Sequential Angle Illumination for OCT Transverse Resolution
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Solution Overview
Problem
Current interferometric imaging systems, particularly in OCT, face limitations in achieving high transverse resolution over an extended focal depth due to the mismatch between illumination and collection numerical apertures, leading to vignetting and motion artifacts, which restricts the resolution beyond that given by the illumination beam.
Innovation Solution
The approach involves sequentially illuminating and imaging a sample at different angles to increase angular diverse scattering information, allowing for depth invariant transverse resolution beyond the limitations of a single scan beam, applicable to both point scanning and multi-beam OCT and holoscopic systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the NA of the collection system is increased to achieve higher transverse resolution, then resolution is improved, but vignetting occurs between illumination and collection apertures outside the focal plane
Solution Approach 1:
The patent introduces angular diversity as an additional dimension for data collection. By acquiring OCT data at multiple illumination angles and combining them through holoscopic reconstruction, the system achieves higher transverse resolution without increasing the collection NA, thereby avoiding vignetting. This transforms the problem from a spatial aperture limitation to an angular sampling problem.
Solution Approach 2:
The patent changes the illumination angle parameter sequentially to collect angular diverse scattering information. By varying the angle of illumination and combining measurements from multiple angles, the system achieves resolution beyond the diffraction limit of the collection NA without experiencing vignetting effects.
2Length of stationary object
If multiple images are taken while changing the focal plane to achieve high resolution in multiple planes, then depth of field is extended, but acquisition time increases
Solution Approach 1:
The patent uses periodic angular scanning to collect data at multiple angles. By sequentially illuminating the sample at different angles and combining the measurements, the system achieves depth-invariant transverse resolution across an extended depth of field without requiring multiple focal plane acquisitions, thereby reducing total acquisition time.
Solution Approach 2:
Instead of extending depth of field by acquiring images at multiple focal planes (z-dimension), the patent uses angular diversity (angular dimension) to achieve depth-invariant resolution. This allows a single focal plane to maintain high resolution across a larger axial range through angular synthesis.
3Object-affected harmful factors
If parallelization is increased to reduce vignetting, then coverage of out-of-focus regions is improved, but scan speed decreases leading to motion artifacts
Solution Approach 1:
The patent segments the angular space into multiple discrete illumination angles. By collecting data at several distinct angles sequentially and combining them through holoscopic reconstruction, the system achieves comprehensive angular coverage without requiring simultaneous multi-beam illumination, thus maintaining high scan speed while eliminating vignetting.
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 method enhances transverse resolution while eliminating vignetting issues, enabling higher imaging resolution than previously achievable with single beam systems, and maintains image quality across an extended depth of field.
Implementation Method 1
increase angular diverse scattering information
Implementation Method 2
interferes with the reference light, generating signal
Data Source
Figure 1~2a
Figure 2b~2c
Figure 2d~3c
AI summary
Various systems and methods for sequential angle illumination to achieve ultra-high resolution optical coherence tomography (OCT) images. One example OCT system includes a light source, a beam divider, sample arm optics, a detector, and a processor. The light source generates a light beam to illuminate the sample. The beam divider separates the light beam into reference and sample arms. The sample arm optics sequentially illuminates a location in the sample with the light beam from different angles. The detector receives light returned from the reference arm and the sample illuminated at each angle and generates signals. The processor combines the signals to generate an image, which has a transverse resolution that is higher than the transverse resolution achieved from the signal generated from a single angle.