3D Continuous Scanning Laser Vibrometry for In-Plane Vibration
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Solution Overview
Problem
Current methods for measuring in-plane vibrations of structures are inefficient, particularly at high frequencies and low response magnitudes, due to the limitations of existing 3D scanning laser vibrometry systems which require lengthy calibration procedures and are not suitable for continuous scanning.
Innovation Solution
A 3D continuous scanning laser vibrometry system with three laser heads and two scan mirrors each, along with a controller, is used to conduct full-field scanning of structures, synchronizing laser spots along a designed scan trajectory, and employing a demodulation method to process in-plane responses for accurate measurement of operating deflection shapes at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional 3D scanning laser vibrometry system is used to measure in-plane vibrations, then measurement capability is provided, but measurement time becomes excessively long and calibration complexity increases
Solution Approach 1:
The patent replaces the mechanical step-wise scanning system with a continuous optical scanning system. The continuous scanning laser vibrometry system uses optical scanning mirrors to continuously move the laser spot across the measurement surface, eliminating the mechanical positioning steps and significantly reducing measurement time while maintaining measurement precision for in-plane vibrations.
Solution Approach 2:
The patent implements preliminary calibration procedures that establish the relationship between scanner positions and measurement points before actual measurement. By pre-configuring the scan trajectory and calibration parameters, the system eliminates time-consuming real-time calibration during measurement, allowing direct continuous scanning and measurement.
2Measurement precision
If a conventional 3D scanning laser vibrometry system is used to measure in-plane vibrations, then measurement capability is provided, but system complexity and calibration difficulty increase
Solution Approach 1:
The patent replaces complex mechanical positioning and calibration systems with an optical continuous scanning system. The scanner controls directly dictate laser spot position through optical deflection, eliminating the need for complex mechanical coordinate transformations and simplifying the calibration process to primarily optical parameter characterization.
Solution Approach 2:
The patent uses a reference object with known geometry to create a calibration model that maps scanner positions to physical coordinates. By scanning the reference object and creating a digital copy of its geometry with associated coordinate information, the system establishes the measurement coordinate system without requiring complex direct calibration of the measurement structure.
3Measurement precision
If traditional vibration measurement devices are used, then out-of-plane vibration measurement is achieved, but in-plane vibration measurement capability is lost
Solution Approach 1:
The patent implements a universal measurement system that can measure both out-of-plane and in-plane vibrations using the same continuous scanning laser vibrometry platform. By incorporating appropriate optical configurations and demodulation methods, the system provides multi-functional capability to measure different vibration components without requiring separate specialized devices.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for rapid and accurate measurement of dense full-field in-plane vibrations and operating deflection shapes at high frequencies, significantly improving measurement speed and accuracy compared to traditional methods, with modal assurance criterion values exceeding 95% compared to commercial systems.
Implementation Method 1
three-dimensional (3D) continuous scanning laser Doppler vibrometry
Data Source
AI summary
The present invention relates to a three-dimensional (3D) continuously scanning laser Doppler vibrometer (CSLDV) system that contains three laser heads with two scan mirrors for each head and a controller, to conduct full-field scanning of a plate-like or beam-like structure under sinusoidal excitations to measure its 3D vibrations and operating deflection shapes, and method of using same.