Multi-Faceted Lidar Mirror Window Layout for Ghost Signal Reduction
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Solution Overview
Problem
Conventional LIDAR systems suffer from spurious light detections due to internal reflections and ambient light, leading to inaccurate distance and location measurements of objects in the environment.
Innovation Solution
Incorporation of baffles to reduce internal reflections and use of optical filters to mitigate ambient light, along with angled optical windows and multi-faceted mirrors to direct light signals effectively, thereby reducing ghost signals and thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LIDAR systems use standard optical paths without additional light-blocking components, then the system structure remains simple, but spurious light detections occur due to internal reflections and ambient light, leading to inaccurate distance and location measurements
Solution Approach 1:
Baffles are introduced as intermediary components between the optical window and the light detector to intercept and block spurious light paths. These baffles serve as mediators that prevent internal reflections and ambient light from reaching the detector, thereby improving measurement accuracy without requiring fundamental changes to the core LIDAR architecture
Solution Approach 2:
The harmful spurious light paths are extracted and blocked separately from the main optical path. By placing baffles in specific positions, the system selectively removes unwanted light (internal reflections and ambient light) while preserving the primary measurement beam, thus improving accuracy without significantly complicating the overall system
2Measurement precision
If the optical window is positioned perpendicular to the light direction for optimal light transmission, then light transmission efficiency is maximized, but internal reflections from the optical window reach the light detector causing spurious detections
Solution Approach 1:
The optical window is positioned at an asymmetric (non-perpendicular) angle relative to the light path. This asymmetric positioning causes internal reflections to diverge from the direct return path to the detector, preventing spurious detections while maintaining sufficient light transmission efficiency for accurate measurements
3Reliability
If external light filters are added to reduce ambient light entering the LIDAR system, then thermal expansion and spurious detections are reduced, but the system complexity and cost increase
Solution Approach 1:
Optical filters are designed to selectively transmit specific wavelength ranges while blocking ambient light. By changing the optical parameters (wavelength selectivity) rather than physically blocking all external light, the system achieves improved reliability and reduced thermal effects without excessive 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
Enhances the accuracy of LIDAR systems by minimizing ghost signals and thermal issues, ensuring precise distance and location measurements of objects in the environment.
Implementation Method 1
Light emitted along the optical axis is reflected from one or more of the reflective facets and is directed toward one or more regions of a scene
Implementation Method 2
light reflected from one or more of the reflective facets and directed toward the one or more regions of the scene is transmitted through the optical window
Implementation Method 3
The filter reduces transmission of at least some wavelengths that are not produced by the light emitter
Implementation Method 4
the rotating mirror may be flanked by one or more baffles that absorb spurious light signals
Data Source
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AI summary
Example embodiments relate to LIDAR systems with multi-faceted mirrors. An example embodiment includes a LIDAR system. The system includes a multi-faceted mirror that includes a plurality of reflective facets, which rotates about a first rotational axis. The system also includes a light emitter configured to emit a light signal toward one or more regions of a scene. Further, the system includes a light detector configured to detect a reflected light signal. In addition, the system includes an optical window positioned between the multi-faceted mirror and the one or more regions of the scene such that light reflected from one or more of the reflective facets is transmitted through the optical window. The optical window is positioned such that the optical window is non-perpendicular to the direction toward which the light emitted along the optical axis is directed for all angles of the multi-faceted mirror.