Light Detector with Segmented Silicon Photomultiplier Array
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Solution Overview
Problem
Current LiDAR systems using non-coaxial optical systems face challenges in accurately measuring distances to both long and short-distance targets due to parallax and dynamic range limitations, leading to difficulties in detecting peak light intensity and increased power consumption.
Innovation Solution
The implementation of a light detector with a two-dimensional array of silicon photomultipliers, where the light-receiving region is divided into ADC and TDC regions, allowing for separate signal processing for long and short-distance targets, enhancing dynamic range and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a non-coaxial optical system is used in LiDAR, then device complexity is reduced, but measurement precision deteriorates due to parallax effects
Solution Approach 1:
The light receiver is divided into multiple light receiving regions (first, second, third regions) that correspond to different depth ranges. Each region is independently controlled to detect reflected light from specific distance ranges, eliminating parallax measurement errors by assigning dedicated detection zones to each region.
Solution Approach 2:
Different light receiving regions are optimized for different measurement characteristics. The first and second regions use integration processing for long-distance targets, while the third region uses time-to-digital conversion for short-distance targets, allowing each region to have specialized detection capabilities suited to its intended use.
2Device complexity
If a single light-receiving region is used, then device complexity is reduced, but measurement precision deteriorates due to inability to handle both long and short-distance targets
Solution Approach 1:
The light receiver is segmented into multiple independently controllable light receiving regions, each optimized for specific distance ranges. This allows simultaneous optimization for both long-distance and short-distance target detection without requiring a single complex region to handle all scenarios.
Solution Approach 2:
The light receiving regions are dynamically selected and controlled based on the distance to the target object. The controller activates specific regions based on real-time measurement requirements, enabling adaptive optimization for different ranging scenarios.
3Ease of operation
If integration processing is used for all regions, then ease of operation is improved, but measurement precision deteriorates for short-distance targets due to saturation
Solution Approach 1:
Different signal processing methods are applied to different light receiving regions based on their intended use. The third light receiving region specifically uses time-to-digital conversion processing optimized for short-distance targets, preventing signal saturation while maintaining operational simplicity through automated region-based processing selection.
4Measurement precision
If time-to-digital conversion is used for all regions, then measurement precision is improved for short-distance targets, but use of energy increases due to processing requirements
Solution Approach 1:
Time-to-digital conversion processing is applied only to the third light receiving region dedicated to short-distance targets, rather than all regions. This localized application reduces overall power consumption while maintaining high precision for short-distance measurements where it is most needed.
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 configuration enables accurate distance measurement for both long and short-distance targets by integrating or averaging signals in the ADC region and using time-to-digital conversion in the TDC region, improving measurement precision and reducing false detections.
Implementation Method 1
a two-dimensional sensor (2D sensor) comprising a plurality of silicon photomultipliers arrayed two dimensionally
Data Source
AI summary
A light detector according to an embodiment includes a light receiver and a controller. The controller is configured to set first and second light-receiving regions. The first light-receiving region includes first and second pixel regions. The second light-receiving region includes a third pixel region. An area of the third pixel region is larger than a total area of the first and second pixel regions. The light receiver is configured to, when light is applied: cause each of the first and second pixel regions within the first light-receiving region to individually output a signal; and cause the third pixel region within the second light-receiving region to output signals collectively.