Chromatic Range Sensor Dynamic Intensity Compensation
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Solution Overview
Problem
Prior chromatic point sensor (CPS) systems experience measurement errors due to variations in the spectral profile of the light source caused by different power levels, leading to inconsistent distance measurements.
Innovation Solution
A CPS system with an optical pen and electronics that include a power level spectral compensation portion to normalize the output spectral profile data, using pre-characterized power level compensation data to correct for intensity inconsistencies arising from different power levels, ensuring accurate distance measurements regardless of the power level used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light source is operated at higher power levels to improve signal strength, then measurement sensitivity is improved, but spectral profile variations cause measurement precision to deteriorate
Solution Approach 1:
The system measures the actual spectral profile at each power level and uses this feedback to dynamically adjust the distance measurement. The spectral compensation module compares the measured spectral profile against reference profiles stored in memory, and automatically selects or adjusts the measurement parameters based on the detected power level characteristics, eliminating the need for manual calibration.
Solution Approach 2:
The system changes the operational parameters (spectral compensation factors) based on the detected power level. Different power levels have different spectral profiles, and the system stores multiple sets of compensation parameters corresponding to different power levels. The system dynamically switches between these parameter sets to maintain measurement accuracy across all power levels.
2Measurement precision
If manual calibration for each power level is implemented to improve measurement precision, then distance measurement accuracy is improved, but device complexity and ease of operation worsen
Solution Approach 1:
The system performs automatic self-calibration by measuring the spectral profile at each power level and autonomously determining the appropriate compensation parameters. The spectral compensation module automatically compares measured spectra with reference data and selects the correct calibration parameters without requiring user intervention, making the system self-sufficient and eliminating complex manual calibration procedures.
Solution Approach 2:
The system pre-stores multiple sets of spectral compensation parameters in memory, each corresponding to a specific power level. This preliminary preparation of calibration data allows the system to quickly switch between calibrated states without performing real-time calibration, reducing both complexity and operation time while maintaining high precision across all power levels.
3Measurement precision
If multiple calibration parameters are stored for different power levels to improve measurement precision, then distance measurement accuracy is improved, but memory requirements and device complexity increase
Solution Approach 1:
Instead of storing complete spectral profiles for every possible power level, the system stores only the essential compensation parameters (such as peak wavelength offsets or scaling factors) that are specific to each power level. This localized storage of critical parameters rather than complete spectral data significantly reduces memory requirements while maintaining the ability to compensate for power level variations.
Solution Approach 2:
The system extracts and stores only the key characteristics of spectral profiles at different power levels (such as peak position, bandwidth, or intensity ratios) rather than storing the entire spectral distribution. This extraction of essential features allows the system to maintain high measurement precision while minimizing memory storage 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 effectively compensates for power-level dependent errors, providing stable and accurate distance measurements by normalizing the output spectral profile data, making the power level selection transparent to the user and reducing measurement variability.
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
Upon reflection from the surface, the light is refocused onto a small detector aperture, such as a pinhole or the end of an optical fiber
Implementation Method 3
the light is refocused onto a small detector aperture
Implementation Method 4
A spectrometer-type detector measures the signal level for each wavelength, in order to determine the surface height
Data Source
AI summary
A chromatic point sensor (CPS) system is provided, which compensates for potential errors due to input spectral profile intensity inconsistencies that arise when driving a CPS illumination source using different power levels. The CPS system includes an optical pen comprising a confocal optical path including a chromatically dispersive element and configured to focus different wavelengths at different distances proximate to a workpiece surface to be measured, an illumination source, and CPS electronics. The CPS electronics include: an illumination source control portion configured to drive the illumination source using different power levels; a CPS wavelength detector comprising a plurality of pixels distributed along a measurement axis of the CPS wavelength detector to provide output spectral profile data; and a power level spectral compensation portion configured to compensate the output spectral profile data to remove or reduce potential errors due to input spectral profile intensity inconsistencies that arise when driving the CPS illumination source using the different power levels.