Anamorphic Prism LiDAR Detection for Dynamic Range and SNR
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Solution Overview
Problem
Existing LiDAR sensors face challenges in achieving a sufficient dynamic range and signal-to-noise ratio (SNR) while detecting objects with varying reflectivities at different distances, often resulting in increased detector costs and image aberrations like astigmatism due to the use of anamorphic lenses.
Innovation Solution
An optical detection system incorporating an anamorph prism system that compresses reflected optical radiation by a predefined factor, expanding the angular spectrum in a specific direction to enhance the dynamic range and maintain SNR, using a two-dimensional detector with a lens system and scanner unit to guide beams across a target scene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If anamorphic lenses with different focal powers are used to optimize the aspect ratio of the laser line's image, then the dynamic range and SNR are improved, but strong image aberrations like astigmatism occur resulting in blurring of the laser line's image
Solution Approach 1:
The patent introduces anamorphic prisms as an intermediary optical element between the receiver lens and detector. These prisms correct the astigmatism and image aberrations introduced by the anamorphic receiver lens, acting as a mediator that separates the function of aspect ratio optimization from image quality maintenance. The prisms specifically address the blurring issue while preserving the SNR benefits of the anamorphic lens configuration.
2Manufacturing precision
If non-rotational symmetric freeform surfaces are used to correct aberrations, then image quality is improved, but manufacturing difficulty and cost increase
Solution Approach 1:
The patent replaces expensive, difficult-to-manufacture freeform surfaces with standard optical components (anamorphic prisms with rotational symmetric surfaces) that are much easier and cheaper to manufacture. While freeform surfaces could correct aberrations, they require complex manufacturing processes; the patent uses readily manufacturable prism components that achieve the same correction function at lower cost and with greater ease of production.
3Adaptability or versatility
If binning several detector pixels is done to extend the active area of the detector, then the dynamic range is extended, but detector costs increase and SNR decreases
Solution Approach 1:
The patent addresses the dynamic range limitation by introducing anamorphic prisms that expand the angular spectrum of the reflected optical radiation in a specific direction. This creates an asymmetric expansion in one dimension (the direction of the laser line) while maintaining pixel resolution in the orthogonal dimension, effectively increasing the detectable scene width without requiring pixel binning. This dimensional approach allows extended dynamic range while preserving SNR.
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 system improves the dynamic range and maintains SNR without increasing costs, while reducing the system's visible size and complexity by using cost-effective components like axisymmetric lenses and band-pass filter coatings, thus enhancing imaging quality and detection capabilities.
Implementation Method 1
The anamorph prism system is configured to compress the reflected optical radiation by expanding an angular spectrum of the reflected optical radiation in the predefined direction by the predefined factor
Implementation Method 2
The lens system is configured to focus the processed beam from the anamorph prism system onto the two-dimensional detector
Implementation Method 3
at least one scanner unit configured to guide the at least one beam along a scan direction across a target scene and/or to guide a reflected optical radiation
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
This disclosure relates to light detection and ranging (LiDAR) systems, such as LiDAR sensors detecting objects with various reflectivities at various distances. An optical detection system (100) of this disclosure comprises a transmitter unit (110) for emitting at least one beam of optical radiation (115), a receiver unit (140, 640, 740) comprising an imaging unit (160) and an anamorph prism system (150, 650, 750), and at least one scanner unit (120) for guiding the beam (115) along a scan direction across a target scene (130) and/or guiding a reflected optical radiation (135) of the beam (115) from the target scene (130) to the receiver unit (140, 640, 740). The anamorph prism system (150, 650, 750) is configured to produce a processed beam (155) by compressing the reflected optical radiation (135) in a predefined direction by a predefined factor. The imaging unit (160) comprises a two-dimensional detector (180) and is configured to generate an image (420) based on the processed beam (155) on the two-dimensional detector (180), the image (420) having an aspect ratio that is based on the predefined factor.