Multilevel Scanner With Beam Deflection for Uniform Scan Planes
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Solution Overview
Problem
Existing multi-plane scanners using tilted mirror facets suffer from distorted scanning planes and asymmetrical vertical resolution due to varying angles of incidence, leading to reduced point density and potential exclusion of regions of interest, especially at long distances.
Innovation Solution
A multi-level scanner with a control unit that adjusts the polygon mirror wheel and beam deflection unit to follow a desired trajectory, compensating for angular asymmetry by using a beam deflection unit like a galvanometer mirror or phased array to ensure precise, flexible scanning along a user-defined path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If tilted mirror facets are used to scan multiple planes, then multi-level scanning capability is improved, but scanning plane distortion and asymmetrical vertical resolution occur
Solution Approach 1:
The patent applies dynamics by making the mirror facets rotatable to change their tilt angles dynamically during operation. The mirror facets can adjust their inclination relative to the rotation axis, allowing the system to switch between scanning a single plane and scanning multiple planes as needed, rather than being fixed in a multi-plane configuration that causes distortion.
Solution Approach 2:
The patent changes the parameter of mirror facet tilt angle to resolve the contradiction. By adjusting the tilt angle parameter of the mirror facets, the system can optimize the scanning configuration for different applications - using non-zero tilt angles for multi-level scanning when needed, and zero tilt angles for precise single-plane scanning to avoid distortion.
2Area of stationary object
If tilted mirror facets are used for multi-plane scanning, then coverage of different heights is improved, but point density decreases and regions of interest may be excluded
Solution Approach 1:
The rotatable mirror facets enable dynamic adjustment of the scanning pattern. The system can adapt the distribution of scan lines across different heights by changing mirror facet angles, allowing optimal point density in regions of interest while still providing multi-level coverage when required.
Solution Approach 2:
The patent applies local quality by allowing different mirror facets to have different tilt angles, creating non-uniform scanning patterns. This enables higher point density to be concentrated in specific regions of interest (such as ground level for vehicle applications) while other areas receive less scanning attention, optimizing the distribution of measurement points according to local requirements.
3Adaptability or versatility
If complex mechanical tilting is added to achieve multi-level scanning, then scanning flexibility is improved, but device complexity increases
Solution Approach 1:
The patent merges the multi-plane scanning function into the existing polygon mirror wheel structure. Instead of adding a separate tilting mechanism to an otherwise fixed mirror system, the mirror facets are integrated with rotatable mounting that allows tilt angle adjustment while maintaining the compact single-unit structure of the polygon mirror.
Solution Approach 2:
The patent uses dynamics to reduce mechanical complexity by making the mirror facets rotatable rather than adding complex mechanical tilting mechanisms. The rotational degree of freedom of the mirror facets provides the necessary scanning flexibility, eliminating the need for additional mechanical tilting systems that would increase device 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 precise, flexible scanning with constant angular offsets, allowing for uniform scanning planes and improved detection capabilities in complex environments without mechanical realignment, especially suitable for mobile applications like driverless vehicles and dynamic surveillance areas.
Implementation Method 1
a polygon mirror wheel (20) that can be rotated about a first rotation axis (19) with several annularly arranged mirror facets (32) which are at least partially tilted relative to one another with respect to the first rotation axis (19)
Implementation Method 2
A beam deflection unit (18) for adjusting an angle of incidence of the light beam (16) on the mirror facets (32) is arranged between the light transmitter (12) and the polygon mirror wheel (20)
Implementation Method 3
Such distance-measuring laser or LiDAR (Light Detection and Ranging) scanners operate according to a time-of-flight principle, measuring the time of flight from the scanner to the scene and back
Implementation Method 4
measuring the time of flight from the scanner to the scene and back, and calculating distance data based on the speed of light
Data Source
Figure 1
Figure 2~3c
Figure 4a~4c
AI summary
A multi-level scanner is described, comprising a light transmitter for emitting a light beam into a monitoring area, a light receiver for receiving the light beam reflected by objects in the monitoring area, an evaluation unit for evaluating a received signal from the light receiver, and a polygon mirror wheel rotatable about a first axis of rotation for periodically deflecting the light beam. The polygon mirror wheel has several ring-shaped mirror facets that are at least partially tilted relative to each other about the first axis of rotation, so that, with each revolution of the polygon mirror wheel, an angular section of the monitoring area is scanned multiple times at different heights, i.e., several superimposed scanning planes. A beam deflection unit for adjusting the angle of incidence of the light beam on the mirror facets is arranged between the light transmitter and the polygon mirror wheel.A control unit is set up to receive a target trajectory curve for the light beam in the monitoring area and to control the polygon mirror wheel and the beam deflection unit in such a way that the light beam scans the monitoring area along the target trajectory curve.