White Light Interferometry Measurement System And Algorithm

The rapid development of ultra-precision machining and semiconductor industry for micro/nano measurement technology is also put forward higher requirements. The traditional contact probe measurement with low efficiency, the increasingly complex structure of surface morphology is difficult to detect and easy to scratch the surface. In this paper, based on white light interferometry, design a complete set of white light interference measuring system and analysis on system performance test and traceability. Specific works are summarized as follows:1. Designed and built the white light interference measuring system, including mechanical support structure, optical interference module, image acquisition module, motion drives, etc. Write the experimental test PC software and improve the interactive software.2. White light interferometry algorithms were studied. This paper studies the time domain algorithms, including interpolation method, gravity method; frequency domain algorithms, including Fourier transform algorithm, spatial frequency domain method; white light phase shifting algorithm. Based on the theory deduction, the characteristics of each algorithm and suitable measuring object were summarized.3. The performance and accuracy of the measurement system was evaluated, indicating the system has good repeatability and stability. With nano measuring machine has carried on the contrast experiment, the results were evaluated, and through the standard material-nano standard template analyzed the traceability of the system.4. For large-size high samples, variable speed scan technique is proposed. This method can shorten scan time, improve scanning efficiency and reduce the effects of human or environmental during the long time scanning process. The scan mode includes predefined mode and auto focus mode, before the scan the predefined pattern need to set the scan step and the upper and lower surfaces of the scanning range; AF mode, according to self-focus function to automatically search the position of the upper and lower surface. This san method only extracts the useful information near the upper and lower surface, and quickly through the intermediate portion of the defocus, greatly increasing the efficiency and accuracy of the experiment.