Multi-Level Scanner with Dynamic Mirror Tilt
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Solution Overview
Problem
Existing multi-level scanners suffer from asymmetrical scanning due to varying angular positions, leading to inconsistent angular resolution and distorted scan lines, which is problematic for applications requiring accurate monitoring of multiple levels, such as driverless vehicles and motorway surveillance.
Innovation Solution
A multi-level scanner design featuring free-form mirror facets with compensating contours and dynamic tilting elements ensures constant angular offsets and deflection angles, using displacement elements to synchronize the light emitter and receiver with the rotational movement of the polygon mirror wheel, maintaining consistent angular resolution across different rotational positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a polygon mirror wheel with inclined facets is used to scan multiple levels, then the monitoring area is scanned at different heights, but the scan lines become distorted and asymmetrical due to varying angles of incidence
Solution Approach 1:
The patent applies the dynamics principle by making the mirror facets tiltable in synchronization with the rotational movement of the polygon mirror wheel. The tilting angle of each facet is dynamically adjusted based on its rotational position to compensate for the asymmetry caused by fixed inclination angles. This dynamic adjustment ensures that the deflection angle remains constant throughout the rotation, maintaining symmetrical and undistorted scan lines across all levels.
2Productivity
If the mirror facets are fixed with different inclination angles, then multiple levels are scanned per revolution, but the vertical angular resolution becomes dependent on the angular position of the mirror wheel
Solution Approach 1:
The patent resolves this contradiction by dynamically tilting the mirror facets during rotation. The tilting mechanism adjusts the inclination angle of each facet in real-time based on its angular position, ensuring that the vertical deflection angle remains constant. This dynamic compensation maintains consistent vertical angular resolution across all rotational positions while preserving the high scanning speed achieved by scanning multiple levels per revolution.
3Device complexity
If a simple polygon wheel is used instead of a raster mirror wheel, then the device complexity is reduced, but the scanning angle range is limited to less than 100°
Solution Approach 1:
The patent overcomes the limited scanning angle range of simple polygon wheels by dynamically tilting the mirror facets during rotation. This tilting mechanism allows each facet to deflect the scanning beam at varying angles, effectively expanding the total scanning angle range beyond what a fixed-geometry polygon wheel could achieve. The dynamic adjustment enables a compact device structure to cover a much broader angular range.
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 design achieves a constant angular resolution in both azimuth and elevation, reducing asymmetry and distortion, thereby enhancing the accuracy and reliability of multi-level scanning, particularly in applications requiring precise monitoring of varied heights and environments.
Implementation Method 1
a light emitter (12) which generates a light beam (16)
Implementation Method 2
a rotating polygon mirror wheel (20) which rotates about a rotation axis (19)
Implementation Method 3
a light receiver (28) which generates a received signal from the light beam (16)
Implementation Method 4
Such distance-measuring laser scanners work according to a light propagation time principle, in which the propagation time from the scanner into the scenery and back is measured
Data Source
Figure 1~4
Figure 5~6
AI summary
A multi-level scanner (10) is described, comprising a light transmitter (12) for emitting a light beam (16) into a monitoring area (22), a light receiver (28) for receiving the light beam (24) reflected by objects in the monitoring area (22), an evaluation unit (30) for evaluating a received signal from the light receiver (28), and a rotatable mirror unit (20) for periodically deflecting the light beam (16, 24), which has several ring-shaped mirror facets (32) arranged tilted relative to each other, in order to scan an angular section of several superimposed planes multiple times per rotation of the mirror unit (20) as the monitoring area (22). In order to compensate for distortions of the several scanned planes, optical elements (12, 14, 26, 28, 32, 40) in the beam path of the light beam (16, 24) have a compensating contour and/or are movable in sync with the rotational movement of the mirror unit (20).