FRFT-Based Newton's Rings Parameter Estimation
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Solution Overview
Problem
Existing interferometric measurement methods, such as the fringe centerline method, are sensitive to noise and obstacles in the interference fringe pattern, leading to inaccurate estimation of physical parameters, especially when occlusions occur.
Innovation Solution
A physical parameter estimating method that employs fractional Fourier transform (FRFT) to calculate the magnitude spectrum of intensity distribution signals from interferometric measurements, allowing for accurate estimation of physical parameters without the need for denoising and reducing human error, by identifying a matched order in the FRFT domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the fringe centerline method is used to process the interference fringe pattern, then the automation degree is improved, but the measurement precision deteriorates due to sensitivity to noise and obstacles
Solution Approach 1:
The patent replaces the traditional mechanical/image-processing-based fringe centerline method with a mathematical transform method (Fractional Fourier Transform). Instead of manually or algorithmically tracing fringe centerlines through noisy images, the invention uses FRFT to directly extract frequency domain characteristics from the interference pattern, substituting complex image processing operations with a robust mathematical transformation that is inherently more resistant to noise and occlusions.
Solution Approach 2:
The invention changes the domain of analysis from the spatial domain (image coordinates) to the frequency domain (FRFT domain). By transforming the interference fringe pattern into the FRFT domain, the method extracts physical parameters based on frequency characteristics rather than spatial positions, making the measurement less sensitive to noise, occlusions, and other disturbances in the original image domain.
2Device complexity
If the ring-counting calculating method is used, then the device complexity is reduced, but the measurement precision deteriorates due to visual fatigue and human error
Solution Approach 1:
The patent replaces the manual ring-counting method with an automated FRFT-based frequency analysis method. Instead of requiring observers to visually count rings and record diameters, the invention uses computational FRFT to automatically extract frequency information from the interference pattern, eliminating human visual fatigue and counting errors while maintaining simplicity in the overall measurement process.
Solution Approach 2:
The invention introduces the FRFT domain as an intermediary between the raw interference image and the final physical parameter measurement. Rather than directly counting rings or tracing centerlines in the image domain, the method uses FRFT transformation as an intermediate step to convert the problem into frequency domain analysis, where physical parameters can be extracted more accurately and automatically.
3Ease of operation
If the fringe centerline method is used, then the intuitiveness is improved, but the measurement precision deteriorates when occlusion exists in the interference fringe pattern
Solution Approach 1:
The patent replaces the intuitive but fragile fringe centerline tracing method with a robust FRFT-based frequency analysis method. While the centerline method provides visual intuitiveness through direct image manipulation, the FRFT method substitutes this with mathematical transformation that maintains ease of operation through automated computation while providing superior resistance to occlusions and noise, thereby improving measurement precision without sacrificing operational simplicity.
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 high-accuracy estimation of physical parameters even in noisy and obstructed conditions, improving automation and reducing errors associated with human observation.
Implementation Method 1
calculating a magnitude spectrum of an intensity distribution signal of at least one first-direction pixel set in the Newton's rings fringe pattern under each fractional Fourier transform (FRFT) order in a searching range of FRFT orders
Implementation Method 2
An interferometric measurement plays an important role in the non-contact measuring methods, and a key point thereof is to analyze and process an interference fringe pattern (for example, a Newton's rings fringe pattern) generated by performing the interferometric measurement on the unit to be measured
Data Source
AI summary
A physical parameter estimating method, a physical parameter estimating device, and electronic apparatus are disclosed. The method includes: reading a Newton's rings fringe pattern obtained by performing an interferometric measurement on a unit to be measured; downsampling the Newton's rings fringe pattern to obtain a downsampled Newton's rings fringe pattern; calculating a magnitude spectrum of an intensity distribution signal of at least one first-direction pixel set in the downsampled Newton's rings fringe pattern under each fractional Fourier transform (FRFT) order in a searching range of FRFT orders, the first-direction direction pixel set including a line of pixels in a first direction, the first direction being one of a row direction and a column direction of the downsampled Newton's rings fringe pattern; determining a matched order of the intensity distribution signal according to the calculated magnitude spectrums; and estimating a physical parameter involved in the interferometric measurement according to at least the matched order. Therefore, physical parameters of the unit to be measured can be estimated with high accuracy even in presence of noise and obstacles in the fringe pattern.