Light Concentrator for SPAD Array Detection Efficiency
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Solution Overview
Problem
The low detection efficiency of Single Photon Avalanche Diode (SPAD) arrays in LiDAR systems due to their relatively low fill factor, which impedes larger scale applications, particularly in high-definition map surveys and autonomous driving.
Innovation Solution
A light concentrating device with an array of light concentrators positioned between the incident light and the SPAD array, featuring an input aperture, a side surface for reflecting light, and an output aperture, optimized to collect and concentrate light from a wide range of angles, thereby increasing the light incident on the photo-sensitive area and minimizing loss on non-sensitive areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a narrow laser beam is used as incident light from the scanner, then high resolution mapping is achieved, but the detection efficiency of the SPAD array remains low due to low fill factor
Solution Approach 1:
The patent introduces a light concentrator that redirects incident light from a narrow beam into a broader angular distribution, effectively transforming the light propagation geometry. The concentrator captures light in a narrow angular range and redistributes it to cover a wider angular range, matching the SPAD array's angular response characteristics and improving detection efficiency without sacrificing resolution
Solution Approach 2:
The patent modifies the angular distribution parameter of the incident light by using a light concentrator with specific geometric parameters (aperture sizes, focal lengths). By adjusting these parameters, the system optimizes the coupling between the narrow laser beam and the SPAD array's photo-sensitive area, thereby improving detection efficiency while maintaining the narrow beam's resolution benefits
2Reliability
If the fill factor of the photo-sensitive area is increased, then detection efficiency improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent introduces a light concentrator as an intermediary optical element between the incident light and the SPAD array. This mediator captures the narrow laser beam and redistributes it to maximize illumination of the photo-sensitive area, thereby improving detection efficiency without requiring changes to the SPAD array structure itself, thus avoiding increased device complexity
Solution Approach 2:
The patent divides the optical system into separate functional components: the light concentrator handles light collection and redistribution, while the SPAD array maintains its original photo-detection function. This segmentation allows each component to be optimized independently, avoiding the need to increase SPAD array complexity to improve detection efficiency
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
Enhances the detection efficiency of the SPAD array by increasing the amount of light collected, allowing for higher resolution and larger scale applications in LiDAR systems.
Implementation Method 1
a side surface in contact with the input aperture and the output aperture. The side surface is configured to reflect the collected light beam towards the output aperture
Implementation Method 2
The photodetector is configured to receive the light beam collected through the output aperture and convert the light beam to an electrical current
Data Source
AI summary
Embodiments of the disclosure provide an optical sensing device for a receiver in an optical sensing system. The optical sensing device includes a light concentrator configured to collect a light beam. The light concentrator includes an input aperture configured to collect the light beam, an output aperture configured to output the light beam, and a side surface in contact with the input aperture and the output aperture. The side surface is configured to reflect the collected light beam towards the output aperture. The optical sensing device also includes a photodetector placed behind the light concentrator. The photodetector is configured to receive the light beam collected through the output aperture and convert the light beam to an electrical current.