper,Firstly,design the optical and structural model of the laser auto-focus precision system,build the basic structure of hardware platform with the laser head,microscopic imaging system,PC,three axis motion platform and so on.The development of machine vision program and motion control program is completed based on Lab VIEW,and achieve the image acquisition,image processing,light intensity analysis,the maximum index and the precision motion control of the three axis motion platform.Complete the Gauss curve fitting algorithm program,and achieve the accurately locate of the maximum point of light intensity.The test results of the laser auto-focus precision system show that,when the system search for the focus plane in the ±80um,the focus error is less than 10um,and the system can meet the requirements.Finally,the paper analyses the system error which affects the precision of the system.At present,there are problems in the system,such as large structure and easy to be influenced by the environmental factors,The next step should be the system structure stability,miniaturization,assisted laser performance and other aspects,to further improve the system performance.