Photosensor Subpixel Layout for Range Parallax Compensation
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Solution Overview
Problem
Bistatic optical systems suffer from parallax effects that cause signal returns from closer objects to be imaged outside the detector's sensitive area, leading to blindness to targets within a certain range, while strong returns from close objects can saturate or damage the detector.
Innovation Solution
A detector configuration with subpixel regions optimized for different target ranges and signal strengths, using avalanche photodiode bias adjustments, customized amplifier gain, and optical reflection or waveguiding structures to scatter or guide light, along with mirrored surfaces and gradient coatings to redirect off-centered signals, preventing saturation and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detector is positioned to receive returns from infinity, then long-range detection sensitivity is optimized, but close objects are imaged outside the sensitive area causing blindness to targets inside a certain range
Solution Approach 1:
The detector is divided into multiple subpixel regions, each optimized to detect returns from specific range intervals. This segmentation allows the detector to simultaneously handle both close and far objects by assigning different subpixel regions to different range zones, resolving the contradiction between optimizing for infinity and detecting close objects.
Solution Approach 2:
Different subpixel regions are assigned different optical sensitivity characteristics and detection thresholds tailored to their specific range zones. Close-range subpixel regions have higher dynamic range and damage thresholds, while far-range subpixel regions have higher optical sensitivity, allowing each region to be locally optimized for its detection task.
2Measurement precision
If all available energy from close objects is received on the sensitive area, then close object detection is maximized, but the detector may saturate or be damaged by optical overload
Solution Approach 1:
The detector surface is segmented into multiple subpixel regions that share the incident energy from close objects. By distributing the optical load across multiple regions rather than concentrating it on a single sensitive area, the system detects close objects effectively while preventing any single region from saturating or suffering optical damage.
Solution Approach 2:
Optical elements such as diffusers or beam splitters are introduced as intermediaries between the close objects and the detector subpixel regions. These intermediaries attenuate and redistribute the strong optical energy from close objects across multiple detector regions, preventing saturation and damage while maintaining detectability.
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 system effectively detects close objects while preventing saturation and damage, maintaining sensitivity across varying ranges and angles, thus enhancing the detector's dynamic range and field-of-view.
Implementation Method 1
an avalanche photodiode (APD) bias of the individual detector subpixel regions can be modified to optimize required optical sensitivity vs. dynamic range and/or damage threshold
Implementation Method 2
optical reflection or waveguiding structures on the detector can be used to scatter or guide light to the sensitive area of the detector
Implementation Method 3
optical reflection or waveguiding structures on the detector can be used to scatter or guide light to the sensitive area of the detector
Implementation Method 4
optical reflection or waveguiding structures on the detector can be used to scatter or guide light to the sensitive area of the detector
Data Source
AI summary
Methods and apparatus for photodetection having parallax compensation for near and far object signal return. In embodiment, a photoreceiver comprising a at least one light-sensitive pixel to transduce light to electrical signals has at least a first one of the pixels including a first subpixel region having a first light response characteristic and a second subpixel region having a second light response characteristic, wherein the first and second light characteristics are configured to correspond to variations in intensity of reflected light from objects at different distances when the portion of the reflected light reaching the first one of the pixels imaged onto the first and second subpixel regions.