Per-Pixel LIDAR Integration Registers for Ambient Noise Thresholding
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Solution Overview
Problem
LIDAR systems face challenges in providing robust distance accuracy down to a few centimeters, especially at an economical cost, due to limitations in existing detector technologies like single photon avalanche diodes (SPADs), which are sensitive to ambient noise and have a limited dynamic range across varying conditions.
Innovation Solution
An optical measurement system that includes photosensitive elements generating signals for photon detection, with an integration register accumulating photon counts to estimate ambient background noise and set signal thresholds, allowing for improved detection of reflected light signals by aggregating photon counts over time intervals and excluding background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SPADs are used to detect photons, then sensitivity to ambient background noise light increases, but measurement precision deteriorates
Solution Approach 1:
The patent segments the detection process into two independent data paths: one for time-correlated single photon counting (histogram generation) and another for total photon counting (integration register). This segmentation allows the system to process background noise and signal photons separately, enabling accurate distance measurement even when SPADs are highly sensitive to ambient background noise light.
Solution Approach 2:
The integration register acts as an intermediary that accumulates total photon counts independently of the time-bin histogram data. By providing a separate total count measurement, it enables background noise estimation and signal threshold setting without being affected by the time-correlation processing, thus mediating between the sensitive SPAD detection and accurate distance measurement.
2Reliability
If SPADs are used to detect photons, then dynamic range is limited, but adaptability to varying conditions deteriorates
Solution Approach 1:
The patent implements a universal data processing architecture where the same photodetector array serves multiple functions through two parallel data paths. The integration register provides total photon count information that complements the time-bin histogram data, enabling the system to adapt to varying conditions (different target distances, ambient light levels) while maintaining the limited dynamic range characteristics of SPADs.
3Measurement precision
If total photon count is accumulated independently in integration register, then background noise estimation improves, but device complexity increases
Solution Approach 1:
The patent merges the functionality of total photon counting with the existing time-correlated single photon counting architecture by using the same photodetector array and coupling it with an integration register. This combining approach enables background noise estimation without requiring a completely separate detection system, thus improving measurement precision while limiting the increase in device complexity.
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
This approach enhances the accuracy of distance measurement in LIDAR systems by effectively filtering out background noise and setting appropriate signal thresholds, leading to improved robustness and cost-effectiveness in achieving precise distance detection.
Implementation Method 1
Each of the photosensitive elements may generate signals when a photon is detected
Data Source
AI summary
An optical measurement system includes a photosensor that includes one or more photosensitive elements. Each of the photosensitive elements may generate signals when a photon is detected, and the number of photons detected for each photosensor may be accumulated in an integration register. The integration register may accumulate photon counts independent of a parallel data path that stores photon counts in time bins based on photon arrival times to form a histogram representation. The total photon count in the integration register can be used to estimate ambient background light and properly set signal thresholds for detecting reflected light signals represented in the histogram.