Radially Arrayed Spectrophotometer Sensor Tilt Correction
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Solution Overview
Problem
Radially arrayed spectrophotometer sensors experience cyclic variations in signal due to tilt, leading to errors in color measurement and reproduction, as signals from sensors further away from the target surface are attenuated while those closer are increased, causing misalignment issues between calibration and measurement surfaces.
Innovation Solution
A method and system that corrects sensor measurements by correlating each sensor's position with a reference frame, determining the magnitude and phase of misalignment, and applying corrective adjustments to the sensor data using a discrete Fourier transform and sinusoidal modeling to account for cyclic modulation effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sensor array is radially arrayed to enable compact design and omnidirectional measurement capability, then the device complexity is reduced and ease of operation is improved, but tilt-induced cyclic variations are introduced causing measurement precision to deteriorate
Solution Approach 1:
The system uses a calibration medium with known reflectance properties to establish a reference signal. By comparing measurements from the calibration medium with expected values, the system calculates correction factors that compensate for tilt-induced variations. These correction factors are then applied to subsequent measurements of unknown samples, effectively using feedback from the calibration process to eliminate measurement errors.
Solution Approach 2:
The invention introduces correction factors as adjustable parameters that modify the raw sensor readings. By calculating these correction factors based on the calibration medium measurements and applying them to transform the sensor signals, the system changes the parameters of the measurement data to compensate for geometric variations caused by tilting, thereby restoring measurement precision.
2Ease of operation
If the sensor plane is tilted with respect to the target surface to accommodate misalignment, then ease of operation is improved, but cyclic variations in signal intensity occur causing measurement precision to worsen
Solution Approach 1:
The system performs a preliminary measurement using a calibration medium with known reflectance properties before measuring unknown samples. This preliminary action allows the system to characterize the tilt-induced variations in advance and calculate correction factors that can be applied to subsequent measurements, effectively preparing compensation data before actual measurement takes place.
Solution Approach 2:
The calibration process creates a feedback loop where the known reflectance values of the calibration medium are compared with actual sensor readings. This feedback enables the system to calculate correction factors that compensate for tilt effects, and these corrected values are then used to process measurements of unknown samples, ensuring accurate results despite plane tilting.
3Measurement precision
If correction factors are applied to compensate for tilt effects, then measurement precision is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The correction factors are calculated in advance during a calibration process using a calibration medium with known properties. By performing this complex calculation beforehand rather than in real-time during sample measurement, the system reduces the processing complexity during actual measurement operations. The pre-calculated correction factors can then be applied efficiently to subsequent measurements.
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 effectively reduces cyclic modulation in sensor signals, providing more accurate color measurements by accounting for tilt-induced variations, ensuring consistent calibration and measurement alignment without requiring sensor repositioning or re-measurement.
Implementation Method 1
receiving with the plurality of sensors radiation reflected off a calibration medium from the illumination source
Implementation Method 2
using a discrete Fourier transform and sinusoidal modeling to account for cyclic modulation effects
Data Source
AI summary
A correction algorithm may be applied for correcting misalignment of a radially-aligned array of sensors. Due to the tilt, signals from sensors that are further away from the media, may become slightly attenuated, while signals from sensors that are closer to the media are slightly increased. The error appears periodic and largely sinusoidal in nature around the array given the circular nature of the array of sensor elements. The algorithm determines the magnitude and phase of a sinusoidal function that best fits the wavelength data. In one embodiment, a discrete Fourier transform may be performed at the ‘frequency’ equivalent to one period around the array to determine the magnitude and phase estimate thereof. Then, a sinusoidal correction function may be generated using the magnitude and the phase in order to correct the reflectance data.