Optical Sampling Apparatus Integrating Cavity Particulate Flow
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Solution Overview
Problem
Spectroscopic measurements of particulate samples, such as powders and granules, face challenges due to non-stationarity and non-linearity issues, particularly the parallel-paths, scatter coefficient, and hidden-mass effects, which render quantitative analysis unreliable, especially in online applications and continuous production environments.
Innovation Solution
A measurement apparatus and method where the sample is made optically thin by flowing through an integrating cavity, eliminating the hidden mass and parallel-path effects, allowing for fully representative and linear measurements by ensuring that the sample is uniformly probed, thereby reducing noise and variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical sampling is used on granule samples, then measurement can be performed, but non-stationary response and non-linearity occur due to parallel-paths, scatter coefficient, and hidden-mass effects
Solution Approach 1:
The granule sample is segmented into many small particles that are conveyed individually through the measurement beam. This segmentation eliminates the hidden-mass effect (each particle is fully probed) and the parallel-paths effect (particles are measured sequentially, not simultaneously along different paths), thereby achieving stationary and linear response for reliable quantitative measurement
Solution Approach 2:
The measurement system transitions from a static sample presentation to a dynamic flow-through configuration. Particles are continuously conveyed through the measurement beam one by one, creating a time-resolved measurement sequence. This dynamic approach eliminates non-stationarity by ensuring each particle is measured under identical optical conditions, with the beam always interacting with a single particle at a time
2Quantity of substance
If a thick sample bed is used to ensure representative sampling, then more sample is measured, but non-stationary response increases due to varying path lengths and scattering
Solution Approach 1:
The system implements continuous measurement of particles as they flow through the beam, ensuring that 100% of the sample is analyzed over time. The continuous flow maintains constant measurement conditions with each particle individually probed, eliminating the non-stationarity that would arise from measuring a static thick bed where path lengths and scattering conditions vary spatially
3Device complexity
If conventional diffuse reflection or transmission geometry is used, then measurement interface is simple, but optical power loss occurs and representative sampling is compromised
Solution Approach 1:
A flow cell is introduced as an intermediary component that guides particles through the measurement beam in a controlled manner. This flow cell ensures optimal optical coupling between the beam and each particle while maintaining a relatively simple overall interface. The flow cell design maximizes optical power transfer to achieve strong signals for representative sampling without excessive complexity
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 method achieves linear and time-stationary measurements, ensuring that virtually 100% of the sample is analyzed, providing accurate and reliable chemical composition analysis of particulate samples, particularly in continuous production settings.
Implementation Method 1
integrating cavity which creates a uniform light distribution through scattering
Implementation Method 2
integrating cavity which creates a uniform light distribution through scattering and reflection
Implementation Method 3
detecting an optical signal from the integrating cavity... by spectral analysis... quantitative analysis of an absorbance spectrum
Data Source
Figure 1A~1B
Figure 1C~2
Figure 3~5
AI summary
Method for measuring a chemical composition of a sample (6,26,36,46,56,82) comprising at least two chemical components, comprises the steps: -illuminating (74) an integrating cavity (1,2a,80,90) by a light source (14), -bringing the sample (6,26,36,46,56,82) into the integrating cavity (1,2a,80,90), -detecting (79) an optical signal from the integrating cavity (1,2a,80,90) using a sensor (19), and -indicating (75) the chemical composition of the sample (6,26,36,46,56,82) by spectral analysis. The sample (6,26,36,46,56,82) forms an optically thin layer in at least one dimension inside the integrating cavity (1,2a,80,90). The patent application contains independent patent claims also for optical measuring apparatus and method for measuring a chemical composition of a sample.