• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.1
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• pp.313-324
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• 1997

The aim of the present study was to describe an safe and convenient method for the early detection of enamel caries using laser fluorescence. Fluorescence from natually carious lesion of human teeth illuminated by an argon laser(488nm) was observed and photographed using barrier filter. Intact enamel was found to fluorescence with a yellowish light. Whereas, incipient caries lesions in the enamel were dearly visible as dark areas in contrast to the fluorescence surroundings. For evaluation of accuracy of this method, lesion depth measured by the laser fluorescence in light microscope was compared with that polarizing microscope. The results from the present study can be summarized as follows : 1. Enamel caries of smooth surface was observed as pale white spot and undefined outline in ordinary light. Whereas, lesion was clearly visible as dark spot in laser fluorescence. 2. There was no difference between ordinary light view and laser fluorescence in occlusal surface and interproximal surface. 3. There was no significant difference between the lesion depth observed by laser fluorescence with light microscope and polarizing microscope. Apparent correlation exists between two groups.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.109-118
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• 1999

The aim of this study was to evaluate the optical density of laser fluorescence for detection of incipient caries. Prepared and polished bovine enamel specimens were demineralized in a STPP solution for varying periods of time between 3 hrs. and 60 hrs. with an area of sound enamel retained on each specimen. The randomized specimens were analyzed for optical density of enamel demineralization using laser fluorescence. The specimens were sectioned and examined lesion depth by polarizing light microscope. Results were analyzed statistically with SAS program. The results from this study can be summarized as follows: 1. Optical density measured by laser fluorescence and lesion depth measured by polarizing light microscope was increased as demineralization time was increased(p<0.001). 2. Between optical density measured by laser fluorescence and lesion depth measured by polarizing light microscope was correlated highly(${\gamma}{\geq}0.74956$, p<0.001). 3. Regressive equation was obtained in this study as follows. Y=[X-0.260851]/0.000271(R-square:0.5618, p<0.001) (X:DENSITY, Y:DEPTH) In summary, optical density measured by laser fluorescence would be within the range of possibility to quantitatively presume demineralization amount of incipient caries lesion

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.979-995
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• 1997

The purpose of this study was to identify the preventive and the progressive inhibitory effects of enamel demineralization with fluoride releasing light-and self-cured orthodontic sealants(FluoroBond), in vitro, under the polarizing light microscope and the scanning electon microscope. The polarizing light microscopic group was subdivided into seven groups(Group A-Group G). The scanning electron microscopic group was also subdivided into seven groups(Group A'-Goup G'). For polarizing light microscopic evaluation, longitudinal sections were made longitudinally by Maruto cutter(Maruto Co., Japan) and Maruto grinding machine(Maruto Co., Japan). Sections were examined and photographed by the polarizing light microscope(Olympus Optical Co., Japan) using crossed polars and with the enamel rod longitudinal axis oriented at $45^{\circ}$ to the extinction position. For scanning electron microscopic evaluation, the specimens were coated with a highly conducting layer of gold palladium in a model Hus-4 high-vacuum evaporator and examined in an ISI-100B scanning electron microcope operated at 20kV. The results of this study were as follows : 1. The mean depths of artificial carious lesions under a polarized light microscope were $Group\;A(5.08{\mu}m),\;Group\;B(47.82{\mu}m,\;Group\;C(8.42{\mu}m),\;Group\;D(7.20{\mu}m),\;Group\;E(85.41{\mu}m),\;Group\;F(60.38{\mu}m),\;Group\;G(60.13{\mu}m)$. 2. There were statistically significant differences in Group B compared with Group A, C, and D(p<0.05), and also, in Group I compared with Group F and Group G(p<0.05). 3. Light-and self-cured orthodontic sealants had the preventive effects of enamel demineralization. 4. Light-and self-cured orthodontic sealants had the progressive inhibitory effects of enamel demineralization. 5. The time progress of demineralizing agent had no influence on the samples of light-and self-cured orthodontic sealants under the scanning electron microscope. 6. There was no difference between the specimens of light-and self-cured orthodontic sealants both in the polarized light microscopic group and in the scanning electron microscopic group.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.2
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• pp.209-222
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• 1997

Authors surveyed the ground water near the waste disposed from a fiberglass production factory to confirm the presence of glassfiber in the water and to determine the effect of sampling conditions and storage on the recovery of fibrous materials in the ground water. Sample was collected at every 4 hours for 48 hours consecutively. After finishing the 48 hours sample, water sampling was done from each tap after repeated turning on and off the water for 30 seconds at each time. Sample was collected in the two 1.5 liter polyethylene bottle after vigorously shaking the bottle with the same water several times with the flowing tap water. At each paired sample, one bottle was stored stand still at room temperature, and the other sample was filtered immediately after sampling. Water was filtered on the Mixed Cellulose Ester filter with negative pressure. Each sample was divided into upper and lower layer. The other bottle was stored at room temperature standstill for 7 days and filtered in the same fashion as the other pair of sample did. Each MCE filter was divided into 4 pieces and one piece was treated with acetone to make it transparent. Each prepared sample was observed by two researchers under the light and polarizing microscopy, scanning electron microscopy and energy dispersive X-ra microanalysis. Fibers were classified by the morphology and polarizing pattern under the polarizing microscope, and count was done. 1. There was a significant fluctuation in number of the fibers, but there was no specific demonstrable pattern. 2. Non-polarizing fibers frequently disappeared after 7 days's storage. But cluster of fibers were found at the wall of the same container by scratching technique. 3. Polarizing fibers were usually found in between the filter and the manicure pasted area. Possible explanations for this phenomenon will be that either these fibers are very light or have electronic polarity. Hence, these fibers are not able to be attached on the surface of slide glass. 4. Under the scanning electron microscopic examination, the fibers which are not refractive under the light microscopy were identified as glassfiber. Other fibers which is refractive under the polarizing microscopy were identified as magnesium silicate fibers. It is strongly suggested that development of standardized method of sample collection and measurement of fibrous material in the water is needed.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.542-544
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• 2007

New liquid crystalline Y-shaped molecules containing 1,3,4-oxadizoles have been synthesized with variation of terminal groups (R = H, $OCH_3$ or $OC_8H_{17}$). The structures of obtained compounds were identified by FT/IR and NMR spectrometry, and their thermal and liquid crystalline properties were investigated by DSC and polarizing optical microscope.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.34-37
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• 2002

Freestanding azobenzene-containing liquidcrystalline network (LCN) films. with macroscopic uniaxial molecular alignment were prepared by insitu photopolymerization. By polarizing microscopy, fiber-like structures aligned in one direction were observed. Furthermore, with a confocal laser scanning microscope (CLSM), it was confirmed that the fiber-like structures were formed even in the bulk of the LCNs. Upon UV light irradiation to cause trans-cis photoisomerization of the azobenzene molecules, the LCNfilms underwent a significant and anisotropic bending toward the irradiation direction of UV light. When the bent LCNfilms were exposed to Vis light, unbending of the LCN films immediately took place and the initial flat LCN films were restored. This bending and unbending behavior of the LCN films could be repeated just by changing the wavelength of the irradiation light. It was suggested that the bending was induced by an absorption gradient which produced a volume difference between the front surface area and the bulk of the network films.

• Journal of the Mineralogical Society of Korea
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• v.11 no.1
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• pp.13-19
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• 1998

Textures of claystones of the Cheonunsan Formation in the Hwasoon area have been studied using optical microscope and electron microprobe. Microscopic images were observed under the optical microscope using the transmitted polarizing light from thin sections and under the electron microprobe using the back-scattered electron beam from the polished sections. Identification of minerals were made using X-ray diffraction analysis and chemical analysis by electon microprobe. Textural analyses show that the original sedimentary claystones rich in aluminium were subjected to metamorphism by which they changed to the metamorphosed claystone consisting mainly of chloritoid, quartz, andalusite and illite. Later intensive hydrothermal kaolinization of this metamorhosed claystones resulted in the formation of high-aluminous claystones rich in kaolinite exhibiting various complicated replacement textures.

• Journal of the Korean Wood Science and Technology
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• v.9 no.1
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• pp.1-12
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• 1981

The structure of spiral thickenings, particulary the appearance, arrangement and orientation of thickenings in compression wood of Torreya nucifera, were studied in detail by light and polarizing microscope, scanning and transmission electron microscope. The results obtained are as follows: (1) Using the inclined sections at an angle of 45 degrees to the fiber axis, it seems that we can not only observe the more accurate transverse view of the thickenings but also investigate the formation of their thickenings. (2) Generally 2-4 pieces of thickenings are projected to the cell lumen as nipple-like appearance in transverse section and are as frequent, well developed, forming pair and have the rope-like appearance in radial surface. (3) The secondary wall of early wood is composed of 3 layers (S1, S2, S3) and orientation of thickening appears S helix but that of late wood is of 2 layers (S1, S2) and that orientation shows Z helix. Above two regions are demaracted at several tracheid cells from the growth ring boundary. (4) Orientation of thickening seems to be a element showing the characteristics of compression wood in Torreya nucifera. (5) It believes that the thickenings of compression wood are integral part of the S3 in early wood tracheids and of the S2 in late wood and have the same orientations as the inner-most microfibrils in these layers. (6) Thickening and cavities seem to be not formed together in a secondary cell wall of same tracheids.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.338-341
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• 2005

We have examined the aspects of the orientational ordering deformation of ferroelectric liquid crystal during bending performance of plastic substrate by analyzing the polarizing optical microscope texture and the birefringence of the cell. Striped texture becomes more prominent as the radius of curvature of substrate gets smaller. The optic axis of the adjacent stripes domain was not same and the relative angle between them becomes larger as the radius of curvature gets smaller. Especially, the optic axis rotation angle of one domain was lager than the other and the liquid crystal molecules in each domain became more coherent. In addition, the birefringence data with obliquely incident light shows the polar direction shift of liquid crystal molecule by bending performance.

• Current Optics and Photonics
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• v.2 no.5
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• pp.474-481
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• 2018

We propose a polarization phase-shifting technique to investigate the thickness of $Ta_2O_5$ thin films deposited on BK7 substrates, using a modified Sagnac interferometer. Incident light is split by a polarizing beam splitter into two orthogonal linearly polarized beams traveling in opposite directions, and a quarter-wave plate is inserted into the common path to create an unbalanced phase condition. The linearly polarized light beams are transformed into two circularly polarized beams by transmission through a quarter-wave plate placed at the output of the interferometer. The proposed setup, therefore, yields rotating polarized light that can be used to extract a relative phase via the self-reference system. A thin-film sample inserted into the cyclic path modifies the output signal, in terms of the phase retardation. This technique utilizes three phase-shifted intensities to evaluate the phase retardation via simple signal processing, without manual adjustment of the output polarizer, which subsequently allows the thin film's thickness to be determined. Experimental results show that the thicknesses obtained from the proposed setup are in good agreement with those acquired by a field-emission scanning electron microscope and a spectroscopic ellipsometer. Thus, the proposed interferometric arrangement can be utilized reliably for non-contact thickness measurements of transparent thin films and characterization of optical devices.