Epi-Detection Optical System for SHG F/B Ratio Measurement
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Solution Overview
Problem
Current methods for measuring the ratio of forward-propagating to backward-propagating second harmonic-generation (SHG) signals in tissues require multiple lens setups, making them unsuitable for in vivo applications, especially in dynamic or thick tissue samples, and result in time-consuming processes that can lead to inaccurate margin assessments during surgeries like breast conservation surgery.
Innovation Solution
A method and optical system that utilize a single image scan with a pinhole mirror and reflective surface to separate and detect both the forward and backward SHG signals, allowing for the measurement of the SHG F/B ratio without a second lens, enabling rapid assessment of tissue samples in the operating room.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a second objective lens is used to collect forward propagating SHG signal, then the SHG F/B ratio measurement can be performed, but the tissue sample must be dissected from the subject and sectioned to allow signal to reach the second detection lens
Solution Approach 1:
The patent combines the functions of forward and backward SHG signal detection into a single epi-detection objective lens system. The beam splitter separates the forward-propagating SHG signal (reflected back through the sample) from the backward-propagating SHG signal, allowing both to be detected simultaneously through one lens without requiring tissue sectioning or a second objective lens.
Solution Approach 2:
The patent introduces a beam splitter as an intermediary optical component that directs forward-propagating SHG signal (which has been reflected back from the sample) to a first detector while allowing backward-propagating SHG signal to reach a second detector. This mediator enables separation of the two signal components without requiring complex multi-lens arrangements or tissue sectioning.
2Measurement precision
If five SHG images are taken over the same region of interest using variable pinhole method, then the SHG F/B ratio can be measured, but the process is time consuming and requires the sample to be kept stationary
Solution Approach 1:
The patent enables continuous simultaneous detection of both forward and backward SHG signals through a single image acquisition process. The beam splitter allows both signal types to be captured in real-time during a single scan, eliminating the need for multiple sequential images and maintaining sample stationarity requirements only for the duration of a single rapid scan rather than multiple acquisitions.
Solution Approach 2:
The patent uses a single image scan with appropriate optical separation to achieve the measurement, which is fewer acquisitions than the five images required by the variable pinhole method. This partial action (single scan versus multiple scans) reduces time loss while still providing sufficient data for accurate F/B ratio calculation.
3Measurement precision
If multiple image scans are performed to measure SHG F/B ratio, then accurate measurement can be achieved, but the sample movement causes SHG intensity variation
Solution Approach 1:
The patent performs preliminary separation of forward and backward SHG signals using a beam splitter during a single image acquisition. By establishing the optical separation path before acquisition and maintaining it throughout the scan, the system eliminates the need for multiple scans that would be susceptible to sample movement, thereby preserving measurement reliability.
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 allows for accurate, rapid measurement of the SHG F/B ratio in a single image scan, reducing the need for sectioning tissues and enabling dynamic imaging, which is crucial for improving surgical precision and reducing the need for additional surgeries by providing real-time margin assessment.
Implementation Method 1
irradiating a object to generate a second harmonic generation (SHG) emission
Implementation Method 2
separating a direct backward-propagating SGH ("B") portion and a backscattered forward-propagating SHG ("F") portion of the SHG emission
Data Source
AI summary
A method and system that enable the measurement of a second-harmonic-generation-forward/backward (SHG F/B) ratio from an object by performing only a single image scan using via epi-imaging using an epi-detection technique. Two simultaneous SGH images (a forward propagating SHG “F” image and a back propagating SHG “B” image) are generated during the single image scan. A pinhole mirror can be used to separate the F-SHG and the B-SHG, which are detected by separate detectors.