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White light interferometry with spectral-temporal demodulation for large-range thickness measurement 被引量:2
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作者 Yunlong Zhu Zhuoran Li +2 位作者 Xu Lu Yonggui Yuan Jun Yang 《Chinese Optics Letters》 SCIE EI CAS CSCD 2022年第9期25-30,共6页
Film thickness measurement can be realized using white light interferometry,but it is challenging to guarantee high precision in a large range of thicknesses.Based on scanning white light interferometry,we propose a s... Film thickness measurement can be realized using white light interferometry,but it is challenging to guarantee high precision in a large range of thicknesses.Based on scanning white light interferometry,we propose a spectral-temporal demodulation scheme for large-range thickness measurement.The demodulation process remains unchanged for either coatings or substrate-free films,while some adjustments are made according to the estimated optical thickness.Experiments show that the single-point repeatabilities for 500 nm SiO_(2) coating and 68μm substrate-free Si film are no more than 0.70 nm and 1.22 nm,respectively.This method can be further developed for simultaneous measurement of surface profile and film thickness. 展开更多
关键词 white light interferometry thickness measurement spectral-temporal demodulation thin film
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Nonlinear phase error analysis of equivalent thickness in a white-light spectral interferometer
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作者 Tong Guo Qianwen Weng +3 位作者 Bei Luo Jinping Chen Xing Fu Xiaotang Hu 《Nanotechnology and Precision Engineering》 EI CAS CSCD 2019年第2期77-82,共6页
A white light spectral interferometry based on a Linnik type system was established to accurately measure the thin film thickness through transparent medium.In practical work,the equivalent thickness of a beam splitte... A white light spectral interferometry based on a Linnik type system was established to accurately measure the thin film thickness through transparent medium.In practical work,the equivalent thickness of a beam splitter and the mismatch of the objective lens introduce nonlinear phase errors.Adding a transparent medium also increases the equivalent thickness.The simulation results showthat the equivalent thickness has a significant effect on thin film thickness measurements.Therefore,it is necessary to perform wavelength correction to provide a constant equivalent thickness for beamsplitters.In the experiments,some pieces of cover glasses as the transparent medium were added to the measured beam and then a standard thin film thickness of 1052.2±0.9 nm was tested through the transparent medium.The results demonstrate that our system has a nanometer-level accuracy for thin film thickness measurement through transparent medium with optical path compensation. 展开更多
关键词 white light spectral interferometry Thin film thickness measurement Nonlinear phase Equivalent thickness Transparent medium
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Loop Topology Based White Light Interferometric Fiber Optic Sensor Network for Application of Perimeter Security 被引量:6
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作者 Libo YUAN Yongtao DONG 《Photonic Sensors》 SCIE EI CAS 2011年第3期260-267,共8页
A loop topology based white light interferometric sensor network for perimeter security has been designed and demonstrated. In the perimeter security sensing system, where fiber sensors are packaged in the suspended c... A loop topology based white light interferometric sensor network for perimeter security has been designed and demonstrated. In the perimeter security sensing system, where fiber sensors are packaged in the suspended cable or buried cable, a bi-directional optical path interrogator is built by using Michelson or Mach-Zehnder interferometer. A practical implementation of this technique is presented by using an amplified spontaneous emission (ASE) light source and standard single mode fiber, which are common in communication industry. The sensor loop topology is completely passive and absolute length measurements can be obtained for each sensing fiber segment so that it can be used to measure quasi-distribution strain perturbation. For the long distance perimeter monitoring, this technique not only extends the multiplexing potential, but also provides a redundancy for the sensing system. One breakdown point is allowed in the sensor loop because the sensing system will still work even if the embedded sensor loop breaks somewhere. 展开更多
关键词 Optical fiber sensors quasi-distributed sensing system perimeter security white light interferometry
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