Movable Coded Mask Imaging for Compact 360-Degree Reconstruction
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Solution Overview
Problem
Coded aperture devices for forming two-dimensional images are either bulky or compromise image quality to achieve compactness.
Innovation Solution
An imaging system with a first mask unit having a hollow cavity and a pattern encoded on its surface, allowing movement relative to a rotational axis, combined with a detector to reconstruct images, and optionally a second mask unit for enhanced imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coded aperture devices are used to form two-dimensional images, then image quality is improved, but the device becomes bulky
Solution Approach 1:
The mask unit is divided into multiple independently movable segments or elements that can be positioned at different locations. This segmentation allows the coded aperture pattern to be distributed across multiple positions rather than requiring a single large mask, thereby reducing the overall device volume while maintaining image quality through computational reconstruction from multiple partial measurements.
Solution Approach 2:
The mask unit is made dynamically movable along the optical axis and/or rotationally, allowing a single compact mask to assume multiple effective positions and orientations. This dynamic capability enables the small mask to encode sufficient spatial information for 2D image reconstruction by capturing multiple projections or views as it moves, replacing the need for a large static mask.
2Volume of moving object
If coded aperture devices are made compact, then device size is reduced, but image quality is compromised
Solution Approach 1:
The mask unit performs periodic motion along the optical axis and/or rotational movement at controlled frequencies. This periodic action allows the compact mask to systematically sample different spatial frequencies and angular views, with the detector recording the time-varying shadow patterns. The periodic motion ensures complete sampling of the object's projection space, enabling high-quality 2D image reconstruction despite the small mask size.
Solution Approach 2:
The system incorporates feedback control where the detector records the actual shadow patterns produced by the moving mask, and this information is used to adjust the mask's motion trajectory or timing. The feedback loop ensures optimal sampling of spatial information and enables computational algorithms to compensate for any deviations or limitations in the mask's motion, thereby maintaining image quality with a compact device.
3Measurement precision
If the mask unit is made movable to improve image quality, then device complexity increases
Solution Approach 1:
The mask unit's translational and rotational movements are merged into a single integrated component or mechanism. Rather than requiring separate actuators for linear positioning and rotation, the design combines these functions into one unified movable mask assembly that can achieve both types of motion simultaneously or sequentially through a single actuation system, thereby reducing overall device complexity.
Solution Approach 2:
The movable mask unit serves multiple functions: it acts as the coded aperture pattern, provides angular modulation through rotation, and enables depth encoding through axial translation. This multi-functionality eliminates the need for separate components for each function, reducing the number of parts and simplifying the overall system architecture while maintaining high image quality through the combined effects of motion and coding.
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
Enhances image quality while maintaining compactness by using a movable mask unit and a position-sensitive detector, allowing for improved image reconstruction.
Implementation Method 1
Coded aperture devices may be employed to block radiation by casting a coded shadow upon a detector and mathematically reconstructing the spatial distribution of the source of radiation from this shadow
Implementation Method 2
a detector configured to receive radiation data from at least one source
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
An imaging system includes a first mask unit having a hollow cavity surrounding a rotational axis. The first mask unit is characterized by a first pattern encoded on its surface. The first pattern defines a height along an axial direction and includes a respective plurality of elements with at least one open element and at least one blocking element in each of the axial direction and the circumferential direction. A detector is configured to receive radiation data from at least one source such that one of the detector and the source is located inside the hollow cavity and another is located outside the hollow cavity. The first mask unit is configured to move relative to the rotational axis in at least one of the axial and circumferential direction until the first pattern is recorded in 360 degrees. A second mask unit may be positioned around the first mask unit.