Time-Resolved Contrast LIDAR for Scattering Environments
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Solution Overview
Problem
Conventional LIDAR systems fail in scattering environments such as rain, fog, or smoke due to light scattering, leading to false readings and inability to operate effectively in challenging conditions, particularly for autonomous vehicles.
Innovation Solution
A LIDAR system that produces a sequence of light pulses and calculates time-resolved contrast using integrated circuits to create a three-dimensional image, overcoming scattering effects by dividing standard deviation by mean signal, and optionally correcting for shot noise, allowing for real-time detection of objects despite environmental interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If time-gated LIDAR is used to remove scattered photons, then scattering effects are reduced, but measurement resolution decreases and processing time increases
Solution Approach 1:
The patent applies periodic pulsed illumination with multiple pulses at different time delays. By transmitting a sequence of pulses with varying delays and analyzing the temporal pattern of returned photons, the system achieves both scattering rejection and high resolution without requiring extremely narrow gating windows. The periodic nature of the pulses allows statistical analysis to distinguish scattered from unscattered photons.
Solution Approach 2:
The system performs preliminary temporal characterization of the propagation medium by analyzing photon arrival times from multiple pulses before making distance measurements. This preliminary action builds a temporal profile of scattering effects that is then used to correctly interpret subsequent measurements, enabling the system to compensate for scattering without sacrificing resolution.
2Measurement precision
If conventional LIDAR is used for distance measurement, then distance precision is achieved, but false readings occur in scattering environments
Solution Approach 1:
The system uses feedback by continuously analyzing the temporal distribution of returned photons from multiple pulses and adjusting the interpretation of distance measurements based on observed scattering patterns. The temporal profile of photon arrivals provides feedback about the medium's scattering characteristics, which is used to correct distance measurements and eliminate false readings caused by scattered photons.
Solution Approach 2:
The patent transmits more pulses than conventional single-pulse LIDAR systems, using a sequence of pulses with different time delays. This excessive action of sending multiple pulses allows the system to gather sufficient statistical data about photon scattering patterns to reliably distinguish scattered from unscattered photons, thereby eliminating false readings while maintaining distance precision.
3Measurement precision
If multiple light pulses are transmitted for contrast calculation, then imaging quality improves, but processing time increases
Solution Approach 1:
The patent replaces complex temporal gating hardware with computational contrast calculation methods. Instead of using hardware to physically gate photons in time windows, the system transmits multiple pulses and uses integrated circuitry to calculate contrast based on the temporal patterns of returned photons. This substitution of computational methods for mechanical gating reduces processing time while maintaining or improving imaging quality.
Solution Approach 2:
The system changes the temporal parameters of pulse transmission by using multiple pulses with different time delays rather than a single pulse or uniformly spaced pulses. This parameter variation in the illumination sequence enables the calculation of time-resolved contrast that improves imaging quality. The integrated circuits process these varied parameters efficiently to reduce overall processing time compared to conventional approaches.
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
Enables high-resolution, real-time three-dimensional imaging and distance detection in challenging environmental conditions, making objects visible and improving navigation in vehicles under scattering conditions.
Implementation Method 1
a laser or LED light source... The system is arranged to produce a sequence of light pulses from the light source
Implementation Method 2
The optics converts the light into a time-resolved signal for reflected light produced by each of the light pulses
Data Source
AI summary
A system and method of LIDAR imaging to overcome scattering effects pulses a scene with light pulse sequences from a light source. Reflected light from the scene is measured for each light pulse to form a sequence of time-resolved signals. Time-resolved contrast is calculated for each location in a scene. A three-dimensional map or image of the scene is created from the time-resolved contrasts. The three-dimensional map is then utilized to affect operation of a vehicle.