Laser Doppler Vibrometer for Buried Object Detection
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Solution Overview
Problem
Conventional landmine detection methods are ineffective for buried objects beneath the seabed, as soft sediment can cause self-burial or movement of objects to greater depths, making it difficult to detect objects several meters below the seabed.
Innovation Solution
A buried object detection system using a moving platform with a low frequency signal source and a multi-beam laser Doppler vibrometer that transmits and receives beams at multiple angles, processing reflections to create a high-resolution three-dimensional image of the seabed, allowing for the identification of objects buried beneath the seabed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional low frequency signal transmission is used for buried object detection, then the method can detect objects near the surface, but it becomes ineffective for objects buried several meters below the seabed due to soft sediment self-burial and movement
Solution Approach 1:
The patent transitions from conventional two-dimensional surface vibration detection to three-dimensional volumetric imaging by transmitting multiple laser beams at different angles and depths. This dimensional expansion enables the system to penetrate and image objects buried several meters below the seabed, resolving the depth limitation of conventional methods while maintaining detection reliability through multi-angle signal transmission and coherent combination processing.
2Measurement precision
If a single laser beam is used for vibration detection, then the device complexity is low, but the resolution and imaging capability are insufficient for high-resolution three-dimensional imaging
Solution Approach 1:
The patent divides the detection system into multiple independent laser beam transmission paths, each targeting specific regions or angles. This segmentation allows the system to achieve high-resolution three-dimensional imaging by combining data from multiple beams, while managing device complexity through modular beam transmission and processing architecture.
Solution Approach 2:
The system employs multiple laser beams transmitted at different angles and depths to create three-dimensional imaging capability. This multi-dimensional approach enhances imaging resolution by capturing volumetric data, while the coherent combination processing integrates signals from multiple beams to maintain image quality without proportionally increasing complexity.
3Measurement precision
If multiple laser beams are transmitted at different angles to achieve high-resolution three-dimensional imaging, then the imaging resolution improves, but the processing complexity increases
Solution Approach 1:
The patent merges signals from multiple laser beams by coherently combining reflections from different transmission angles. This merging process integrates volumetric data into a unified three-dimensional image, achieving high-resolution imaging while managing processing complexity through systematic signal integration and coherent combination algorithms.
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
The system achieves high-resolution three-dimensional imaging and effective detection of objects buried meters below the seabed, providing enhanced resolution and ability to differentiate man-made objects from natural formations.
Implementation Method 1
transmitting a low frequency signal to an area of the seabed
Implementation Method 2
determines vibration based on a Doppler shift in the reflected laser beam
Implementation Method 3
a laser Doppler vibrometer (LDV) that transmits a laser beam and determines vibration based on a Doppler shift
Implementation Method 4
transmits a plurality of transmission beams to the area of the seabed at a respective plurality of angles
Data Source
AI summary
A system and method to detect an object buried beneath the seabed are described. The system includes a moving platform, a low frequency signal source coupled to the platform to transmit a low frequency signal to an area of the seabed, and a laser Doppler vibrometer (LDV) coupled to the platform to transmit a plurality of transmission beams to the area of the seabed at a respective plurality of angles at each position of a plurality of positions of the platform over the area. The LDV includes a plurality of receivers that receive a respective plurality of reflection beams resulting from the plurality of transmission beams. A processor develops a three-dimensional image that indicates the object, the processor determining a reflection value at each point of the three-dimensional image as a coherent combination of reflection from the point contributing to each of the plurality of reflection beams.