Z-Polarization Optical System for Fundus Imaging Ghost Flare Suppression
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Solution Overview
Problem
Conventional fundus imaging techniques suffer from ghost flare due to unnecessary light reflection, particularly when irradiation light has a wide angle, as existing methods either fail to prevent overlapping optical paths or block necessary light, leading to incomplete suppression of ghost flare.
Innovation Solution
An optical system with a polarization control unit that makes light irradiated to the eye z-polarization axisymmetric with respect to the optical axis, using z-polarizers or a polarization beam splitter to block z-polarization of reflected light, ensuring that only necessary light is captured by the light-acceptance unit, such as a camera or lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a linear polarization device is used to block unnecessary light, then ghost flare is suppressed, but reflected light from spaces other than parallel or orthogonal to the optical axis cannot be fully blocked due to polarization rotation
Solution Approach 1:
The patent changes the polarization parameter from linear polarization to z-polarization (radial or azimuthal polarization symmetric with respect to the optical axis). This parameter change enables effective blocking of unnecessary light from all angles while maintaining suppression of ghost flare, overcoming the limitation of linear polarization devices that fail when light comes from oblique angles.
Solution Approach 2:
The patent introduces asymmetric polarization distribution (z-polarization) where the polarization direction varies with the angle of incident light. Instead of a fixed linear polarization direction, the polarization symmetry is with respect to the optical axis, creating different polarization states for different incident angles, which enables comprehensive blocking of unnecessary light.
2Loss of energy
If conventional polarization methods are used, then some unnecessary light is blocked, but when irradiation light has a wide angle, most optical paths overlap and ghost flare cannot be prevented
Solution Approach 1:
The patent employs z-polarization (radial or azimuthal polarization) instead of conventional linear polarization. This parameter change in the polarization state enables the system to handle wide-angle irradiation light effectively, preventing optical path overlap and ghost flare while maintaining the ability to block unnecessary light.
Solution Approach 2:
The patent transitions from one-dimensional linear polarization to two-dimensional z-polarization symmetric with respect to the optical axis. This dimensional change in polarization configuration allows effective management of light from multiple angles, preventing ghost flare even when irradiation light has a wide angle.
3Object-affected harmful factors
If shielding methods are used to block unnecessary light, then ghost flare is reduced, but when irradiation light has a wide angle, the image becomes large and necessary light is also blocked
Solution Approach 1:
The patent uses z-polarization (radial or azimuthal polarization) instead of conventional shielding methods. This parameter change in polarization state enables selective blocking based on polarization direction rather than physical obstruction, allowing unnecessary light to be blocked while preserving necessary light from the fundus, even with wide-angle illumination.
Solution Approach 2:
The patent extracts and blocks only the z-polarized unnecessary light component using a polarization control unit, while allowing other components (including necessary light from the fundus) to pass through. This selective extraction approach avoids the problem of blocking necessary light that occurs with conventional shielding methods.
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
Effectively blocks unnecessary light and suppresses ghost flare occurrence, allowing for clear observation of the fundus image by ensuring that only relevant light is recorded, thereby improving the quality of fundus imaging.
Implementation Method 1
a polarization control unit for making light irradiated to the eye z-polarization axisymmetric with respect to an optical axis
Implementation Method 2
blocking the z-polarization of reflected light reflected on the eye and directed to the light-acceptance unit
Data Source
AI summary
An optical system for observing reflected light from a fundus includes: an irradiation unit for irradiating an eye with light exited from a light source; a light-acceptance unit for accepting reflected light reflected on a fundus of the eye; and a polarization control unit for making light irradiated to the eye z-polarization axisymmetric with respect to an optical axis and blocking the z-polarization of reflected light reflected on the eye and directed to the light-acceptance unit.