• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.323-326
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• 2000

In this study, we used Brewster-Angle Microscope(BAM) to study on the molecular orientation of monolayer on the water surface. The behaviors of molecules on three different subphase have been observed. Reproducible $\pi$-A isotherm have been obtained only on information about phase transition by molecular area. BAM facilitates the observation of morphology by optical anisotropy and thickness in monolayer and multilayers as BAM is shown to be sensitive to anisotropy of film. Every transition was found by BAM technique, either as a dramatic change in degree of contrast or as a sudden alteration of molecular action and $\pi$-A isotherm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.81-87
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• 1999

The surface morphology of liquid crystal alignment layer has been investigated by using Brewster angle microscope(BAM) for the first time. The samples used in this work for liquid crystal alignment layer were mechanically rubbed polyimide films. The rubbing pattern on this layer has been analyzed with the terms of microgroove and rubbing induced optical birefringence. For the mechanically rubbed surface, the geometrical factors of microgroove play the major role for the formation of rubbing pattern. We propose that the BAM can be used as a powerful tool not only for observing the rubbing pattern, but also for inspecting the surface defects.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.38-42
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• 2001

To observe the Langmuir films, displacement current measuring system(Nippon Laser & Electronics), $\pi-A$ isotherms measuring device, and Brewster Angle Microscope(BAM) were used. As results, for 8A5H, big tilt angle changes of many molecules were detected before liquid expanded phase when the monolayer was compressed and expanded by barrier. Also many small and bright points were detected by BAM when the displacement current radically changed. In $\pi$-A isotherms, surface pressure of 8A5H was radically decreased between 35 and 40[mN/m] and monolayer was assumed to be collapsed in solid condensed phase, since large bright domain was observed without change of displacement current and this bright boundary was not classified part of domain in BAM image. If we observe behaviors of molecules on the water surface in these three measurement at the same time, we can get more precise informations on L films and it could be good data for fabricating LB films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.147-151
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• 1996

Brewster angle microscopy(BAM) makes it possible to observe the monolayer states on the water subphase and the phase transitions from a gaseous phase via a expanded phase to a condensed phase. Also BAM can be used to observe the films on the solid substrate such as Langmuir-Blodgett(LB) films. In this Paper Polyamic Acid Alkylamine Salts(PAAS) was used for forming L films and LB films and $\pi$-A isotherm showed pressure of each phase. We obtained BAM images as surface pressure increased. Images of LB films were compared with data from ellipsometry which was used to measure the film thickness. Images of both L films and LB films were analyzed with computer in the point of brightness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.98-102
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• 2002

We investigated domains and conoscope under the polarizing microscope and the index of refraction on the c-plate GMO which has the ferroelectric and ferroelastic phase at room temperature. To observed the change of refractive index in connection with domain, we developed an apparatus to obtain the refractive index by measuring the Brewster's angle. The resolution of the minimum rotation angle of this apparatus is $0.001^{\circ}$. To obtain the refractive index map on the sample, the moving distance of XY stage loaded sample holder is 60 mm and the minimum moving distance is 0.002 mm. Also, To obtain the indicatrix for single crystal, vertical turntable with sample holder and XY stage was loading on horizontal turntable. The minimum resolution angle of this vertical turntable is $0.001^{\circ}$. We measured the refractive index of transparent materials such as ferroelectrics. In the case of $Gd_{2}(MoO_{4})_{3}$, the Brewster angle is $62.11^{\circ}$ and then, the refractive index is 1.8895 by using He-Ne Laser. Also the refractive distribution of c-plate GMO was obtained with $400{\mu}m{\times}120{\mu}m$.

• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.208-213
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• 1999

We proposed a new technique to precisely calibrate the angle of incidence in spectroscopic ellipsometer. The proposed technique can be useful to the thickness measurement of semiconductor thin films and optical thin films. The usefulness has been confirmed experimentally. We cut a block of optical glass into two pieces and made a prism as well as a slab using each piece. The apex angle and the angle of the minimum deviation of prism were measured. From these angles, the refractive index of glass material was calculated. From the analysis of the spectro-ellipsometric data collected near Brewster's angle, we could not only determine the error in the angle of incidence in the spectroscopic ellipsometer, but also calibrated the angle of incidence to the accuracy of 0.01 degree.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.282-287
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• 1995

We have studied the characteristics of a cw Ti:sapphire laser pumped by an Ar-ion laser. Ti:sapphire is one of the most attractive materials for the generation of ultra-short pulses because of its very broad gain bandwidth. We used a 4.1 mm thick, 0.15 wt. % $Ti^{3+}$ -doped, Brewster-angled Ti:sapphire crystal and made a folded cavity to create a strong focusing mode. The folding angle of the cavity was adjusted to $15.4^{\circ}$ to compensate for the astigmatism from the Brewster-angled Ti:sapphire crystal. 5 WAr-ion laser was used as a pumping source. We observed that the Ti:sapphire cw output power was sensitively changed with respect to the condition of the folded cavity. The threshold pumping power was 2 Wand the slope efficiency was 16% when an output coupler of 10% transmission was used. The maximum output power was more than 450 mW at 5 W pumping. mping.

• Journal of the Korean Applied Science and Technology
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• v.21 no.2
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• pp.164-173
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• 2004

The capacity and long life of gel electrolyte batteries is connected with gas recombination producting $PbO_2$ and Pb electrode. We prepared with sulfuric acid gel electrolyte to know gel characteristics per density to assemble valve regulated lead-acid (VRLA) batteries. We studied on actions of sulphuric acid gel electrolyte by measuring electrolyte dispersion using Brewster-angle microscope (BAM), charge-discharge cycle, and electrode structure using scanning election microscope (SEM). Sulphuric acid density 1.210 showed excellent gel dispersion in sol condition, electrode condition after fifty cycles in this study.

• Journal of the Korean Applied Science and Technology
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• v.20 no.4
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• pp.296-308
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• 2003

The capacity and long life of gel electrolyte batteries is connected with gas recombination producting $PbO_2$ and Pb electrode. We were prepared with phosphoric acid gel electrolyte to know gel characteristics per density to assemble VRLA batteries. We studied by measuring electrolyte dispersion using Brewster-angle microscope(BAM), charge-discharge cycle and electrode structure using scanning election microscope(SEM) per electrolyte density. As a results, phosphoric acid density 1.210 was excellent gel dispersion in sol condition, electrode condition after fifty cycles in this study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.610-612
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• 1999

In this study, we used both displacement-current method and BAM(Brewster-Angle Microscope) to study on the molecular orientation of monolayer on the water surface. The displacement-current method measured behaviors of molecules by current and BAM was shown to be sensitive to film anisotropy even when the molecules were not tilted as long as the unit cell was anisotropic. Every transition was visible with BAM technique, either as a dramatic change in decree of contrast or as a sudden alteration of the mosaic domain texture.