Fundus Imaging Alignment With Split Optical Channels
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Solution Overview
Problem
Existing ophthalmic imaging instruments, such as fundus cameras, face challenges in achieving optimal optical performance, including field-of-view, image quality, reflection artifact reduction, precise alignment, effective focusing, and cost-efficiency, while maintaining a compact design.
Innovation Solution
The ophthalmic imaging instrument employs multiple optical channels, including visible and near-infrared illumination channels, phase detection auto-focus imaging, and alignment channels, utilizing polarization and dichroic beamsplitters to separate illumination and imaging beams, and uses data processing units for optimal alignment, thereby improving image quality and reducing reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a beamsplitter is used to separate illumination and imaging beams, then image quality is improved by reducing reflection artifacts, but device complexity increases
Solution Approach 1:
The patent extracts the illumination beam path from the imaging beam path by using a beamsplitter to separate them. This allows independent optimization of each path - the illumination path can be tailored for even lighting while the imaging path is optimized for image quality, reducing cross-interference and reflection artifacts between the two functions
Solution Approach 2:
The beamsplitter acts as an intermediary optical element that mediates between the illumination source and the imaging detector. It enables the coexistence of two separate optical paths within a single instrument, allowing both illumination and imaging functions to operate simultaneously without direct interference
2Measurement precision
If multiple optical channels are added for alignment and focusing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the optical system into multiple specialized channels: an illumination channel for even lighting, an imaging channel for fundus capture, and alignment channels for positioning. Each channel is optimized for its specific function, allowing high precision in alignment and focusing without requiring the entire system to be overly complex
Solution Approach 2:
The alignment channels provide self-service functionality by automatically detecting and indicating misalignment conditions. The system includes features that self-diagnose positioning errors and guide the user to correct them, reducing the need for complex manual alignment procedures
3Ease of operation
If the instrument is made compact, then ease of operation is improved, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The patent employs a nested optical design where components are arranged concentrically and in overlapping configurations. The illumination and imaging paths are nested within each other, sharing common optical elements where possible. This nesting allows the entire optical system to be compressed into a compact form factor while maintaining the precise relative positioning of critical components
Solution Approach 2:
The patent utilizes parameter changes in the optical design, such as varying focal lengths, aperture sizes, and beam diameters at different stages of the optical path. By carefully controlling these parameters, the system achieves compact dimensions while preserving the precision required for accurate optical alignment and imaging performance
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 enhances image quality by accurately determining the optimal working distance and minimizing reflection artifacts, allowing for better fundus imaging with minimal distortion, while maintaining a compact and cost-effective design.
Implementation Method 1
The optical system may also require a beamsplitter such as polarization beamsplitter for separating the illumination and imaging beams from each other
Implementation Method 2
An objective lens is configured to receive the light from the retina and form an image of the retina at an intermediate image plane
Data Source
AI summary
An ophthalmic apparatus comprises a visible light illumination channel, which illuminates a retina of an eye of a patient under examination by visible light. A near-infrared illumination channel illuminates the retina of the eye of the patient under examination by near-infrared light. An imaging channel receives light from the retina of the eye illuminated by the visible light and/or the near-infrared light. A target channel outputs fixation image content to a patient whose eye is under the examination for fixation of a gaze direction of the patient. An alignment arrangement illuminates the anterior part of the eye and reflections therefrom are received by two of a fundus camera sensor and a first and second pupil camera sensors. A data processing unit determines an optimal positional alignment of the eye for imaging a fundus of the eye by a fundus camera sensor based on still image and/or video capture of the anterior part of the eye.