Measurement of Film Structure Using Time-Frequency-Domain Fitting and White-Light Scanning Interferometry

A new technique is proposed for measuring film structure based on the combination of time- and frequency-domain fitting and white-light scanning interferometry. The approach requires only single scanning and employs a fitting method to obtain the film thickness and the upper surface height in the frequency and time domains, respectively. The cross-correlation function is applied to obtain the initial value of the upper surface height, thereby making the fitting process more accurate. Standard films (SiO2) with different thicknesses were measured to verify the accuracy and reliability of the proposed method, and the three-dimensional topographies of the upper and lower surfaces of the films were reconstructed.

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Application of Time-Frequency Domain Transform to Three-Dimensional Interpolation of Medical Images

Journal of Computational Biology ◽

10.1089/cmb.2017.0038 ◽

2017 ◽

Vol 24 (11) ◽

pp. 1112-1124

Author(s):

Shengqing Lv ◽

Yimin Chen ◽

Zeyu Li ◽

Jiahui Lu ◽

Mingke Gao ◽

...

Keyword(s):

Frequency Domain ◽

Medical Images ◽

Three Dimensional ◽

Time Frequency

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Initial Value Problems in the Time-Frequency Domain

Pseudo-Differential Operators, Generalized Functions and Asymptotics ◽

10.1007/978-3-0348-0585-8_9 ◽

2013 ◽

pp. 189-197

Author(s):

Lorenzo Galleani

Keyword(s):

Frequency Domain ◽

Initial Value Problems ◽

Initial Value ◽

Time Frequency

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Study on Spatial Frequency Domain Algorithm and White Light Interference System Based on NMM

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.738-739.904 ◽

2015 ◽

Vol 738-739 ◽

pp. 904-910

Author(s):

Li Jian ◽

Li Hua Lei ◽

Dong Sheng Li ◽

Yun Xia Fu ◽

Yuan Li ◽

...

Keyword(s):

Spatial Frequency ◽

Frequency Domain ◽

White Light ◽

Three Dimensional ◽

Step Height ◽

Light Interference ◽

Interference System ◽

Measuring Machine ◽

White Light Interference ◽

Spatial Frequency Domain

White light interference technique for topography measurement effectively avoids phase ambiguity in phase-shifting interferometry. The spatial frequency domain algorithm based on scanning white light interference technique has the advantage of insensitivity to noise and higher calculation accuracy compared with other methods. The white light interference sensor is constructed based on nano positioning and nano measuring machine (NMM), the calibrated step height standard of 100±3nm is measured. The spatial frequency domain algorithm is adopted for data processing, the repetitive test result of 97.9nm and standard deviation of 0.48nm are achieved. To verify the measuring ability of complex device, the number ‘242’ on ink box is measured and three-dimensional reconstruction is conducted. The high precision and traceable measurements of micro/nano scale step height standard and complex devices are realized by the white light interference system based on NMM with steady frequency laser interferometer built-in.

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Three-dimensional acoustic impedance mapping of human skin by improved time-frequency domain analysis.

Japanese Journal of Applied Physics ◽

10.35848/1347-4065/abf512 ◽

2021 ◽

Author(s):

EDO BAGUS PRASTIKA ◽

Atsushi Imori ◽

Tomohiro Kawashima ◽

Yoshinobu Murakami ◽

Naohiro HOZUMI ◽

...

Keyword(s):

Frequency Domain ◽

Human Skin ◽

Acoustic Impedance ◽

Three Dimensional ◽

Domain Analysis ◽

Frequency Domain Analysis ◽

Time Frequency

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A Gyro Signal Characteristics Analysis Method Based on Empirical Mode Decomposition

Journal of Sensors ◽

10.1155/2016/3613878 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

Qinghua Zeng ◽

Shanshan Gu ◽

Jianye Liu ◽

Sheng Liu ◽

Weina Chen

Keyword(s):

Frequency Domain ◽

Empirical Mode Decomposition ◽

Three Dimensional ◽

Allan Variance ◽

Analysis Method ◽

Time Frequency ◽

Noise Characteristics ◽

Mode Decomposition ◽

Signal Characteristics ◽

Characteristics Analysis

It is difficult to analyze the nonstationary gyro signal in detail for the Allan variance (AV) analysis method. A novel approach in the time-frequency domain for gyro signal characteristics analysis is proposed based on the empirical mode decomposition and Allan variance (EMDAV). The output signal of gyro is decomposed by empirical mode decomposition (EMD) first, and then the decomposed signal is analyzed by AV algorithm. Consequently, the gyro noise characteristics are demonstrated in the time-frequency domain with a three-dimensional (3D) manner. Practical data of fiber optic gyro (FOG) and MEMS gyro are processed by the AV method and the EMDAV algorithm separately. The results indicate that the details of gyro signal characteristics in different frequency bands can be described with the help of EMDAV, and the analysis dimensions are extended compared with the common AV. The proposed EMDAV, as a complementary tool of the AV, which provides a theoretical reference for the gyro signal preprocessing, is a general approach for the analysis and evaluation of gyro performance.

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The Efficacy of Virtual Chromoendoscopy in the Diagnosis of Portal Hypertensive Gastropathy

Journal of Gastrointestinal and Liver Diseases ◽

10.15403/jgld.2014.1121.253.chr ◽

2016 ◽

Vol 25 (3) ◽

pp. 289-293

Author(s):

Anda Carmen Achim ◽

Stefan Cristian Vesa ◽

Eugen Dumitru

Keyword(s):

Diagnostic Criteria ◽

White Light ◽

Narrow Band Imaging ◽

Endoscopic Examination ◽

Kappa Statistics ◽

Portal Hypertensive Gastropathy ◽

Mosaic Pattern ◽

White Light Endoscopy ◽

A New Technique ◽

Virtual Chromoendoscopy

Background: Diagnosis of portal hypertensive gastropathy (PHG) is based on endoscopic criteria. I-scan technology, a new technique of virtual chromoendoscopy, increases the diagnostic accuracy for lesions in the gastrointestinal tract. Aim: To establish the role of i-scan endoscopy in the diagnosis of PHG. Method: In this prospective study, endoscopic examination was conducted first by using white light and after that i-scan 1 and i-scan 2 technology in a group of 50 consecutive cirrhotic patients. The endoscopic diagnostic criteria for PHG followed the Baveno criteria. The interobserver agreement between white light endoscopy and i-scan endoscopy was determined using Cohen’s kappa statistics. Results: Forty-five of the 50 patients met the diagnostic criteria for PHG when examined by i-scan endoscopy and 39 patients were diagnosed with PHG by white light endoscopy. The strength of agreement between the two methods for the diagnosis of PHG was moderate (k=0.565; 95%CI 0.271-0.859; p<0.001). I-scan 1 classified the mosaic pattern better than classic endoscopy; i-scan 2 described better the red spots. Conclusion: I-scan examination increased the diagnostic sensitivity of PHG. The diagnostic criteria (mosaic pattern and red spots) were easier to observe endoscopically using i-scan than in white light.Abbreviations: FICE: Fuji Intelligent chromoendoscopy; GAVE: gastric antral vascular ectasia; NBI: narrow band imaging; PHG: portal hypertensive gastropathy; PHT: portal hypertension; UGIB: upper gastrointestinal bleeding.

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