Axial clearance measurement method based on wavelength division multiplexing with all-fiber microwave photonic mixing.

Rotor-stator axial clearance plays a pivotal role in ensuring the safety and efficiency of major rotating machinery. This paper introduces an innovative clearance measurement method based on wavelength division multiplexing (WDM) combined with all-fiber microwave photonic mixing. The method is distinguished by large measurement range, high accuracy and low drift.

High-speed nonlinear frequency sweeping signal distance extraction algorithm based on the table lookup method.

In the domain of frequency sweeping interferometry, the accurate extraction of distance information from nonlinear frequency scanning signals holds paramount significance in ensuring meticulous measurements of high precision. This paper presents a novel, to the best of our knowledge, high-speed distance extraction algorithm based on the table lookup method and validates its feasibility through theoretical models, simulations, and practical experiments. The proposed algorithm achieves comparable accuracy to traditional methods involving resampling and Hilbert transform.

High precision dynamic measurement method for axial clearance based on time division multiplexing with dispersive interferometry.

Rotor-stator axial clearance is a crucial design parameter affecting rotating machines' efficiency and safety. To accurately measure the dynamic axial clearance in high-speed machinery, a precise method based on time division multiplexing with frequency domain interferometry has been proposed. This method has proven robust and accurate through simulations and experiments.

High-accuracy measurement system for rotor-stator axial clearance in narrow spaces based on all-fiber microwave photonic mixing.

In this paper, a high-accuracy measurement method for rotor-stator axial clearance in narrow spaces is proposed. The optical path structure based on all-fiber microwave photonic mixing is established. To improve the accuracy and expand the measurement range, the total coupling efficiency over the entire measurement range at different working distances of fiber probe was evaluated by Zemax analysis tool and theoretical model.

Robust five-degree-of-freedom measurement system with self-compensation and air turbulence protection.

A robust five-degree-of-freedom (5-DOF) measurement system is proposed in this paper. The compact optical configuration with high resolution is designed based on lens combination and multiple reflections. Beam drift and dual-beam parallelism are monitored and compensated by autocollimator units and a polarizer unit respectively.

Fast algorithm based on the Hilbert transform for high-speed absolute distance measurement using a frequency scanning interferometry method.

Frequency scanning interferometry using state-of-the-art high-speed frequency-swept laser source can be utilized to measure absolute distance on the order of micrometers to centimeters. Current distance demodulation methods based on fast Fourier transform (FFT) or fringe counting cannot achieve satisfactory accuracy when the number of sampling points within a frequency-sweeping period is small; the conventional Hilbert transform is more accurate, but it needs arctangent calculation and phase unwrapping, which is time consuming. So we propose a fast algorithm based on the conventional Hilbert transform to recover the distance from the interference signal.