Particle Size Detection Using Segmented Detector Array
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Solution Overview
Problem
Conventional methods for detecting particle size in fluids, such as liquid particle counters, face limitations due to the use of single sensing elements, which struggle to accurately distinguish between small and large particles and are prone to errors from out-of-focus imaging and background scattering, leading to inaccurate particle size determination.
Innovation Solution
A system and method utilizing a digital detector with an optical lens and a laser source to emit a laser beam, which generates a metric for scattered light intensity, allowing for the correction of particle size determination by comparing initial intensity to data on focused and defocused particles, enabling precise differentiation between particle sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensing element (photodiode or photomultiplier tube) is used for particle detection, then the device complexity is reduced, but the measurement precision deteriorates because it cannot distinguish between small particles at the center and large particles at the periphery of the laser beam
Solution Approach 1:
The single sensing element is replaced with a segmented array of sensing elements (photodetectors) arranged in multiple rows and columns. Each element detects light scattering from particles passing through its specific region, enabling spatial resolution and accurate particle size determination while maintaining reasonable device complexity
Solution Approach 2:
The detection system transitions from a single-point detection (0D) to a two-dimensional array of sensing elements. This dimensional expansion allows simultaneous detection of particles at different positions across the laser beam cross-section, resolving the ambiguity between small central particles and large peripheral particles
2Ease of operation
If light scattering detection is performed with a laser beam having greater intensity at the center than at the periphery, then the ease of operation is improved, but the measurement precision deteriorates because small particles at the center and large particles at the periphery produce similar scattering signals
Solution Approach 1:
The detector array segments the detection field into multiple spatial zones corresponding to different regions of the laser beam. This segmentation allows the system to maintain the simple Gaussian laser profile while accurately measuring particles regardless of their position in the beam, as each detector element records scattering from its specific zone
Solution Approach 2:
The system uses the spatial distribution of scattered light signals across the detector array to infer particle position and size. By analyzing which detector elements receive scattering signals and their relative intensities, the system provides feedback that enables accurate particle characterization despite the non-uniform laser intensity profile
3Device complexity
If conventional particle detection methods are used, then the device complexity is kept simple, but the reliability deteriorates due to inability to distinguish multiple particles in the field of view and susceptibility to background scattering
Solution Approach 1:
The detector array divides the field of view into multiple independent sensing zones. When multiple particles pass through the beam simultaneously, each particle scatters light to different detector elements based on its position, allowing the system to reliably distinguish and count multiple particles that would be indistinguishable to a single sensing element
Solution Approach 2:
The system detects variations in the spatial distribution pattern of scattered light across the detector array. Different particle positions create distinct spatial patterns, analogous to color changes, enabling reliable particle identification and size measurement even in the presence of background scattering
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 solution enhances the accuracy of particle size detection by reducing background noise and distinguishing between small and large particles, even when they are out of focus, thereby improving the precision of particle size measurement in fluids like ultrapure water.
Implementation Method 1
The scattered light is scattered from one or more particles passing through the sample area. The scattered light includes light from the first laser beam.
Implementation Method 2
A first imaging device that includes an optical lens and a digital detector. The first laser beam is directed to pass through the sample area by the first imaging device.
Data Source
AI summary
Examples disclosed herein relate to system and method for detecting the size of a particle in a fluid. The system includes a conduit for transporting a fluid and a sample area. Some of the fluid passes through the sample area. A first imaging device has an optical lens and a digital detector. A laser source emits a first laser beam. The digital detector generates a metric of an initial intensity of a scattered light that passes through the optical lens. The scattered light is scattered from particles passing through the sample area, and includes light from the first laser beam, which passes through the sample area. A controller outputs a corrected particle intensity based upon a comparison of the initial intensity to data representative of intensity of a focused and defocused particle. The corrected particle intensity generates a corrected metric corresponding to an actual size of the particles.