Asymmetric Light Diffusion in 3D Triangulation Image Sensors
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Solution Overview
Problem
Existing 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 preservation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If symmetrical light diffusion is used to spread light across the image sensing area, then light distribution is improved, but sub-pixel resolution and measurement precision deteriorate due to blurring in orthogonal directions
Solution Approach 1:
The patent applies asymmetry by using an asymmetrically light diffusing layer that has different diffusion properties in orthogonal directions. The layer diffuses light primarily in the vertical direction (along columns) while minimizing diffusion in the horizontal direction (along rows), thereby achieving uniform light distribution without the blurring that would compromise sub-pixel resolution in the critical measurement direction
Solution Approach 2:
The asymmetrically light diffusing layer provides local quality by creating direction-specific light diffusion characteristics. Different regions of the layer (corresponding to different pixel columns) receive and diffuse light according to the asymmetric pattern, allowing each column to have optimized light distribution properties that enhance peak detection accuracy while preserving horizontal resolution
2Measurement precision
If light is spread across multiple pixels to achieve sub-pixel resolution, then measurement precision improves, but loss of information occurs in orthogonal directions due to blurring
Solution Approach 1:
The asymmetrically light diffusing layer creates an asymmetric light distribution pattern where light from a single object point is spread across multiple pixels primarily in the vertical direction. This asymmetric spreading enables sub-pixel resolution through peak detection while the minimal horizontal spreading preserves spatial information and prevents blurring in the orthogonal direction
3Illumination intensity
If conventional light diffusion is used to enhance light spread, then illumination uniformity improves, but manufacturing precision deteriorates due to loss of detail
Solution Approach 1:
The asymmetrically light diffusing layer provides direction-dependent light diffusion, spreading light uniformly in the vertical direction to improve illumination while maintaining sharp horizontal edges. This asymmetric diffusion pattern allows the system to achieve good light distribution without the isotropic blurring that would compromise manufacturing precision and detail preservation
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 in height or depth measurements by distributing light evenly along columns, reducing blurring in orthogonal directions, thus enhancing accuracy and detail preservation in 3D imaging.
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
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.