Contrast Phantom for Passive Millimeter Wave Imaging
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Solution Overview
Problem
Passive millimeter-wave imaging systems require a method to verify performance and generate contrast for detecting concealed objects, as existing systems lack calibrated temperature steps and effective imaging phantoms for millimeter-wave frequencies.
Innovation Solution
A contrast phantom system with a transparent slab and a thermal backdrop, where the slab has multiple portions of varying thickness, and a thermal illuminator, to produce discrete, calibrated temperature steps by controlling the radiation reflection and absorption, allowing a millimeter-wave camera to image different effective temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transparent slab with multiple portions of varying thickness is used, then discrete calibrated temperature steps are produced, but device complexity increases
Solution Approach 1:
The transparent slab is divided into multiple portions with varying thicknesses (e.g., 3mm, 6mm, 9mm, 12mm sections). Each thickness portion creates a distinct temperature step when illuminated by the thermal illuminator, enabling discrete calibrated temperature measurements without requiring multiple separate phantom objects.
Solution Approach 2:
Different regions of the transparent slab are assigned different thicknesses to create localized variations in thermal properties. The slab transitions from uniform thickness to having specific thicker and thinner sections, where each local region produces a different apparent temperature when viewed by the millimeter-wave camera.
2Reliability
If a thermal illuminator and reflective backdrop are used to generate contrast, then imaging capability is enhanced, but the system requires additional components increasing complexity
Solution Approach 1:
A thermal illuminator is introduced as an intermediary component that provides controlled thermal radiation to the transparent slab. This illuminator acts as a mediator between the phantom structure and the millimeter-wave camera, enabling the creation of calibrated temperature steps through controlled thermal emission and reflection.
Solution Approach 2:
The system uses a controllable thermal illuminator that can adjust its emission parameters (temperature, intensity) to create different contrast conditions. By changing the thermal parameters of the illuminator, the system can generate various apparent temperature steps in the phantom without physically reconfiguring the slab structure.
3Measurement precision
If the wire grid polarizer is rotated to vary apparent temperature, then contrast for detecting concealed objects is enhanced, but the system requires active mechanical components
Solution Approach 1:
The wire grid polarizer is made rotatable to dynamically change its orientation relative to the thermal illuminator and phantom. This dynamic adjustment allows the system to vary the polarization state of incident radiation, creating different apparent temperature contrasts in the imaged scene without requiring multiple static phantom configurations.
Solution Approach 2:
The rotation of the wire grid polarizer changes the polarization parameter of the incident millimeter-wave radiation. By adjusting this polarization parameter, the system modulates the contrast of reflected thermal radiation from different portions of the transparent slab, enabling enhanced detection of concealed objects through polarization-based contrast variation.
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 the verification of passive millimeter-wave system performance by providing discrete temperature steps, enhancing the ability to detect concealed objects through calibrated temperature variations, improving imaging accuracy and reliability.
Implementation Method 1
the polarizer is positioned between a thermal illuminator and a thermal emitter such that energy from the thermal illuminator traveling towards the thermal emitter is transformed into linearly polarized energy
Implementation Method 2
the thermal emitter is configured to reflect at least a portion of the linearly polarized energy towards a millimeter-wave camera
Implementation Method 3
the slab has multiple portions of varying thickness, and a thermal illuminator, to produce discrete, calibrated temperature steps by controlling the radiation reflection and absorption
Data Source
AI summary
In a system that includes a wire grid polarizer, the polarizer is positioned between a thermal illuminator and a thermal emitter such that energy from the thermal illuminator traveling towards the thermal emitter is transformed into linearly polarized energy. In the system, the thermal emitter is configured to reflect at least a portion of the linearly polarized energy towards a millimeter-wave camera and there is a motor coupled with the wire grid polarizer and configured to rotate the polarizer in a manner that varies an apparent temperature of the thermal emitter based on the reflected portion of the linearly polarized energy.