Superpixel Modulation with Curtain Gating for Ambient Light Suppression
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Solution Overview
Problem
Existing methods for superpixel modulation do not effectively suppress ambient light, leading to reduced signal-to-noise ratio and inaccurate 3D scanning of moving objects.
Innovation Solution
A system that modulates the sensitivity of photodetector pixels using curtain and superpixel modulation, where curtain modulation suppresses ambient light by dynamically controlling active and inactive regions, and superpixel modulation allows for rapid data acquisition at lower spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If curtain modulation is used to suppress ambient light, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
The photodetector array is segmented into multiple independently controllable regions or superpixels, allowing selective activation of only those pixels currently receiving collimated light. This segmentation enables ambient light suppression by keeping inactive pixels dark while maintaining measurement precision through selective readout of active regions.
Solution Approach 2:
The system dynamically adjusts which pixels are active versus inactive based on the real-time position of the moving collimated light beam. By continuously updating the active region to match the current beam location, the system maintains high signal-to-noise ratio while minimizing the number of actively reading pixels, thus reducing overall device complexity requirements.
2Productivity
If superpixel modulation is used for rapid data acquisition, then productivity is improved, but measurement precision is reduced
Solution Approach 1:
Multiple adjacent pixels are merged into superpixel groups that share common readout circuitry and control signals. This merging allows rapid data acquisition by reducing the number of independent readout operations needed, while the underlying individual pixel measurements are still captured and can be processed at higher resolution when needed, thus maintaining measurement precision capability.
Solution Approach 2:
The system uses partial action by activating and reading out only the necessary superpixel groups that contain active pixels receiving light, rather than reading the entire photodetector array. This selective partial readout improves productivity by reducing data transmission and processing requirements while maintaining measurement precision for the relevant regions.
3Measurement precision
If the active region is kept small to suppress ambient light, then signal-to-noise ratio is improved, but the area for light detection is reduced
Solution Approach 1:
The active region is dynamically resized and repositioned to match the spatial extent of the moving collimated light beam at any given moment. This dynamic adaptation ensures the active region area is minimized for ambient light suppression while still covering the entire area where signal light is present, thus maintaining optimal signal-to-noise ratio without unnecessary area reduction.
Solution Approach 2:
A control system acts as an intermediary between the moving light beam and the photodetector array, continuously calculating which pixels should be active based on beam position and intensity distribution. This intermediary control ensures the active region precisely matches the signal light footprint, optimizing the balance between ambient light suppression and detection area utilization.
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 signal-to-noise ratio and enhances the accuracy of 3D scanning by suppressing ambient light and enabling accurate data acquisition in a single camera frame, even with moving objects.
Implementation Method 1
a light source that illuminates a scene with collimated light
Implementation Method 2
a photodetector that measures light reflecting from the scene
Implementation Method 3
the sensitivity of the photodetector pixels to light is modulated
Data Source
Figure 1~2
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AI summary
An imaging system with a light source controls the sensitivity of pixels to light, by performing both superpixel modulation and curtain modulation. The superpixel modulation may facilitate rapid data acquisition. The curtain modulation may suppress the effect of ambient light. In superpixel modulation, each pixel set may be modulated by a separate superpixel modulation signal that causes sensitivity of the pixel set to light to vary over time, and each superpixel may include a pixel from each pixel set. The curtain modulation may cause pixels in only a small region of the photodetector to be sensitive to light. The curtain modulation may cause the small region to move to track the dot of light, by changing which pixels are in the region. This invention may be used for 3D scanning.