Optical Microscopy Contrast via Inverted Geometry and Absorptive Layers
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Solution Overview
Problem
Conventional optical techniques for observing samples and detecting chemical or biological species, such as SPR and SERS, face limitations in achieving high spatial resolution and satisfactory contrast, especially when observing small objects or in biological applications, due to difficulties with light intensity and reflection issues.
Innovation Solution
The use of a transparent substrate with a metal coating and a thin, absorbent layer observed in reverse geometry, allowing for high contrast and independent variation with microscope opening, utilizing the imaginary part of the refractive index to enhance contrast across a wide range of angles, and potentially incorporating a functionalization layer for specific detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SPR or SERS techniques are used with a functionalized metal layer illuminated by a bundle of collimated light, then the detection function is achieved, but the spatial resolution is limited and contrast is lost
Solution Approach 1:
The patent inverts the conventional observation geometry by placing the objective lens between the light source and the sample, allowing light to enter through the objective lens rather than requiring collimated light to illuminate the sample from above. This inversion enables the use of the objective lens to both focus light and collect reflected light, achieving high spatial resolution while maintaining contrast through the lens's inherent focusing capability.
Solution Approach 2:
The objective lens is given multiple functions: it serves as both the light-focusing element and the light-collection element. By making the objective lens multi-functional, the system eliminates the need for separate collimated light illumination and detection components, thereby achieving high spatial resolution without sacrificing contrast that would otherwise be lost in conventional setups.
2Measurement precision
If parallel lighting beam is used for plasmonic imaging, then the detection function is maintained, but the resolution is limited to a few dozen microns
Solution Approach 1:
The patent inverts the conventional imaging setup by placing the objective lens between the light source and the sample. This allows the objective lens to focus light onto the sample and simultaneously collect the reflected light, achieving high spatial resolution without requiring complex parallel lighting configurations. The inverted geometry simplifies the overall device while dramatically improving resolution.
3Illumination intensity
If annular lighting is used to achieve extinction condition, then contrast is improved, but the light intensity is reduced and implementation is difficult
Solution Approach 1:
The patent inverts the conventional setup by placing the objective lens between the light source and the sample. This inversion allows the system to achieve high contrast without requiring complex annular lighting configurations. The objective lens naturally focuses light onto the sample and collects reflected light, providing high contrast images with standard light sources and eliminating the implementation difficulties associated with annular lighting.
4Illumination intensity
If conical lighting with large angle is used, then extinction is achieved, but contrast is reduced due to loss of light intensity
Solution Approach 1:
The patent inverts the conventional geometry by placing the objective lens between the light source and the sample. This allows the system to achieve high contrast without requiring conical lighting with large angles. The objective lens focuses light onto the sample and collects reflected light efficiently, maintaining high light intensity while achieving the necessary extinction condition for high contrast images.
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 provides a high and consistent contrast for microscopic observations and biological detections, improving sensitivity and resolution, and allows for the detection or dosage of chemical or biological species with enhanced imaging quality.
Implementation Method 1
a thin layer (1) having a complex refractive index not 1 = n1 - i.k1, whose imaginary component is not negligible, deposited on a transparent substrate (st)
Implementation Method 2
a transparent substrate (st) with a metal coating and a thin, absorbent layer observed in reverse geometry
Data Source
Figure 1~2
Figure 3~5
Figure 4-1~4-2
AI summary
The invention relates to a method for observing a sample (EO) under optical microscopy, in incoherent, unpolarised light, using a sample substrate (SAC) comprising a contrast-amplifying layer (CA) having a complex index of refraction. The invention also relates to a method for detecting or metering at least one chemical or biological species using such a sample substrate.