Study On The Optical Profiler Of Three Color Combined Light Source

The surface micro-morphology and structural quality of the parts are closely related to their functional properties.The surface topography measurement is of great significance for the surface quality and its functional properties.The white light interference surface topography measurement method has the characteristics of non-contact,high efficiency and high accuracy,and is particularly suitable for high-precision measurement of functional surfaces such as MEMS,IC,and micro-nano optics.This paper focuses on the shortcomings of the existing white light interferometry system,such as low contrast of the interferometric signal,high requirement on the vertical scanning sampling frequency,and low automation of the measurement,and studies on the light source,surface restoration,and autofocus positioning.The main work is as follows:1.A lighting system with RGB three-color combination light source instead of white LED light source was designed and constructed to effectively improve the spectral distribution characteristics of the light source,thereby greatly improving the contrast of the interference signal.2.The spatial frequency domain analysis algorithm of the interferometric signal under the three-color combined light illumination is studied and implemented.It can realize the high-precision recovery of the surface topography when scanning the low sampling frequency vertically,which greatly improves the measurement efficiency.3.Several commonly used focus evaluation operators were studied and compared,and an evaluation operator that was not affected by changes in the background light intensity and sensitive to interference fringes was selected,furthermore,based on the autofocus scanning algorithm,a quick and accurate autofocus scanning function of the profiler is realized.4.The three-color combined light source,spatial frequency domain analysis of interference signals,topography recovery algorithm and auto-focus algorithm were applied to the self-developed optical profiler,and experimental tests were conducted.Good results were obtained.