Polarization Splitter and Quarter-Wave Plate for Opaque Substrate Observation
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Solution Overview
Problem
Existing object observation systems cannot obtain transmission patterns when the substrate contains blood due to its low transmission coefficient, making it impossible to observe objects on opaque substrates.
Innovation Solution
An object observation system comprising a light source emitting rectilinearly polarized light, a support for a translucent or opaque substrate, a polarization separator, and a quarter-wave plate, which directs incident light to the substrate and backscattered light to a detector, allowing for the collection of diffraction patterns from objects on opaque substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmission imaging is used to observe objects on a substrate, then diffraction patterns can be obtained for identification, but the method fails when the substrate is opaque or contains blood due to low transmission coefficient
Solution Approach 1:
The patent inverts the observation geometry from transmission mode to reflection mode. Instead of illuminating the substrate from below and detecting transmitted light, the system illuminates from above and collects backscattered light reflected from the substrate surface, enabling observation of objects on opaque substrates that previously could not be imaged
Solution Approach 2:
The patent introduces a polarization separator and quarter-wave plate as intermediary optical components. These components separate the incident polarized light from the backscattered light based on polarization state, enabling the detection system to distinguish useful signal from parasitic reflections and substrate background, thereby achieving clear imaging on opaque substrates
2Ease of operation
If standard reflection imaging is used on opaque substrates, then objects can be observed, but parasitic reflections from the substrate surface degrade image quality and prevent diffraction pattern formation
Solution Approach 1:
The patent changes the polarization state parameter of the incident light using a quarter-wave plate, converting linearly polarized light to circularly polarized light. This parameter change causes the backscattered light to have a different polarization state than parasitic reflections, enabling their separation by the polarization separator and thus improving image quality
Solution Approach 2:
The polarization separator acts as an intermediary that selectively transmits or reflects light based on its polarization state. It separates the useful backscattered signal from parasitic reflections, acting as a filter that improves signal-to-noise ratio and enables clear observation on opaque substrates
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
Enables the observation and analysis of diffraction patterns from objects on opaque substrates, facilitating the identification, counting, and monitoring of microorganisms, even on blood agar, by eliminating parasitic reflections and improving image quality.
Implementation Method 1
a light source capable of emitting linearly polarized light
Implementation Method 2
a quarter-wave plate
Implementation Method 3
a polarization splitter capable of reflecting linearly polarized light in a second polarization direction and of transmitting linearly polarized light in a third direction
Implementation Method 4
determine a biological species of a bacterium by studying the transmission pattern obtained by scattering incident photons by the bacterium
Implementation Method 5
the low transmission coefficient of blood prevents the diffraction pattern from forming
Data Source
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AI summary
The invention relates to a system (1) for observing objects, including: a light source (3); a holder (12) suitable for receiving an opaque or translucent substrate; a detector (7) suitable for collecting back-scattered light issued from the interaction between the light emitted by the light source (3) and the objects; a polarisation splitter (9); and a quarter-wave plate (10), the splitter (9) and the quarter-wave plate (10) being arranged so that the splitter (9) directs the light emitted by the light source (3) toward the solid substrate and directs the back-scattered light issued from the interaction between the light emitted by the light source (3) and the objects toward the detector (7).