Macro-Scanning Structure With MEMS Mirror for 2D Laser Scanning
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Solution Overview
Problem
Existing LIDAR systems face challenges in achieving a desired horizontal and vertical field of view, resolution, scanning range, and frame rate due to the need for large scanning subsystems to accommodate both transmission and reception, which precludes the use of small MEMS mirrors.
Innovation Solution
A combination of a macroscopic polygon mirror or prism and a MEMS mirror is used to steer light beams in two dimensions, with the macro scanner also serving as a receiver, allowing for a horizontal and vertical laser scan pattern and enabling parallel measurements using an array of photodetectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large scanning subsystem is used to accommodate both transmission and reception, then the field of view and resolution are improved, but the device size increases and MEMS mirrors cannot be used
Solution Approach 1:
The scanning subsystem is segmented into two independent components: a macro scanner (polygon mirror or prism) for one dimension and a MEMS mirror for the other dimension. This segmentation allows each component to be optimized independently - the macro scanner provides the necessary aperture for receiver alignment while the MEMS mirror provides precise angular control, achieving high measurement precision without requiring a large integrated scanning subsystem.
Solution Approach 2:
The macro scanner is designed to serve dual functions: it scans the transmit light beam in one dimension and simultaneously serves as the receiver aperture for collecting backscattered light. This multi-functionality eliminates the need for separate transmission and reception optics, reducing overall device size while maintaining the required field of view and resolution.
2Length of moving object
If a collimated laser beam is used to extend range, then the scanning time increases for horizontal and vertical coverage
Solution Approach 1:
The scanning task is divided between two mirrors with different characteristics: the macro scanner handles coarse positioning in one dimension (e.g., horizontal) while the MEMS mirror handles fine scanning in the perpendicular dimension (e.g., vertical). This segmentation allows parallel scanning operations that reduce total scan time while maintaining the collimated beam's extended range capability.
Solution Approach 2:
The system transitions from sequential one-dimensional scanning to two-dimensional parallel scanning by introducing the MEMS mirror orthogonal to the macro scanner's rotation axis. This dimensional addition allows the system to cover the entire field of view simultaneously in both dimensions, dramatically reducing scan time while preserving the long-range capability provided by collimated beams.
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
This configuration enhances scanning efficiency, enabling faster data acquisition and improved signal-to-noise ratio while allowing for a compact design that incorporates MEMS mirrors, thus optimizing field of view, resolution, and frame rate.
Implementation Method 1
a microelectromechanical system (MEMS) mirror arranged on the transmission path and configured to oscillate about a first scanning axis to steer the transmit light beam in a first dimension of a field of view
Implementation Method 2
a macro scanner arranged on the transmission path and on a receiver path, the macro scanner configured to rotate about a second scanning axis to steer the transmit light beam in a second dimension of the field of view
Implementation Method 3
the macro scanner is further configured to receive from the field of view a receive light beam that is produced from transmit light beam via backscattering
Implementation Method 4
a photodetector arranged on the receiver path and configured to receive the receive light beam from the macro scanner and generate a measurement signal representative of the receive light beam
Data Source
AI summary
A light scanning system includes a transmitter configured to transmit a transmit light beam along a transmission path; a microelectromechanical system (MEMS) mirror arranged on the transmission path and configured to oscillate about a first scanning axis to steer the transmit light beam in a first dimension; a macro scanner arranged on the transmission path and on a receiver path, the macro scanner configured to rotate about a second scanning axis to steer the transmit light beam in a second dimension, where the macro scanner is further configured to receive a receive light beam that is produced from the transmit light beam via backscattering, and where the macro scanner is configured to direct the receive light beam further along the receiver path; and a photodetector configured to receive the receive light beam from the macro scanner and generate a measurement signal representative of the receive light beam.