Gradient Index Lens Spectrophotometer for Film Thickness
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Solution Overview
Problem
Current inline spectrophotometers for high-end printing systems are expensive and require extensive calibration, making them unsuitable for in-line color and thickness measurements in printing or publishing systems.
Innovation Solution
A compact, low-cost spectrophotometer system is developed using a gradient index lens and a linear variable filter with a bandpass coating, positioned between the substrate and a linear sensor, to measure film thickness by analyzing spectral reflectivity, allowing for in-line thickness monitoring and adjustment of deposition parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current inline spectrophotometers are used for high-end printing systems, then measurement precision is improved, but device cost and complexity increase significantly
Solution Approach 1:
The spectrophotometer is divided into distinct functional modules: an illuminator module that emits light at the film, a sensing module with linear sensor and lens array, and a processor module. This segmentation allows each component to be optimized independently and simplifies the overall system architecture, reducing complexity while maintaining measurement precision for film thickness characterization.
Solution Approach 2:
A gradient index lens is introduced as an intermediary optical element between the linear sensor and the film surface. This lens focuses reflected light from the film onto the linear sensor, enabling precise spectral reflectivity measurements without requiring complex optical assemblies. The intermediary lens simplifies the optical path while maintaining measurement accuracy.
2Measurement precision
If current inline spectrophotometers are used for high-end printing systems, then measurement precision is improved, but device cost increases
Solution Approach 1:
The system employs commercially available, cost-effective components such as standard linear sensors (e.g., from Hamamatsu or Teledyne) and off-the-shelf gradient index lenses. These components can be readily procured and replaced if needed, significantly reducing the manufacturing cost of the spectrophotometer while maintaining sufficient measurement precision for industrial film thickness monitoring applications.
Solution Approach 2:
The spectrophotometer is designed with universal applicability across different film types and substrate materials. The same basic optical configuration and processing algorithms can measure thickness of various coatings (e.g., photoreceptor layers, protective coatings, functional films) on different substrates, eliminating the need for multiple specialized instruments and reducing overall system cost.
3Productivity
If in-line spectrophotometer is implemented for automatic scanning, then productivity is improved, but extensive calibration techniques are required
Solution Approach 1:
The spectrophotometer incorporates self-calibration capabilities through processing algorithms that automatically reference known standards or use internal reference measurements. The system can perform self-diagnosis and adjustment, reducing the need for manual calibration interventions and minimizing downtime. This self-service approach maintains high productivity while simplifying operational complexity.
Solution Approach 2:
The system implements continuous feedback loops where measured film thickness values are compared against target specifications, and deposition parameters are automatically adjusted in real-time. This closed-loop control enables automatic scanning and monitoring without extensive manual calibration, as the system continuously adapts to maintain accuracy. The feedback mechanism simplifies operation while sustaining high productivity through automated quality control.
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 provides accurate, cost-effective in-line measurements of film thickness and color output, enabling real-time feedback for improved printing quality and reduced operational costs.
Implementation Method 1
configuring a linear sensor to receive light reflecting off the deposited film on the substrate surface via a gradient index lens
Implementation Method 2
The linear variable filter is an optical filter having a bandpass coating. A property of the bandpass coating is varied across the length of the linear variable filter so as to shift a center wavelength
Implementation Method 3
configuring a linear sensor to receive light reflecting off the deposited film on the substrate surface
Data Source
AI summary
A method for providing film-thickness analysis with a spectrophotometer includes configuring an illuminator to emit a light beam at a film deposited on a substrate surface, configuring a linear sensor to receive light reflecting off the deposited film on the substrate surface via a gradient index lens and a linear variable filter, and configuring a processor to determine thickness of the film based on spectral reflectivity of the film received from the linear sensor.