Two Cell Echo DWS for Cloudy Sample Analysis
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Solution Overview
Problem
Current methods for dynamic light scattering, such as Diffusing Wave Spectroscopy, are time-consuming and limited to quasi-transparent samples, requiring lengthy measurements and sample dilution for cloudy samples like milk, which hinders the characterization of viscoelastic properties.
Innovation Solution
A measuring device utilizing a two-cell echo DWS method with rapid rotation of a frosted glass pane to generate ensemble-averaged correlation echoes, allowing for the determination of the intensity autocorrelation function with minimal time averaging, significantly reducing measurement time by a factor of 100-1000.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional DWS measurement methods are used, then measurement precision can be maintained, but measurement time is excessively long
Solution Approach 1:
The frosted glass pane is rotated at a constant frequency to periodically modulate the light scattering paths, generating correlation echoes that encode the intensity autocorrelation function. This periodic modulation allows the measurement to capture ensemble-averaged information over multiple rotation cycles, achieving precise correlation function determination in much shorter time compared to traditional continuous averaging methods.
Solution Approach 2:
The frosted glass pane is rotated during the measurement process to pre-establish an ensemble-averaged signal distribution before the actual correlation measurement is completed. This preliminary rotation-based averaging prepares the optical paths in advance, so that when the correlation measurement is taken, the data already reflects ensemble-averaged behavior, eliminating the need for lengthy post-measurement averaging.
2Adaptability or versatility
If classical static and dynamic light scattering methods are used, then simple scattering processes can be analyzed, but only quasi-transparent samples can be examined
Solution Approach 1:
A frosted glass pane is introduced as an intermediary diffusing element between the laser source and the sample. This diffuser creates multiple scattered light paths that probe the sample from different angles and positions simultaneously. The frosted glass acts as a mediator that transforms the direct beam into a diffuse illumination field, enabling the measurement of optically cloudy samples that would otherwise be inaccessible to conventional light scattering methods.
Solution Approach 2:
The illumination is segmented into multiple independent scattering paths by the rotating frosted glass pane. Each point on the frosted glass creates a separate light path through the sample, and the rotation samples different spatial segments of the sample. This segmentation of the optical path allows the measurement to probe heterogeneous and cloudy samples effectively, as each segment contributes independent information to the overall correlation signal.
3Object-affected harmful factors
If heavy dilution is applied to cloudy samples, then measurement becomes possible with classical methods, but sample concentration is reduced
Solution Approach 1:
The frosted glass diffuser serves as an intermediary that enables direct measurement of undiluted cloudy samples. By creating multiple scattered light paths, the diffuser allows the probe light to penetrate and interact with the concentrated sample without requiring dilution. The diffuser mediates between the coherent laser light and the turbid sample, making the measurement possible while preserving the native sample concentration and properties.
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 enables rapid characterization of viscoelastic properties in cloudy samples with improved signal/noise ratio and reduced measurement time, allowing for characterization of relaxation in under a minute, particularly relevant for complex systems with viscoelastic properties in the frequency range of 0.1-1000 rad/sec.
Implementation Method 1
The light beam first runs through a cell filled with a highly viscous colloidal suspension before it reaches the measuring cell itself... a light source for generating a laser beam (1) which illuminates an opaque (cloudy) solid substance (2) (e.g. a frosted glass pane). The diffusely transmitted light illuminates the sample (4)
Implementation Method 2
the dynamic multiple scattering of a cloudy sample being determined by an autocorrelation function of the scattered and detected light... The light beam first runs through a cell filled with a highly viscous colloidal suspension before it reaches the measuring cell itself
Implementation Method 3
a detection unit which registers the reflected or transmitted light (5,6)... the dynamic multiple scattering of a cloudy sample being determined by an autocorrelation function of the scattered and detected light
Data Source
Figure 1
Figure 2
AI summary
Measuring instrument has light source for producing laser beam (1), which lights (2) up an opaque solid substance. One light source lights up two consecutive units, which contains one, having a constant frequency oscillator or rotation unit (2b) and the another one the substance (probe), which can be examined.