Research On Measurement Of 3D Surface Topography Based On Scanning White-light Interferometry

Scanning white-light interferometry for 3D surface topography has a wide application. In this paper the methods of 3D surface topography are reviewed, and their advantages and disadvantages are compared. Then the high-precision 3D surface topography based on scanning white-light interferometry is concentrated.In the paper, a scanning white-light interferometer based on Linnik interferometry is set up for experimental research. To obtain a series of interferograms, the reference arm is used as the scanning arm, which is driven by a PZT actuator. The interferograms are grabbed by a CCD camera and analyzed to determine the comparative height of the measured surface. To know the factors affecting the experimental accuracy, the PZT scanning interval and non-linearity, CCD imaging quality and the wavelength disturbance of the white-light source, etc, are investigated. The calibration methods of the corresponding parameters related to the topographic accuracy are studied.To determine the height data of the 3D surface topography from the scanning white-light interferometry, the computational algorithm in the frequency domain for demodulating the interferograms and the technique for reducing the ambiguity in the phase data are studied.In the end of the paper, the computational algorithm is verified by means of a simulation method. The simulation results are illustrated that the algorithm can overcome the phase ambiguities in the interferogram demodulation. Our research results show that scanning white-light interferometry can achieve both large measurement range and high accuracy. Especially in emerging light direction, the measurement accuracy can reach nanometer.