Speckle Vibration Sensing With Multi-Beam Eye-Safe Detection
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Solution Overview
Problem
Existing vibration detection systems, such as Laser Doppler Vibrometers and speckle analysis, face limitations including noise from rough surfaces, complexity, and the need for high laser power, which can exceed eye safety guidelines, and are limited by camera frame rates and light intensity issues, making them unsuitable for real-time, qualitative detection of surface vibrations without potentially harmful radiation.
Innovation Solution
A system utilizing a diffractive optical element to project a multi-beam pattern with a low-power light source, focusing the backscattered speckle field onto an imaging sensor, and employing algorithms to analyze light intensity and filter out noise, allowing for real-time detection of surface vibrations without exceeding eye safety guidelines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If defocused speckle imaging is used to capture meaningful information, then the measurement area is improved, but light intensity drops substantially requiring higher laser power
Solution Approach 1:
The patent segments the measurement area into multiple focused regions by using an array of microlenses, where each microlens focuses light from a specific region onto a corresponding pixel region on the sensor. This allows the entire surface area to be measured while maintaining high light intensity in each focused region, resolving the contradiction between measurement area and light intensity.
2Speed
If high-speed camera is used to capture vibrations, then frequency band is improved, but real-time performance deteriorates due to large number of frames requiring memory and analysis
Solution Approach 1:
The patent extracts vibration information directly from individual focused speckle images using signal processing algorithms, rather than requiring sequences of defocused images. By taking out the essential vibration signal from each frame through autocorrelation analysis, the system achieves high frequency band coverage while maintaining real-time performance with minimal frame processing.
3Measurement precision
If LDV is used to measure surface vibrations, then measurement precision is improved, but device complexity increases and expert operation is required
Solution Approach 1:
The patent creates a simplified optical copying system that replicates the measurement capability of complex LDV systems. By using a simple laser source, diffractive optical element, and imaging sensor to capture and analyze speckle patterns, the system achieves comparable vibration measurement precision while dramatically reducing device complexity and eliminating the need for expert operation.
4Illumination intensity
If laser power is increased to compensate for light intensity drop, then light intensity is improved, but eye safety limitations are exceeded
Solution Approach 1:
The patent segments the light collection function across multiple microlenses, where each microlens collects and focuses light from its corresponding region. This segmentation allows the system to maintain high light intensity at the sensor level through efficient optical focusing rather than increasing overall laser power, thereby preserving eye safety while achieving sufficient signal intensity for vibration detection.
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
Enables accurate detection of surface vibrations, including physiological signals from humans, in real-time and over varying distances, while ensuring eye safety and improving signal-to-noise ratio, suitable for applications like vehicle occupancy monitoring and environmental hazard detection.
Implementation Method 1
A diffractive optical element is used to split the single beam into a multi-beam pattern
Implementation Method 2
focusing the backscattered speckle field onto an imaging sensor
Implementation Method 3
speckles are characterized by an intensity pattern produced by mutual interference of a set of wave fronts
Data Source
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AI summary
A system for detecting vibrations from a surface is provided. The system includes a coherent light source for projecting a multi-beam pattern onto the surface and an imaging device for mapping a speckle field generated by each spot formed on the surface by the multi-beam pattern to a unique region of an imaging sensor. The system further includes a processor for processing speckle field information received by the imaging sensor and deriving surface vibration information.