Decoupled Numerical Aperture Optical Coherence Tomography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optical coherence tomography (OCT) systems face a trade-off between achieving high lateral resolution and maintaining a large depth range, as increasing the numerical aperture for better lateral resolution reduces the accessible depth range and introduces aberrations, making it difficult to detect early stages of diseases like age-related macular degeneration effectively.
Innovation Solution
The system decouples the numerical aperture for illumination and detection, using a 2D detector with a confocal diaphragm to achieve high lateral resolution without compromising the depth range, and corrects aberrations by spatially resolving the measurement radiation in the conjugate pupil plane, allowing for improved signal-to-noise ratio and image correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the numerical aperture of the optical system is increased to achieve high lateral resolution, then the lateral resolution is improved, but the accessible depth range is reduced
Solution Approach 1:
The patent segments the optical system into two independent numerical aperture parameters: NA_illumination for the illumination path and NA_detection for the detection path. This allows each path to be optimized independently - NA_illumination can be kept small to maintain large depth range, while NA_detection can be large to achieve high lateral resolution in the detected image
Solution Approach 2:
Different parts of the optical system are assigned different numerical aperture characteristics tailored to their specific functions. The illumination optics use a small NA to illuminate a large axial range, while the detection optics use a large NA to collect measurement radiation with high spatial resolution, creating local optimization in each subsystem
2Measurement precision
If the numerical aperture of the optical system is increased to achieve high lateral resolution, then the lateral resolution is improved, but optical aberrations increase
Solution Approach 1:
The patent separates the illumination and detection paths with different numerical apertures, allowing the detection path to use high NA for resolution without forcing the illumination path to use high NA, thereby avoiding the associated aberrations in the illumination process
Solution Approach 2:
The patent introduces a confocal diaphragm as an intermediary element in the detection path that spatially filters the measurement radiation. This diaphragm, positioned at an intermediate image plane, allows only radiation from the focal region to pass through, improving resolution while the system can compensate for aberrations through spatial resolution in the conjugate pupil plane
3Length of stationary object
If the numerical aperture is decreased to extend the depth range, then the accessible depth range is increased, but the lateral resolution deteriorates
Solution Approach 1:
The patent divides the optical system into independent illumination and detection subsystems with different NA values. The illumination subsystem uses small NA to achieve large depth range, while the detection subsystem uses large NA to maintain high lateral resolution, thus resolving the contradiction through functional segmentation
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 enables the generation of high-resolution, three-dimensional images of the retina with an extended depth range, effectively improving the detection of retinal structures and correcting aberrations, thereby enhancing the diagnosis of eye diseases.
Implementation Method 1
the detection beam path, which receives the measurement radiation from the illumination and measurement beam path and the reference radiation from the reference beam path and guides them in a superimposed manner onto at least one 2D detector
Data Source
AI summary
An optical coherence tomograph includes a wavelength tunable illuminating device, an illumination and measurement beam path with a dividing element and a scanner and a front optical unit and a reference beam path, a detection beam path and a flat panel detector. A beam splitter conducts the separated measurement radiation to the detection beam path and an optical element acts only on the illumination radiation. The optical element sets the numerical aperture of the illumination of the illumination field in the eye. An optical element acts only on the measurement radiation and sets the numerical aperture with which measurement radiation is collected in the eye. An aperture is arranged in front of the flat panel detector in an intermediate image plane and defines the size of an object field. The flat panel detector has a spatial resolution of 4 to 100 pixels in a direction.