Semiconductive Oxide Contrast Phantoms for Millimeter Wave Imaging Calibration
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Solution Overview
Problem
Active millimeter wave imaging systems face challenges in accurately detecting threat objects due to their inability to effectively resolve differences in grayscale images, necessitating a method to assess and improve their contrast resolution.
Innovation Solution
A contrast phantom made from electrically conductive materials like semiconductive oxides with varying reflection coefficients is used to test the contrast resolution of these systems, comprising regions with specific reflection coefficients and conductivities, allowing for the evaluation of the imaging system's ability to distinguish between different grayscale values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used in the phantom, then manufacturing cost and complexity increase, but the reflection coefficient stability and contrast resolution assessment accuracy deteriorate
Solution Approach 1:
The patent changes the material parameter from conventional conductors (metal, graphite) to semiconductive oxide materials with specific properties. This parameter change provides stable reflection coefficients (0.5-0.9) across millimeter wave frequencies while maintaining manufacturing feasibility through deposition processes, resolving the contradiction between reliability and complexity
Solution Approach 2:
The patent uses composite structures combining semiconductive oxide layers with substrate materials. This composite approach achieves stable electromagnetic properties and controlled reflection coefficients while keeping the phantom construction manageable through standardized deposition techniques on common substrates
2Measurement precision
If the electrically conductive material thickness is increased, then the reflection coefficient increases, but the contrast resolution between different regions decreases
Solution Approach 1:
The patent applies local quality by creating regions with different semiconductive oxide thicknesses (50-200 nm range) to achieve different reflection coefficients. This allows precise control of local electromagnetic properties to create distinguishable contrast regions while maintaining adequate signal strength through optimized minimum thickness
Solution Approach 2:
The patent changes the thickness parameter of the semiconductive oxide layer to precisely control reflection coefficients. By maintaining thickness in the 50-200 nm range, the system achieves both adequate signal reflection and sufficient contrast differentiation between regions with varying thickness
3Ease of manufacture
If conventional conductive materials like metal or graphite are used, then ease of manufacture improves, but the frequency dependence of reflection coefficient worsens
Solution Approach 1:
The patent changes from conventional conductive materials to semiconductive oxide materials with specific electrical properties. This material parameter change eliminates frequency-dependent reflection coefficient variations while maintaining manufacturability through established deposition processes, resolving the contradiction between ease of manufacture and reflection consistency
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 contrast phantom effectively assesses and improves the contrast resolution of active millimeter wave imaging systems, enabling them to better detect threat objects by providing a standardized method to evaluate and calibrate their grayscale image generation capabilities.
Implementation Method 1
These systems illuminate a human target with millimeter wave radiation, generally in a range from 1-500 GHz, and collect signals reflected off a body
Implementation Method 2
The present contrast phantoms are made from electrically conductive materials, such as doped semiconductive oxides
Data Source
AI summary
The present disclosure is directed to a contrast phantom having a first region with a first reflection coefficient, a second region with a second reflection coefficient, and a third region with a third reflection coefficient, wherein the first reflection coefficient, the second reflection coefficient and the third reflection coefficient are increasing or decreasing in value in discrete steps, and wherein at least one of the regions includes an electrically conductive material having a thickness of about 200 μm. Methods of testing the contrast resolution of an active millimeter wave imaging system using the contrast phantom are also described.