Iterative Calibration Factor for Optical Property Determination
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Solution Overview
Problem
Existing methods for determining the optical properties of samples, such as diffuse reflectance spectroscopy, rely on a priori knowledge of the sample's diffusion model, which limits their applicability to complex samples and introduces dependencies between optical property estimates at different wavelengths.
Innovation Solution
A method involving the application of an updating factor based on backscattering distance and the use of a calibration factor that is updated iteratively to improve the estimation of optical properties, allowing for more accurate determination of reflectance and absorption coefficients without relying on a specific diffusion model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light scattering model is used to represent the evolution of the reduced scattering coefficient in the calibration sample, then the determination of optical properties can be performed, but the method becomes unsuitable for complex samples whose prior scattering model is unknown and introduces dependencies between optical property estimates at different wavelengths
Solution Approach 1:
The patent extracts and removes the dependency on a priori scattering models from the calibration process. Instead of requiring a light scattering model to represent the evolution of the reduced scattering coefficient, the method uses measured backscattered signals directly from calibration samples to determine calibration factors. This extraction of the model dependency allows the method to be applied to complex samples whose scattering behavior is unknown or cannot be modeled.
Solution Approach 2:
The patent uses calibration samples that replicate the optical properties of the actual samples being measured. By measuring backscattered signals from calibration samples with known optical properties and using these to determine calibration factors, the method creates a direct empirical mapping without requiring theoretical scattering models. This copying approach ensures the method works for any sample type, including complex biological tissues.
2Measurement precision
If a light scattering model is used to describe the evolution of the scattering coefficient, then optical properties can be determined, but estimates of optical property at different wavelengths are not independent of each other
Solution Approach 1:
The patent segments the determination of optical properties at each wavelength by using independent calibration factors for each wavelength. Instead of using a continuous scattering model that couples all wavelengths, the method determines separate calibration factors from backscattered signals measured at each wavelength. This segmentation allows each wavelength's optical property estimate to be independent, eliminating the artificial dependencies introduced by model-based approaches.
3Measurement precision
If a calibration factor is applied to the signal measured by the photodetector, then the determination of optical properties can be performed, but the precision of optical property estimation is limited without updating the calibration factor
Solution Approach 1:
The patent implements feedback by iteratively updating the calibration factor based on the measured backscattered signals and the determined optical properties. The calibration factor is not fixed but is refined through multiple iterations, with each iteration improving the accuracy of the optical property estimation. This feedback mechanism ensures that the calibration factor remains representative of the actual sample properties being measured, significantly improving measurement precision and reliability.
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 enhances the precision of optical property estimation by using a calibration factor that is representative of the sample's optical properties, reducing errors and improving the accuracy of measurements across various wavelengths.
Implementation Method 1
a light source capable of emitting a beam of light towards a surface of said sample, so as to form, on said surface, an elementary zone of illumination
Implementation Method 2
a photodetector, capable of acquiring, a backscatter signal, representative of radiation backscattered by the sample
Implementation Method 3
a photodetector, capable of acquiring, a backscatter signal
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A
AI summary
The invention concerns the technique of optical scatter measurement of a sample, and more particularly the analysis of a signal representative of the radiation back-scattered by a sample illuminated by a light beam. The aim of such an analysis is to determine optical properties of the sample. The method implemented is an iterative method for applying, to the analysed signal, a calibration factor taking optical properties of the sample into consideration.