Anti-vibration white light interferometry method based on non-uniform sampling correction

Abstract

The invention discloses an anti-vibration white light interferometry method based on non-uniform sampling correction. The method comprises the following steps: collecting the white light interferogram sequence and the quasi-monochromatic light interferogram sequence of the object to be tested; Fig. calculates the vibration inclined plane based on frequency domain peak sub-pixel positioning, and uses these inclined planes to calculate the non-uniform phase shift sampling interval of each pixel position in the white light interferogram; uses non-uniform Fourier transform to correct the white light interference signal; The corrected white light interference signal is used to extract the peak position of the modulation degree, so as to restore the topography distribution of the surface of the measured object. The present invention adopts a dual-channel white light interference system to obtain a monochromatic light interferogram sequence and a white light interferogram sequence respectively, and uses the monochromatic light interferogram sequence to solve and calculate the sampling interval error under the influence of vibration, thereby correcting the distorted white light interference signal , to restore the topography distribution of the surface of the measured object, this method has low cost and high measurement accuracy.

Description

technical field [0001] The invention belongs to the field of optical interferometry measurement, in particular to an anti-vibration white light interferometry method based on non-uniform sampling correction. Background technique [0002] White light scanning interferometry has the advantages of simple structure, high measurement accuracy, and non-contact. At present, this technology is widely used in many fields such as aerospace, material science, and machining. Since white light scanning interferometry uses a low-coherence light source, the coherence length is only a few microns, and white light interference fringes can only be observed when the optical path difference is close to zero. Therefore, the requirements for the measurement environment are relatively high, and the environmental vibration of the measurement site It will affect its measurement accuracy, making it difficult to apply this technology to the processing site. [0003] To solve this problem, many differ...

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Problems solved by technology

[0004] At present, VEECO has proposed a method, using white light source as test light and laser light source as reference light, so that the two beams share the same path, and use the reference signal to obtain the motion of the scanning device and the vibration of the system to calculate the actual step. long, and substitute the actual step length into the center of mass detection algorithm to obtain the position information of the coherent peak. This method has a small amount of calculation, but the measurement accuracy is low and it is not suitable for large vibrations; Tereschenko from the University of Kassel, Germany proposed a method, combining Michelson white light interferometer and laser ranging interferometer, using photodiode to collect the interference signal of infrared light source and solving the actual position of the interferogram obtained by the area array detector, using interpolation method to To correct the white light interference signal, the device structure of this method is relatively complicated and the cost is high

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