3D mmWave Reflection Imaging Beat Pattern Correction
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Solution Overview
Problem
Two-sided reflection-based millimeter wave imaging systems suffer from wavelength-dependent beat patterns when coherently combining images from each side, leading to distorted image quality and reduced visibility through occluded regions.
Innovation Solution
A system and method that employs a beat pattern correction operator, combining first and second image data using weighted phase correction terms, and a matched filter reconstruction algorithm to mitigate image beat patterns in two-sided millimeter wave imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If two-sided reflection-based millimeter wave imaging is used to overcome occlusion by opaque portions, then image volume and visibility through occluded regions are improved, but wavelength-dependent beat patterns appear causing distorted image quality
Solution Approach 1:
The patent applies parameter changes by modifying the phase correction terms in the image combination process. Specifically, it changes the phase parameters from the standard coherent combination approach to include wavelength-dependent phase correction factors, thereby eliminating beat patterns while preserving the benefits of two-sided imaging for increased image volume
Solution Approach 2:
The patent converts the harmful beat pattern effect into a beneficial solution by analyzing the mathematical cause of the beat patterns and designing a correction operator that uses the same coherent combination approach but with modified phase terms. This transforms the wavelength-dependent interference from a harmful artifact into a correctable parameter, allowing the system to maintain high image volume while achieving accurate image quality
2Measurement precision
If coherent combination of images from each side is used, then image accuracy is improved, but beat patterns are introduced that reduce measurement precision
Solution Approach 1:
The patent modifies the combination parameters by introducing wavelength-dependent phase correction terms that compensate for the beat pattern effects. This allows the system to maintain the accuracy benefits of coherent combination while correcting the information loss caused by beat pattern distortion through parameter optimization
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 proposed solution successfully mitigates image beat patterns, enhancing image resolution and accuracy, particularly in high-throughput applications with occluded scenes, achieving system resolutions of δx = 17.07 mm, δy = 4.62 mm, and δz = 7.26 mm with improved image volume and accuracy of 0.8 mm in the y and z directions.
Implementation Method 1
A system for producing three-dimensional millimeter wave images of an object includes a first array of millimeter wave transmitting and receiving antennas arranged in a first plane and operative to provide first image data
Implementation Method 2
The image reconstruction processor is configured to combine the first image data and the second image data using a beat pattern correction operator to yield the three-dimensional image of the object
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The present application is directed to image beat pattern mitigation in two-sided reflection based 3-D millimeter wave imaging. In one example, active millimeter-wave (mmWave) imaging illuminates a scene with a source of mmWave energy and forms images based on the reflected energy. Two-sided reflection imaging can be used to overcome the occlusion by the opaque objects that would plague a transmission imaging approach. The system can produce beat-pattern-free 3-D images of the products inside an optically-opaque corrugated cardboard shipping box and further, the two-sided reflection imaging approach with image beat pattern correction shows an increased image volume even if portions of the scene are occluded.