Transparent Object Thickness and Lateral Position Sensor
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Solution Overview
Problem
Current roll to roll manufacturing processes face challenges in accurately measuring the thickness and lateral position of transparent webs, particularly due to the limitations of ultrasonic sensors and the need for improved sensing capabilities to enhance the intricacy and cost-effectiveness of manufactured products.
Innovation Solution
A sensor system utilizing a camera with a digital microscope objective and a Ronchi grating illuminated by an LED light source, which measures the shift in the object plane and relative signal strength to simultaneously determine the optical path length and lateral position of transparent objects with submicron resolution, leveraging image processing algorithms to analyze the intensity variations and standard deviation of the grating columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ultrasonic sensors are used to measure transparent webs, then the sensor can detect transparent materials, but the measurement resolution is poorer compared to light-based sensors
Solution Approach 1:
The patent replaces ultrasonic (acoustic) sensing with optical sensing. The optical sensor system uses a light source, objective lens, and camera to detect transparent webs, achieving superior resolution compared to ultrasonic sensors while maintaining the ability to detect transparent materials.
Solution Approach 2:
The patent changes the measurement parameter from acoustic wave properties to optical properties. By measuring the optical path length through the transparent web using light interference and focal plane shifts, the system achieves both transparency compatibility and high resolution measurement.
2Measurement precision
If lateral shear interferometry is used to measure thickness and index of refraction, then both parameters can be simultaneously measured, but the system complexity increases
Solution Approach 1:
The patent extracts and measures only the optical path length product of thickness and index of refraction, rather than requiring separate measurement of both parameters. This simplifies the system by eliminating the need for lateral shear interferometry while still providing useful thickness information for roll-to-roll manufacturing control.
Solution Approach 2:
The patent uses a simple, inexpensive optical setup with LED light source, standard objective lens, and digital camera instead of complex interferometric equipment. This disposable-like simplicity enables easy integration into roll-to-roll manufacturing while achieving the necessary measurement capability.
3Measurement precision
If light-based sensors are used for opaque webs, then high resolution measurement is achieved, but the sensor cannot effectively measure transparent materials
Solution Approach 1:
The patent uses the transparent web itself as an optical element that manipulates light. By measuring the focal plane shift caused by the web's optical path length, the system converts the transparency interference into a useful measurement signal, allowing high-resolution measurement of transparent materials.
Solution Approach 2:
The patent changes the measurement approach from detecting light reflection or absorption (for opaque materials) to detecting focal plane shifts and optical path length changes (for transparent materials). This parameter change enables high-resolution measurement of transparent webs using optical methods.
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
The system achieves submicron resolution in measuring thickness and lateral position, surpassing the resolution of state-of-the-art acoustic sensors and providing accurate, cost-effective measurements, thereby enhancing the complexity and economic viability of roll to roll manufacturing processes.
Implementation Method 1
A transparent object disposed fully or partially between the object lens and the surface will shift the position of the object plane, the shift in object plane being proportional to the thickness of the object
Implementation Method 2
the transparent object, when partially inserted between the objective lens and the surface, will focus a fraction of the light on a lower plane, this fraction of light being proportional to the fraction of the lens field of view occupied by the transparent object and related to lateral position
Data Source
AI summary
System for measuring thickness and lateral position of a transparent object. The system includes a camera having a sensor for receiving light, the camera including an objective lens for focusing on an object plane and having an optical axis and a field of view. A source of light is provided to illuminate a surface having variations in reflected light intensity. The surface is spaced apart from the objective lens and disposed at an angle with respect to the optical axis of the objective lens. A transparent object disposed fully or partially between the objective lens and the surface will shift the position of the object plane, the shift in object plane being proportional to the thickness of the object, and the transparent object, when partially inserted between the objective lens and the surface, will focus a fraction of the light on a lower plane, this fraction of light being proportional to the fraction of the lens field of view occupied by the transparent object that is related to lateral position.