Fluorescence Detection Optical System Using Polarization Crosstalk Reduction
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Solution Overview
Problem
Fluorescence detecting optical systems face challenges with crosstalk between excitation light and fluorescent light due to overlapping wavelength bands, leading to degraded detection performance and noise interference from reflected excitation light.
Innovation Solution
A fluorescence detecting optical system that includes a light source unit emitting excitation light with a specific polarization component, an objective lens to focus the light, and a light delivery unit with beam splitters and quarter-wave plates to separate and redirect excitation light, minimizing crosstalk and noise by converting reflected excitation light to a perpendicular polarization component and reflecting it away from the optical path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wavelength bands passed by the excitation light filter and the fluorescent light filter are made narrow to prevent crosstalk, then crosstalk between excitation light and fluorescent light is reduced, but the intensities of the excitation light and fluorescent light decrease, resulting in degradation of detection performance
Solution Approach 1:
The patent converts the harmful reflected excitation light into a beneficial signal by using a polarizer to block it and a photodetector to detect the polarization state changes. The reflected excitation light, which was previously causing crosstalk and noise, is now used to provide feedback for focus control and system alignment, transforming a harmful factor into a useful one.
Solution Approach 2:
The patent introduces a polarizer as an intermediary element between the light source and the sample, and between the sample and the photodetector. This polarizer mediates the interaction between excitation light and fluorescent light by selectively blocking reflected excitation light based on its polarization state, enabling effective separation without requiring narrow bandwidth filters that would reduce light intensity.
2Measurement precision
If multiple excitation light filters and fluorescent light filters are designed to prevent overlapping wavelength bands, then crosstalk between adjacent channels is reduced, but the device complexity increases
Solution Approach 1:
The patent extracts the wavelength separation function from multiple filters and concentrates it into a single polarizer element. By removing the need for multiple excitation and fluorescent light filters, the system simplifies the filter configuration while maintaining effective channel separation through polarization-based discrimination of reflected excitation light.
Solution Approach 2:
The polarizer serves multiple functions simultaneously: it blocks reflected excitation light, enables focus control through polarization state detection, and facilitates channel separation in multi-channel detection systems. This multi-functional element replaces what would otherwise require multiple specialized filters, reducing overall device complexity.
3Device complexity
If software compensation is used to correct crosstalk, then hardware filter complexity is reduced, but the detection accuracy varies greatly depending on selected coefficient values and is difficult to apply reliably
Solution Approach 1:
The patent replaces software-based crosstalk compensation with a physical optical solution using a polarizer. Instead of relying on computational algorithms with variable coefficient values that affect detection accuracy, the system uses the polarizer's physical property of selective light blocking to achieve reliable and consistent crosstalk reduction, providing deterministic performance independent of software parameter selection.
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 effectively reduces crosstalk and noise, enhancing the detection performance of fluorescence detecting systems by preventing excitation light from entering the photodetector and improving the separation of excitation and fluorescent light signals without the need for software compensation.
Implementation Method 1
a first quarter-wave plate disposed between the second and first beam splitters; and a second quarter-wave plate disposed between the third beam splitter and the first beam splitter
Implementation Method 2
a first polarizing beam splitter disposed between the objective lens and the fluorescence detector so as to transmit light having a first polarization component and reflect light having a second polarization component perpendicular to the first polarization component
Data Source
AI summary
A fluorescence detecting optical system, and a multi-channel fluorescence detection apparatus comprising same, comprising a light source that emits excitation light, a polarizer that transmits light having a predetermined polarization component, a polarizing beam splitter that transmits light having a predetermined polarization component and reflects light having a different polarization component than the predetermined polarization component, and a quarter-wave plate converting linearly polarized to circularly polarized light or vice versa.