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4. Speckle interferometric investigation of argon pressure-induced surface roughness modifications in RF-sputtered MoO[sub]3 filmS. Soumya, R. Arun Kumar, S. Sreejyothi, Vimal Raj, Mohanachandran Nair Sindhu Swapna, Sankaranarayana Iyer Sankararaman, 2021, izvirni znanstveni članek Opis: Film quality analysis is of more considerable signifcance due to its diversifed applications in various felds of technology.
The present work reports the speckle interferometric analysis of the argon pressure-induced surface roughness modifcations
of RF sputtered MoO3 flms. The paper suggests a new method of surface quality analysis of thin flms through a parameter
δ, which is the diference between the initial and fnal inertia moment values in the study of the thermal-induced dynamic
speckle pattern. The limitations of root mean square surface roughness analysis of the atomic force microscopic image of the
flms is also exemplifed. The research suggests that argon pressure plays a vital role in the surface property of RF sputtered
flms and also that the dynamic speckle analysis can give precise information about the quality of flms. The contour plot of
particle displacement vector under thermal stress, suggests the degree of uniformity in the distribution of particles in the flm.
Ključne besede: speckle pattern interferometry, time history of speckle pattern, cross correlation, inertia moment
Objavljeno v RUNG: 04.07.2022; Ogledov: 1155; Prenosov: 0
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5. Fractal and inertia moment analyses for thin film quality monitoringMohanachandran Nair Sindhu Swapna, 2022, izvirni znanstveni članek Opis: The widespread applications of thin films in optronics demand innovative techniques for its characterizations. The work reported here proposes electronic speckle pattern interferometry and fractal-based methods for assessing the quality of thin films taking the industrially relevant molybdenum oxide (MoO3) incorporated niobium oxide (Nb2O5) films. The films with different levels of MoO3 incorporation (1, 2, 3, 5, and 10 wt. %) are prepared by radio frequency sputtering. The study reveals the structure modifications of Nb2O5 from the orthorhombic to monoclinic phases with an associated morphological variation revealed through atomic force microscopy and field-emission scanning electron microscopy analyses. The films’ specklegrams are recorded under thermal stress; the inertia moment (IM) and fractal analyses are computed and compared with the root-mean-square surface roughness of the films. The lacunarity analysis of the AFM films agrees well with the specklegrams. Thus, the lower IM and lacunarity values of the specklegrams can be regarded as indicators of the good quality of thin films.
Ključne besede: cross-correlation, fractal dimension, inertia moment, lacunarity, speckle, surface roughness.
Objavljeno v RUNG: 30.06.2022; Ogledov: 1171; Prenosov: 0
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6. Development of prototype of electronic speckle interferometry based spirometerMohanachandran Nair Sindhu Swapna, KUMAR ARUN, KUMAR SUNIL, SREEJYOTHI S, RAJ VIMAL, SANKARARAMAN SANKARANARAYANA IYER, 2021, izvirni znanstveni članek Opis: The paper reports the design, construction, and calibration of the prototype of a spirometer based on electronic
speckle interferometry (ESPI). The conventional ESPI setup is modified by incorporating a DNM (Diaphragm-Nozzle-Mouthpiece) module comprising a metallic diaphragm, regulated airflow channel, and a mouthpiece. The
exhaled air after a deep breathe is channelled to the DNM module where the diaphragm gets deformed. From the
circular fringe pattern obtained by subtracting the speckled images before and after deformation of the metallic
diaphragm, the radius of curvature (R) due to deformation is calculated using the principle of Newton’s rings.
The value of R and peak expiratory flow rate (PEFR) from the standard spirometer reading are correlated. From
the 640 observations spread over the range 100 - 500 L/min in the standard spirometer, an empirical relation
is set in terms of R from the scatter plot. The ESPI spirometer (ESPIS) is validated by determining the value of
R corresponding to a particular PEFR from the empirical relation and also from the standard spirometer. The
PEFR calculated from ESPIS matches well with the standard spirometer reading, which suggests that the system
designed and constructed can be used for biomedical applications for assessing lungs’ efficiency.
Ključne besede: Speckle, Spirometer, DNM module, ESPIS, Peak expiratory flow rate
Objavljeno v RUNG: 28.06.2022; Ogledov: 1143; Prenosov: 0
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