Method for determining relative degrees of reflectance of a measurement surface

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Solution Overview

Problem

Existing methods for determining the relative degrees of reflection on measurement surfaces are either too slow or lack sufficient spatial resolution, which is crucial for applications like solar thermal tower power plants and architectural measurements.

Innovation Solution

A method involving the movement of a measurement spot along two non-parallel paths, with spatially resolved images recorded at intersection points using evaluation lines, allowing for higher measurement point density and faster determination of relative degrees of reflection, even with inhomogeneous intensity profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single path movement is used to scan the measurement surface, then the measurement process is simple, but the spatial resolution and measurement point density are insufficient

Engineering Contradiction:
Improvespatial resolutionVSAvoidmeasurement path complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measurement surface is scanned by dividing the path into multiple straight line segments (first measurement spot path and second measurement spot path) that intersect at evaluation lines. This segmentation allows higher measurement point density at intersections while keeping each individual path segment simple and straight, resolving the contradiction between spatial resolution and path complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from a single one-dimensional path scan to a two-dimensional grid-like measurement pattern by introducing evaluation lines that intersect the measurement paths. This dimensional expansion creates intersection points that serve as high-density measurement locations, improving spatial resolution without requiring continuous scanning across the entire surface.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If more measurement points are recorded to improve spatial resolution, then the measurement accuracy increases, but the measurement time increases

Engineering Contradiction:
Improvespatial resolutionVSAvoidmeasurement speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

Evaluation lines are pre-defined and the measurement spot paths are planned to intersect these lines at specific points before measurement begins. This preliminary planning ensures that measurement points are concentrated at critical intersection locations, achieving high spatial resolution only where needed rather than uniformly across the entire surface, thus reducing total measurement time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The measurement system applies different measurement densities to different regions: high density at intersection points of evaluation lines and lower density in between. This local quality approach concentrates measurement resources at critical locations where reflectance determination is most important, improving overall measurement efficiency while maintaining necessary spatial resolution.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If a measurement spot with inhomogeneous intensity profile is used, then the light source is more practical and easier to implement, but the measurement accuracy deteriorates

Engineering Contradiction:
Improvelight source implementationVSAvoidreflectance determination accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The invention extracts and isolates the maximum gray value from each image at the intersection points, ignoring the inhomogeneous intensity distribution across the measurement spot. By focusing only on the peak value and not the overall intensity profile, the method eliminates the influence of inhomogeneous illumination, allowing practical light sources to be used without compromising measurement accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The evaluation method changes from considering the full intensity distribution of the measurement spot to using only the maximum gray value parameter. This parameter transformation makes the measurement insensitive to intensity profile variations, enabling the use of practical inhomogeneous light sources while maintaining measurement precision through a simplified evaluation metric.

Inventive Principle:
Principle #35Parameter changes

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 approach enables faster and more spatially resolved determination of relative degrees of reflection, reducing the need for precise calibration and accommodating various intensity distributions, thus improving measurement efficiency and accuracy.

Implementation Method 1

the measurement surface is exposed to measurement radiation, so that a measurement spot is formed on the measurement surface

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3861324B1Method for determining relative degrees of reflectance of a measurement surface
Publication Date: 2022.08.10 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3861324B1 patent drawingFigure 1
  • EP3861324B1 patent drawingFigure 2
  • EP3861324B1 patent drawingFigure 3

AI summary

The invention relates to a method for determining relative degrees of reflectance of a measurement surface, having the method steps A. Applying measurement radiation to the measurement surface, such that a measurement spot is produced on the management surface, B. moving the measurement spot along at least a first straight measurement spot path, over the measurement surface in accordance with a first path movement, C. recording a first image set of a plurality of locally resolved images of the measurement surface during the first path movement according to step B, and D. determining relative degrees of reflectance for a plurality of local points of the measurement surface. The invention is characterized in that in method step B the measurement spot is additionally moved at least along a second straight measurement path, which is not parallel to the first measurement set path, in a second path movement over the measurement surface, in such a way that a first measurement path region of the measurement surface, over which the measurement sweeps during the first path movement at least overlaps a second measurement path region of the measurement surface over which the measurement spot sweeps during the second path movement, in that in method step C a recording of a second image set of a plurality of locally resolved images of the measurement surface is carried out during the second path movement according to step B, and in that in method step D an evaluation is carried out at intersection points, whose location points on the management surface are defined by evaluation lines, wherein a first group of straight evaluation lines within the first measurement path region and at least a second group of straight evaluation lines within the second measurement path region are predefined and/or determined, wherein these groups have at least two evaluation lines which are spaced apart from each other, the evaluation lines of the first group are parallel to the first measurement spot path and the evaluation lines of the second group are parallel to the second measurement spot path, and each evaluation line of the first group has an intersection point with each evaluation line of the second group, wherein for each image set, in each case for each intersection point, a maximum grey value is determined, and in that in method step D relative degrees of reflectance of the measurements surface are determined at least on a subset of the intersection points, depending on these grey values.