Full-Range Optical Coherence Tomography Phase Modulation
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Solution Overview
Problem
Current optical coherence tomography (OCT) systems suffer from limited imaging range due to the loss of phase information, resulting in half-range images with complex conjugate artifacts, and existing techniques to achieve full-range imaging are either expensive, have limited travel range, or require high-density scans and increased processing power.
Innovation Solution
An imaging system that includes a phase modulator to induce positive and negative phase modulation, allowing for the reconstruction of phase information and generation of full-range OCT images without the limitations of existing methods, using a phase galvo or photonic integrated circuit to adjust the phase of the optical signal and combine positively-tuned and negatively-tuned images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional OCT imaging is used, then the system is simple and cost-effective, but the imaging depth range is limited due to complex conjugate artifacts
Solution Approach 1:
The patent applies dynamics by making the optical path length tunable and adjustable during the imaging process. A tuning mechanism is introduced that dynamically changes the optical path length in the reference arm, allowing the system to adaptively compensate for the complex conjugate artifact limitation. This dynamic adjustment enables the system to access both positive and negative depth ranges, effectively doubling the imaging depth range without requiring a fundamentally complex system redesign.
Solution Approach 2:
The patent changes the optical path length parameter dynamically during imaging. By introducing a tuning mechanism that adjusts the reference arm optical path length, the system transforms the fixed parameter limitation into a variable parameter system. This parameter change approach allows the system to shift the DC line position and eliminate complex conjugate overlap, achieving full-range imaging while maintaining relative system simplicity.
2Length of moving object
If a piezo stage is used to achieve full-range imaging, then the imaging depth range is extended, but the travel range is limited and the cost increases
Solution Approach 1:
The patent achieves multi-functionality by designing a tuning mechanism that serves multiple purposes: it extends the imaging depth range, provides adaptability for different imaging scenarios, and eliminates the need for specialized piezo stages with limited travel ranges. The universal tuning approach allows the system to handle both small and large depth range requirements by adjusting the optical path length accordingly, making the system versatile without being constrained by the limited travel range of piezo actuators.
3Measurement precision
If high density scans are performed to achieve full-range imaging, then the imaging quality is improved, but the scan time and processing power requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-tuning the optical path length to the appropriate position before performing the scan. This preliminary adjustment of the reference arm optical path length ensures that the imaging is performed at the optimal depth range from the start, eliminating the need for post-processing or multiple high-density scans to achieve full-range coverage. The scan can proceed at standard density while still achieving high imaging quality across the extended depth range.
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 effectively doubles the imaging depth range by eliminating complex conjugate artifacts, achieving full-range OCT imaging in a more compact and cost-effective manner without the need for high-density scans or restricted tuning ranges.
Implementation Method 1
a phase modulator configured to adjust a phase of light detected by the spectrometer by inducing a positive phase modulation that increases the phase and inducing a negative phase modulation that decreases the phase
Implementation Method 2
The reflected lights are then optically combined in a detection arm in a manner that produces an optical signal having an interference pattern
Data Source
AI summary
A full-range imaging method doubles imaging range of conventional techniques by removing mirror images of an imaged object that limit conventional images to a “half-range” and that are caused in part by the loss of phase information in a detected signal. Phase information of the detected signal is reconstructed with an averaging technique based on a modulated phase induced in the detected signal during scanning.