Double-Clad Optical Fibre Microprobe for Raman Spectroscopy
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Solution Overview
Problem
Current optical fibre probes for Raman spectroscopy face challenges due to silica Raman background interference and the need for bulky, precision-aligned free-space optics, which hinder their application in chemical sensing, particularly in medical diagnostics.
Innovation Solution
A double-clad optical fibre probe with an integrated micro-filter, comprising a short pass or band pass filter and a long pass filter, is used to suppress silica Raman background and Rayleigh scattering, allowing efficient transmission of Raman scattered wavelengths, and a surface-enhanced Raman scattering (SERS) substrate is applied using photochemical deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If free-space optics (lenses and mirrors) are used to couple light into and out of the optical fibre probe, then light coupling is achieved, but the probe becomes bulky and requires precision alignment
Solution Approach 1:
The patent merges the filtering function and light coupling function directly into the fibre probe tip structure. The band pass filter and long pass filter are integrated with the fibre bundle end, eliminating the need for separate free-space optics. This consolidation reduces the number of components and simplifies the overall probe structure while maintaining effective light coupling.
Solution Approach 2:
The fibre probe tip structure serves multiple functions simultaneously: it acts as the light coupling interface, houses the filtering mechanisms (band pass filter and long pass filter), and provides the sampling aperture. This multi-functional integration eliminates the need for separate dedicated components for each function, reducing probe complexity.
2Measurement precision
If bulky filters are used to eliminate silica Raman background, then signal-to-noise ratio is improved, but optical losses increase and probe size increases
Solution Approach 1:
The patent applies filtering selectively at specific locations within the probe structure. The band pass filter is positioned to filter silica Raman background from the excitation light path, while the long pass filter is positioned to filter Rayleigh scattered light from the sample. This localized filtering approach achieves the required signal-to-noise ratio improvement without requiring bulky filters throughout the entire optical path.
Solution Approach 2:
The patent changes the spectral parameters of the light paths by introducing specific filter characteristics. The band pass filter transmits only the excitation wavelength range while blocking silica Raman signals, and the long pass filter transmits Raman scattered wavelengths while blocking Rayleigh scattering. These parameter changes enable effective background suppression with compact filter components.
3Reliability
If free-space optics are used for transmission of Raman signals, then signal transmission is achieved, but device complexity and alignment requirements increase
Solution Approach 1:
The patent merges the signal transmission function directly into the fibre bundle structure. The collection fibres transmit Raman signals directly to the detector without requiring intermediate free-space optics. This integration maintains reliable signal transmission while eliminating complex optical components and alignment requirements.
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
The solution reduces optical losses, eliminates the need for bulky optics, and enables the creation of compact, flexible probes with improved signal-to-noise ratio, suitable for minimally invasive medical diagnostics and other sensing applications.
Implementation Method 1
a band pass filter configured to transmit an excitation wavelength and block a silica Raman background
Implementation Method 2
a long pass filter configured to block Rayleigh scattered light from a sample and transmit Raman scattered wavelengths
Implementation Method 3
a double-clad optical fibre probe tip, the double-clad optical fibre (DCF) having a single mode core, multimode inner cladding, and outer cladding
Implementation Method 4
a surface-enhanced Raman scattering (SERS) substrate is applied using photochemical deposition
Data Source
AI summary
The present application discloses a spectroscopy probe for a Raman spectroscopy system, and methods for preparing filters for the probe. A method for forming an SERS substrate which can optionally be used with the probe is also described. The spectroscopy probe is formed using a double-clad optical fibre probe tip, the double-clad optical fibre (DCF) having a single mode core, multimode inner cladding, and outer cladding, and a micro-filter fixed to the distal end of the optical fibre probe tip. The micro-filter has a short pass or band pass filter configured to align with the DCF core to filter silica Raman background generated by laser excitation in the single mode core, and a long pass filter configured to suppress Rayleigh scattering from the sample while allowing Raman scattered wavelengths to be transmitted through the inner cladding.