Triangulation Sensor Surface Reflectance Pre-Scan
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Solution Overview
Problem
Conventional triangulation measurement techniques face challenges in accurately measuring surfaces with varying reflectance properties, particularly mirror-like surfaces, due to issues with double reflections and inhomogeneous illumination, leading to reduced precision and measurement errors.
Innovation Solution
A method and device that utilize a triangulation-based fringe or pattern projection optical sensor to identify and segment regions with ambiguous measuring conditions by analyzing the optical behavior of the surface, employing defined illumination and digital models to determine surface properties and adjust measurement parameters, thereby reducing the impact of double reflections and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional triangulation measurement is used on surfaces with varying reflectance properties, then measurement speed is maintained, but measurement precision deteriorates due to double reflections and inhomogeneous illumination
Solution Approach 1:
The patent segments the measurement process into two distinct phases: a pre-measurement phase to capture illumination conditions and determine surface reflectance properties, and a subsequent measurement phase to acquire distance data. This segmentation allows the system to identify and compensate for problematic areas like double reflections before main measurements are taken, thereby improving measurement precision without requiring fundamental changes to the triangulation measurement system.
Solution Approach 2:
The patent implements preliminary action by performing a pre-measurement scan to determine illumination conditions and surface optical properties before conducting the main measurement. This preliminary data collection enables the system to identify areas with double reflections or inhomogeneous illumination and adjust measurement parameters accordingly, improving precision while maintaining system simplicity.
2Measurement precision
If multiple measurements are performed to account for varying surface properties, then measurement precision improves, but measurement time increases
Solution Approach 1:
The patent segments measurements into a quick pre-scan phase and a main measurement phase. The pre-scan captures essential illumination and surface property information that is then reused for the main measurement, avoiding the need for multiple redundant measurements while maintaining precision.
Solution Approach 2:
By performing preliminary measurements to determine surface optical properties and illumination conditions, the system prepares data that can be used to guide and optimize subsequent measurements. This preliminary action reduces the need for repeated measurements, thereby improving precision without proportionally increasing measurement time.
3Reliability
If illumination intensity is increased to improve signal detection on reflective surfaces, then measurement reliability improves, but double reflections become more prominent
Solution Approach 1:
The patent employs feedback by using pre-measurement data about surface reflectance properties and illumination conditions to guide and adjust subsequent measurements. This feedback loop allows the system to identify areas where double reflections are problematic and adjust measurement parameters or exclude those areas from analysis, maintaining reliability while mitigating the harmful effects of double reflections.
Solution Approach 2:
The system performs preliminary measurements to characterize surface optical properties and illumination conditions before main measurements. This preliminary information enables the system to anticipate and compensate for double reflection issues, maintaining measurement reliability without requiring excessive illumination intensity that would exacerbate double reflections.
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
The solution enables robust and reliable measurement results by distinguishing between primary and secondary reflections, ensuring accurate distance data acquisition even on challenging surfaces, and optimizing measurement conditions for improved precision and speed.
Implementation Method 1
the point or region to be illuminated is illuminated with measuring light and at least one image is captured by means of the optical sensor of at least one illumination at the object caused by illuminating the object
Data Source
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AI summary
Method of identifying a surface point or region (14,15) of an object to be measured of particular measuring properties for optical measurement of the respective point or region (14,15) by means of an optical sensor (10), the optical sensor (10) providing defined measuring conditions at least regarding emission of measuring light and reception of reflected measuring light in a defined spatial relationship. The method comprises defining a point or region (14,15) of interest of the object, determining an optical property of the defined point or of the defined region (14,15) with respect to a desired optical measurement and deriving an object information base on the optical property. The determination of the optical property is performed by optically pre-measuring the point or region (14,15) using the optical sensor (10) by illuminating the point or the region (14,15) with the measuring light, capturing at least one image by means of the optical sensor (10) of at least one illumination (Lr,Li) at the object and analysing respective illuminations (Lr,Li) regarding position and/or appearance plausibility with respect to the measuring conditions of the optical sensor (10); alternatively or additionally analysing a digital model of the object to be measured by digitally aligning the digital model in accordance with an orientation of the object relative to the optical sensor (10) and determining reflectivity properties of the point or region (14,15) based on the aligned model regarding an illumination with the measuring light in the orientation of the object relative to the optical sensor.