Research And Application Of Micro White Light Profiler

With the development of modern technology and the large-scale use of precision machining elements,higher requirements are put forward for the detection accuracy of surface parameters such as the surface roughness of the processing elements.In order to meet the needs of industrial production on-site testing,higher requirements are put forward for the performance,accuracy and function of the detector.In this paper,the white light micro-interferometry and phase-shifting technology are combined to design the optical-mechanical system structure.On this basis,a miniature white-light profiler was developed to achieve high-precision and rapid measurement of the surface roughness of precision processed elements.Aiming at the on-site roughness measurement of the optical elements produced by the point diamond lathe,the upmarket white light profiler,portable white light profiler,contact profiler,interference microscope and other measuring equipment are analyzed.Considering of the requirements of the measurement convenience,accuracy and cost controllability,the instrument type is determined.Firstly,the interference principle of monochromatic light and white light and their respective characteristics were analyzed and compared.Furthermore,the effects of monochromatic light and white light as interference light sources are compared.Then,the different types of phase extraction algorithms are theoretically analyzed.The effects of the three-step phase shift method and the five-step phase shift method are compared and analyzed in terms of phase shift error.The seven-step phase shift method uses a linearly varying modulation degree for phase shift,which can effectively reduce errors.In the hardware architecture,the vertical adjustment frame is used as the base,and the main body of the portable white light profiler is used as the optical system.The base and the optical system are connected in a stable double clamping manner to realize the integration of the instrument and improve the stability and anti-interference ability of the system.What’s more,a multi-dimensional measurement platform in the space of the element to be tested is installed,which can not only realize the measurement of large-diameter components,but also measure the edge position of elements.Finally,the modular analysis of the measurement software is carried out by using the idea of object-oriented modular programming.The measurement system is divided into main program module,real-time sampling and displacement scanning module,data processing and result display module.The interface communication between the modules can ensure the independence of the software modules and improve the maintainability of the measurement system.In order to verify the stability,accuracy and practicability of the instrument,a micro white light profilometer was used to measure the three-dimensional roughness of the surface of flat mirror,thin section,toughened film,mobile phone back shell and CGH.At the same time,the same type of white light profilometer was used to measure the above samples under the same detection environment,and the measurement results were compared to verify the reliability of the instrument.The results show that the roughness measurement accuracy is 0.1nm,the repeatability accuracy is better than 0.01 nm,and the lateral resolution is better than 1μm,which proves that the instrument measurement system can meet the requirements of industrial on-site rapid measurement.