Optical Interference Noise Removal via Segmentation and SVD
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional noise removal techniques in optical interference measurements are insufficient, particularly in terms of sensitivity, leading to residual noise in interferograms.
Innovation Solution
An optical interference measuring apparatus and method that employs a signal processing unit to perform noise removal through filtering and singular value decomposition, along with model parameter estimation and optimal model selection to enhance noise reduction and resolution in interferograms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional noise removal techniques are used, then measurement sensitivity is improved, but noise in interferograms is not sufficiently reduced
Solution Approach 1:
The noise removal process is segmented into multiple distinct stages: (1) filtering periodic noise using a synchronous bandpass filter, (2) removing Gaussian noise using singular value decomposition, and (3) reconfiguring the interferogram using an optimal model. This segmentation allows each technique to target specific noise types, achieving comprehensive noise reduction while maintaining measurement sensitivity.
Solution Approach 2:
The patent applies preliminary filtering actions before final analysis. The synchronous bandpass filter is applied first to remove periodic noise components, and singular value decomposition is applied to remove Gaussian noise, preparing the interferogram for subsequent optimal model-based reconfiguration. These preliminary actions reduce noise early in the processing chain, improving overall measurement precision.
2Object-generated harmful factors
If filtering is applied to remove noise, then noise reduction is improved, but measurement resolution may be affected
Solution Approach 1:
The patent employs feedback mechanisms in the singular value decomposition process, where the decomposition is applied iteratively and the results are fed back to refine the noise removal. The optimal model reconfiguration also uses feedback from the filtered interferogram to adjust and improve the final result, ensuring that resolution is maintained while noise is reduced.
Solution Approach 2:
The patent changes processing parameters adaptively. The synchronous bandpass filter uses adjustable frequency parameters to target specific noise frequencies, while the singular value decomposition uses adjustable threshold parameters to control noise removal intensity. The optimal model reconfiguration adjusts model parameters based on the interferogram characteristics, allowing noise reduction without compromising resolution.
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 approach effectively reduces noise in interferograms, improving measurement sensitivity and resolution by filtering out periodic and Gaussian noise components, and reconfiguring intensity profiles based on optimal models, resulting in higher quality depth-direction analysis.
Implementation Method 1
acquire an interferogram of an interference wave by irradiating a measurement target and a reference surface with electromagnetic waves and causing a reflected wave from a reflecting surface of the measurement target to interfere with a reflected wave from the reference surface
Implementation Method 2
configure an intensity profile in a depth direction by performing Fourier transform of the interferogram
Implementation Method 3
perform filtering by deleting data in regions other than a pass region which is a region set with reference to a measurement target installation position from the intensity profile and reconfigure an interferogram by performing inverse Fourier transform of an intensity profile after the filtering
Implementation Method 4
calculate a singular value diagonal matrix S by performing singular value decomposition of the diagonal constant matrix D, delete a noise component from the singular value diagonal matrix, and reconfigure an interferogram by using a singular value diagonal matrix from which the noise component is deleted
Data Source
AI summary
Provided is an optical interference measuring apparatus including a measuring unit configured to acquire an interferogram of an interference wave by irradiating a measurement target and a reference surface with electromagnetic waves and causing a reflected wave from a reflecting surface of the measurement target to interfere with a reflected wave from the reference surface and a signal processing unit configured to configure an intensity profile in a depth direction by performing Fourier transform of the interferogram. The signal processing unit includes at least one of a first noise removal unit to remove noise with filtering by deleting data in regions other than a pass region which is a region set with reference to a measurement target installation position from the intensity profile and a second noise removal unit to remove noise by performing singular value decomposition of the interferogram to delete noise component.