Laser Scanning Device Virtual Receiver Cell Segmentation
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Solution Overview
Problem
Existing laser scan devices face challenges in achieving high location resolution and signal-to-noise ratio, especially at large distances and high scanning speeds, due to the interference of ambient light and the limitations of current signal processing methods.
Innovation Solution
The proposed laser scan setup features a configuration with multiple transmission and recipient units, where the radiation and reception divergences in the scanning direction are significantly larger than in the cross-scanning direction, allowing for a high overlap of measurement fields and improved signal processing through accumulation of digitized recipient signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the receiver area and reception divergence are increased to detect reflected laser pulses at long distances, then the signal detection capability is improved, but the influence of ambient light on the receiver signal increases
Solution Approach 1:
The field of view is divided into multiple measurement fields that overlap in the scan direction. Each measurement field is processed independently, allowing the system to accumulate signals from multiple pulses while maintaining spatial resolution. This segmentation enables selective signal accumulation from specific angular regions, reducing ambient light interference while improving signal detection.
Solution Approach 2:
The system emits laser pulses in periodic sequences and accumulates receiver signals from multiple pulses over time. By synchronizing the accumulation window with the periodic pulse emission and using the known scan position for each pulse, the system enhances the reflected signal through temporal averaging while rejecting random ambient light fluctuations.
2Productivity
If the scan speed is increased to improve productivity, then the measurement efficiency is improved, but the spatial resolution of the depth profile decreases
Solution Approach 1:
The system pre-calculates the overlap regions between consecutive measurement fields based on the scan speed and pulse frequency. By knowing in advance which signal portions belong to which measurement fields, the system can accumulate signals at high scan speeds without losing spatial resolution, as the accumulation process is guided by pre-determined spatial boundaries.
Solution Approach 2:
The patent introduces temporal accumulation as an additional dimension to compensate for the loss of spatial resolution. By accumulating signals from multiple pulses in the time domain while maintaining angular discrimination through the segmented field approach, the system recovers spatial resolution information that would otherwise be lost at high scan speeds.
3Length of stationary object
If the distance to target objects increases, then the field of view is extended, but the spatial resolution of the depth profile decreases
Solution Approach 1:
By dividing the total field of view into multiple overlapping measurement fields, the system maintains fine angular resolution for each segment even when the total coverage distance is large. Each measurement field processes signals with high angular precision, and the overlapping regions provide redundancy that maintains resolution across the entire extended 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 configuration enhances the signal-to-noise ratio and improves the location resolution of the depth profile, enabling effective three-dimensional measurement of scenes at large distances with high scanning speeds.
Implementation Method 1
To determine the distance to a target object based on the time-of-flight method, individual laser pulses are emitted sequentially at a frequency limited by the maximum expected travel time of a laser pulse. The travel time of each laser pulse corresponds to the time between the emission of the laser pulse and its reception.
Implementation Method 2
a receiver unit for receiving each portion of a laser pulse reflected from a target object, a storage and evaluation unit for determining distances from receiver signals generated by the receiver unit
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for the three-dimensional measurement of a setting from a great distance, and a laser scanning device suitable for this purpose. The field of view (FOV) of a laser scanning device is divided into virtual receiver cells (VE) forming a row or a matrix which, in a scanning direction (Rs), are many times smaller than a measurement field (M) within the field of view (FOV) to which a laser pulse (LP) is applied. A receiver signal is formed from the portion (LP) of the laser pulse (LP) that is reflected from a measurement field (M) and detected, and said receiver signal is digitalised and allocated to each virtual receiver cell (VE) that lies in the measurement field (M) in question. The virtual receiver cells (VE) are thus allocated multiple digitalised receiver signals from which an accumulated receiver signal is formed.