An Improved Data Processing Algorithm for Spectrally Resolved Interferometry Using a Femtosecond Laser

• Published in: Sensors Vol. 24; no. 9; p. 2869
• Main Authors: Liu, Tao, Matsukuma, Hiraku, Suzuki, Amane, Sato, Ryo, Gao, Wei
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 30.04.2024
• Subjects: absolute distance measurement; Accuracy; Algorithms; Chemical technology; Data processing; Electronic data processing; Fourier transforms; Interferometry; inverse Fourier transform; Lasers; Liu, Timothy; Measurement techniques; spectrally resolved interferometry; Spectrum analysis; TP1-1185; spectrally resolved interferometry; inverse Fourier transform; absolute distance measurement
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s24092869

Spectrally resolved interferometry utilizing a femtosecond laser is widely employed for absolute distance measurement. However, deviations in the output time pulse of the conventional algorithm through inverse Fourier transform are inevitable. Herein, an improved data processing algorithm employing a time-shifting parameter is proposed to improve the accuracy of spectrally resolved interferometry. The principle of the proposed time-shifting algorithm is analyzed theoretically after clarifying the deviation source of the conventional algorithm. Simulation and experimental work were conducted to indicate the improvement in the accuracy of the output absolute distance. The results demonstrated that the proposed algorithm could reduce the deviation of output distances towards the reference values, reaching 0.58 μm by half compared to the conventional algorithm. Furthermore, the measurement uncertainty was evaluated using the Guide to the Expression of Uncertainty in Measurement (GUM), resulting in an expanded uncertainty of 0.71 μm with a 95% confidence.