Ophthalmic Lens Refraction Measurement Using Support Shadow Geometry
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Solution Overview
Problem
Existing methods for determining refractive characteristics of ophthalmic lenses, such as spherical power and prismatic deviation, are hindered by the use of patterned plates or markers that degrade image quality, interfere with centering and alignment marks, and introduce systematic errors due to prismatic deviations, increasing costs and complexity.
Innovation Solution
A method that captures the shadow of support elements on an ophthalmic lens without additional optical elements, using the geometric characteristics of the support to determine refractive characteristics by analyzing the deformation and displacement of the shadow, allowing for precise determination of spherical power and prismatic deviation without disturbing the image or adding cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a patterned plate is inserted between the lens and the image capture device, then the refractive characteristics can be determined, but the distance between the lens and the image capture device must be increased, leading to deterioration in image quality and increased distortion
Solution Approach 1:
The invention extracts the measurement function from a separate patterned plate and integrates it into the support structure itself. The support elements are positioned at known coordinates on the support, eliminating the need for a separate patterned plate and allowing measurement without increasing the distance between lens and image capture device.
Solution Approach 2:
The invention merges the support structure with the measurement reference system. The support elements that hold the lens also serve as the reference pattern for measurement, combining two functions into one structure and eliminating the need for additional optical elements.
2Measurement precision
If a patterned plate is inserted between the lens and the image capture device, then the refractive characteristics can be determined, but the cost of the device increases
Solution Approach 1:
The support structure is designed to serve multiple functions: holding the lens during mounting operations and providing the reference pattern for refractive measurement. This multi-functionality eliminates the need for a separate patterned plate, reducing device complexity and cost.
Solution Approach 2:
The support structure provides its own reference pattern through its geometrically precise elements, eliminating the need for external measurement aids. The support serves itself as the measurement reference, reducing the need for additional components.
3Measurement precision
If markers are added to the lens for determining refractive characteristics, then the measurement can be performed, but the markers interfere with reading the lens centering and alignment marks, degrading image quality
Solution Approach 1:
The invention separates the measurement reference elements from the lens itself, placing them on the support structure instead. This segmentation allows the lens markings to remain visible while providing a separate reference system for measurement, eliminating interference between the two functions.
4Measurement precision
If additional optical elements are added to determine refractive characteristics, then the measurement capability is improved, but the system complexity and cost increase
Solution Approach 1:
The invention extracts the measurement reference from external optical elements and embeds it directly into the support structure. This eliminates the need for separate patterned plates or markers, reducing the number of optical elements in the system.
Solution Approach 2:
The support structure is designed to serve dual purposes: mechanical support for the lens and optical reference for measurement. This multi-functionality eliminates the need for additional optical elements, simplifying the overall system.
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 precise and economical determination of refractive characteristics, correcting for systematic errors and improving the accuracy of centering and alignment, without the need for additional optical elements or markers, thus enhancing the precision and efficiency of ophthalmic lens mounting processes.
Implementation Method 1
capturing, using means for capturing image, in an image capture plane substantially perpendicular to an optical axis of the lens, an image of the support illuminated by the rays coming from said illumination means and having passed through said lens
Implementation Method 2
determining at least one characteristic representative of the geometry of this image of the support and deducing from this characteristic representative of the geometry of the support, said characteristic of desired refraction
Data Source
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AI summary
The invention relates to a method of determining at least one refraction characteristic of an ophthalmic lens (20), according to which: a) the lens is disposed on a support (10) comprising at least one holding element (12, 13, 14), in contact with one of the main faces of the lens in a zone of contact of reduced area with respect to the area of the main faces of this lens; b) the lens placed on its support is illuminated with the aid of illuminating means (40); c) an image of the holding element of the support illuminated by the rays (R1, R2) emanating from said illuminating means and having passed through the lens is captured with the aid of image capture means (30) in an image capture plane substantially perpendicular to an optical axis (AO) of the lens (20); d) the image of said support holding element is identified, on this image, and at least one characteristic representative of the geometry of the image of said holding element is determined; e) said sought-after refraction characteristic is deduced from at least this characteristic representative of the geometry of the image of said holding element.