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High Precision Optical Path Difference Compensation Method Based on Three- Parameter Cosine Fitting Method
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DOI：10.1109/JLT.2022.3170090.png)
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Abstract
En 中文
For low fineness extrinsic Fabry-Perot inter-ferometer (EFPI) sensors, the discrete gap transform (DGT) algorithm can be usually adopted to acquire the cavity length, and the magnitude of its demodulation error is often larger than several hundred picometer. In this paper, three-parameter cosine fitting (TPCF) method is proposed to compensate for the EFPI cavity length error caused by traditional spectrum truncation, which can improve the demodulation accuracy by 3800 times of that of DGT. This method has a large cavity length demodulation range of 20 mu m similar to 30000 mu m with a maximum error of 65 pm, which was proved by numerical simulation. The experiment shows that when the cavity length is 31 mu m and 282.3 mu m, the demodulation resolutions with a confidence interval of 68.27% are 15.142 pm and 27.582 pm, respectively, and its actual demodulation time is no more than 0.021 s. Compared with the traditional cavity length demodulation algorithms, the proposed algorithm has broader demodulation range, higher demodulation accuracy and resolution. Moreover, it will be unrestricted by wavelength shift for more than one period and can realize real-time fast demodulation.
Keywords:
Demodulation
Optical fiber sensors
Optical interferometry
Optical fibers
Optical variables measurement
Fitting
Interference
Demodulation
extrinsic Fabry-Perot interferometer
high precision
phase difference compensation
three-parameter cosine fitting method
Journal
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