Uniaxial Crystal Flow Cell C-Axis Orientation for SNR
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Solution Overview
Problem
In particle measuring devices, birefringence in crystalline flow cells leads to the generation of extraordinary light, causing astigmatism and degrading the light condensing performance and signal-to-noise ratio (SNR) due to the anisotropy of the crystalline material, particularly in interference systems.
Innovation Solution
A flow cell made of uniaxial crystal material is configured such that the crystallographic c-axis is perpendicular to both the receiving direction and polarization direction of the scattered light, preventing extraordinary light from forming and thus reducing astigmatism and improving SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crystalline flow cell is used to detect light for particle counting, then the flow cell can be produced with required optical characteristics and mechanical strength, but birefringence occurs when scattered light passes through the light transmitting plate, causing astigmatism and degrading light condensing performance and SN ratio
Solution Approach 1:
The patent applies local quality by orienting the c-axis perpendicular to the scattered light path only in the specific region where scattered light passes through, while other regions can have different orientations. This localized optimization eliminates birefringence effects in the critical path without compromising the overall structural integrity or optical characteristics of the flow cell.
Solution Approach 2:
The patent introduces asymmetry by deliberately setting the c-axis orientation at a specific angle (perpendicular) relative to the scattered light direction, rather than using a random or conventional orientation. This asymmetric arrangement is specifically designed to eliminate the harmful birefringence effect while maintaining the crystalline material's inherent strengths.
2Ease of operation
If the polarization direction of irradiation light is set perpendicular to the receiving direction of scattered light, then the polarization direction of scattered light coincides with the c-axis direction, but this causes the scattered light to serve as extraordinary light due to birefringence, leading to astigmatism
Solution Approach 1:
Instead of adjusting the polarization direction to avoid the problem, the patent inverts the approach by changing the c-axis orientation relative to the fixed polarization direction. By setting the c-axis perpendicular to the scattered light path, the patent transforms the problematic extraordinary light into ordinary light, effectively eliminating birefringence effects.
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 configuration suppresses extraordinary light generation, enhancing the light condensing performance and SNR by ensuring that scattered light behaves as ordinary light, leading to more accurate particle detection and measurement.
Implementation Method 1
Due to anisotropy of the crystalline material having the optical axis, birefringence occurs when the scattered light passes through the light transmitting plate
Implementation Method 2
Due to anisotropy of the crystalline material having the optical axis, birefringence occurs when the scattered light passes through the light transmitting plate
Data Source
AI summary
A flow cell includes a body and a flow channel. The body is formed out of blocks made of an uniaxial crystal material and joined to one another. The flow channel is formed inside the body, so that the flow cell is configured to be used to measure particles passing through the flow channel based on reception of scattered light generated from the particles. A crystallographic c-axis in a predetermined part of the body is configured to being substantially perpendicular to both a receiving direction and a polarization direction of the scattered light.