Telecentric Eye Exam Instrument with Movable Mirror
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Solution Overview
Problem
Current eye examination instruments, such as Scanning Laser Ophthalmoscopes, face challenges in accurately assessing the functionality of the macular region of the retina, particularly in determining the independence of stimulus location from the background, and in providing precise, objective evaluations of retinal sensitivity and fixation ability without pupil dilation or uncomfortable flashes.
Innovation Solution
A compact, cost-effective Scanning Laser Ophthalmoscope with a confocal IR imaging system and a telecentric projection system, utilizing a Maxwellian view illumination and a line-scanning laser optical system, allows for continuous tracking and precise measurement of retinal sensitivity and fixation ability, with stimuli projected independently of the background using a movable mirror and LED light sources, ensuring uniform illumination and stable output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an LCD display is used to produce stimuli, then various types of patterns and stimuli can be projected onto the retina, but the location of stimuli is limited to discrete points depending on the pixel of the LCD screen
Solution Approach 1:
The patent replaces the LCD display (electromechanical system with discrete pixels) with a laser projection system that uses optical scanning to generate stimuli. The laser beam is directed by scanning mirrors to project stimuli at any continuous location on the retina, eliminating the discrete pixel limitation of LCD displays while maintaining the ability to present various stimulus patterns.
2Reliability
If pupil dilation is performed to improve retinal imaging, then better access to the retina is achieved, but it requires additional medication and increases examination complexity
Solution Approach 1:
The patent changes the wavelength parameter of the illumination light to infrared, which has longer wavelength and can penetrate the ocular media more effectively. This allows high-quality retinal imaging through the natural pupil size without requiring dilation, as the infrared light achieves sufficient transmission and image quality at smaller aperture sizes.
3Reliability
If a conventional scanning laser ophthalmoscope is used, then retinal imaging is achieved, but the stimuli and background projected onto the retina are not independent
Solution Approach 1:
The patent segments the optical path into separate channels: one for projection of stimuli and background, and another for detection of retinal responses. By using beam splitters and separate optical paths, the system can independently control the stimulus presentation and the background illumination, allowing the stimuli and background to be varied independently without affecting each other.
4Ease of manufacture
If a line-scanning laser optical system is used, then cheaper optics can be employed, but the system is confocal only in one direction
Solution Approach 1:
The patent employs dynamic scanning of the laser line across the retina, using galvanometer mirrors to rapidly sweep the illumination and detection lines. This dynamic scanning approach allows the system to achieve high effective resolution through temporal sampling, compensating for the reduced spatial confocality in the non-scanned direction and maintaining good optical image resolution while using simpler, less expensive optics.
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
The instrument provides high-resolution, objective evaluations of retinal morphology and functionality, enabling accurate classification of retinal sensitivity and fixation stability without pupil dilation, reducing discomfort and calibration issues, and offering automatic data analysis for clinical assessment.
Implementation Method 1
The selected wavelength of the light source 4 is a suitable compromise between the produced scattering (the longer the wavelength, the more the scattering because a deep light penetration into the eye's tissues takes place)
Implementation Method 2
The reflected light is confocally received from the illuminated portion of the retina and provides an output light in a line focus configuration
Implementation Method 3
a Maxwellian view illumination is used in the imaging system of the instrument of the invention
Implementation Method 4
The projection system has a telecentric design which guarantees a uniform illumination over the whole projection region with no dependence on the projection angle
Implementation Method 5
The stimulus projection path from the second source of light (i.e., from pinhole 114 which, as said, can be considered the location of the second source of light) to the retina is designed to be telecentric and to provide a uniform illumination not dependent on the projection angle. The movable mirror 112 allows very low aberrations with low cost optics
Implementation Method 6
The first source of light 4, which is substantially a point source of light... has preferably a central wavelength within the infrared (IR) range, for example at 850 nm
Data Source
AI summary
The present invention relates to an instrument for eye (E) examination, the system including an imaging system (2) to produce images of a portion of the.eye to be examined; a projection system (3) to project a stimulus of visible light on a location in the portion of the eye to be examined and a background light on the portion of the eye- to be examined; in which the projection system (3) has a telecentric design to uniformly project the stimulus and the background and includes a light source (114) and a movable mirror (112) which is moved according to the location of stimulus projection.