Lidar Optical Assembly Using Single MEMS Mirror and Dual Wedges
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Solution Overview
Problem
Existing lidar systems have limited field of view and are costly and complex to calibrate, especially when attempting to achieve a wider field of view using multiple MEMS or fixed mirrors, which are not robust against vehicular vibrations.
Innovation Solution
A lidar system configuration using a single 1D MEMS mirror with a vertical-line arrangement of laser beams and two optical wedges to direct beams in complementary directions, along with shutters for time-multiplexing, to achieve a 120° horizontal field of view without the need for multiple mirrors or 2D MEMS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If multiple MEMS or fixed mirrors are used to achieve a wider field of view, then the field of view is improved, but the device complexity and calibration difficulty increase
Solution Approach 1:
The patent divides the field of view coverage into multiple segments, each handled by a separate optical wedge. The first optical wedge directs beams in a first direction and the second optical wedge directs beams in a second direction, allowing the system to achieve a wide total field of view while keeping each individual wedge relatively simple and reducing overall system complexity
Solution Approach 2:
The patent introduces optical wedges that deflect laser beams in different spatial directions (first direction and second direction), adding dimensional diversity to the beam routing. This allows a single 1D MEMS mirror to achieve wide field of view coverage by combining deflections in multiple dimensions rather than requiring multiple mirrors
2Area of moving object
If multiple MEMS or fixed mirrors are used to achieve a wider field of view, then the field of view is improved, but the calibration difficulty increases
Solution Approach 1:
By segmenting the field of view into distinct regions handled by separate optical wedges, each wedge can be calibrated independently for its specific angular range. This reduces the overall calibration complexity compared to calibrating multiple mirrors to work together across the entire field of view
Solution Approach 2:
The patent employs shutters for time-multiplexing, alternately directing laser beams through different optical paths. This periodic switching allows the system to sequentially calibrate and operate different wedge configurations, simplifying the calibration process compared to simultaneously coordinating multiple mirrors
3Area of moving object
If multiple MEMS or fixed mirrors are used to achieve a wider field of view, then the field of view is improved, but the reliability against vehicular vibrations deteriorates
Solution Approach 1:
The patent combines multiple optical wedges with a single 1D MEMS mirror to achieve wide field of view coverage. This merging reduces the total number of moving components compared to using multiple MEMS mirrors, thereby improving reliability and robustness against vehicular vibrations while maintaining the expanded field of view
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 configuration provides a wider field of view of 120° while maintaining robustness against vehicular vibrations and reducing costs and complexity, with improved object detection capabilities and reduced calibration requirements.
Implementation Method 1
a first-optical wedge configured to generally direct laser-beams in a first-direction with respect to a bore-axis of the system
Data Source
Figure 1
Figure 2
AI summary
A lidar system (10) includes a laser-source (18) configured to emit a plurality of laser-beams (20), and a single movable-mirror (22) positioned to reflect the plurality of laser-beams (20) from the laser-source (18). The movable-mirror (22) is operable to pivot about a single rotation-axis (24), The system (10) includes a first-optical wedge (26) configured to direct at least a first-laser-beam (28) of the plurality of laser-beams (20) reflected by the movable-mirror (22) in a first-direction (30) with respect to a bore-axis (32) of the system (10), and a second-optical-wedge (34) configured to direct at least a second-laser-beam (36) of the plurality of laser-beams (20) reflected by the movable-mirror (22) in a second-direction (38) with respect to the bore-axis (32) of the system (10), where the second-direction (38) characterized as different from the first-direction (30). The system (10) also includes a first-shutter (40) interposed between the first-optical-wedge (26) and the movable-mirror (22), and a second-shutter (42) interposed between the second-optical-wedge (34) and the movable-mirror (22). The first-shutter (40) and the second-shutter (42) are independently and alternately operable to a transmissive-state and a blocking-state.