CARS Microscope Integrating OCT for Refractive Index Mapping
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Solution Overview
Problem
Conventional microscopes, such as fluorescence confocal and non-linear optical microscopes, cannot acquire the optical characteristics like index of refraction and transmittance of biological samples, which are essential for detailed analysis.
Innovation Solution
A CARS microscope with an optical parametric oscillator as the Stokes light source, allowing for variable wavelength and enabling the detection of CARS light and index of refraction, combined with Optical Coherence Tomography (OCT) for quantitative spatial distribution, and using a photonic crystal fiber for broader bandwidth, facilitating high-speed data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If conventional fluorescence confocal or non-linear optical microscopes are used, then molecular species distribution can be observed, but optical characteristics like index of refraction and transmittance cannot be acquired
Solution Approach 1:
The patent combines CARS microscopy and OCT into a single integrated system. The CARS microscope includes an OCT unit that uses the same pump light and Stokes light sources, allowing simultaneous acquisition of molecular species distribution (via CARS) and optical characteristics (via OCT). This merging resolves the contradiction by enabling both types of information to be obtained without requiring separate microscope systems.
Solution Approach 2:
The patent creates a multi-functional microscope system that can perform both CARS imaging (for molecular identification) and OCT imaging (for optical property measurement) using shared optical components. The pump light source and Stokes light source serve dual purposes: generating CARS signals for molecular spectroscopy and providing the light field for OCT interference measurements. This universality allows a single device to acquire comprehensive sample information including index of refraction and transmittance.
2Measurement precision
If an optical parametric oscillator is used as Stokes light source for variable wavelength, then detection precision of CARS light improves, but device complexity increases
Solution Approach 1:
The patent integrates the optical parametric oscillator (OPO) system into the CARS microscope framework, combining wavelength-tunable Stokes light generation with CARS detection. The OPO provides variable wavelength output that can be precisely tuned to match specific molecular vibration frequencies, enhancing CARS signal specificity. By merging the OPO control system with the existing CARS optical path and detection system, the patent achieves high measurement precision while managing system complexity through integrated design.
3Productivity
If photonic crystal fiber is used for broader bandwidth, then data acquisition speed increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses photonic crystal fiber as an intermediary component to generate broadband Stokes light with broader spectral bandwidth. This broadband light source enables faster data acquisition by providing sufficient spectral coverage across multiple molecular vibration modes simultaneously, reducing the need for sequential wavelength scanning. The photonic crystal fiber's specialized structure (with air holes arranged in a periodic pattern) enables exceptional bandwidth while the patent manages manufacturing precision requirements through careful design specifications and quality control of the fiber fabrication process.
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 acquisition of detailed information on the spatial distribution of molecular species and optical characteristics, providing more comprehensive data than conventional microscopes.
Implementation Method 1
Based on the distribution of wavelength and intensity of the anti-Stokes light, the spatial distribution of a specific substance in the sample can be observed
Implementation Method 2
A CARS microscope with an optical parametric oscillator as the Stokes light source, allowing for variable wavelength
Implementation Method 3
A CARS microscope is configured to irradiate a sample with two types of lights including pump light and Stokes light, and to observe anti-Stokes light generated as a result of the resonance of the frequency difference between these lights with the natural vibration of the molecules of the sample
Implementation Method 4
CARS is the emission of light due to third-order polarization
Implementation Method 5
the resonance of the frequency difference between these lights with the natural vibration of the molecules of the sample
Implementation Method 6
Combined with Optical Coherence Tomography (OCT) for quantitative spatial distribution
Data Source
Figure 1~2(c)
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Figure 5~6
AI summary
A conventional microscope to measure the spatial distribution of substance species has difficulty in measurement of the spatial distribution of index of refraction of a sample, and information acquired is limited. A microscope includes: a first light dividing part 102 that divides a light flux of light from a light source 110 into a first pump light flux and a second pump light flux; a Stokes light source 104 that receives the second pump light flux as an input and outputs a Stokes light flux; a multiplexing part 108 that multiplexes the first pump light flux and the Stokes light flux to generate a multiplexed light flux; a first light-collecting part 109 that collects the multiplexed light flux in a sample 110; a first detector 113 that detects CARS light generated from the sample, the CARS light having a wavelength different from the multiplexed light flux; a second light dividing part 107 that lets at least one of the second pump light flux and the Stokes light flux branch partially as a reference light flux; a second multiplexing part 017 that multiplexes a light flux from the sample and the reference light flux to generate interfering light; and a second detector that detects the interfering light.