Dual-Surface XRF Analysis for Layered Sample Characterization
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Solution Overview
Problem
Analyzing layered samples using X-ray fluorescence (XRF) is challenging, especially when only a limited number of spectral lines are available, as it is difficult to determine the origin of measured signals from elements present in multiple layers, leading to incomplete analysis in industrial settings.
Innovation Solution
A method involving two X-ray measurements, one from each major surface of a layered sample, to obtain two X-ray intensity values for calculating multiple layer parameters such as concentration, density, and thickness, using an iterative process to converge on accurate values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a single XRF measurement is taken from one surface of a layered sample, then the measurement process is simple and quick, but only one analysis parameter can be obtained which is insufficient for determining multiple layer parameters when elements are present in multiple layers
Solution Approach 1:
The patent applies inversion by measuring the layered sample from both the front surface and the back surface. By inverting the measurement approach (taking measurements from opposite sides), the method obtains two independent intensity values that provide sufficient information to calculate multiple analysis parameters including layer thicknesses and concentrations, resolving the limitation of single-surface measurements
Solution Approach 2:
The patent transitions from a one-dimensional measurement (single surface) to a two-dimensional measurement approach (both surfaces). By adding the dimension of measuring from the opposite side, the system gains additional independent data that enables determination of multiple layer parameters simultaneously
2Measurement precision
If X-ray measurements are taken through layers of finite thickness, then information about elements in different layers can be obtained, but X-rays from one layer are partially absorbed by another layer making it difficult to determine signal origin
Solution Approach 1:
By measuring from both surfaces, the patent creates a system of equations where the absorption effects working in opposite directions can be mathematically resolved. The inversion approach allows determination of which layer contributes to the signal by comparing intensity ratios from front and back measurements
Solution Approach 2:
The patent uses an iterative calculation process where initial estimates of layer parameters are refined through repeated calculations. The feedback loop continuously improves the accuracy of determining signal origin by comparing calculated intensities with measured intensities from both surfaces
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 allows for the determination of double the number of analysis parameters compared to traditional methods, enabling the measurement of layer thicknesses and concentrations that were previously impossible to obtain, by inverting the sample or measuring from different sides, thereby providing sufficient data for accurate analysis.
Implementation Method 1
The measurement of samples by X-ray fluorescence (XRF) is a technique well known for industrial analysis
Implementation Method 2
With layers of finite thickness, X-rays on one layer may pass through another layer and be partially absorbed
Data Source
AI summary
A method of making X-ray fluorescence, XRF, measurements of a layered sample is described. At least two measurements are made, one through one surface of the sample and another through the opposite surface. This may be conveniently done by inverting the sample between the measurements. The data from the additional measurements may be used to calculate multiple parameters of the sample, such as the concentration, density or thickness of each of the layers.