Variable Width Projection Diaphragm for Uniform Retinal Illumination
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Solution Overview
Problem
Confocal line scanning eye examination apparatuses face challenges with low radiance white light sources, leading to noisy images and insufficient light power, especially in peripheral regions, and struggle to achieve uniform brightness and high contrast images with wide fields of view.
Innovation Solution
The apparatus employs a light source with a projection diaphragm and confocal diaphragm having elongated openings with varying widths, optically conjugated with the retina, to increase light power and reduce noise, and uses a projection mask with a rectilinear edge to separate illumination and reflected light beams, minimizing reflections and ensuring uniform image brightness across the field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low radiance white light sources (e.g., LED) are used in confocal line scanning apparatus, then device complexity and production costs are reduced, but image quality deteriorates due to noisy images and insufficient light power
Solution Approach 1:
The patent changes the geometric parameters of the projection diaphragm opening, specifically making the width variable along the elongated direction to optimize light distribution. This allows low radiance sources to achieve uniform illumination without requiring high-power expensive light sources, thus resolving the contradiction between manufacturing ease and image quality
Solution Approach 2:
The projection diaphragm implements local quality by having different opening widths at different positions along its elongated structure. This non-uniform geometry compensates for the non-uniform light emission characteristics of LED sources, achieving uniform light power distribution across the illuminated retinal line while using cost-effective low radiance sources
2Power
If the light beam width is increased to improve illumination power, then light power increases, but undesired reflections increase due to larger beam overlap with optical components
Solution Approach 1:
The projection diaphragm applies local quality by varying the opening width along its elongated direction. This creates a tailored light beam profile that concentrates power where needed while maintaining sufficient separation from optical components, thus increasing light power without proportionally increasing undesired reflections
Solution Approach 2:
The scanning mechanism dynamically moves the shaped light beam across the retina, allowing the optimized beam geometry to be applied sequentially to different regions. This dynamic approach enables adequate illumination power while minimizing reflections at any given moment during the scanning process
3Device complexity
If a standard rectangular projection diaphragm opening is used, then device complexity is reduced, but brightness uniformity deteriorates especially in peripheral regions
Solution Approach 1:
The projection diaphragm opening transitions from a simple rectangular shape to an elongated shape with variable width along its length. This geometric modification creates local variations in light transmission that compensate for the natural decrease in light power toward peripheral regions, achieving uniform brightness across the illuminated area while maintaining relatively simple device structure
Solution Approach 2:
The patent changes the geometric parameters of the projection diaphragm opening, specifically making the width variable along the elongated direction to optimize light distribution. This parameter optimization enables uniform brightness without requiring complex additional optical elements, thus resolving the contradiction between device simplicity and brightness uniformity
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 configuration enhances image quality by increasing light power in peripheral regions, reducing noise, and achieving uniform brightness and high contrast images, even with wide fields of view, while minimizing reflections and production costs, making the apparatus suitable for industrial-scale production.
Implementation Method 1
at least an illuminator (11) adapted to project a light beam (1) on an optical illumination path (1A), along a first optical axis (O1), to illuminate the retina (101) of an eye (100), said illuminator comprising at least a light source (111)
Implementation Method 2
separation means of the light beams adapted to separate the projected light by said illuminator from the light reflected by the retina and directed toward said acquisition means
Implementation Method 3
scanning means adapted to move the light beam projected by the illuminator on the surface of the retina along a scanning direction
Implementation Method 4
acquisition means adapted to receive light reflected by the retina along an optical imaging path having a second optical axis and to acquire images of the retina
Data Source
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AI summary
An eye examination apparatus that comprises: - at least an illuminator (11, 12) adapted to project a light beam (1) on an optical illumination path (1A) along a first optical axis (O1) to illuminate the retina (101) of an eye (100), said illuminator comprising at least a light source (111, 121, 125) and at least a projection diaphragm (114, 124) adapted to shape the light beam (1), during the operation of said examination apparatus said projection diaphragm being optically conjugated with the retina; - acquisition means (27) adapted to receive light (2) reflected by the retina and to acquire images of the retina; - scanning means (17) adapted to move the light beam (1) projected on the surface of the retina along a scanning direction; - separation means (16) of the beams adapted to separate the light (1) projected by said illuminator from the light (2) reflected by the retina; The projection diaphragm comprises at least a projection opening (1140, 1240) having an elongated shape and variable width, said projection opening comprising at least a portion having a width larger than the width of said projection opening at the first optical axis (O1).