Error Correction for FSI-Based System without Cooperative Target Using an Adaptive Filtering Method and a Phase-Matching Mosaic Algorithm

Abstract

Featured Application: Absolute distance measurement and surface profiling.Abstract: In our frequency scanning interferometry-based (FSI-based) absolute distance measurement system, a frequency sampling method is used to eliminate the influence of laser tuning nonlinearity. However, because the external cavity laser (ECL) has been used for five years, factors such as the mode hopping of the ECL and the low signal-to-noise ratio (SNR) in a non-cooperative target measurement bring new problems, including erroneous sampling points, phase jumps, and interfering signals. This article analyzes the impacts of the erroneous sampling points and interfering signals on the accuracy of measurement, and then proposes an adaptive filtering method to eliminate the influence. In addition, a phase-matching mosaic algorithm is used to eliminate the phase jump, and a segmentation mosaic algorithm is used to improve the data processing speed. The result of the simulation proves the efficiency of our method. In experiments, the measured target was located at eight different positions on a precise guide rail, and the incident angle was 12 degrees. The maximum deviation of the measured results between the FSI-based system and the He-Ne interferometer was 9.6 µm, and the maximum mean square error of our method was 2.4 µm, which approached the Cramer-Rao lower bound (CRLB) of 0.8 µm.polarization-maintaining fiber to eliminate the influence of tuning nonlinearity. This method is a common and effective method, but it creates a dispersion mismatch problem that results in target peak broadening. Fortunately, many dispersion compensation methods had been proposed and proved efficiently [20][21][22]. In our experiments without cooperate targets, we use an ECL that has been used for five years, so the SNR is low, and mode-hoping signals often occur. These bring new problems: erroneous sampling points and interfering signals. Our paper analyzes the influences of erroneous sampling points and interfering signals, and then an adaptive filtering method is proposed to eliminate the influences completely. In addition, a phase-matching mosaic algorithm and a segmentation mosaic algorithm are adopted to eliminate the phase jump and improve the data processing speed, respectively.The article is organized as follows: Section 2 reviews the principle of the FSI-based system and discusses the measurement errors caused by erroneous sampling points and interfering signals. Then, an adaptive filtering method, a phase-matching mosaic algorithm, and a segmentation mosaic algorithm are proposed to eliminate the erroneous sampling points and phase jump and reduce the data processing time. In Sections 3 and 4, the results of the simulation and experiment prove the efficiency of the methods that were proposed in Section 2. Finally, a brief conclusion is given in Section 5.

Special Issue on Precision Dimensional Measurements

“…Xiong et al calculated the effective center wavelength for heterodyne interferometry of an optical frequency comb [23]. Gao et al propose a technique to compensate the FS interferometer [24] and Xiong et al propose an adaptive filtering method to correct errors due to interfering signals of FS interferometer [25]. In the area of grating diffraction-based interferometer, a double diffraction heterodyne interferometer was developed by Chang [26].…”

Enhancement of frequency scanning interferometry signal for non-cooperative target based on generative adversarial network

“…The direct power amplification of the measurement light is the easiest method to use; therefore, many schemes for cooperative and non-cooperative target measurements use laser power amplifiers to strengthen the return light by increasing the power of the probe light [19][20][21]. Additionally, using a focusing system to focus the probe light on the surface to be measured can increase the power of the reflected light [22][23][24]. Another good solution is to allow more returned light to be recovered.…”

Compensation of Frequency Drift in Frequency-Sweep Polarization-Modulation Ranging System

“…Absolute distance measurement (ADM) technologies are of significant application in scientific and engineering fields such as large equipment manufacturing, spacecraft fabrication, and general-purpose coordinate measurements [1][2][3]. Various methods of ADM have been developed over the past decades, such as phase shift-based ranging [4][5][6], frequency scanning interferometry-based ranging [7][8][9][10], multi-wavelength interference-based ranging [11][12][13][14], and femtosecond optical comb-based ranging [10,[15][16][17]. In recent years, the latter three technologies have achieved great accuracy in laboratory, but the systems are complex and their performance needs to be enhanced in an industrial setting.…”