Sub-terahertz Imaging Apparatus Brightness Uniformity Control
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Solution Overview
Problem
Imaging apparatuses capturing images with sub-terahertz waves face challenges in controlling uneven brightness, which affects the accuracy of dangerous object detection due to variations in the properties of imaging targets.
Innovation Solution
An imaging apparatus that includes a sub-terahertz wave emitter, a detection device with a planar arrangement of pixels to accumulate intensity over a predetermined time, and a controller to adjust the operation based on the traveling state of the target, ensuring the image sensor receives cumulative intensities that level out phase interference and reduce brightness unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sub-terahertz wave imaging is used to capture images of imaging targets, then the ability to detect dangerous objects is enabled, but uneven brightness occurs in the images regardless of the properties of the imaging targets
Solution Approach 1:
The patent applies periodic action by accumulating signal intensities over multiple periods of the sub-terahertz wave. The accumulation time is set to be equal to or longer than one period of the sub-terahertz wave, which allows the phase interference patterns to average out over time. This temporal integration of periodic signals eliminates the uneven brightness caused by phase differences while preserving the dangerous object detection capability.
Solution Approach 2:
The patent implements continuity of useful action by continuously accumulating the intensity of reflected waves over an extended period. Rather than using single-point measurements, the system continuously integrates signal intensities from multiple wave cycles, maintaining the detection function while eliminating the harmful brightness unevenness through continuous temporal averaging.
2Illumination intensity
If the accumulation time for intensity is increased to level out phase interference, then brightness uniformity is improved, but the imaging speed decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the accumulation time parameter. The accumulation time is specifically set to be equal to or longer than one period of the sub-terahertz wave (T = 1/f, where f is the frequency). This precise parameter setting ensures that the accumulation covers exactly one or more complete cycles of the wave, which is the minimum time required to average out phase interference while minimizing the impact on imaging speed.
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 solution effectively controls uneven brightness in images captured with sub-terahertz waves, enhancing the accuracy of dangerous object detection by stabilizing image quality regardless of the imaging target's properties.
Implementation Method 1
an emitter that emits the sub-terahertz wave to the imaging target
Implementation Method 2
a reflected wave which is the sub-terahertz wave emitted from the emitter and reflected by the imaging target
Data Source
AI summary
An imaging apparatus captures an image of a person passing through a predetermined space, using a sub-terahertz wave. The imaging apparatus includes an emitter that emits the sub-terahertz wave to the person, and a detection device. The detection device includes: an optical system that images a reflected wave which is the sub-terahertz wave emitted from the emitter and reflected by the person; and a plurality of pixels that are disposed in a planar arrangement and each receive the reflected wave imaged by the optical system, and generates an image based on cumulative intensities, each being obtained by accumulating an intensity of the reflected wave received by each of the plurality of pixels for a predetermined time, and the planar arrangement of the plurality of pixels. The predetermined time is λ/1778 seconds or longer, when the wavelength of the sub-terahertz wave is taken as λ mm.