Lidar Window Secondary Detector for Interference Source Detection
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Solution Overview
Problem
Lidar systems face challenges in rapidly detecting interference sources such as scratches, water drops, and dirt on the window, which degrade signal quality and are difficult to distinguish from external influences, especially in dynamic environments like moving vehicles, where fast detection is crucial for reliable operation.
Innovation Solution
Incorporating a secondary detector attached to the window's coupling-out surface to detect scattered light, which is evaluated by a control unit to identify interference sources, and using beam optics that can swivel to correlate deflection positions with scattered light intensity for precise source localization, along with a band-pass filter to differentiate internal and external light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a software-based estimate of range reduction is used to detect interference sources, then the system can identify contamination, but the detection speed is slow with lags in the range of minutes and longer
Solution Approach 1:
The detection function is segmented into two independent detector units: a primary detector for normal operation and a secondary detector specifically for interference source detection. This segmentation allows the secondary detector to specialize in rapid interference detection without affecting the primary detection function, resolving the contradiction between detection accuracy and speed.
Solution Approach 2:
A secondary detector is introduced as an intermediary component that specifically monitors scattered light from interference sources. This intermediary detector provides rapid interference detection capability, eliminating the slow software-based estimation while maintaining accurate interference source identification.
2Reliability
If multiple sensors are used to monitor the surrounding area and compare outputs to detect blocked sensors, then sensor blockage can be identified, but the system requires a standardized environment or stationary vehicle for direct comparability
Solution Approach 1:
The interference detection function is extracted from the main detection system by placing the secondary detector at a specific location on the window. This extracted secondary detector monitors only scattered light from interference sources, independent of the external environment, allowing reliable interference detection without requiring standardized environmental conditions or vehicle stationarity.
3Speed
If the secondary detector is positioned to detect scattered light at the coupling-out surface of the window, then interference sources can be rapidly detected, but the system complexity increases with additional detector units
Solution Approach 1:
The secondary detector is positioned at a specific local position on the window (the coupling-out surface) where scattered light from interference sources emerges. This localized positioning allows the secondary detector to specifically monitor interference sources without requiring a complex array of detectors, achieving rapid detection with minimal additional system complexity.
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 rapid and effective detection of interference sources during vehicle operation, reducing false alarms and improving signal quality by focusing on internal light sources and using geometrical correlations to accurately determine interference source positions and types.
Implementation Method 1
Roughness of the surface of the window, water drops, or contamination may cause scattering of the light in several directions or reflection in unintended directions
Implementation Method 2
The window is a refracting optical element, through which the signal light passes twice
Implementation Method 3
a portion of the light may have an angle relative to the (local) upper surface of the window, which is less than the angle of the total internal reflection
Data Source
AI summary
A lidar system having interference source detection, in particular, for a vehicle. An emitter unit and a detector unit are provided, so that reflected light for sampling a surrounding area may be detected. The light emitted by the emitter unit travels through a window out of the housing, and the light reflected by the surrounding area travels through the window into the housing. At least one secondary detector is provided, which is attached to a coupling-out surface of the window. The secondary detector is configured to detect scattered light propagating inside of the window. The lidar system includes a control unit, which is configured to evaluate scattered light detected by the at least one secondary detector, in order to detect interference sources on or in the window.