Limsuwan, Pichet

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Investigation of the characteristic of the Nd:YAG laser for standard wavelength in metrology
(2013-10-08)
Potirak, Prayut
;
Ranusawud, Monludee
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Limsuwan, Pichet
;
Buranasiri, Prathan
This research studied characteristics of the Nd:YAG laser with second harmonic generation (SHG) at 532 nm. It can be develop as a standard wavelength according to the recommendation made by the Comite' International des Poids et Measures (CIPM). This study investigates various parameters that effect wavelength and laser power of the Nd:YAG laser such as injection current of diode laser, temperature of Nd:YAG crystal and second harmonic generator crystal. Its wavelength can be tuned in the range of standard wavelength at 532.24503 nm with 10<sup>-7</sup> of stability. © (2013) Trans Tech Publications, Switzerland.
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Investigation of direct metal laser sintering process of iron powder with low laser power
(2018-01-01)
Thongsuwan, S.
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Ranusawud, A.
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Limsuwan, P.
;
Jaiyen, S.
;
Buranasiri, P.
Laser additive manufacturing (LAM) is layer by layer built up a 3-D part using either a bed or stream of powdered material. In this paper, the heat transfer and melt solidification of iron powder in the direct metal laser sintering (DMLS) process with low laser powers have been experimental investigated. The experimental results of various properties of each layer and properties among the multiple layers due to the laser power, the scanner rate, of the frequency of the laser pulse, have been shown and discussed. The process will be improved by numerical modeling in the future.
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Optical tweezer system with no fluorescent confocal microscope for trapping colloidal nanoparticles
(2018-01-01)
Nuansri, R.
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Buranasiri, P.
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Limsuwan, P.
;
Ou-Yang, H. D.
We describe two optical tweezer systems for the studies of laser trapping of fluorescent colloidal nanoparticles (NPs). The first one, conventional optical tweezer system widely used in laser trapping, requires a fluorescent confocal microscope for observing trapped NPs. The second system, with no microscope, is presented for the first time in this work. The quantity of trapped NPs for this system is estimated from the transmitted laser light intensity that passes through the fluorescent colloidal NPs. Then the transmitted laser light is converted into the voltage signal and measured by an oscilloscope. A small capillary tube to be filled by the colloidal NPs is developed and used in the second system. This tube can be used with light-sensitive cameras for which a danger of damaging by high light intensities exists. Finally, we show that the results obtained using the both tweezer systems are in good agreement.
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Effect of temperature on the absorption of rubidium vapor cell D2 line studied by two-photon absorption spectroscopy
(2018-01-01)
Thanaboonrungroch, Nut
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Buranasiri, Prathan
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Limsuwan, Pichet
;
Yindeesook, Witoon
In this research, the effect of temperature on the absorption of rubidium vapor cell D<inf>2</inf> line was studied by Two-photon absorption spectroscopy. The diameter and length of cylindrical rubidium vapor cell used in this research are 25.65 mm and 82.12 mm, respectively. The temperature of rubidium cell was varied from room temperature to approximately 80 °C using a peltier-thermoelctric module. The laser diode at 778 nm was used as a light source for two-photon absorption spectroscopy. The absorption spectra of rubidium D<inf>2</inf> hyperfine transitions were recorded in the range of 200-1100 nm.The results show that the absorption peak at high temperature is higher than that of lower temperature.
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Observations of the initial stages on reactive gas-timing sputtered TaO thin films by dynamic in situ spectroscopic ellipsometery
(2019-06-01)
Chittinan, D.
;
Buranasiri, P.
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Lertvanithphol, T.
;
Eiamchai, P.
;
Patthanasettakul, V.
Dynamic in-situ spectroscopic ellipsometry (iSE) was employed to investigate the growth mechanism of the tantalum oxide (TaO) film on silicon wafer substrate deposited by reactive gas-timing RF magnetron sputtering compared with conventional reactive sputtering. The effect of reactive gas timing parameter on physical structure and optical property were analyzed by both the continuous and island film growth model with Tauc-Lorentz optical model. The variation of refractive index, film thickness and void volume fraction were obtained from dynamic fits of iSE data indicated that the growth process of the amorphous TaO thin films was divided into two regimes: the nucleation stage and continuous-layer stage. These stages were observed during deposition although the initial film growth stage corresponds to the island film growth model. The study demonstrates that sputtered TaO by the RGT technique at the O<inf>2</inf> on-off gas timing has played a crucial factor in improving the formation of nucleation stage and that the deposited TaO thin films were high deposition rate with high refractive index. The complementary field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) showed a good agreement with the film thickness and morphology obtained from dynamic iSE measurement. The real-time monitoring of iSE offers important evidences to understand the growth mechanism of reactive gas-timing technique.
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The investigation of iodine cell temperature control in frequency stabilized Nd:YAG laser system
(2017-01-01)
Potirak, P.
;
Ranusawud, M.
;
Limsuwan, P.
;
Buranasiri, P.
In this research, the temperature characteristics of a 10 cm long iodine cell used in diode-pumped Nd:YAG laser system has been investigated. Here, the laser system were frequency stabilized by locking their frequency-doubled output at 563 THz. The absolute frequency measurement of the a<inf>10</inf> hyperfine components of molecular iodine R(56) 32-0 line with effect to various temperatures is reported. With the iodine cell temperature control, the output frequency is tuned in the range of standard frequency at 563.2602235 THz with about 10<sup>-9</sup> of stability.
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Limsuwan, Pichet

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