Broad-Spectrum Triangulation for 3D Profiling of Specular Surfaces
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Solution Overview
Problem
Existing 3D optical measurement technologies, such as laser triangulation and spectral confocal imaging, face issues with high cost, complexity, and poor performance on specularly reflected objects due to narrow spectrum light sources and complex light paths.
Innovation Solution
A 3D measurement method utilizing a broad spectrum light source with a dispersion lens and high resolution imaging lens, combined with a displacement driving mechanism and data processing system, to establish a mapping relation between object and image plane coordinates, enabling accurate 3D profiling of objects with large tolerance angles and reduced system volume and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser triangulation measurement uses collimated laser (narrow spectrum), then cost and efficiency are improved, but imaging quality of specularly reflected objects deteriorates
Solution Approach 1:
The patent changes the spectral parameter from narrow spectrum (laser) to broad spectrum light source. This parameter change allows the system to maintain the cost advantages of laser triangulation while improving imaging quality on specularly reflected objects by using a broad spectrum light source with spectral width greater than 10nm, which provides better angular compatibility and imaging performance
2Measurement precision
If spectral confocal imaging measurement uses focused light beam, then imaging quality and angle compatibility are improved, but system complexity and cost increase
Solution Approach 1:
The patent extracts the spectrometer from the system configuration. By using a broad spectrum light source and removing the need for spectral analysis, the system eliminates the complex spectral confocal imaging components while maintaining improved imaging quality and angle compatibility through the dispersion lens and imaging lens arrangement
Solution Approach 2:
The patent makes the dispersion lens serve multiple functions: it disperses the broad spectrum light source, focuses different wavelengths at different heights, and works with the imaging lens to create the measurement system. This multi-functionality reduces system complexity by eliminating the need for separate spectrometer components
3Measurement precision
If spectral confocal imaging uses dispersion confocal and spectral measurement, then measurement accuracy is improved, but system size and cost increase
Solution Approach 1:
The patent removes the spectrometer and spectral analysis components from the system. By using a broad spectrum light source that directly provides the necessary spectral information without requiring post-measurement spectral analysis, the system eliminates the large and complex spectral confocal imaging apparatus while maintaining measurement accuracy
Solution Approach 2:
Instead of using a narrow spectrum laser and analyzing the reflected light spectrum to determine height (spectral confocal approach), the patent inverts the approach by using a broad spectrum light source where the dispersion lens directly focuses different wavelengths at different heights, eliminating the need for spectral analysis and reducing system size
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 method achieves high measurement precision and compatibility on specularly reflected objects, reducing system complexity and cost while expanding application scenarios, including measurement of objects like metals and glass with surface features.
Implementation Method 1
the dispersion lens is arranged to focus colored light with different colors of the divergent beam at different heights surface of the measured object to form a focused light beam
Implementation Method 2
the dispersion lens is arranged to focus colored light with different colors of the divergent beam at different heights surface of the measured object to form a focused light beam
Implementation Method 3
the high resolution imaging lens focuses the reflected light beam to the imaging detector for imaging
Implementation Method 4
the imaging detector and the data processing system are configured to convert an optical signal into an electric signal
Data Source
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AI summary
Disclosed is a method for measuring a triangular profile based on a broad spectrum light source, including the following steps: first, building a laser triangulation measurement model; putting a calibrator in the laser triangulation measurement model, measuring object plane coordinates (x, z) of the calibrator by virtue of a measuring instrument, driving the calibrator many times to acquire object plane coordinates of a plurality of groups of calibrators and corresponding image plane coordinates, so as to obtain a coefficient-determined relational expression of a two-variable linear function; and finally, putting a measured object in the laser triangulation measurement model, acquiring, by an imaging detector, image plane coordinates (u, v) of a surface of the measured object plane, calculating a coordinate z of the surface of the measured object through the relational expression of the function, driving, by a displacement driving mechanism, the measured object to move relative to an optical axis of a focused light beam in a perpendicular direction to measure a coordinate y, and splicing an object plane profile (x, z) in a displacement distance to obtain a whole object plane profile of the measured object, so as to obtain a 3D size of the whole measured object. The present invention features a large tolerance angle, high compatibility, and a high measurement accuracy, and the volume and cost are greatly reduced.