Transparent Sheet Profile Measurement Using Segmented Outline Targets
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Solution Overview
Problem
Existing methods for measuring the profile and reflective optical power of transparent sheets face challenges such as overlapping reflections from multiple surfaces, inability to discriminate individual surface reflections, requirement for separate thickness measurement, and limitations in measuring near the edges of the sheet, which restrict accurate determination of transmissive optical power.
Innovation Solution
The use of outline targets with a thin outline thickness allows for the discrimination of individual surface reflections, eliminating the need for thickness measurement and enabling accurate measurement near the edges, by employing a novel lighting and imaging design that includes a conveyor, light source, camera, and processing circuit to compute reflective and transmissive optical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filled targets are used for measuring reflected images from transparent sheets, then the measurement can be performed, but the reflected images from multiple surfaces overlap and it is impossible to reliably discriminate which part of the reflection is from which surface
Solution Approach 1:
The patent divides the target into multiple discrete points arranged in a pattern rather than using a solid filled shape. This segmentation allows the reflected image to be broken into separate distinguishable components, enabling identification of which reflection corresponds to which surface. The discrete points create separated reflected images that can be individually analyzed to determine surface profile and optical properties.
2Measurement precision
If filled targets are used, then reflection measurement is possible, but the reflected composite measurement grows as surfaces become further apart, requiring independent thickness measurement
Solution Approach 1:
The patent extracts the thickness information from the reflection measurement process itself by using the discrete point pattern. The spacing and arrangement of the discrete points in the reflected image directly encode thickness information, eliminating the need for separate thickness sensors or independent thickness measurement systems. This integration reduces overall system complexity while maintaining measurement precision.
3Measurement precision
If solid targets are used, then reflection measurement is possible, but it is impossible to measure distortion very near the edge of the transparent sheet because the reflection may be truncated
Solution Approach 1:
By using discrete points rather than a solid target, the patent ensures that individual points remain distinguishable even when near the edges of the transparent sheet. The segmented nature of the target allows measurement at the edges without the truncation problem that occurs with solid targets, as each discrete point creates a separate reflected image that can be identified even when partially at the edge.
4Measurement precision
If filled targets are used, then reflection measurement is possible, but the reflected images from multiple surfaces overlap making it impossible to provide information about surface interaction and transmissive optical power
Solution Approach 1:
The discrete point pattern segments the reflected images from multiple surfaces into separately identifiable components. This allows the system to not only measure each surface's reflection independently but also analyze the interaction between surfaces by observing the relative positions and characteristics of the separated reflected images, enabling calculation of transmissive optical power.
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 simplifies the measurement system, reduces costs, improves accuracy across various glass thicknesses, and allows for reliable measurements up to the edges of the sheet, enabling the computation of transmissive optical power and sheet thickness independently.
Implementation Method 1
a light source (15) mounted on a first side of the conveyor (13), the light source (15) projecting a plurality of two-dimensional images (31) across the width of the conveyor (13) wherein the plurality of two-dimensional images (31) appear continuously and simultaneously on the transparent sheet (11)
Implementation Method 2
a camera (18) oriented to continuously and simultaneously detect a plurality of reflected two-dimensional images corresponding to the plurality of two-dimensional images
Data Source
AI summary
This present invention relates to an apparatus and method for measuring the profile and reflective optical power of one or more surfaces of transparent sheets and transmissive optical power and thickness of one or more transparent sheets at a plurality of locations over the complete transparent sheet. The measurement results are presented to a user graphically and all data is stored for further processing, process control, and quality assurance.