scholarly journals Laser frequency scanning interferometry based on estimating signal parameters via rotational invariance technique

2021 ◽  
Vol 70 (3) ◽  
pp. 034205-034205
Author(s):  
Xu Jing-Xiang ◽  
◽  
Kong Ming ◽  
Xu Xin-Ke
Keyword(s):  
Laser Frequency ◽  
Rotational Invariance ◽  
Frequency Scanning ◽  
Signal Parameters ◽  
Frequency Scanning Interferometry

scholarly journals Absolute Distance Measurement Using Frequency-Scanning Interferometry Based on Hilbert Phase Subdivision

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5132 ◽  
Author(s):  
Shuo Jiang ◽  
Bo Liu ◽  
Huachuang Wang ◽  
Bin Zhao
Keyword(s):  
Laser Frequency ◽  
Optical Path Difference ◽  
Path Difference ◽  
Distance Measurement ◽  
Beat Signal ◽  
Interference Signal ◽  
Time Points ◽  
Frequency Scanning ◽  
Frequency Scanning Interferometry ◽  
External Clock

In order to eliminate the influence of laser frequency nonlinearity, the frequency-scanning interferometry (FSI) often uses the beat signal of an auxiliary interferometer as the external clock. The time points at every amplitude peaks and bottoms of the auxiliary beat signal are selected as the sampling time points for the main interferometer signal. To satisfy the Nyquist sampling requirement, the optical path difference (OPD) of the delay fiber in auxiliary interferometer should be at least twice longer than the measurement distance. In this paper, we proposed a method to shorten the length of delay fiber. The Hilbert transform was used to extract the phase of the auxiliary interference signal and calculate the time points corresponding to subdivided phase intervals. Then, the main interference signal was resampled at these moments, and the fast Fourier transform was performed on the resampled signal. The experimental results showed that the target at the distance of about 5 m was measured when the OPD of the auxiliary interferometer was about 4.5 m. The standard deviation of the distance measurement results could reach 4.64 μm.

scholarly journals A method of suppressing vibration for high precision broadband laser frequency scanning interferometry

2016 ◽  
Vol 65 (20) ◽  
pp. 209501
Author(s):  
Liu Guo-Dong ◽  
Xu Xin-Ke ◽  
Liu Bing-Guo ◽  
Chen Feng-Dong ◽  
Hu Tao ◽  
...  
Keyword(s):  
High Precision ◽  
Laser Frequency ◽  
Frequency Scanning ◽  
Broadband Laser ◽  
Frequency Scanning Interferometry

scholarly journals An efficient method for the compensation of dispersion mismatch in the frequency-scanning interferometry

2021 ◽  
Author(s):  
Qiang Zhou ◽  
Tengfei Wu ◽  
Yang Liu ◽  
yue shang ◽  
Jiarui Lin ◽  
...  
Keyword(s):  
Efficient Method ◽  
Frequency Scanning ◽  
Frequency Scanning Interferometry

scholarly journals Vibration Compensation of the Frequency-Scanning-Interferometry-Based Absolute Ranging System

2019 ◽  
Vol 9 (1) ◽  
pp. 147 ◽  
Author(s):  
Fu-Min Zhang ◽  
Ya-Ting Li ◽  
Hao Pan ◽  
Chun-Zhao Shi ◽  
Xing-Hua Qu
Keyword(s):  
Standard Deviation ◽  
Vibration Frequency ◽  
Phase Modulation ◽  
Vibration Velocity ◽  
Sinusoidal Vibration ◽  
Vibration Effect ◽  
Frequency Scanning ◽  
Blind Area ◽  
Frequency Scanning Interferometry ◽  
Vibration Compensation

The frequency-scanning-interferometry-based (FSI-based) absolute ranging technology is a type of ranging technology possessing a high precision and no ranging blind area, so it can be used for non-cooperative targets. However, due to a tiny movement of a target, the Doppler shift and the phase modulation are introduced into the beat signal which results in ranging accuracy decrease. In order to solve this problem, first the model of vibration effect is established, and then the beat signals of two adjacent scanning periods are processed to produce a signal that is immune to vibration. The proposed method is verified by the experiments, and the experimental results show that the effect of vibration compensation is better for the target with a lower vibration velocity and at a lower vibration frequency (lower than 6 Hz). When the target is subjected to a sinusoidal vibration with an amplitude of 10 μm at a frequency of 1 Hz, by using the proposed method the standard deviation is reduced from 775 to 12 μm. Moreover, in the natural environment, by using vibration compensation the standard deviation is reduced from 289 to 11 μm.

scholarly journals Direction-of-Arrival Estimation for 2D Coherently Distributed Sources with Nested Array Based on Matrix Reconstruction

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Yu Xiao ◽  
Tao Wu ◽  
Yiwen Li ◽  
Xinping Ma ◽  
Yijie Huang
Keyword(s):  
Cross Correlation ◽  
Direction Of Arrival ◽  
Estimation Algorithm ◽  
Rotational Invariance ◽  
Correlation Matrices ◽  
Linear Arrays ◽  
Signal Parameters ◽  
Matrix Reconstruction ◽  
Pair Matching ◽  
The Difference

This paper has made proposition of a nested array and an estimation algorithm for direction-of-arrival (DOA) of two-dimensional (2D) coherently distributed (CD) sources. According to the difference coarray concept, double parallel hole-free virtual uniform linear arrays are generated by virtue of vectorization operation on cross-correlation matrices of subarrays. Sensor coordinates of virtual arrays are derived. Rational invariance relationships of virtual arrays are derived. According to the rotational invariance relationships, matrices satisfying rotation invariance are constructed by extracting and regrouping the receive vectors of the virtual arrays, and then an estimation of signal parameters via rotational invariance techniques- (ESPRIT-) like framework on matrix reconstruction is deduced. Optimal configuration of the nested array as well as computational complexity are analyzed. Without pair matching, the proposed method can resolve more sources than the sensor number. Simulation outcomes indicate that the proposed method tends to have a better performance as compared to the traditional uniform arrays that have similar number of sensors.

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