Reflective CARS Microscope with Phase Sensor for Surface Positioning
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Solution Overview
Problem
Current optical measurement techniques, such as reflective CARS, struggle to accurately detect the surface position of measurement targets like cell membranes due to the lack of shape information, which is crucial for analyzing surface receptors and cancerization, and existing multi-modal devices fail to provide the necessary precision for nanometer-scale adjustments.
Innovation Solution
An optical measuring device that combines a pump beam and a Stokes beam with a phase sensor to detect the surface position of a sample with high accuracy, using an interferometer to generate interference beams and control the relative position between the objective lens and the sample, allowing for precise adjustment and molecular information acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If reflective CARS is used to measure surface state, then signal intensity increases, but shape information is not acquired making surface position identification difficult
Solution Approach 1:
The patent combines reflective CARS microscopy and OCT into a single measurement system. The CARS beam path and reference beam path are integrated through optical components (beam splitters, mirrors) to simultaneously obtain both molecular information (from CARS) and shape information (from OCT interference patterns), resolving the contradiction between signal intensity and position identification accuracy.
Solution Approach 2:
The measurement system performs multiple functions: it detects molecular vibrations via CARS while simultaneously acquiring surface topography via OCT. The single optical system serves dual purposes, allowing the device to both enhance signal intensity through reflective CARS and precisely identify surface positions through OCT-based shape information.
2Measurement precision
If a cell membrane surface is to be measured with nanometer precision, then position adjustment accuracy of less than or equal to 10 nm is required, but existing devices cannot achieve this precision
Solution Approach 1:
The patent replaces mechanical position adjustment mechanisms with optical interference-based detection. Instead of relying on mechanical stages with limited precision, the system uses OCT interference patterns to optically detect surface positions with nanometer accuracy, substituting mechanical control with optical measurement and feedback.
Solution Approach 2:
The system employs feedback by using the OCT-acquired shape information to guide and adjust the CARS measurement positioning. The interference pattern data provides real-time feedback on surface topography, enabling the system to automatically adjust and maintain nanometer-scale positioning accuracy for membrane surface measurements.
3Adaptability or versatility
If CARS and OCT are combined as in Patent Literature 3, then both structural and molecular information can be obtained, but pulse mismatch occurs and surface position detection with high precision is impossible
Solution Approach 1:
The patent modifies the temporal parameters of the laser pulses to resolve the mismatch issue. By adjusting pulse durations, timing delays, and synchronization between the CARS excitation pulses and OCT reference pulses, the system achieves both multi-functional measurement capability and high-precision surface detection without the pulse timing conflicts present in previous combined systems.
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 detection of surface positions with accuracy of less than or equal to 3 micrometers, facilitating the acquisition of molecular information on the surface of measurement targets like cell membranes with high precision and signal-to-noise ratio.
Implementation Method 1
a phase sensor configured to identify a surface position of the sample by causing a reflected beam from the sample that has passed through the objective lens and the reference beam to interfere with each other and detecting an intensity of the reflected beam or a phase of the reflected beam with respect to the reference beam
Implementation Method 2
an objective lens configured to focus the combined beam of the pump beam and the Stokes beam onto the sample held on the sample stage
Implementation Method 3
a combining unit configured to coaxially combine the pump beam with the Stokes beam
Implementation Method 4
CARS is based on a nonlinear optical phenomenon that when two light beams with different wavelengths are allowed to become incident on an object, a CARS beam is obtained that has a wavelength corresponding to the vibration of molecules forming the object
Data Source
AI summary
To measure a surface state, reflective CARS is suitable in terms of the signal intensity. However, with the reflective CARS, it has been difficult to identify the surface position because the shape information is not acquired. Thus, a reflective CARS microscope is combined with a high-resolution phase sensor. The surface position is identified with the phase sensor, and reflected CARS generated from the surface is detected, so that composition analysis is performed.