Pulsed Optical Source for OCT Motion Artifact Reduction
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Solution Overview
Problem
Optical coherence tomography (OCT) systems face challenges with motion artifacts due to sample and probe motion, leading to degraded image quality and inaccurate clinical interpretations, particularly in medical imaging where high sensitivity and fast image acquisition are required.
Innovation Solution
The implementation of a pulsed or wavelength-swept optical source with a broadband spectrum, synchronized with the detector array's readout rate, reduces motion artifacts by shortening the effective signal integration time and eliminating fringe washout, allowing for high-sensitivity, motion-artifact-free imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous-wave broadband light source is used in spectral-domain optical coherence tomography, then high signal-to-noise ratio is achieved, but motion artifacts and fringe washout occur due to long integration time
Solution Approach 1:
The patent applies periodic pulsed illumination instead of continuous-wave illumination. The light source emits broadband light in periodic pulses synchronized with the detector array readout rate, creating distinct illumination periods followed by dark periods. This periodic action allows the detector to integrate signal only during the pulse duration, effectively reducing integration time from milliseconds to nanoseconds while maintaining high signal-to-noise ratio through coherent detection during the illuminated periods.
Solution Approach 2:
The patent introduces dynamic timing control by synchronizing the pulsed light source with the detector array readout rate. The system dynamically adjusts the pulse timing and duration to match the specific motion characteristics of the sample, optimizing the integration window to capture signal before motion artifacts occur. This dynamic synchronization enables adaptive control of integration time based on real-time motion conditions.
2Measurement precision
If long integration time is used for signal detection, then signal-to-noise ratio is improved, but motion-induced signal fading and spatial resolution degradation occur
Solution Approach 1:
The system uses periodic pulsed illumination where the light source emits brief nanosecond-duration pulses synchronized with detector readout. During each pulse, the detector integrates signal with high signal-to-noise ratio, then during the subsequent dark period, the integrated signal is read out without additional integration. This periodic action effectively decouples the signal integration time from the total frame time, achieving high signal-to-noise ratio with minimal integration time, thereby preventing motion-induced signal fading and spatial resolution degradation.
3Productivity
If fast image acquisition rate is implemented, then productivity is improved, but sensitivity to sample motion increases due to integration effect
Solution Approach 1:
The patent implements periodic pulsed illumination synchronized with the detector array readout rate, where each pulse duration is set to match the desired effective integration time. By increasing the pulse repetition rate to match higher detector readout rates, the system achieves faster image acquisition while maintaining constant pulse duration, thereby keeping effective integration time short and motion artifact sensitivity low even at high productivity.
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 significantly reduces motion-induced signal fading and spatial resolution degradation, enabling high-speed, high-sensitivity imaging with improved image quality and reduced artifacts in biomedical applications.
Implementation Method 1
Spectral-domain optical coherence tomography (SD-OCT) as described in A. F. Fercher et al., 'Measurements of intraocular distances by backscattering spectral interferometry,'
Implementation Method 2
Spectral-domain optical coherence tomography ('SD-OCT') makes use of low-coherence spectral interferometry to obtain cross-sectional images of a biological sample.
Implementation Method 3
an optical source can emit a broadband spectrum in a pulsed mode, for example, by Q-switching or mode locking
Implementation Method 4
an optical source can emit a broadband spectrum in a pulsed mode, for example, by Q-switching or mode locking
Implementation Method 5
axial reflectance profile (A-line) is obtained by performing a discrete Fourier transform of the acquired data
Data Source
AI summary
A system and method for imaging of a sample, e.g., biological sample, are provided. In particular, at least one source electro-magnetic radiation forwarded to the sample and a reference may be generated. A plurality of detectors may be used, at least one of the detectors capable of detecting a signal associated with a combination of at least one first electro-magnetic radiation received from the sample and at least one second electro-magnetic radiation received from the reference. At least one particular detector may have a particular electrical integration time, and can receive at least a portion of the signal for a time duration which has a first portion with a first power level greater than a predetermined threshold and a second portion immediately preceding or following the first portion. The second portion may have a second power level that is less than the predetermined threshold, and extends for a time period which may be, e.g., approximately more than 10% of the particular electrical integration time.