Target Mark Locating with SPAD Blur Imaging and Light-Fan Scanning
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Solution Overview
Problem
Current target reflector search devices in surveying technologies face challenges in quickly and accurately locating reflective targets, particularly in differentiating actual measurement targets from spurious reflections and achieving precise distance measurement, especially in geodetic surveying applications.
Innovation Solution
The implementation of a target reflector search device that emits a light fan, which can be moved orthogonally to its initial direction, using a position-resolving optoelectronic detector with a SPAD array and an imaging optical unit to analyze reflections within a fan-shaped reception region, allowing for precise position determination and rough distance estimation through time-of-flight analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional searchlight fan is used to scan for retroreflective objects, then the device can automatically locate targets, but the acquisition speed and accuracy are insufficient and spurious reflections cannot be effectively differentiated
Solution Approach 1:
The patent divides the search space into multiple overlapping search regions (first search region and second search region) that are scanned at different times. By segmenting the scanning process and comparing results across multiple regions, the system can differentiate actual targets from spurious reflections through spatial and temporal correlation analysis.
Solution Approach 2:
The patent performs a preliminary coarse scan of the search space using a first search region before conducting a more precise scan with a second search region. This preliminary action allows the system to identify potential target locations and then verify them through subsequent scanning, improving both accuracy and reliability.
2Reliability
If the search device scans the entire surrounding area to ensure target detection, then coverage is complete, but the acquisition time increases significantly
Solution Approach 1:
The patent segments the search space into multiple overlapping regions that are scanned sequentially. This segmentation allows the system to divide the total scanning time into smaller intervals while maintaining complete coverage through the overlap between regions, thus reducing acquisition time without sacrificing detection completeness.
Solution Approach 2:
The patent uses multiple overlapping search regions where some areas are scanned more than once. This excessive action in certain regions ensures complete coverage and reliable detection while the overall segmented approach maintains efficient timing by parallelizing the scanning of different regions.
3Reliability
If the light fan is emitted continuously to improve target detection, then detection reliability improves, but energy consumption increases
Solution Approach 1:
The patent employs periodic scanning of the search regions rather than continuous illumination. The light fan is emitted in periodic cycles, alternating between different search regions, which maintains reliable detection capability through repeated measurements while significantly reducing overall energy consumption compared to continuous operation.
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 enables faster and more accurate acquisition of reflective targets, improves differentiation between actual and spurious reflections, and provides geodetic accuracy in target location, enhancing the efficiency of surveying devices like total stations and laser scanners.
Implementation Method 1
an emitting unit (8), which emits optical radiation in the form of an emission fan (13) oriented in a first direction to illuminate the target mark (10)
Implementation Method 2
which receives reflected portions or components of the optical radiation of the emission fan as reflections (21) from the target mark (10) within a fan-shaped reception region (20)
Implementation Method 3
reflected portions or components of the optical radiation of the emission fan as reflections (21)
Implementation Method 4
a distance measuring unit (23), which ascertains at least one distance (43) on the basis of a signal runtime of a light pulse of the emission fan (13)
Data Source
AI summary
A target reflector search device. This device comprises an emitting unit for emitting an emission fan, a motorized device for moving the emission fan over a spatial region, and a receiving unit for reflected portions of the emission fan within a fan-shaped acquisition region, and a locating unit for determining a location of the reflection. An optoelectronic detector of the receiving unit is formed as a position-resolving optoelectronic detector having a linear arrangement of a plurality of pixels, each formed as an SPAD array, and the receiving unit comprises an optical system having an imaging fixed-focus optical unit, wherein the optical system and the optoelectronic detector are arranged and configured in such a way that portions of the optical radiation reflected from a point in the acquisition region are expanded on the sensitivity surface of the optoelectronic detector in such a way that blurry imaging takes place.