A demodulation method of spatial domain based on low-coherence interferometry is proposed. The original signal of spatial domain acquired by linear CCD is filtered with all-phase filter to obtain the fringe pattern, and the phase signal of the spatial frequency domain is retained after filtering. The fringe pattern analysis is employed to avoid phase ambiguity and realize large measurement range in demodulation. Afterwards, using the centroid position of the fringe, the peak position of a single fringe pattern can be obtained, and finally the accurate peak position is calculated with seven-step phase-shifting interferometry. The demodulation method is demonstrated experimentally with Fabry-Perot sensing system. At room temperature, it is proved that the full-scale measurement error is less than 0.019% in the range of 11 kPa to 290 kPa. From −20 °C to 70 °C, the accuracy is stable and the maximum error is less than 0.054 kPa. The demodulation method has the potential to enhance the measurement accuracy and adaptability in actual environment for universal applications.

中文翻译：

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一种高精度、适应性强的低相干干涉空间域解调方法

提出了一种基于低相干干涉测量的空间域解调方法。线阵CCD获取的原始空间域信号经过全相位滤波器滤波得到条纹图，滤波后保留空间频域相位信号。采用条纹图分析，避免相位模糊，实现解调大测量范围。之后，利用条纹的质心位置，可以得到单个条纹图案的峰值位置，最后用七步相移干涉法计算出准确的峰值位置。解调方法通过法布里-珀罗传感系统进行实验证明。在室温下，证明在11 kPa至290 kPa范围内满量程测量误差小于0.019%。从-20°C到70°C，精度稳定，最大误差小于0.054 kPa。该解调方法具有提高测量精度和实际环境适应性的潜力，适用于普遍应用。