Retinal Imaging Sensor Integrating Multiple Scans for Signal-to-Noise Ratio
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Solution Overview
Problem
Confocal line scanning eye examination apparatuses lack effective solutions for controlling the quantity of light reflected from the retina, leading to variable image brightness and low signal-to-noise ratio, especially for retinas with low reflectivity, and are costly to implement for improving image quality.
Innovation Solution
An eye examination apparatus that automatically adjusts the quantity of light by integrating reflected light during multiple optical scans, using a light detection device and control unit to optimize exposure and adjust the illuminator power, allowing the image sensor to combine light from multiple scans to produce a single image, rather than relying on post-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the exposure time or sensor gain is decreased to prevent saturation for highly reflective retinas, then image saturation is avoided, but image brightness becomes insufficient and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies dynamics by making the exposure time adjustable and adaptive rather than fixed. The control unit dynamically modifies the exposure time parameter based on real-time feedback from the measured retina reflectivity, allowing the system to optimize between preventing saturation and maintaining sufficient brightness for each individual patient's retina characteristics.
Solution Approach 2:
The patent implements feedback by measuring the reflectivity of the retina and using this measurement to automatically adjust the exposure time or sensor gain. The control unit receives the reflectivity measurement and modifies the acquisition parameters accordingly, creating a closed-loop system that adapts to varying retina reflectivity conditions.
2Stability of the object's composition
If post-processing is used to adjust image brightness, then brightness uniformity is improved, but signal-to-noise ratio remains low and implementation cost increases
Solution Approach 1:
The patent applies preliminary action by measuring the retina reflectivity before acquiring the final retinal images. This preliminary measurement allows the system to pre-adjust the exposure time or sensor gain parameters, ensuring optimal signal-to-noise ratio is achieved during the actual image acquisition phase rather than attempting to correct it through post-processing.
Solution Approach 2:
The system performs self-service by automatically measuring reflectivity and adjusting acquisition parameters without requiring manual intervention or complex post-processing operations. The control unit autonomously optimizes the imaging parameters based on the measured reflectivity, eliminating the need for expensive post-processing hardware and software solutions.
3Measurement precision
If intense visible light is used to illuminate the retina for measurement, then reflectivity measurement is possible, but the pupil closes before final images can be acquired
Solution Approach 1:
The patent applies segmentation by separating the measurement function from the imaging function. The system uses infrared light specifically for reflectivity measurement, which does not cause pupil constriction, while using visible light for final image acquisition. This functional segmentation allows both operations to occur without the pupil closure problem that would result from using visible light for measurement.
Solution Approach 2:
The patent utilizes color changes (wavelength changes) by switching between infrared illumination for measurement and visible light illumination for imaging. The infrared wavelength used for reflectivity measurement does not trigger the pupillary light reflex, allowing the pupil to remain open and enabling subsequent visible light imaging to proceed without time loss.
4Measurement precision
If multiple separate images are acquired and combined through post-processing, then signal-to-noise ratio is improved, but hardware costs increase significantly
Solution Approach 1:
The system achieves self-service by using the retinal reflectivity measurement itself to determine the optimal acquisition parameters. Instead of requiring multiple separate acquisitions and complex post-processing hardware, the system uses the measured reflectivity value to calculate and apply the appropriate exposure time or gain setting, achieving high signal-to-noise ratio with simple, cost-effective 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
This solution ensures consistent image brightness, improves the signal-to-noise ratio, and allows for flexible video acquisition settings, while being cost-effective and suitable for industrial-scale production, reducing the need for expensive hardware.
Implementation Method 1
an image sensor (27) arranged to receive said light reflected by the retina and to acquire one or more images of the same retina
Implementation Method 2
They collect and descan the light reflected by the retina making it pass through a fixed diaphragm
Data Source
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AI summary
The present invention relates to an eye examination apparatus comprising: - at least an illuminator (11) adapted to project a light beam (1) to illuminate the retina (101) of an eye (100); - image sensor (27) adapted to receive light (2, 202 ) reflected by the retina and to acquire images of the retina; - scanning means (17) adapted to perform optical scans of the retina moving the light beam (1) projected by said illuminator on the retina along a scanning direction (DS); separation means (16) of the light beams adapted to separate the light (1) projected by said illuminator from the light (2) reflected by the retina and directed toward said image sensor (27); - a control unit (40) to control the operation of said scanning apparatus. During the operation of said apparatus, in order to acquire each single image of a region of the retina to be framed, said image sensor integrates light (2, 202) reflected by the retina during at least two complete optical scans of said region of the retina by said scanning means.