Optical Component Face Measurement Using Segmented Deflectometry
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Solution Overview
Problem
Current methods for measuring the geometric structure of optical components, particularly ophthalmic lenses, face challenges in achieving precise and absolute measurements of both faces without prior knowledge of the component's refractive index or topography, often requiring expensive and complex point-to-point probing techniques.
Innovation Solution
A method involving zonal or multipoint measurements using digital reconstruction of signals from both faces, where one measurement is in reflection and the other in transmission, allowing for independent determination and estimation of each face's structure without prior knowledge, employing cost functions to quantify differences and achieve precise height evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional point-to-point probing methods are used to measure both faces of optical components, then measurement precision can be maintained, but device complexity and cost increase significantly
Solution Approach 1:
The patent divides the measurement task into two independent face measurements, each using simple deflectometry equipment. By measuring each face separately with independent probe signals, the system avoids the need for complex simultaneous multi-face measurement equipment, thereby reducing device complexity while maintaining measurement precision for each face
Solution Approach 2:
The patent introduces digital reconstruction as an intermediary computational step that bridges the two separate face measurements. By digitally reconstructing the geometric structure from independent measurements of each face, the system achieves complete component characterization without requiring complex hardware that can directly measure both faces simultaneously
2Productivity
If transmission measurements are used to measure both faces simultaneously, then measurement speed improves, but measurement precision deteriorates due to combined effects of both faces
Solution Approach 1:
The patent segments the measurement process into two independent measurements, each targeting a single face with its own probe signal. This segmentation eliminates the combined effects problem where both faces interfere with each other in transmission measurements, thereby restoring measurement precision while maintaining the efficiency of optical measurement methods
Solution Approach 2:
Instead of using transmission measurements that pass through both faces (forward approach), the patent inverts the approach by using reflection measurements where the probe signal interacts with only one face at a time. This inversion allows independent determination of each face's geometric structure without mutual interference
3Measurement precision
If prior knowledge of refractive index or topography is required for absolute measurement, then measurement precision can be achieved, but ease of operation decreases
Solution Approach 1:
The patent implements a self-service measurement system where the deflectometry measurements of each face provide sufficient information for digital reconstruction without requiring external input of refractive index or topography data. The system determines the geometric structure autonomously from the measurement data itself, eliminating the need for prior knowledge and simplifying operation while maintaining absolute measurement precision
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 approach enables fast, precise, and cost-effective measurement of optical components' geometric structure, suitable for industrial applications like ophthalmic lenses, with improved precision and reduced equipment complexity compared to traditional methods.
Implementation Method 1
a first computation means (CM1) producing a first map (MS1) of normals to the first face (10) from the deformation of an optical signal reflected by the first face (10)
Implementation Method 2
a second computation means (CM2) producing a second map (MS2) of normals to the second face (20) from the magnification of an optical signal transmitted by the first and second faces (10, 20)
Data Source
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AI summary
The subject of the present invention is a method and a system for measuring the geometric or optical structure of an optical component. In particular, the invention relates to a method for measuring the geometric structure of a component bounded by a first side (10) and a second side (20), said method comprising steps of: (S1) measuring a first signal (MS1) resulting from a first conversion of a first probe signal (PS1), by at least said first side (10); (S2) measuring a second signal (MS2) resulting from a second conversion of a second probe signal (PS2), by at least said second side (20); (S3) determining a third conversion making it possible to convert a first set of coordinates (R1) associated with the measurement of the first signal (MS1) to a second set of coordinates (R2) associated with the measurement of the second signal (MS2); (S10) estimating said first side (10) using the first signal (MS1), said first simulation and a first cost criterion (V1) quantifying a difference between the estimation (ES1) and the first signal (MS1); and (S20) estimating said second side (20) using the second signal (MS2), said second simulation, said third conversion and a second cost criterion (V2) quantifying a difference between the estimation (ES2) and the second signal (MS2).