Dr. Junchen Liu Profile

Dr. Junchen Liu

at Tianjin Univ

SPIE Involvement:

Author

Publications (3)

Proceedings Article | 27 November 2023 Poster + Paper

Ultra-sensitive absolute angular position sensing using pixelated metasurface

Wanghang Gu, Junchen Liu, Xinghua Qu, Fumin Zhang

Proceedings Volume 12771, 1277120 (2023) https://doi.org/10.1117/12.3000304

KEYWORDS: Angle measurement, Visualization, Information visualization, Visual optics, Light sources, Detector arrays, Autocollimators, Sensing systems, Plasmonics, Modulation frequency

Read Abstract +

Proceedings Article | 27 November 2023 Paper

Frequency modulation continuous wave speed-distance synchronous measurement with variable period frequency parameter estimation traced to optical frequency comb

Junchen Liu, Mengxin Liu, Wanghang Gu, Fumin Zhang, Xinghua Qu

Proceedings Volume 12769, 1276911 (2023) https://doi.org/10.1117/12.3000131

KEYWORDS: Laser frequency, Frequency modulation, Modulation frequency, Frequency combs, Signal processing, Precision measurement, Laser optics, Laser systems engineering, Target detection, Modulation

Read Abstract +

Proceedings Article | 8 July 2022 Paper

Simultaneous high-precision velocimetry and ranging based on beat frequency signal splitting via a FMCW lidar with Fabry-Pérot cavity

Junchen Liu, Xingrui Cheng, Fumin Zhang, Xinghua Qu

Proceedings Volume 12282, 1228205 (2022) https://doi.org/10.1117/12.2612256

KEYWORDS: LIDAR, Distance measurement, Velocity measurements, Signal processing, Ranging, Frequency modulation, Velocimetry

Read Abstract +

In industrial sites, large-scale advanced manufacturing equipment such as optical diamond cutting lathes require stable operation during processing and are very sensitive to operating speed. However, the vibration generated by the environment or equipment will interfere with its operation and machining accuracy. A precise laser interference measurement system is required to monitor the running speed and position of the three-axis tool of the lathe in real time, providing accurate parameters for the closed-loop control system of the equipment, and improving the stability of lathe operation. Frequency-modulated continuous-wave (FMCW) lidar is widely used in the field of industrial measurement due to its non-contact, high accuracy, and fast dynamic response. The basic principle of FMCW lidars is to measure the velocity of a moving object through the Doppler frequency shift phenomenon. But the vibration generated by the moving object will cause the spectrum to broaden and the precision and repeatability of measurement to decrease. Therefore, we propose a large-bandwidth triangular wave-modulated lidar structure with Fabry-Pérot(F-P) cavity to achieve real-time high-precision measurement of the speed and distance of moving targets. This structure is based on the F–P resonance peaks generated by changing the length of the F-P cavity to accurately split the beat signal generated in the sweep frequency range of 1545-1565nm to obtain 40 sets of data with equal frequency intervals of 62GHz, effectively solve the problem of excessive data volume when measuring the continuous moving target speed and reduces the complexity of the algorithm. Splitting the measured beat signal based on the resonance peaks signal of the F-P cavity, which reduces the phase delay of the beat signal corresponding to the up- and down-scanning, thus reducing the signal spectrum broadening caused by frequency deviation and nonlinear, and increasing the target measurement resolution, accuracy and range. The experimental results show that for speeds of up to 250mm/s, the mean standard deviation was less than 152μm/s, the mean error was less than 183μm/s, the relative error of the mean value of speed measurement does not exceed 0.22%, and the standard deviation of the distance measurement results within a range of 4m under various speed conditions does not exceed 17μm, the error does not exceed 14μm, it has good accuracy and repeatability for the speed and distance measurement. The lidar architecture solution we proposed has important application value for large-scale industrial equipment measurement and operation monitoring.

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years