Fundus Optical Path Separation for Wide-Angle OCT Imaging
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Solution Overview
Problem
Existing fundus observation apparatuses face challenges in achieving wide-angle imaging of the eye's fundus at a low cost and with a simple configuration, particularly when combining scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) systems, as they require expensive high-speed scanners and struggle to maintain optical paths within 180 degrees, leading to difficulties in parallel imaging and measurement.
Innovation Solution
A fundus observation apparatus using a deflecting member, such as a hole mirror, to separate and couple the optical paths of illumination and returning light, allowing for wide-angle scanning without sharing optical scanners, and integrating an OCT optical system to perform OCT measurement while observing the fundus at a wide angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a scanning laser ophthalmoscope (SLO) is used to achieve wide-angle fundus imaging, then the field of view is improved, but the device complexity and cost increase due to requiring expensive high-speed scanners
Solution Approach 1:
The patent combines the illumination optical system and the light receiving optical system into a single integrated fundus observation optical system. The deflecting member serves dual functions: it scans the illumination light across the fundus while also directing the returning light to the image sensor. This merging eliminates the need for separate scanning mechanisms in both illumination and detection paths, reducing device complexity and cost while maintaining wide-angle imaging capability
Solution Approach 2:
The deflecting member is designed to perform multiple functions simultaneously: it acts as both the scanning element for the illumination light and the beam splitter/director for the returning light. This multi-functional design replaces what would traditionally require separate high-speed scanners for both illumination scanning and detection, thereby reducing device complexity while achieving wide field of view
2Device complexity
If the optical paths of illumination light and returning light are kept within 180 degrees, then the device complexity is reduced, but the ability to perform parallel OCT measurement and SLO imaging is compromised
Solution Approach 1:
The patent separates the optical paths spatially by positioning the OCT optical system in a different dimension or location relative to the fundus observation optical system. The optical path coupling separating member enables the OCT measurement light to traverse through or alongside the SLO optical path without interfering with the illumination and returning light paths. This dimensional separation allows both SLO imaging and OCT measurement to proceed in parallel while maintaining relatively simple optical path geometries
Solution Approach 2:
The optical path coupling separating member acts as an intermediary that couples the OCT optical system with the fundus observation optical system. It enables the OCT measurement light to access the fundus through the same deflecting member while separating the OCT returning light from the SLO returning light. This intermediary component facilitates parallel operation of both systems without requiring complex optical path folding beyond 180 degrees
3Productivity
If expensive high-speed scanners are used to achieve wide-angle imaging, then the imaging speed and quality are improved, but the cost increases
Solution Approach 1:
The deflecting member performs self-service by simultaneously executing the scanning function for illumination light and the beam directing function for returning light. Its natural deflection motion inherently provides the scanning capability needed for wide-angle imaging without requiring additional high-speed scanner components. This self-service approach achieves imaging functionality while avoiding the cost of expensive dedicated scanning devices
Solution Approach 2:
The patent merges the scanning function and the beam directing function into a single deflecting member, eliminating the need for separate high-speed scanners. This consolidation achieves wide-angle imaging at lower cost by using a single component that naturally provides scanning motion through its deflection mechanism, rather than requiring expensive dedicated scanning hardware
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
Enables wide-angle fundus observation with an affordable and straightforward setup, facilitating simultaneous OCT measurement and SLO imaging beyond 180 degrees without the need for high-speed scanners, thus enhancing imaging capabilities and cost-effectiveness.
Implementation Method 1
a deflecting member configured to couple an optical path of the illumination light and an optical path of the returning light and to scan the fundus with the illumination light by deflecting the illumination light
Implementation Method 2
an OCT optical system including an optical scanner and configured to perform OCT scan that irradiates measurement light deflected by the optical scanner onto the subject's eye and detects interference light between returning light of the measurement light and reference light
Data Source
AI summary
A fundus observation apparatus includes an illumination optical system, a two-dimensional image sensor, and a deflecting member. The illumination optical system is configured to illuminate a fundus of a subject's eye with line-shaped illumination light. The two-dimensional image sensor is configured to receive returning light of the illumination light from the fundus on a movable focal plane at a position substantially conjugate optically to the fundus. The deflecting member is configured to couple an optical path of the illumination light and an optical path of the returning light and to scan the fundus with the illumination light by deflecting the illumination light in synchronization with a movement of the focal plane. The deflecting member has a configuration that allows the returning light to be transmitted through a first region and to reflect the illumination light in a second region different from the first region.