Shape Measurement System Speckle Noise Correction
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Solution Overview
Problem
The measurement accuracy of a target object's shape is compromised due to noise from the positional relationship between the measurement device and the object, particularly when a rough surface is inclined, leading to high repetitive reproducibility errors caused by speckles generated by laser light.
Innovation Solution
A shape measuring system that includes a distance measuring head, a distance measuring device, and a control device to analyze the distance detection waveform, calculate feature amounts, and perform correction or reliability weighting to improve measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser light is used to measure the shape of a rough inclined surface, then non-contact measurement is achieved, but speckle noise causes measurement errors with high repetitive reproducibility
Solution Approach 1:
The patent applies periodic action by performing multiple measurements at the same location and combining the results. The measurement process is repeated multiple times, and the final measurement value is determined through statistical processing of these periodic measurements, which reduces the impact of speckle noise while maintaining measurement efficiency.
Solution Approach 2:
The patent changes the parameter of measurement timing by performing measurements at different time points. Since speckle patterns change randomly over time, taking measurements at multiple time points and combining them statistically reduces the influence of speckle noise, thereby improving measurement accuracy without requiring additional hardware.
2Measurement precision
If multiple measurements are performed with reliability weighting, then measurement accuracy improves, but measurement time increases
Solution Approach 1:
The patent applies partial action by performing a limited number of repeated measurements (not excessive) and using statistical processing to obtain the final result. This approach achieves sufficient accuracy improvement without requiring an excessive number of measurements, thus balancing measurement accuracy with time efficiency.
3Measurement precision
If the beam diameter of laser light is reduced to improve spatial resolution, then measurement detail improves, but measurement error due to inclination increases
Solution Approach 1:
The patent changes the parameter of beam diameter dynamically. By adjusting the beam diameter according to the inclination angle of the measurement surface, the system maintains optimal measurement conditions: smaller beam diameter for steep inclines to reduce error, and larger beam diameter for shallow inclines to maintain spatial resolution, thus balancing both requirements.
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 system enables high-accuracy shape measurement of target objects by correcting measurement errors and weighting reliability, effectively mitigating the impact of speckle-induced noise on rough inclined surfaces.
Implementation Method 1
a distance measuring device configured to generate a distance detection waveform based on the reflected light
Implementation Method 2
a laser light source configured to emit laser light
Data Source
AI summary
A shape of an object is measured with a high degree of accuracy. A shape measurement system comprises: a distance measuring head for irradiating an object with light and receiving light reflected from the object; a distance measuring device for generating a distance detection waveform on the basis of the reflected light; and a control device for analyzing the distance detection waveform and calculating a measured distance value to the object. The shape measurement system is characterized in that the control device calculates a feature amount of the distance detection waveform and performs at least one of a process of correcting an error in the measured distance value by substituting the feature amount into a correction formula and a process of performing a confidence weighting of an error in the measured distance value by substituting the feature amount into a confidence weighting formula.