Complex Refractive Index Measurement via Interference Imaging
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Solution Overview
Problem
Existing optical phase measurement methods are not suitable for measuring the complex refractive index of materials due to issues with multiple reflections and the extinction coefficient of absorbing materials.
Innovation Solution
A method and device that collect interference images of a reference area and a sample under test, determine the normalized light intensity map and optical path difference, establish a reflective film transmission matrix model, and calculate the complex refractive index distribution profile based on the measured reflection coefficient and optical path difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical phase measurement method is used, then non-destructive measurement and high measurement efficiency are achieved, but measurement accuracy deteriorates due to multiple reflections and extinction coefficient of absorbing materials
Solution Approach 1:
The patent introduces an intermediary reference standard (reference area with known optical properties) that mediates between the incident light and the sample under test. By measuring the sample relative to this reference, the system compensates for multiple reflections and extinction coefficient effects, enabling accurate complex refractive index measurement while maintaining high measurement efficiency
Solution Approach 2:
The patent replaces traditional mechanical measurement approaches with an optical interference-based measurement system. By using interference imaging and transmission matrix theory, the system achieves non-contact, non-destructive measurement of complex refractive index distribution, eliminating the need for physical contact or destructive sampling
2Reliability
If optical phase measurement method is used, then non-destructive measurement is achieved, but measurement accuracy deteriorates due to extinction coefficient of absorbing materials
Solution Approach 1:
The patent changes the measurement parameters by measuring not just phase but also amplitude and interference patterns across the entire optical path. By using the transmission matrix model that incorporates both real and imaginary parts of the refractive index, the system can accurately measure complex refractive index of absorbing materials without destructive contact
Solution Approach 2:
The reference area serves as an intermediary that provides known optical characteristics for comparison. By measuring the sample under test relative to this reference and using the transmission matrix to account for optical path differences, the system achieves accurate measurement of absorbing materials while maintaining non-destructive measurement capability
3Ease of operation
If traditional refractive index measurement methods are used, then measurement simplicity is maintained, but adaptability deteriorates for films with interference and absorbing materials
Solution Approach 1:
The patent creates a universal measurement system that can handle multiple types of films including transparent films, absorbing materials, and interference structures. By using interference imaging combined with transmission matrix theory, the same measurement approach adapts to different film characteristics without requiring separate measurement procedures for each material type
Solution Approach 2:
The system adapts to different film structures by dynamically adjusting the transmission matrix model parameters. The method accounts for variations in optical path difference, reflection coefficients, and extinction coefficients, enabling the same measurement apparatus to accurately characterize diverse film materials from transparent to absorbing types
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 allows for accurate determination of the complex refractive index distribution profile of a film, improving measurement accuracy and flexibility while addressing limitations of existing methods.
Implementation Method 1
collecting the interference image of the reference area and the sample under test
Implementation Method 2
establishing the measurement model based on the reflective film transmission matrix model
Implementation Method 3
calculating the complex refractive index distribution profile of the film under test
Data Source
AI summary
The invention discloses a method for obtaining the complex refractive index distribution profile of a film. S101, the interference image of the reference area and the sample under test is collected; S102, the normalized light intensity map and the optical path difference of the sample under test relative to the reference area is determined through the recovery algorithm based on the obtained interference image; S103, the measurement model is established based on the reflective film transmission matrix model; S104, the relationship between the measured reflection coefficient and optical path difference of the area under test of the sample under test relative to the reference area and the measurement model is determined; S105, the complex refractive index distribution profile of the film under test is calculated based on the measured reflection coefficient and optical path difference of the area under test of the film relative to the reference area and the relationship.