Contact Surface Profilometer Based On Scanning White Light Interference Method

Contact and non-contact measurement are two principal measuring methods in engineering measurement domestic and overseas today. White light interferometry is widely used for non-contact measurements. But because of some restrictions such as shape, surface optical character, surface processing quality, measurement range in non-contact measurement, the additional purchase of specialized contact measuring instrument is required, which increases the cost. On the other hand, the measurement for workpieces involves not only roughness, but also waviness and shape error in engineering applications, which requires the profilometer owns the characters of high-precision and large range at the same time. So, it will be very worthy and necessary of improving existing non-contact measurement profilometer based on white–light scanning interferometry to achieve two different measurement. The main research contents are as follow:Proposed to apply the white light interferometry to contact measurement, expounded the measurement principles of the device, analysed the factors that influence the interferential stripes.Designed a stylus sensor used for translating surface height signal into interference stripes signals, which are transformed to digital signal by CCD and image collecting card. Finally, Achieved the output of surface information by the application software.Established Mathematic models of different curve fitting and gauss filter. Developed a application software in C++ on Borland C++ Builder platform, the user can conveniently set parameters for measuring, and choose the ways for fitting and filtering. The roughness and waveness parameters and curved face contours parameters are calculated. Some necessary graphs are also displayed. All of those can be printed out.For verifying its precision and feasibility, some experiments are conducted with this system through measuring the templet gauge and bearing inner and outer ball track as well as the ball. The theoretical resolving power of the profilometer is up to nanometer. The scope of measurement could be reached 5mm and 50mm, vertically and horizontally, respectively.Performance indexes are obtained about the instrument's precision through the evaluation test.