Multi-Static Coherent LiDAR Apertures for Speckle-Tolerant Ranging
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Solution Overview
Problem
LiDAR systems face challenges in achieving high signal-to-noise ratio due to speckle effects from rough surfaces and limited aperture configurations, which result in suboptimal performance for both long-range and short-range target detection, and difficulty in isolating transmit and receive paths in monostatic configurations.
Innovation Solution
A multi-static coherent LiDAR system with multiple receive apertures and an optical phased array, where each receive aperture is configured to receive a portion of the collected optical wave along a specific collection angle, and circuitry processes signals to determine distance based on combined components from multiple detectors, optimizing aperture arrangement and using optical phased arrays for steering and focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a monostatic aperture configuration is used to simplify system design, then device complexity is reduced, but signal-to-noise ratio deteriorates due to difficulty in isolating transmit and receive paths
Solution Approach 1:
The system divides the aperture into multiple spatially separated transmit and receive apertures (multi-static configuration), allowing physical isolation of transmit and receive paths while maintaining system functionality. This segmentation resolves the contradiction by enabling path isolation without requiring a single complex monostatic aperture.
Solution Approach 2:
The patent transitions from a single-aperture monostatic configuration to a multi-aperture bistatic configuration, adding spatial dimensionality to the system. By distributing apertures across multiple locations and using optical phased arrays for beam steering, the system achieves transmit-receive isolation while maintaining detection capability.
2Device complexity
If a single aperture is used for both transmit and receive to reduce device complexity, then device complexity is improved, but measurement precision deteriorates due to speckle effects from rough surfaces
Solution Approach 1:
The system segments the aperture into multiple transmit and receive elements, enabling spatial diversity in signal collection. This segmentation allows the system to average out speckle effects across multiple independent detection paths, improving measurement precision without requiring a single complex aperture.
Solution Approach 2:
The patent changes the spatial parameters of the aperture configuration by distributing multiple apertures across different locations and orientations. This parameter change enables the system to collect signals from multiple spatial perspectives, reducing speckle-induced measurement errors while maintaining overall system simplicity.
3Device complexity
If aperture space is limited, then device complexity is reduced, but signal-to-noise ratio deteriorates due to limited photon collection
Solution Approach 1:
The system exploits the spatial dimension by arranging multiple apertures in specific geometric configurations and using optical phased arrays for electronic beam steering. This dimensional approach allows the system to collect photons from multiple spatial directions, increasing total photon collection without increasing the footprint of individual aperture elements.
Solution Approach 2:
The optical phased array enables each aperture element to serve multiple functions by dynamically steering beams to different targets and collecting returns from multiple directions. This multi-functionality increases photon collection efficiency within limited aperture space while maintaining system simplicity.
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 increases the collection of backscattered photons while reducing background leakage, improves tolerance to speckle effects, and enhances performance across various range distances by optimizing the use of available aperture space and reducing interference.
Implementation Method 1
an optical phased array within the receive aperture, the optical phased array being configured to receive at least a portion of a collected optical wave arriving at the receive aperture along a respective collection angle
Implementation Method 2
Each detector comprises a coherent detector configured to optically combine the received portion of the collected optical wave with a local oscillator optical wave to provide a combined optical wave
Implementation Method 3
coherent detector configured to optically combine the received portion of the collected optical wave with a local oscillator optical wave
Implementation Method 4
The optical source used in a continuous wave (CW) LiDAR system is typically a laser, which provides an optical wave that has as narrow linewidth and has a peak wavelength that falls in a particular range
Implementation Method 5
the photons backscattered from the target object(s) are collected
Data Source
AI summary
At least one beam of an optical wave is transmitted along a transmission angle toward a target location from a send aperture of a transmitter. A collected optical wave is received at receive apertures of two or more receivers. Each receiver comprises: a receive aperture arranged in proximity to at least one of the send aperture or a receive aperture of a different receiver, an optical phased array within the receive aperture, which receives at least a portion of a collected optical wave arriving at the receive aperture along a respective collection angle, and a detector that provides a signal based on the received portion of the collected optical wave. An estimated distance associated with the collected optical wave is determined based on a combination that includes a respective component corresponding to each of two or more of the signals provided from the detectors of the two or more receivers.