• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.38-43
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• 2004

This paper describes the construction of a circular polariscope. Generally, a circular polariscope contains four optical elements and a light source. The first element following the light source is called the linear polarizer. It converts the ordinary light into plane-polarized light. The second element is a quarter wave plate which converts the plane-polarized light into circularly polarized light. Following the quarter wave plate, a specimen made of transparent photoelastic material is located in a loading device. The second quarter wave plate is set and the last element is the analyzer. These polarizing elements, two quarter wave plates and two linear polarizing filters, were purchased from the USA. Frames and other structures for holding polarizing filters were machined and assembled to be rotated. Light box, which includes four incandescent lamps and two sodium-vapor lamps, was made. In order to proof the function of the newly built polariscope, Tardy compensation test was applied to a rectangular shaped specimen made of poly-carbonate material (PSM 1). The error of the fringe constant, which was measured by the newly built polariscope, was within 4.4 percent compared to the standard value of this material. It is possible to make a good quality of polariscope if accurate polarizing filters will be used.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.189-195
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• 2003

The objective of this study is to improve the optical sensitivity of laser fluorescence for detection of incipient enamel caries. An incipient carious lesion was formed in various stages by placing an enamel specimen of a bovine tooth in STPP demineralization solution. After measuring the optical density of the lesion surface by laser fluorescence induced by argon laser and various alter of yellow(500-520nm), amber(520-540nm), orange(540-560nm), and red(560-580nm), the specimen was cut vertically to measure the depth of the lesion using a polarizing microscope. SAS statistical program was used to analyze the relationship between the optical density of the lesion suface and the depth of the lesion. The results were as follows: 1. The optical density of early carious lesion, measured by laser fluorescence with amber and orange filter, and lesion depth observed by polarizing microscope, were increased as demineralization time increased. 2. The correlation coefficient between optical density of the lesion surface and the histological depth of the lesion was the highest in orange filter(r=0.49), followed by amber(r=0.32), yellow(r=0.13) and red(0.01). 3. Regression analysis showed that the most linear relationship between the optical density and the lesion depth was existed in orange filter group. In regard above results, laser fluorescence could be considered to be reliable for optical diagnosis of dental caries.

• Journal of IKEEE
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• v.26 no.3
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• pp.416-421
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• 2022

In this study, we present a fully automated system that combines camera technology with liquid crystal technology to create a polarization camera capable of detecting the partial linear polarization of light reflected from an object. The use of twisted nematic (TN) liquid crystals that electro-optically modulate the polarization plane of light eliminates the need to mechanically rotate the polarizing filter in front of the camera lens. Images obtained using these techniques are imaged by computer software. In addition, liquid crystal panels have been produced in a square shape, but many camera lenses are usually round, and lighting or other driving units are installed around the lens, so space is optimized through the application of a circular liquid crystal display. Through the development of this technology, an electrically switchable and space-optimized liquid crystal polarizer is developed.