Fundus Imaging Optics With Pupil Beam Separation for Higher Contrast
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Solution Overview
Problem
Existing confocal eye fundus inspection apparatuses with line scanning face challenges in reducing parasitic light from the crystalline lens, leading to image blurring and requiring complex data processing and lengthy acquisition times, especially in eyes affected by cataract or other disorders.
Innovation Solution
The apparatus employs light beam separation at the pupil level and uses shaped light beams with elongated projection and acquisition regions, synchronized scanning, and advanced image processing to enhance contrast and reduce parasitic light effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the confocal diaphragm opening width is increased to illuminate a wider retinal region, then the illuminated area increases, but the ability to filter parasitic light from the crystalline lens deteriorates
Solution Approach 1:
The pupil is divided into two separate zones: an illumination zone through which the excitation light beam passes, and a detection zone through which the emitted light beam passes. This spatial segmentation prevents parasitic light scattered in the crystalline lens from entering the detection path, while allowing a sufficiently wide illumination area for adequate light output.
Solution Approach 2:
The patent introduces filter means with specific optical properties that selectively block parasitic light from the crystalline lens while allowing fluorescence light from the retina to pass. These filter means act as intermediaries that differentiate between useful signal and harmful interference based on their optical characteristics.
2Illumination intensity
If the light beam width is increased to compensate for limited LED radiance, then sufficient light output is achieved, but image resolution and contrast deteriorate due to increased parasitic light
Solution Approach 1:
By segmenting the pupil into separate illumination and detection zones, the system can use a wider light beam for adequate illumination intensity while preventing scattered parasitic light from degrading image quality. The spatial separation ensures that only light from the illuminated retinal region enters the detection path.
Solution Approach 2:
The patent applies different optical properties to different regions of the optical path. The illumination zone allows broad light distribution for sufficient intensity, while the detection zone implements strict filtering and spatial confinement to maintain high image contrast and resolution by excluding parasitic light.
3Measurement precision
If light beam separating means are added to reduce parasitic light, then image contrast improves, but device complexity increases
Solution Approach 1:
The patent implements beam separation through simple spatial segmentation of the pupil into illumination and detection zones, avoiding complex mechanical beam separating means. This approach achieves effective parasitic light reduction through straightforward optical geometry rather than complex additional components.
Solution Approach 2:
The filter means serve multiple functions simultaneously: they block parasitic light from the crystalline lens, transmit fluorescence light from the retina, and can be integrated into existing optical paths without requiring separate dedicated components for each function.
4Object-affected harmful factors
If the confocal diaphragm opening is made narrow to improve parasitic light filtering, then filtering capability improves, but insufficient light reaches the sensor for adequate image acquisition
Solution Approach 1:
The segmentation of the pupil into separate illumination and detection zones allows the detection zone to be optimally sized for sensitive detection without requiring a narrow confocal diaphragm opening. The spatial separation ensures that even with a larger detection zone opening, only light from the corresponding retinal region is detected, maintaining filtering capability while increasing light intensity.
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 achieves high-contrast color or fluorescence images with wide field views, enabling efficient quantitative measurements and reducing reconstruction artifacts, while being cost-effective and suitable for industrial production.
Implementation Method 1
They comprise, besides the components described above, filter means capable of blocking the reflected excitation light and allowing fluorescence light, emitted by particular fluorescent substances present on the retina
Implementation Method 2
illumination means (12) comprising at least a light source and adapted to project a first light beam (1) to illuminate a retina (101) of an eye (100); an optical lighting path (1A) for the first light beam (1)
Implementation Method 3
scanning means (17) adapted to move the first light beam (1) on the retina
Implementation Method 4
filter means capable of blocking the reflected excitation light and allowing fluorescence light, emitted by particular fluorescent substances present on the retina
Data Source
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AI summary
Eye fundus inspection apparatus (500) comprising: - illumination means (12) comprising at least a light source (121, 123, 124, 126) and adapted to project a first light beam (1) towards a retina (101) of an eye (100); - an optical lighting path (1A) for said first light beam; - acquisition means (27) adapted to receive a second light beam (2) coming from the retina; - an optical acquisition path (2A) for said second light beam; - scanning means (17) adapted to scan said first light beam (1) on the retina with a linear movement, according to a first scanning direction (S1), or with a circular movement about a rotation axis (A), according to a second scanning direction (S2); - light beam separating means (16) adapted to define separate passage zones for said first and second light beams (1, 2) at a pupil of the eye; - a control unit (120) adapted to control operation of said inspection apparatus; - first light beam shaping means (11) and second light beam shaping means (23, 271, 272) that allow obtaining improved retinal images.