Optical Switch Synchronization for Laser Scanning Efficiency
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Solution Overview
Problem
Conventional laser scanning devices suffer from inefficiencies due to the 'clipping' and 'tilting' effects, which result in a significant loss of laser pulses and reduced scanning performance, especially at the edges of the scanning fan, leading to incomplete environmental measurements.
Innovation Solution
The implementation of an optical switch that synchronizes the switching of the laser beam between different mirror facets of a beam deflection device, ensuring the laser beam always uses a favorable path with a larger effective receiving area, thereby avoiding clipping and tilting effects, and allowing all emitted laser pulses to be utilized for measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser beam is emitted to the beam deflection device without optical switching, then the device structure is simple, but the laser beam is clipped at mirror facet transitions causing insufficient transmitted power and loss of laser pulses
Solution Approach 1:
An optical switch is introduced as an intermediary component between the laser transmitter and the beam deflection device. This optical switch selectively directs the laser beam to different mirror facets, preventing clipping effects at facet transitions and ensuring complete beam transmission without requiring complex structural modifications to the core scanning mechanism.
Solution Approach 2:
The system dynamically switches the laser beam path based on the rotational position of the mirror facets. The optical switch operates in synchronization with the rotating beam deflection device, continuously adjusting the beam direction to maintain optimal incidence on the active mirror facet throughout the rotation cycle, thereby maximizing scanning efficiency.
2Reliability
If a more powerful laser transmitter is installed to increase the received signal in outer areas, then the received signal intensity increases, but the cost increases and the receiver could be overloaded in remaining areas
Solution Approach 1:
Instead of uniformly increasing laser power across all scanning areas, the optical switch enables localized optimization by directing the beam to different mirror facets at different times. This ensures that each mirror facet receives the full beam power when active, providing sufficient signal strength in outer scan areas without overloading the receiver in inner areas, as the beam is never split or clipped.
3Productivity
If the optical switch is added to synchronize laser beam switching between mirror facets, then all emitted laser pulses can be utilized for measurement increasing scanning efficiency, but the device complexity increases
Solution Approach 1:
The optical switch serves as a minimal-complexity intermediary that enables full utilization of emitted laser pulses. By placing the switch in the beam path before the rotating deflection device, it coordinates with the mirror facet rotation to ensure continuous, clipping-free beam transmission, achieving 100% laser pulse utilization without requiring complex modifications to the mirror facets or receiver system.
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 solution significantly increases the scanning efficiency by up to 50% for devices with mirror prisms and up to 20% for those with mirror pyramids, ensuring all emitted laser pulses contribute to the measurement, resulting in a more comprehensive and accurate 3D point cloud of the environment.
Implementation Method 1
at each transition from one mirror facet to the next, the emitted laser beam does not strike the currently active mirror facet used for the scan fan with its entire beam cross-section; that is, it is clipped both when entering and exiting the active mirror facet
Implementation Method 2
the orientation of the active mirror facet relative to the receiving laser beam changes during rotation, thus altering the effective receiving area available for deflecting the received pulses into the receiver
Implementation Method 3
the pulsed laser beam is scanned as a fan across a certain angular range, thus scanning a different point in the environment with each laser pulse. The corresponding laser pulse is reflected from each scanning point and deflected as a received pulse towards the receiver via the same mirror facet
Implementation Method 4
From time-of-flight measurements of the reflected laser pulses, the distances to the scanning points are determined, and from these distances—knowing the position of the device and the scanning direction—a point model ('3D point cloud') of the environment is created
Data Source
Figure 1~2
Figure 3a~5
Figure 6
AI summary
The present invention relates to a device (1) for measuring an environment (2), comprising a beam deflection device (12) with at least three mirror facets (15j) rotatably mounted about a rotation axis (13) for common rotation, a laser transmitter (10) for emitting a laser beam (4) via a first path (W1) onto each of the mirror facets (15j), a laser receiver (18) for receiving the laser beam received back via this mirror facet (15j), and an optical switch (21) for switching the laser beam at a timed interval between the first and a second path (W2) directed onto each of the other mirror facets (15j), wherein the switching interval of the optical switch (21) is synchronized with the rotation of the mirror facets (15j) and the laser receiver (18) is also configured to receive the laser beam (4) received back via the said other mirror facet (15j).