Ophthalmic Fundus Imaging for Microcoria With Adaptive Slit Illumination
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Solution Overview
Problem
Existing ophthalmic apparatuses face challenges in acquiring high-quality images of a subject's eye, particularly when the pupil is microcoria, leading to reduced light entry and degraded image quality due to varying eye states such as dioptric power.
Innovation Solution
An ophthalmic apparatus with a slit-shaped illumination system, optical scanner, and imaging system that uses a rolling shutter method to synchronize light reception with the movement of slit-shaped illumination, allowing for high-quality image acquisition by controlling the position and movement of optical components based on the subject's eye state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional illumination systems are used, then the apparatus can operate with standard components, but image quality degrades when the pupil is microcoria due to reduced light entry
Solution Approach 1:
The illumination optical system dynamically adjusts the slit position in the optical axis direction based on the dioptric power of the subject's eye. The controller moves the slit to different positions along the optical axis to compensate for variations in eye state, ensuring optimal light entry and image quality regardless of whether the pupil is microcoria or normal size.
Solution Approach 2:
The system changes the physical position parameter of the slit along the optical axis to adapt to different eye conditions. By varying the slit position based on measured dioptric power, the system optimizes illumination intensity and light entry for each subject's specific eye state, resolving the contradiction between maintaining standard operation and adapting to varying conditions.
2Measurement precision
If the slit position is fixed, then the apparatus structure is simpler, but image quality varies with different dioptric powers
Solution Approach 1:
The slit is configured to be movable along the optical axis under controller actuation. This dynamic positioning capability allows the system to adjust the slit position according to the subject's dioptric power, maintaining high image quality across different eye conditions while adding only minimal complexity through a motorized adjustment mechanism.
Solution Approach 2:
The controller receives information about the subject's dioptric power and uses this feedback to automatically adjust the slit position. This closed-loop control system ensures optimal image quality by continuously adapting the illumination parameters to match the subject's specific eye characteristics, resolving the trade-off between fixed simplicity and adaptive precision.
3Ease of operation
If standard illumination patterns are used, then the system is easier to operate, but contrast is reduced when imaging fundus with varying pupil sizes
Solution Approach 1:
The system uses a slit-shaped illumination pattern that can be positioned at different locations in the optical axis direction to optimize local illumination conditions. By adjusting the slit position based on dioptric power, the system creates optimal local illumination geometry for each subject's eye, enhancing fundus image contrast while maintaining ease of operation through automated control.
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 high-quality imaging of the fundus with strong contrast and reduced impact from varying eye states, using a simple configuration that adapts to different pupil sizes and shapes.
Implementation Method 1
an optical scanner configured to deflect the illumination light to guide the illumination light to a fundus of a subject's eye
Implementation Method 2
an imaging optical system configured to guide returning light of the illumination light from the fundus to an image sensor
Data Source
AI summary
An ophthalmic apparatus includes a light source, an illumination optical system, an optical scanner, an imaging optical system, and a controller. The illumination optical system generates slit-shaped illumination light. The optical scanner deflects the illumination light to guide the illumination light to a fundus of a subject's eye. The imaging optical system guides returning light of the illumination light from the fundus to an image sensor. The controller controls the image sensor using a rolling shutter method. The illumination optical system includes a slit-shaped aperture arranged at a position substantially conjugate optically to the fundus, an iris aperture arranged between the light source and the slit, and configured to be at a position substantially conjugate optically to an iris of the subject's eye; and an optical element arranged between the light source and the iris aperture, to deflect the light from the light source.