Optical Reader Stray Light Reduction Polarizer
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Solution Overview
Problem
Existing ELISPOT readers face challenges with stray light, which decreases image contrast and complicates the analysis of biological samples, due to reflections and scattering within the lens system and on metal surfaces.
Innovation Solution
The optical reader employs polarized light for illumination and uses a polarizer to block unwanted stray light, with a circular polarizer and a second polarizer arranged between the beam splitter and imaging device to maintain image contrast, and an integrating sphere for uniform illumination, along with filters for specific wavelength ranges to accommodate both ELISPOT and FluoroSpot assays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a camera and illuminating arrangement are used to detect spots in ELISPOT assays, then automated sample analysis is achieved, but stray light is generated by reflections and scattering within the lens system and on metal surfaces, decreasing image contrast
Solution Approach 1:
A polarizer is introduced as an intermediary component between the lens system and the camera sensor. This polarizer selectively blocks polarized stray light while allowing non-polarized or differently polarized light from the sample to pass through, thereby reducing stray light interference without compromising automated analysis capability
Solution Approach 2:
The patent changes the polarization state parameter of light in the optical system. By using polarized illumination and placing a polarizer in the detection path, the system exploits polarization as a controllable parameter to differentiate between useful signal light and harmful stray light, resolving the contradiction between automation and image quality
2Object-affected harmful factors
If a polarizer is used to block polarized stray light, then image contrast is improved, but the device complexity increases due to additional optical components
Solution Approach 1:
The polarizer serves multiple functions simultaneously: it blocks polarized stray light to improve contrast, and when combined with polarized illumination, it helps define the illumination geometry. This multi-functionality reduces the need for additional separate components, mitigating the complexity increase
3Illumination intensity
If an integrating sphere is used to achieve uniform illumination, then illumination uniformity is improved, but the device complexity and size increase
Solution Approach 1:
The patent transitions from point-source or directional illumination to omnidirectional illumination by introducing an integrating sphere. This dimensional change in light distribution geometry achieves uniform illumination across the sample area, with the sphere's diffuse reflective interior ensuring even light distribution without requiring complex multi-element illumination systems
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 significantly reduces stray light, enhancing image contrast and allowing for high-quality imaging of biological samples, improving the accuracy of analysis in ELISPOT and FluoroSpot assays.
Implementation Method 1
Both the reflections of the lens surfaces and scattering on the metallic surfaces of the lens system maintain the polarization of the light. Therefore, this stray light can be effectively removed by using polarized light for illuminating the samples and polarizing the light reflected by the sample before the light is captured by the imaging device.
Implementation Method 2
By directing the light from the illuminating arrangement via the beam splitter and the lens system to the well of the microplate
Implementation Method 3
By directing the light from the illuminating arrangement via the beam splitter and the lens system to the well of the microplate, it is possible to form a uniform and bright spot on the bottom of the well
Implementation Method 4
a circular polarizer is arranged between the beam splitter and the lens system
Data Source
Figure 1~2
Figure 3
AI summary
The optical reader for analyzing biological samples comprises a reading plane (3) for receiving a microplate (1), an illuminating arrangement (4) configured to illuminate samples in the wells (2) of the microplate (1), an imaging device (6) arranged to receive light from the microplate (1), a beam splitter (7), which is arranged to direct light from the illuminating arrangement (4) towards the reading plane (3) and to direct light received from the microplate (1) to the imaging device (6), and a lens system (8) arranged between the beam splitter (7) and the reading plane (3) to focus the light received from the illuminating arrangement (4) to a sample and to focus an image of the sample to the imaging device (6). The optical reader is configured to transmit from the illuminating arrangement (4) to the lens system (8) only light having a specific polarization, and the optical reader comprises a polarizer (10, 19) that is arranged between the lens system (8) and the imaging device (6) and configured to block polarized light reflected from the surfaces of the lens system (8).