Modeling and Analysis of Phase Fluctuation in a High-Precision Roll Angle Measurement Based on a Heterodyne Interferometer

Abstract

Heterodyne interferometry is a high-precision method applied in roll angle measurements. Phase metering is essential for high precision. During a high-precision measurement, a phase fluctuation appears even when the roll angle does not vary, which has never been analyzed before. Herein, the reason for the phase fluctuation is revealed, which results from the frequency-difference fluctuation and time difference between measurement and reference beams. A mathematical model of that phase-fluctuation mechanism is established, and that model provides a theoretical basis for analyzing and reducing the phase fluctuation. The impact that the main factors have on the phase metering is analyzed quantitatively, and experiments are carried out to validate the model. Finally, the phase fluctuation decreases to 0.02° by frequency reduction, which conversely verifies the theoretical model.

High Accuracy Acquisition of 3-D Flight Trajectory of Individual Insect Based on Phase Measurement

“…Based on multi-baselines interferometry theory, range differences between the target and different antennas can be used to take angle measurement. Contrast to the DOA method, which is based on the phase interferometry, the proposed method has an advantage of no phase ambiguity and angle measurement accuracy can be guaranteed with high accuracy range information [13,23]. …”

A high-precision measurement of small roll angular displacements based on AOMs and its error impact analysis

“…Frequency reduction is an effective method to reduce the fluctuation of phase shift difference, so two acousto-optic modulators (AOMs) are employed to generate the orthogonal polarization beam with a low frequency difference. The phase difference fluctuation is eventually reduced to 0.02 degrees [25].…”

“…The polarization phase detection methods have been adopted by many researchers because of their advantages of having a simple structure and high resolution. Enhanced resolution approaches and error analysis based on polarization phase detection were also studied in our previous work [19,[25][26][27][28]. But due to the frequency-difference fluctuation and time difference between the photodetectors in the measurement and reference beams, the phase shift difference fluctuates greatly, which worsens the measurement accuracy.…”

Grating-Corner-Cube-Based Roll Angle Sensor

“…Several non-contact roll angle measurement methods have been reported, including the polarization–modulation method [ 8 , 9 , 10 ], interference method [ 11 , 12 , 13 , 14 , 15 ], and differential position measurement method [ 16 , 17 , 18 , 19 , 20 , 21 ]. The principle behind the polarization–modulation method involves the modulation of the polarization state of the measurement beam through roll angle variation, wherein the roll angle can be calculated based on intensity measurements.…”