Switchable Objective Lens for OCT Alignment
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Solution Overview
Problem
Current optical coherence tomography instruments face challenges in accurately aligning with the eye, particularly in achieving proper axial and lateral positioning relative to the pupil, which can result in inaccessible areas of the retina and requires complex, slow, and inaccurate alignment methods.
Innovation Solution
An ophthalmic optical coherence tomography instrument with a switchable objective lens that can be set between posterior and anterior imaging configurations, allowing for adjustable scanning of the sample light across the retina, and a controller that facilitates alignment by detecting structures within the eye and adjusting the objective's position to correct offsets, enabling precise alignment and improved imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pupil camera with shallow depth of field is used for alignment, then alignment can be performed, but the method becomes optically complex, slow, and inaccurate
Solution Approach 1:
The patent creates a virtual image of the pivot point that can be captured by a standard camera without requiring special optical arrangements. By projecting the pivot point through the objective lens to form a virtual image at a convenient location, the system eliminates the need for complex pupil camera optics while maintaining alignment accuracy.
Solution Approach 2:
The patent introduces a virtual image as an intermediary between the pivot point and the camera sensor. This virtual image serves as a measurable reference that can be captured by standard imaging equipment, replacing the need for direct observation of the actual pivot point which requires complex optical arrangements.
2Reliability
If the scan pivot point is not precisely aligned with the pupil, then areas of the interior of the eye become inaccessible, but achieving precise alignment requires complex and slow methods
Solution Approach 1:
The patent replaces complex mechanical alignment procedures with an optical imaging method. Instead of using mechanical adjustment mechanisms and visual inspection, the system uses optical projection and digital image processing to automatically determine and verify alignment, significantly reducing alignment time while improving precision.
Solution Approach 2:
The system performs self-alignment by automatically capturing the virtual pivot point image, processing it to determine pivot point location, and comparing it with the pupil position. This automated self-service alignment eliminates the need for operator intervention and complex manual adjustment procedures.
3Measurement precision
If the objective is fixed in posterior imaging configuration, then retina imaging is optimized, but alignment with the pupil becomes difficult
Solution Approach 1:
The patent makes the imaging system dynamic by allowing the objective lens to switch between anterior and posterior imaging configurations. The system dynamically adapts its optical configuration based on the operational phase: using anterior configuration for alignment (where the virtual pivot point is accessible) and posterior configuration for retina imaging (where retinal quality is optimized).
Solution Approach 2:
The patent divides the imaging process into distinct phases with different optical configurations. The alignment phase uses anterior imaging configuration to facilitate easy pivot point alignment, while the measurement phase switches to posterior imaging configuration for optimized retina imaging. This segmentation allows each phase to use the most appropriate optical setup.
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
The solution enables more accurate and efficient alignment of the optical coherence tomography instrument with the eye, ensuring comprehensive imaging of the retina by correcting axial and lateral offsets, thereby improving the quality and accessibility of optical coherence tomography measurements.
Implementation Method 1
The returning light from the sample arm and the reference arm are recombined by the coupler to generate an interference pattern. The interference pattern contains information about the optical path travelled by the reflected sample light
Implementation Method 2
an objective having a posterior imaging configuration to project the apparent point source onto a pivot point on a pivot plane between the objective and the subject position
Implementation Method 3
a sample optical system includes an optical arrangement which applies a one or two-dimensional angular scan pattern to the sample beam in order to scan the sample beam across the interior of the eye
Data Source
AI summary
An ophthalmic optical coherence tomography instrument, method, and computer-readable medium. The instrument includes a scanner defining an apparent point source for scanning sample light across a subject position and an objective having a posterior imaging configuration to project the apparent point source onto a pivot point between the objective and the subject position. The objective is settable between the posterior imaging configuration for scanning the sample light across a retina of an eye at the subject position and an anterior imaging configuration for scanning the sample light across a pivot plane. An axial region from which an interferogram is detectable extends across the pivot plane while the objective is in the anterior imaging configuration. A pupil alignment method uses the anterior imaging modality to obtain a structure position of a structure of an eye's anterior segment and then an offset between the structure position and a reference position.