Polarization Control for Optical Tomography Spectrometers
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Solution Overview
Problem
Optical tomography systems using SD-OCT face image quality deterioration due to fluctuations in the state of polarization of interference light, particularly when using spectrometers with polarization characteristics and single-mode fibers in endoscopes, which affect the wavelength spectrum output and tomographic image quality.
Innovation Solution
Incorporating a polarization setting means to stabilize the state of polarization of interference light before it reaches the spectrometer, either by dividing and synthesizing linearly polarized light or converting it to non-polarized light, ensuring consistent polarization and minimizing the impact of polarization-dependent diffractive efficiency variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diffractive optics spectrometer is used in SD-OCT measurement, then spectral division and detection efficiency are improved, but polarization characteristics cause wavelength spectrum fluctuations and image quality deterioration
Solution Approach 1:
A polarization controller is introduced as an intermediary device between the optical fiber and the diffractive optics spectrometer. This controller mediates the polarization state of the interference light before it reaches the spectrometer, ensuring that polarization fluctuations do not directly affect the spectral measurement. The polarization controller acts as a buffer that decouples the fiber's polarization variations from the spectrometer's polarization-sensitive diffraction process.
Solution Approach 2:
The invention dynamically adjusts the polarization state parameter of the interference light using a polarization controller. By changing the polarization orientation to align with the groove direction of the diffractive optics, the system optimizes diffracting efficiency and eliminates wavelength spectrum fluctuations. This parameter adjustment compensates for polarization variations introduced by fiber bending and twisting.
2Use of energy by moving object
If single-mode fiber is used to guide light in endoscope, then light transmission is improved, but fiber folding and twisting cause polarization fluctuation of interference light
Solution Approach 1:
The polarization controller serves as an intermediary that compensates for polarization distortions introduced by the fiber. It is positioned after the fiber to correct the polarization state of the emerging light, effectively decoupling the fiber transmission function from the polarization stability requirement.
Solution Approach 2:
The system employs a feedback mechanism where the polarization controller continuously monitors and adjusts the polarization state of the interference light. By detecting polarization fluctuations and applying real-time corrections, the system maintains stable polarization despite fiber bending and twisting, ensuring consistent spectral measurement quality.
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 prevents fluctuations in the wavelength spectrum output and improves tomographic image quality by maintaining consistent polarization, thereby reducing errors and enhancing image resolution in optical tomography systems.
Implementation Method 1
a diffractive optics is employed as the spectrometer
Implementation Method 2
a polarization setting means which causes the interference light guided by the waveguide means to enter the spectrometer after setting the state of polarization of the interference light
Implementation Method 3
as a system of rapidly obtaining a tomographic image without changing the optical path length of the reference light, there has been proposed an SD-OCT system using an SD-OCT (spectral domain OCT) measurement. In the SD-OCT measurement, a tomographic image is formed without scanning in the direction of depth, by dividing broadband, low coherence light from a light source by the use of a Michelson interferometer
Data Source
AI summary
In an optical tomography system, an interference light obtained by multiplexing the reflected light from the object and the reference light is guided to an interference light detecting means by a waveguide means. The interference light detecting means has a spectrometer spectrally dividing the interference light. A polarization setting means which causes the interference light guided by the waveguide means to enter the spectrometer after setting the state of polarization of the interference light guided by the waveguide means to a predetermined state of polarization is provided between the waveguide means and the spectrometer.