Swept Source OCT Fast Scanning Mechanism
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Solution Overview
Problem
Existing swept source OCT systems require high sweep rates to achieve faster imaging, which results in reduced optical power and imaging range due to less light traveling through the gain medium, limiting the system's ability to produce high-quality images efficiently.
Innovation Solution
Implementing a fast scanning mechanism in the sample arm with a slowly swept light source, allowing multiple lateral scans over the same area during a wavelength sweep, reducing the need for rapid sweep speeds and enabling higher power and greater imaging range by maximizing light amplification through multiple passes through the gain medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the sweep rate of the light source is increased to improve imaging speed, then the imaging acquisition rate improves, but the optical power emitted by the source decreases
Solution Approach 1:
The patent introduces a fast scanning mechanism in the sample arm that operates independently from the light source sweep rate. This adds a temporal dimension to data acquisition, allowing multiple lateral scans to be performed during a single wavelength sweep, thereby decoupling imaging speed from sweep rate and resolving the contradiction between imaging acquisition rate and optical power.
Solution Approach 2:
The system performs multiple lateral scans continuously during each wavelength sweep of the light source, maximizing the utilization of available optical power. This continuous acquisition approach allows the system to accumulate sufficient data for high-quality imaging without requiring faster sweep rates, thus maintaining optical power while improving imaging capability.
2Speed
If the sweep rate of the light source is increased to improve imaging speed, then the imaging acquisition rate improves, but the imaging range decreases
Solution Approach 1:
By adding the fast scanning dimension in the sample arm, the patent enables sufficient data acquisition for extended imaging ranges without relying on increased sweep rates. The system can perform multiple scans at each wavelength point, accumulating enough signal strength even when the light source sweeps more slowly, thus preserving imaging range while maintaining acquisition speed.
Solution Approach 2:
The system performs multiple lateral scans at each wavelength position before moving to the next wavelength, preliminarily accumulating sufficient signal data. This approach ensures that even with slower sweep rates and longer imaging ranges, the system gathers adequate optical power information for high-quality imaging across the extended range.
3Illumination intensity
If the instantaneous line width of the source is increased to provide more optical power, then the optical power improves, but the useful imaging range reduces
Solution Approach 1:
The patent changes the operational parameters by performing multiple lateral scans at each wavelength point, allowing the system to use broader line widths (which provide more optical power) without sacrificing imaging range. The accumulated data from multiple scans compensates for the reduced spectral resolution, maintaining useful imaging range while benefiting from higher optical power.
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 higher optical intensities and extended imaging range while maintaining frame rates, enabling linear sweeps and simplifying signal processing, thereby improving the overall performance of the OCT system.
Implementation Method 1
An alternative OCT technique uses a swept source. In one known implementation, the wavelength or frequency of a laser is swept over a range supported by the laser's gain medium.
Implementation Method 2
The range of emitted wavelengths is dependent on a gain medium of the source. This approach allows for higher optical intensities and extended imaging range while maximizing light amplification through multiple passes through the gain medium.
Implementation Method 3
The 2×2 coupler splits and directs a portion of the light to the reference and sample arms (106, 108) of a Michelson interferometer. Light reflecting from the two arms are combined at the 2×2 coupler.
Implementation Method 4
The OCT imaging system also includes a reference arm, a projector, and a sensor. The two beams containing the interfering signals are sent to a dual balanced detector.
Data Source
AI summary
A method and apparatus are provided for a swept source optical coherence tomography (OCT) system utilizing a fast scanning mechanism in the sample arm and a slowly swept light source. The position data is collected rapidly while the wavelength of the source is swept slowly. The system reduces the sweep speed requirements of the light source enabling higher power, greater imaging range, and linear sweeps of the source frequency. The OCT components (or most of them) may be implemented within a hand held imaging probe. In operation, a triangulation scan may be used to orient the imaging probe with respect to a fixed coordinate system; preferably, OCT data captured by the device is then transformed to that same orientation with respect to the fixed coordinate system to improve the scanning results.