Phase Difference Element for Uniform Laser Spot in Particle Detector
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Solution Overview
Problem
Fine particle detectors face measurement errors due to variations in the flow position of particles within the sample flow, which are exacerbated by increased flow pressure, making it difficult to maintain uniform laser strength distribution and achieve high-precision, high-speed measurement.
Innovation Solution
A fine particle detector system that uses a phase difference element to divide light into regions, causing a phase difference between wavefronts, which widens the laser spot in the Y-axis direction, resulting in a uniform strength distribution over a wide range, thereby equalizing the effective laser strength emitted to particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow pressure of the sample flow is raised to increase the measurement speed, then the measurement speed is improved, but the flow width of the sample flow is widened, making it difficult to stably equalize the effective strength of the laser emitted to the particles
Solution Approach 1:
The patent divides the laser beam into multiple independent beams along the flow direction (X-axis) using a beam splitter and mirrors. Each beam is focused onto a different position in the sample flow, creating multiple focused spots. This segmentation allows the laser to simultaneously illuminate particles across a wider flow range, maintaining uniform illumination even when flow pressure increases and flow width expands, thus resolving the contradiction between measurement speed and laser strength uniformity.
Solution Approach 2:
The patent introduces the X-axis dimension (flow direction) to the laser illumination scheme. Instead of focusing all laser light onto a single point in the Y-Z plane, the system creates multiple focused spots distributed along the X-axis. This dimensional extension allows the laser to cover a broader effective area in the sample flow, compensating for the increased flow width caused by higher flow pressure and maintaining uniform illumination conditions.
2Measurement precision
If the spot shape is deformed to an ellipse to suppress differences in laser strength between fine particles, then measurement precision is improved, but the flow width of the sample flow cannot be stably equalized when flow pressure is raised
Solution Approach 1:
The patent segments the laser illumination into multiple independent beams distributed along the flow direction. Each beam creates a focused spot that can be independently optimized for uniformity. This segmentation allows the system to maintain elliptical spot shapes with uniform strength distribution while simultaneously covering a wider effective area through the multiple spots, thus achieving both precision and high measurement speed even at elevated flow pressures.
Solution Approach 2:
The patent extends the laser illumination from a two-dimensional focused spot to a three-dimensional distribution of multiple spots along the flow direction. This dimensional change allows the system to maintain uniform illumination in the Y-direction (through elliptical spot shaping) while simultaneously covering a broader X-direction range, enabling stable equalization of laser strength across particles even when flow pressure increases the flow width.
3Device complexity
If a single focused laser spot is used to illuminate fine particles, then the device complexity is low, but measurement precision deteriorates due to variations in flow position causing differences in laser strength
Solution Approach 1:
The patent divides the single laser beam into multiple independent beams using beam splitters and mirrors. Each beam is then focused onto a different position in the sample flow, creating multiple focused spots. This segmentation increases device complexity but achieves superior measurement precision by ensuring uniform laser illumination across all particle positions, eliminating the measurement errors caused by flow position variations that occur with a single focused spot.
Solution Approach 2:
The patent transitions from a single-point focused illumination to a multi-point distributed illumination along the flow direction. By introducing the X-axis dimension with multiple spaced-apart focused spots, the system achieves uniform coverage across the sample flow. This dimensional expansion of the illumination pattern compensates for flow position variations and maintains consistent laser strength delivery to particles regardless of their exact position in the flow.
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 effectively suppresses differences in laser emission strength between particles caused by flow position variations, enabling high-precision and high-speed measurement by maintaining a consistent laser spot strength across the sample flow.
Implementation Method 1
a phase difference element that has a plurality of regions divided in the Y-axis direction and causes a phase difference between wavefronts of light passing through the plurality of regions
Implementation Method 2
focusing the light on a sample flow through which fine particles flow
Data Source
AI summary
A fine particle detector includes a light emitting system letting light from a light source pass through a phase difference element and focusing the light on a sample flow through which fine particles flow. When the direction of the sample flow is an X-axis direction, the light is emitted to the sample flow in a Z-direction, and a ZX-plane is orthogonal to a Y-direction, then the phase difference element has a plurality of regions divided in the Y-axis direction and causes a phase difference between wavefronts of the light passing through the plurality of regions.