Fusion Draw Glass Thickness Mapping Using Laser Interference
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Solution Overview
Problem
Existing methods for in-line thickness measurement of glass sheets during fusion draw processes face challenges due to variations in size, position, and orientation, leading to inaccurate measurements and increased glass breakage from physical contact, especially as glass sheets become thinner and larger.
Innovation Solution
A contactless method using coherent light interference through the glass sheet, with laser beams passing through and reflecting multiple times to create an interference fringe pattern, analyzed by an optical line scan sensor, allowing for a wider measurement range and eliminating the need for precise glass positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If contactless optical measurement is used, then glass breakage is reduced, but measurement precision deteriorates due to position and orientation variations
Solution Approach 1:
The system dynamically adapts to glass sheet position and orientation variations by using a laser line scanner that captures the entire thickness profile across the glass surface. The measurement beam is distributed across multiple points rather than focused at a single location, allowing the system to accommodate positional variations without requiring precise positioning or risking glass breakage from contact.
Solution Approach 2:
The invention transitions from point-based thickness measurement to line-based measurement across the glass surface. By projecting a laser line and scanning across the thickness direction, the system measures the entire thickness profile simultaneously, converting a one-dimensional point measurement problem into a two-dimensional line measurement that is tolerant of position and orientation variations.
2Manufacturing precision
If glass sheets are made thinner and larger, then product quality improves, but measurement accuracy deteriorates due to increased position and orientation variance
Solution Approach 1:
The system uses a laser line scanner to measure the entire thickness profile across the glass sheet surface in one measurement pass. This line-based measurement approach captures thickness variations across the entire glass area, providing comprehensive quality data for large, thin glass sheets without being affected by their size or position variations during conveyance.
Solution Approach 2:
The measurement system is designed to handle multiple glass sheet sizes and thicknesses using the same line scanning approach. The system can measure both small and large glass sheets, as well as sheets with varying thicknesses, making it universally applicable to different product specifications without requiring adjustment or repositioning.
3Measurement precision
If contact-based measurement is used, then measurement precision improves, but glass breakage increases
Solution Approach 1:
The invention replaces mechanical contact-based thickness measurement with non-contact optical measurement using laser line scanning and interferometry. This substitution eliminates the need for physical contact between the measurement sensor and the glass surface, thereby preventing glass breakage while maintaining measurement capability through optical interference patterns.
Solution Approach 2:
The system uses optical fields (laser light) as an intermediary to measure glass thickness without direct contact. The laser light interacts with the glass surface and internal structures, and the reflected or transmitted light carries thickness information that is captured by sensors, serving as a non-contact mediator between the measurement system and the glass.
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 accurate, non-destructive thickness measurement of glass sheets by providing a wider measurement range and reducing glass breakage, while outputting a thickness map rather than a single trace, enhancing production efficiency and quality control.
Implementation Method 1
coherent light interference through the glass sheet, with laser beams passing through and reflecting multiple times to create an interference fringe pattern
Implementation Method 2
laser beams passing through and reflecting multiple times to create an interference fringe pattern
Implementation Method 3
A contactless method using coherent light interference through the glass sheet
Data Source
AI summary
A system that measures thickness of a glass includes a laser that transmits a laser beam through the glass; a sensor that senses an interference pattern of the laser beam through the glass; and a computer that processes sensor data corresponding to the interference pattern received from the sensor to determine the thickness of the glass.