Asymmetric Light Diffusion in 3D Image Sensors for Sub-Pixel Depth
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Solution Overview
Problem
Conventional 3D imaging systems based on light triangulation face challenges in achieving sub-pixel resolution for height or depth measurements due to symmetrical light diffusion, which causes blurring and loss of detail in orthogonal directions.
Innovation Solution
Employ an asymmetrically light diffusing layer that spreads light predominantly in one direction (columns) while minimizing diffusion in the orthogonal direction (rows) to enhance sub-pixel resolution for height or depth measurements without compromising detail resolution in the orthogonal direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If symmetrical light diffusion is used to spread light across the image sensor, then light distribution is improved, but resolution in orthogonal directions deteriorates due to blurring
Solution Approach 1:
The patent applies asymmetry by using an asymmetrically light diffusing layer that has different diffusion properties in different directions. The layer diffuses light strongly in the column direction (parallel to the light line) to improve light distribution and sub-pixel resolution, while minimizing diffusion in the row direction (orthogonal to the light line) to preserve detail resolution and avoid blurring.
Solution Approach 2:
The asymmetrically light diffusing layer provides local quality by creating direction-dependent light diffusion. It allows strong light spreading in the direction where sub-pixel resolution is needed (column direction) while maintaining sharpness in the direction where detail resolution is critical (row direction), thus optimizing different regions for different functional requirements.
2Measurement precision
If light is spread extensively to achieve sub-pixel resolution, then depth measurement precision is improved, but detail resolution in orthogonal direction deteriorates
Solution Approach 1:
The asymmetrically light diffusing layer resolves this contradiction by creating asymmetric light diffusion patterns. It spreads light extensively in the column direction to enable accurate sub-pixel resolution for depth measurements, while constraining light diffusion in the row direction to preserve detail resolution and prevent information loss about object surface features.
Solution Approach 2:
The asymmetrically light diffusing layer segments the light diffusion function into two distinct directional components: strong diffusion in the column direction for depth measurement precision, and minimal diffusion in the row direction for detail preservation. This segmentation allows independent optimization of both competing requirements.
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
Improves sub-pixel resolution for depth measurements by distributing light evenly along columns, maintaining accurate detail resolution in rows, thus enhancing the precision of 3D imaging without blurring.
Implementation Method 1
an asymmetrically light diffusing layer covering the image sensing area so that incident light towards the image sensing area will pass through and be spread by the asymmetrically light diffusing layer
Data Source
Figure 1
Figure 2A~2C
Figure 2D~2F
AI summary
Image sensor (331; 431; 531') for use in a camera (330; 530) of an imaging system (305) for three-dimensional imaging of an object (320) based on light triangulation, the camera (330; 530) and the imaging system (305). The image sensor (331; 431, 531') comprising an image sensing area (333; 433; 533) that comprises rows (438) and columns (435) of pixel elements configured to sense light. An asymmetrically light diffusing layer (337; 437; 537) covers the image sensing area (333; 433; 533) so that incident light towards the image sensing area (333; 433; 533) will pass through and be spread by the asymmetrically light diffusing layer (337; 437; 537). Said light asymmetrically diffusing layer (337; 437; 537) is configured to spread light in a high diffusion direction and in a low diffusion direction that is orthogonal to the high diffusion direction. The high diffusion direction is along said columns (435) of pixels and the low diffusion direction is along said rows (438) of pixels, whereby the light when reaching the image sensing area (433; 533) will be spread to a greater extent along the columns (435) of pixels than along the rows (438) of pixels.