Khlayboonme, S.Tipawan
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Khlayboonme, S.Tipawan
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Khlayboonme, S. Tipawan
Khlayboonme, S. T.
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s.tipawan.kh@kmitl.ac.th
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Item type:Publication, Phase-shifting interferometry for surface roughness measurement on glass substrates(2014-01-01); Thowladda, W.Phase-shifting interferometry based on Michelson interferometer is purposed to measure surface roughness of glass slides which are widely used as substrates for thin-film coating processes. For the interferometry system, an optical flat with a flatness of λ/20 is used as a reference mirror. The high accuracy of the phase-shifting is achieved by a piezoelectric-driven linear translation stage of the reference mirror. The reference-phase difference between the twointerfering beams is shifted by every π/2 in phase-shifting. Five frames of interferograms under various phase differences of 0, π/2, π, 3π/2 and 2p are recorded by a CCD camera. Each image pixel of these frames is interpreted to access interference intensity information by five-step phaseshifting algorithm for phase calculation, which in turn relates to surface height. The purpose-built interferometry is tested by the surfaces of two optical flats with flatness of λ/10 and λ/4, which are used as the test surfaces. Our measured flatness results are consistent with those of the commercial optical profilometer. The usefulness of the purpose-built interferometry is demonstrated on two types of the glass slides. Aluminum thin films are also deposited on these glass slides by the RF magnetron sputtering method to enhance reflectivity of the glass slide surfaces. The surface profiles and flatness parameters of these glass slides have been reported. © (2014) Trans Tech Publications, Switzerland. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Nanocrystalline diamond films deposited by two-step approach from CH4/H2 microwave plasma: The influence of reactor pressure(2013-08-30); Thowladda, W.The morphology, growth rate and atomic-bonding structure of nanocrystalline diamond films deposited on Si substrates were investigated under various pressures of the reactor. The films were deposited by CH<inf>4</inf>/H<inf>2</inf> microwave plasma with two-step deposition and H<inf>2</inf>-plasma cleaning processes. The pressures of 1, 2, 5, 9, and 25 kPa were used for deposition. In situ gas-phase species, including electron density, were monitored by an optical spectrometer and impedance analyzer. The films were characterized by SEM, Raman microscope, and white light reflectrometer. When the pressure increased, the surface smoothness and diamond grain size increased, amorphous carbon content decreased, and the intensity ratio of CH/H<inf>β</inf> for the growth step increased. The growth rate was in proportional to the ratio of CH/H<inf>β</inf> for the nucleation step but in inverse proportion to the electron density. The growth rates decreased from 370 nm/h for 1 kPa to 320 nm/h for 2 kPa. After that, the growth rate rapidly increased to 460 nm/h for 9 kPa, but it gradually decreased to 450 nm/h for 25 kPa. The film refractive indices were 2.16 for 5 kPa, 2.21 for 9 kPa, and 2.38 for 25 kPa. The films grown under 1 and 2 kPa showed highly light absorption. © (2013) Trans Tech Publications, Switzerland.