Grating Device Spatial Resolution Refractive Index Imaging
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Solution Overview
Problem
Existing optical characterization systems lack the capability for spatially resolved measurements of surface refractive index, which is essential for precise analysis of samples, particularly in biosensors and fluid samples.
Innovation Solution
A surface refractive index scanning system utilizing a grating device with adjacent regions of different grating periods, illuminated by a light source, and an imaging spectrometer with a 2-dimensional image sensor to capture and process light spectra, allowing for non-scanning, time- and spatially resolved measurements of refractive index changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical characterization system is used, then the system structure is simple, but spatially resolved measurement capability is lost
Solution Approach 1:
The grating device is divided into multiple adjacent grating regions (first grating region, second grating region, etc.) each with different grating periods. This segmentation allows each region to provide optical resonances at different wavelengths, enabling spatially resolved measurements across the sample surface without requiring physical scanning mechanisms.
Solution Approach 2:
The patent transitions from one-dimensional spatial scanning to two-dimensional spatial encoding by using multiple grating regions with different periods arranged in the transverse direction. Each grating period corresponds to a specific wavelength band, creating a wavelength-spatial mapping that enables simultaneous multi-point measurement across the sample surface.
2Measurement precision
If physical scanning is used to achieve spatially resolved measurements, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The grating device is pre-configured with multiple grating regions having different grating periods before measurement begins. This preliminary configuration encodes spatial information into the spectral domain, allowing the imaging spectrometer to capture all spatial positions simultaneously in a single snapshot, eliminating the need for time-consuming physical scanning during measurement.
Solution Approach 2:
The patent replaces mechanical scanning systems with an optical encoding system. Instead of physically moving the sample or detector to achieve spatial resolution, the system uses optical resonance phenomena where different grating periods produce resonances at different wavelengths, allowing spatial information to be extracted from spectral data captured by the imaging spectrometer.
3Measurement precision
If multiple grating regions with different periods are used, then spatial measurement capability is improved, but device complexity increases
Solution Approach 1:
The grating device serves multiple functions simultaneously: it acts as both the sample holder and the spatial encoding element. The multiple grating regions with different periods are integrated into a single device structure that also supports the sample, eliminating the need for separate scanning mechanisms and reducing overall system complexity despite the increased grating structure complexity.
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 precise, spatially resolved characterization of refractive index changes on a sample surface without physical scanning, enhancing measurement resolution and accuracy for fluid samples and biosensors.
Implementation Method 1
the first and second grating periods are chosen to provide optical resonances for light respectively in a first wavelength band and a second wavelength band
Implementation Method 2
A surface refractive index image acquiring system... a grating device for receiving the sample, the device comprising at least a first grating region having a first grating width along a transverse direction, and a second grating region having a second grating width in the transverse direction
Implementation Method 3
an imaging spectrometer comprising an entrance slit having a longitudinal direction oriented to coincide with the invariant direction of the optical element, the imaging spectrometer further comprising a 2-dimensional image sensor
Data Source
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AI summary
The invention relates to a surface refractive index scanning system for characterization of a sample. The system comprises a grating device for holding or receiving the sample, the device comprising at least a first grating region having a first grating width along a transverse direction, and a second grating region having a second grating width in the transverse direction. The first grating region and the second grating region are adjacent in the transverse direction, wherein the first grating region has a grating period Λ1 in a longitudinal direction, and the second grating region has a grating period Λ2 in the longitudinal direction, where the longitudinal direction is orthogonal to the transverse direction. A grating period spacing ΔΛ = Λ1 − Λ2 is finite. Further, the first and second grating periods are chosen to provide optical resonances for light respectively in a first wavelength band and a second wavelength band, light is being emitted, transmitted, or reflected in an out-of-plane direction, wherein the first wavelength band and the second wavelength band are at least partially non-overlapping in wavelength. The system further comprises a light source for illuminating at least a part of the grating device with light at an illumination wavelength band. Additionally, the system comprises an imaging system for imaging the emitted, transmitted or reflected light from the grating device. The imaging system comprises an optical element, such as a cylindrical lens or a bended mirror, configured for focusing light in a transverse direction and for being invariant in an orthogonal transverse direction, the optical element being oriented such that the longitudinal direction of the grating device is oriented to coincide with the invariant direction of the optical element, and an imaging spectrometer comprising an entrance slit having a longitudinal direction oriented to coincide with the invariant direction of the optical element. The imaging spectrometer further comprises a 2-dimensional image sensor. The invention further relates to a method.