Chromatic Point Sensor Dual Path Spectrum Compensation
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Solution Overview
Problem
Chromatic point sensors face measurement errors due to workpiece-specific spectral reflectivity variations, which existing systems struggle to compensate for effectively, leading to inaccuracies in distance measurements.
Innovation Solution
A chromatic point sensor system with dual optical paths, one confocal and one non-dispersive, allows for simultaneous acquisition of spectral profile data to compensate for material reflectivity variations, enabling robust error compensation by distinguishing distance-dependent and independent profile components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single confocal optical path is used for distance measurement, then measurement speed is improved, but measurement precision deteriorates due to workpiece-specific spectral reflectivity variations
Solution Approach 1:
The optical measurement system is segmented into two distinct optical paths: a first confocal optical path for distance measurement and a second non-dispersive optical path for spectral reflectivity characterization. This segmentation allows each path to perform its specific function optimally, with the confocal path maintaining high-speed distance measurement and the non-dispersive path providing accurate material property data for error compensation.
Solution Approach 2:
The second non-dispersive optical path acts as an intermediary that characterizes the workpiece material's spectral reflectivity properties. This intermediary measurement enables the system to understand and compensate for material-specific effects that would otherwise degrade the precision of the primary distance measurement, without interfering with the high-speed operation of the confocal path.
2Measurement precision
If compensation for spectral reflectivity variations is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The spectral reflectivity characterization function is extracted from the primary confocal measurement path and implemented through a separate second optical path. This extraction allows the compensation mechanism to be added without complicating the core confocal distance measurement system, maintaining its simplicity and high-speed performance while enabling precision improvement through material property compensation.
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 configuration provides more accurate and reliable distance measurements by compensating for errors associated with workpiece-specific spectral reflectivity variations, improving measurement precision and reliability.
Implementation Method 1
an optical element having axial chromatic aberration, also referred to as axial or longitudinal chromatic dispersion, may be used to focus a broadband light source such that the axial distance to the focus varies with the wavelength
Implementation Method 2
A confocal beam is split, and the split portions of the beam are spatially filtered at their focus with a confocal aperture
Implementation Method 3
a broadband light source such that the axial distance to the focus varies with the wavelength
Data Source
AI summary
A chromatic point sensor system configured to compensate for potential errors due to workpiece material effects comprises a first confocal optical path including a longitudinally dispersive element configured to focus different wavelengths at different distances proximate to a workpiece; a second optical path configured to focus different wavelengths at substantially the same distance proximate to the workpiece; a light source connected to the first confocal optical path; a light source connected to the second optical path; a first confocal optical path disabling element; a second optical path disabling element; and a CPS electronics comprising a CPS wavelength detector which provides output spectral profile data. The output spectral profile data from the second optical path is usable to compensate output spectral profile data from the first confocal optical path for a distance-independent profile component that includes errors due to workpiece material effects.