Yang Lian-gen, Yu Zai-xin, He Lang, Wang Xuan-ze. Four-wavelength switching interference measurement system for surface topography[J]. Journal of Applied Optics, 2015, 36(6): 847-851. DOI: 10.5768/JAO201536.0601005
Citation: Yang Lian-gen, Yu Zai-xin, He Lang, Wang Xuan-ze. Four-wavelength switching interference measurement system for surface topography[J]. Journal of Applied Optics, 2015, 36(6): 847-851. DOI: 10.5768/JAO201536.0601005

Four-wavelength switching interference measurement system for surface topography

  • Phase-shifting interferometry is an important measurement method for surface topography, but the depth measuring range is limited by the wavelength.A four-wavelength interference measurement system for surface topography was proposed.Through rotating the filters, 4 light sources with different wavelengths were switched out from LED light, and the single wavelength interference was conducted in turn. A data processing method for multiple wavelength interference images was put forward, which used the algorithm of elliptic fitting and the combination of varied scales to achieve wide-range highprecision surface topography measurement on the condition of calculating the phase point-by-point and frame-by-frame. Experimental results show that under the measurement depth expanded to nearly 41 times, the relative measurement error of surface roughness of square wave specimen with multiple grooves is only 4.09%,compared to the data calibrated by China Institute of Metrology. Therefore, the system can realize high-precision measurement for surface topography in a certain range.
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