Laser Differential Confocal Microscopy for High-Resolution Raman Spectroscopy
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Solution Overview
Problem
Existing confocal Raman microscopy systems face limitations in achieving high spatial resolution and precise micro-area spectral measurement due to low signal noise ratio, large pinhole sizes, and inability to control the size of the converging spot, which restricts their application in various research fields.
Innovation Solution
A laser differential confocal mapping-spectrum microscopic imaging method and device that utilizes Rayleigh light for real-time focus-tracking and spatial position detection, combined with Raman spectrum detection, to achieve high spatial resolution and controllable converging spot size, enabling 'mapping & spectrum in one' imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large pinhole size is used to increase the passing through rate of the spectrum, then the spectrum detection capacity is improved, but the FWHM of confocal axial intensity curve increases and positioning accuracy is reduced
Solution Approach 1:
The patent divides the detection system into two independent channels: a Rayleigh light detection channel for focus positioning and a Raman scattering light detection channel for spectral analysis. This segmentation allows each channel to be optimized independently - the Rayleigh channel uses a small pinhole for high positioning accuracy while the Raman channel can use a larger pinhole for higher spectrum passing through rate, resolving the contradiction between the two requirements.
2Measurement precision
If the pinhole size is reduced to improve spatial resolution, then positioning accuracy is improved, but the signal noise ratio is reduced and spectrum detection capacity is compromised
Solution Approach 1:
The patent introduces Rayleigh light as an intermediary signal that is strongly reflected by the sample surface and transmitted through the pinhole to the detector. This intermediary signal provides a strong reference for focus positioning without being affected by the weak Raman scattering light, thereby maintaining high signal noise ratio while achieving high spatial resolution through the small pinhole aperture.
3Measurement precision
If conventional confocal microscopy is used for spectrum detection, then spectral analysis is achieved, but real-time focus tracking is not possible and environmental factors like temperature and vibration affect measurement accuracy
Solution Approach 1:
The patent establishes a feedback mechanism where the Rayleigh light signal is continuously detected to monitor focus status in real-time. The focus positioning information derived from the Rayleigh light intensity variations is fed back to control the sample stage, enabling automatic real-time focus tracking that compensates for environmental factors like temperature changes and vibration, thereby maintaining high spectral measurement accuracy.
4Measurement precision
If a small pinhole is used to achieve high spatial resolution, then the converging spot size is reduced, but the energy of Raman scattering light is further reduced due to the blocking effect of the pinhole
Solution Approach 1:
The patent segments the light detection path into two separate channels: one for Rayleigh light and one for Raman scattering light. The Rayleigh channel uses a small pinhole to achieve high spatial resolution for focus positioning, while the Raman channel can use a larger pinhole or different optical configuration to maximize the collection of weak Raman scattering light energy, thus resolving the contradiction between small converging spot size and Raman light energy collection.
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 significantly improves the spatial resolution and accuracy of spectral measurements, allowing for precise detection of micro-area spectra and geometric position information, while reducing the influence of environmental factors like temperature and vibration.
Implementation Method 1
excited Rayleigh light and Raman scattering light that carries the spectral characteristics of the measured sample
Implementation Method 2
excited Raman scattering light that carries the spectral characteristics of the measured sample
Implementation Method 3
based on the property that the zero-cross point of the differential confocal curve accurately corresponds to the focus of the objective, spectral information at the focus of the excitation spot being accurately captured
Implementation Method 4
the laser focuses on a measured sample and excites the Raman scattering light carrying the spectral characteristics of the sample
Data Source
AI summary
The present invention belongs to a technical field of optical microscopic imaging and spectral measurement, and discloses a laser differential confocal mapping-spectrum microscopic imaging method and device. The core concept of the present invention is to combine the differential confocal detection and the spectrum detection techniques and use a dichroic beam splitting system (13) to separate the Rayleigh light for geometric position detection from the Raman scattering light for spectrum detection, by mean of the property that the zero-cross point of the differential confocal curve (43) accurately corresponds to the focus of the objective, the spectral information at focus of the excitation spot being accurately captured by the zero trigger to accomplish the spectrum detection with high spatial resolution. Therefore, the present invention provides a method and device that may be able to accomplish the spectrum detection with high spatial resolution to a micro-area of a sample.