Shielded Light Detector Array for LiDAR Crosstalk Reduction
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Solution Overview
Problem
Light detection devices in automatic driving technology face challenges in increasing image resolution due to crosstalk and noise between light receiving elements, which are exacerbated by reverse bias voltage and dead time in Geiger mode operations, requiring optimization of signal-to-noise ratio (SNR).
Innovation Solution
A light detection apparatus with multiple light receiving arrays, including first, second, and third arrays with varying crosstalk rates and shielding configurations, controlled by a unit to optimize the operation point and maximize SNR by adjusting reverse bias voltage and dead time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of light receiving elements per unit area is increased to improve resolution, then measurement precision is improved, but crosstalk between elements increases causing noise and image blurring
Solution Approach 1:
The light detection apparatus is divided into multiple independent light receiving elements arranged in an array. Each element is isolated from others through individual shielding structures, allowing high-density arrangement while preventing crosstalk. The segmentation of detection functions across multiple elements enables high-resolution distance imaging without the noise problems that would result from using a single large detector.
Solution Approach 2:
The harmful crosstalk effect is extracted and isolated from the light receiving elements through individual shielding structures. Each light receiving element is equipped with its own shield that blocks stray light and prevents photons detected by one element from being falsely detected by adjacent elements. This extraction of the crosstalk problem through physical shielding allows high-density element arrangement while maintaining signal purity.
2Reliability
If reverse bias voltage is increased to improve sensitivity, then detection capability is improved, but crosstalk and noise increase reducing signal-to-noise ratio
Solution Approach 1:
Individual shielding structures are introduced as intermediary elements between the light receiving elements and the external environment. These shields act as mediators that block stray light and prevent crosstalk from reaching the sensitive photodetectors. By placing this intermediary shielding layer, the system can operate at higher reverse bias voltages for improved sensitivity without suffering from the increased crosstalk and noise that would otherwise accompany such high-voltage operation.
3Productivity
If dead time is reduced to improve productivity, then detection speed is improved, but crosstalk and noise characteristics deteriorate
Solution Approach 1:
The shielding structures are pre-configured around each light receiving element before detection begins. This preliminary arrangement of physical barriers ensures that when detection operates at high speeds with reduced dead time, there is already in place the necessary protection against crosstalk. The preliminary action of positioning shields around each element allows the system to maintain short dead times for high productivity while the pre-established shielding prevents noise and crosstalk from degrading signal quality.
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 solution effectively minimizes noise and crosstalk, optimizing the signal-to-noise ratio of the first light receiving array while reducing the influence of noise and crosstalk, thereby enhancing the resolution and accuracy of distance images.
Implementation Method 1
first light detectors arranged at a first interval and converting reception light into first signals, second light detectors comprising a first crosstalk rate and converting reception light into second signals
Implementation Method 2
when an operation is performed in a Geiger mode using an avalanche photodiode as the light receiving element
Data Source
AI summary
A light detection apparatus has an array of first light detectors arranged at a first interval and configured to convert reception light into first signals, second light detectors having a first crosstalk rate and configured to convert reception light into second signals, wherein surfaces of the second light detectors are shielded from light, third light detectors having a second crosstalk rate different from the first crosstalk rate and configured to convert reception light into third signals, wherein surfaces of the third light detectors are shielded from light, and control circuitry configured to control an operation point of the array based on the second signals and the third signals.