Target Mark Locating With SPAD Light-Fan Reflection Detection
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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 is movable in a second direction orthogonal to its initial direction, using a position-resolving optoelectronic detector with a linear arrangement of Single Photon Avalanche Photodiodes (SPAD) arrays, allowing for precise position and distance determination of reflective targets through analysis of light pulses and their reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a light fan is emitted and moved to scan the spatial region, then the coverage area and detection capability are improved, but the acquisition time and system complexity increase
Solution Approach 1:
The spatial region is divided into multiple angular sectors using a light fan that can be rotated or pivoted. The detector array is segmented into multiple pixels that can independently detect reflections from different sectors, allowing parallel processing of multiple spatial regions simultaneously.
Solution Approach 2:
The system transitions from point-by-point scanning to planar angular sector coverage by emitting a light fan that spans a range of angles. This adds an angular dimension to the detection capability, allowing the entire spatial region to be covered in a single measurement rather than requiring sequential scanning.
2Measurement precision
If a position-resolving optoelectronic detector with multiple pixels is used, then the position resolution and measurement precision are improved, but the device complexity and cost increase
Solution Approach 1:
The detector is divided into an array of multiple pixels, with each pixel independently detecting light from a specific angular sector. This segmentation allows precise position resolution by determining which pixel receives the reflected light, while keeping each individual pixel simple in structure.
Solution Approach 2:
The same detector array serves multiple functions: it detects the presence of reflective targets, determines their angular position, and provides position resolution. This multi-functionality reduces the need for separate systems for each measurement task, thereby reducing overall device complexity.
3Area of stationary object
If the light fan is moved to rotate or pivot over a spatial region, then the solid angle range coverage is improved, but the mechanical complexity and potential for misalignment increase
Solution Approach 1:
The light fan is made rotatable or pivotable to dynamically adjust the angular coverage range. This dynamic capability allows the system to adapt to different measurement scenarios and cover various solid angle ranges as needed, while the mechanical design is kept relatively simple by using standard rotational or pivotal movements.
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 rough distance measurement with geodetic accuracy, enhancing the efficiency of surveying devices like total stations and laser scanners.
Implementation Method 1
an emitting unit, which emits optical radiation in the form of an emission fan oriented in a first direction to illuminate the target mark
Implementation Method 2
a receiving unit, which receives reflected portions or components of the optical radiation of the emission fan as reflections
Implementation Method 3
The optoelectronic detector is position-resolving in this case and is especially arranged and configured or formed in such a way that a position resolution can be carried out using it within the light fan
Implementation Method 4
a distance measuring unit, which ascertains distance values to the reflection on the basis of a runtime measurement of a light pulse from the emission fan to the reflection and back
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.