LiDAR System with Compressed Instantaneous Field-of-View
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Solution Overview
Problem
Existing LiDAR systems face challenges in maintaining a high signal-to-noise ratio (SNR) over a wide scan range while adhering to safety thresholds and minimizing the impact of solar background radiation, particularly in automotive applications where large fields of view and high resolution are required.
Innovation Solution
The implementation of a modified LiDAR system with spatially minimized sunlight collection and reduced optical signal divergence, achieved through a focal-plane array with compressed instantaneous field-of-view (IFOV) and composite field-of-view (CFOV) that matches the scene's sub-region, allowing for improved SNR without increasing laser power and using narrow solar-bandpass filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the field of view of the receiver is reduced to minimize sunlight collection, then the signal-to-noise ratio is improved, but the total image field of view is reduced
Solution Approach 1:
The patent divides the scene into multiple sub-regions, each interrogated by a focused optical signal with specific divergence angles. The receiver's field of view is segmented to match each sub-region, allowing minimized sunlight collection per sub-region while collectively covering the entire scene through scanning across multiple sub-regions.
2Measurement precision
If the laser signal divergence is reduced to improve signal-to-noise ratio, then the solar background noise is reduced, but the lateral extent of the interrogated sub-region is reduced
Solution Approach 1:
The patent applies different divergence characteristics to different spatial directions. The optical signal has a first divergence in a first direction and a second divergence in a second direction, creating an asymmetric illumination pattern that optimizes signal concentration in the range direction while minimizing solar background collection in the azimuth direction.
3Measurement precision
If narrow solar-bandpass filters are used to reduce solar background noise, then the signal-to-noise ratio is improved, but the system complexity increases
Solution Approach 1:
The patent extracts and removes the need for narrow solar-bandpass filters by using an alternative approach: minimizing sunlight collection through geometric optics design (focused signal transmission with controlled divergence and matched receiver field of view). This extracts the solar rejection function from the spectral domain to the spatial domain, eliminating complex filtering requirements.
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 approach enhances SNR throughout the entire scan range, reduces solar background noise, and maintains eye safety by reducing laser divergence and solar flux density, enabling high-resolution imaging with reduced motion blur and improved image quality.
Implementation Method 1
each pixel exhibits an instantaneous field-of-view having a first angular range in the first direction and a second angular range in the second direction, and wherein the plurality of pixels are arranged such that they collectively define a focal-plane array
Implementation Method 2
a transmitter operative for interrogating a sub-region of a scene with an optical signal, the optical signal having an illumination pattern having a first divergence in a first direction and a second divergence in a second direction
Implementation Method 3
LiDAR—and more particularly time-of-flight (TOF) based LiDAR—is a distance range measurement technique in which a brief laser light pulse is emitted
Data Source
AI summary
Disclosed are improved LiDAR systems and methods that achieve an improved signal-to-noise by interrogating a sub-region of a scene with an optical signal. An instantaneous field-of-view (FOV) of each detector pixel is narrowed along a first direction to reduce detection of solar-generated photons. Instantaneous FOVs of the pixels are compressed along the first direction to provide a composite FOV that is narrower than a total FOV. To sample the total FOV of a scene, the optical signal and composite FOV of the receiver are scanned across the scene along the first direction.