Lidar Sensor Microlens Arrangement Separates Scattered Light
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Solution Overview
Problem
Lidar sensors face challenges in distinguishing between useful backscattered light from environmental objects and scattered light caused by protective glass contaminants or defects, which can interfere with accurate distance measurement and image sharpness, especially at long ranges.
Innovation Solution
A lidar sensor design incorporating a microlens arrangement between the objective and detector, which separates scattered light from useful light by imaging scattered light sharply in a specific plane and using an aperture mask to reduce scattered light portions, while maintaining the overall length of optical paths unchanged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective glass is integrated into the lidar sensor housing to protect internal components from environmental influences, then the protection of internal components is improved, but scattered light is generated due to contaminants or defects on the protective glass surface
Solution Approach 1:
The patent extracts and separates scattered light from useful light using a microlens array positioned in front of the detector. Each microlens focuses light from a specific angular direction, allowing the detector to spatially distinguish between scattered light (from protective glass contaminants) and useful backscattered light (from distant objects), thereby removing the harmful effect of scattered light while maintaining the protective glass
Solution Approach 2:
The microlens array acts as an intermediary optical element between the protective glass and the detector. It mediates the light paths by creating angle-selective imaging, where scattered light and useful light are focused to different positions on the detector surface, enabling their separation without removing the protective glass
2Length of stationary object
If the lidar sensor is designed for long range detection (100m to 300m), then the detection range is improved, but the ability to distinguish scattered light from useful light becomes more difficult
Solution Approach 1:
The patent applies local quality by making each microlens in the array have a specific angular acceptance characteristic. Each microlens is optimized to accept light from a particular angular range, creating localized angular selectivity across the detector surface. This allows precise differentiation between scattered light and useful light even at long ranges where the angular separation is minimal
Solution Approach 2:
The patent transitions from spatial separation to angular separation by using the microlens array to encode angular information into spatial positions on the detector. This adds an angular dimension to the light detection, enabling differentiation between scattered and useful light based on their different incident angles rather than just their spatial origins
3Measurement precision
If an angle-selective element is used to select a particular angle range for backscattered light, then the selection of useful light is improved, but scattered light from other angles cannot be effectively separated
Solution Approach 1:
The patent segments the angular detection space by dividing the detector surface into multiple zones, each associated with a specific microlens that accepts light from a particular angular range. This segmentation allows simultaneous detection of multiple angular ranges, creating a comprehensive angular filter that blocks scattered light from all angles while passing useful light from the desired angular range
Solution Approach 2:
The patent enables dynamic angular selection by allowing the system to programmatically activate or deactivate specific microlenses or detector zones based on the desired field of view. This dynamic control allows the angle-selective element to adapt to different detection scenarios, optimizing the separation between scattered and useful light for various operating conditions
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 reliable separation of scattered and useful light, allowing for accurate distance measurement and improved environment recognition by reducing the impact of protective glass defects, enhancing the safety and reliability of environment recognition systems.
Implementation Method 1
scattered light generated in the region of the protective glass (e.g., due to rain drops or dirt particles, etc. present on the surface of the protective glass) and useful light received from the environment
Implementation Method 2
the microlens arrangement is arranged between the objective and the light detector in such a way that scattered light generated in the region of the protective glass and useful light received from the environment are influenced by the microlens arrangement in such a way that a substantially separate use of the scattered light and of the useful light is made possible
Implementation Method 3
The transmission unit comprises, for example, a laser diode or a laser diode arrangement and is configured to generate a laser light and to radiate it via a transmission path of the lidar sensor
Implementation Method 4
The detector is configured to receive light influenced by the microlens arrangement and to convert it into a corresponding measurement signal
Data Source
AI summary
A lidar sensor and an environment recognition system. The lidar sensor includes: a transmission unit, a protective glass, an objective, a microlens arrangement, and a detector. The transmission unit is configured to generate a laser light and radiate it into an environment of the lidar sensor. The protective glass, the objective, the microlens arrangement, and the detector are arranged in a reception path of the lidar sensor. The objective is configured to image objects from the environment. The microlens arrangement is between the objective and the detector in such a way that scattered light generated in the region of the protective glass and useful light received from the environment are influenced by the microlens arrangement so that a separate use of the scattered light and of the useful light is made possible. The detector is configured to convert light influenced by the microlens arrangement into a measurement signal.