Optical Distance Measurement Using Beam Orientation Segmentation
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Solution Overview
Problem
Optical distance measurement methods face limitations in accuracy due to environmental influences like vibrations and rough surfaces, leading to measurement uncertainties caused by 'speckle effects' in interferometric and chromatic-confocal methods.
Innovation Solution
The method involves defining an optical measurement point region by the beam cross section corresponding to a multiple of the standard deviation of the Gaussian beam profile, altering the measurement direction to ensure area centroids lie within this region, and averaging distance information from multiple measurements to reduce statistical uncertainty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical distance measurement is performed on rough surfaces using interferometric or chromatic-confocal methods, then measurement range and speed are improved, but measurement precision deteriorates due to speckle effects and environmental vibrations
Solution Approach 1:
The measurement process is segmented into multiple individual measurements taken at different orientations around the measurement point. Instead of performing a single measurement, the method divides the measurement into multiple segments (individual measurements) that are subsequently combined through statistical evaluation, thereby reducing the impact of speckle effects and vibrations on overall measurement precision while maintaining high measurement speed
Solution Approach 2:
The method changes the orientation parameter of the measurement by performing individual measurements at different orientations around the measurement point. This parameter change allows the system to capture multiple independent measurements that can be statistically combined, reducing the influence of speckle effects and environmental vibrations on the final distance measurement accuracy
2Loss of time
If a single point measurement is performed, then measurement time is reduced, but measurement reliability deteriorates due to statistical uncertainty from speckle effects
Solution Approach 1:
The system performs preliminary individual measurements at different orientations before final evaluation. These preliminary measurements are quickly acquired and then subjected to statistical evaluation to determine the final distance value, reducing the impact of random speckle effects while maintaining efficient measurement timing
Solution Approach 2:
The method incorporates feedback through statistical evaluation of multiple individual measurements. The system evaluates the results of individual measurements taken at different orientations and uses this feedback to determine the final distance value with reduced statistical uncertainty, thereby improving measurement reliability without significantly increasing measurement time
3Manufacturing precision
If measurement radiation is focused to a small spot, then lateral resolution is improved, but measurement precision deteriorates due to increased sensitivity to surface roughness and vibrations
Solution Approach 1:
The measurement is segmented into multiple individual measurements taken at different orientations around the focused measurement spot. This segmentation allows the system to maintain the high lateral resolution provided by the focused beam while reducing the impact of surface roughness and vibrations through statistical evaluation of multiple measurements
Solution Approach 2:
The method changes the orientation parameter while keeping the focused spot size constant. By performing measurements at different orientations around the same focused spot, the system maintains high lateral resolution while reducing the influence of surface roughness and vibrations on distance measurement precision through statistical combination of results
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 enhances the precision and reliability of distance measurements, particularly on rough surfaces, by accounting for edge regions and varying signal strengths, thereby reducing measurement errors and improving accuracy.
Implementation Method 1
an optical measurement point region is defined by the beam cross section of said radiation on the object, in particular by a cross section corresponding to a maximum of ten times, in particular a maximum of eight times, in particular a maximum of six or four times, the standard deviation σ of a Gaussian steel profile of the measurement radiation
Implementation Method 2
reception of measurement radiation reflected at the object
Data Source
AI summary
A distance measuring method for a point on an object is performed by emitting measurement radiation. When an optical measurement axis of the measurement radiation is aligned with the point to be measured, an optical measurement point region is defined by the beam cross section of the radiation on the object. The beam cross section may be, for example, a maximum of eight times the standard deviation of a Gaussian steel profile of the measurement radiation. The the distance to the point on the object is determined by receiving measurement radiation reflected from the object. The method includes altering, at least once, a measurement direction as emission direction of the measurement radiation with respective emission and reception of the measurement radiation. Altering the measurement direction is carried out such that respective area centroids defined by the beam cross section on the object lie within the measurement point region.