Research On Surface Morphology Measurement System Based On Structured Illumination

Surface topography is an important geometric feature for samples in the product manufacturing and scientific research.Its measurement,analysis and evaluation are of great significance for the guarantee of surface functional quality characteristics.The structured illumination microscopy technique,which is based on the principle of wide field microscopy,obtains the three-dimensional datas by modulating the surface or structure information of the object to be measured,removing the defocus signal interference,and vertically axial scanning.The method has the characteristics of non-contact,high efficiency and high precision,and can be applied not only to the reflective surface but also to the topography measurement of the scattering surface.This paper focuses on microscopic measurement technology using structured illumination.The main work is as follows:1.Based on the principle of wide field microscopy,the point spread function and optical transfer function of structured illumination microscopy system was studied.The reason for optical sectioning ability in the structured illumination microscope was explained from the perspective of frequency domain,and the stripes of different spatial frequencies were analyzed.The influence of the optical sectioning ability was researched to select the appropriate fringe period.2.Imaging systems and lighting systems for structured illumination microscopes was studied.Based on the principle of Kohler illumination,a method to design the illumination system for the structured illumination microscope was proposed.By using stocked lenses and an infinity objective lens combined with a digital micromirror array(DMD),it not only facilitated adjustment of the surface light intensity and the field of view,but also benefited to ensure the uniformity of structured illumination stripes.Futher,the measurement process and principle of synchronous control of the structured illumination microscope were studied based on the above optical system.3.Optical sectioning methods in the structured illumination microscope such as two-shot method based on HiLo or Hilbert transform,three phases shift method and multi phases shift method were compared in terms of the difficulty of implementation and robustness.And the accuracy and efficiency of different peak extraction algorithms were analyzed.Finally,the suitable high-precision surface reconstruction algorithm for 3D surface topography is obtained.4.The prototype of structured illumination microscope for three-dimensional surface measurement was designed and constructed.The performance test was compared with the commercial confocal microscope and the white light interferometer.The results show that the structured light microscope has good perfermance for both the scattering surface and the functional surface.