• Title/Summary/Keyword: birefringence

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One Image Analysis for 2-D Birefringence Measurements by Chromatic Aberration (색수차를 이용한 2차원 복굴절측정 장치의 개발에 관한 연구)

  • Kim, Jong-Sun;Yoon, Kyung-Hwan
    • Proceedings of the KSME Conference
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    • pp.1761-1766
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    • 2004
  • Recently, Plastic optical products are widely used. Injection molding process has advantages of low cost and high productivity. However, it remains a residual birefringence and residual stress by difference cooling. The present study focused on measuring birefringence in optical plastic parts using interference color pattern. The main idea of an analysis comes from chromatic aberration which is caused by difference light wavelengths. As a result, a complete system measuring the high order 2-D birefringence pattern was built. Further investigation is under way to improve the accuracy of birefringence measurement system by diode laser.

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Influence of Injection Molding Conditions on the Birefringence of Disks (사출성형 조건이 디스크의 복굴절에 미치는 영향)

  • Lee, Ho-Sang;Park, Min-Gyu
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.9 no.5
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    • pp.28-33
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    • 2010
  • A computer code was developed to simulate all three stages of the injection molding process: filling, packing and cooling by finite element method. The constitutive equation used here was compressible Leonov model. The PVT relationship was assumed to follow the Tait equation. The flow-induced birefringence was related to the calculated flow stresses through the linear stress-optical law. Based on the simulation, the Taguchi method was used to investigate the influences of injection molding conditions on the birefringence of a center gate disk. In addition, the optimal processing conditions were selected to minimize the birefringence and the birefringence difference along the positions of the disk.

Influences of Injection Molding Conditions on the Birefringence of a Disk (사출성형 조건이 디스크의 복굴절에 미치는 영향)

  • Park M.G.;Lee D.H.;Lee H.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.305-309
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    • 2005
  • A computer code was developed to simulate all three stages of the injection molding process ? filling, packing and cooling by finite element method. The constitutive equation used here was compressible Leonov model. The PVT relationship was assumed to follow the Tait equation. The flow-induced birefringence was related to the calculated flow stresses through the linear stress-optical law. Based on the simulation, the Taguchi method was used to investigate the influences of injection molding conditions on the birefringence of a center gate disk. In addition, the optimal processing conditions were selected to minimize the birefringence and the birefringence difference along the positions of the disk.

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Prediction of birefringence distribution in cylindrical glass compression test (유리 압축 실험에서의 복굴절 분포 예측)

  • Lee J.;Na J.W.;Rhim S.H.;Oh S.I.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.95-100
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    • 2004
  • An analysis using FEM simulation was conducted to predict residual stresses and birefringence in simple compressed cylindrical glass as a preliminary part of the optimum design determination of optical lenses. The FEM simulation with the Maxwell viscoelastic constitutive model was used to predict thermal induced residual stresses and birefringence during the compression test considering stress relaxation. Also the linear photoelastic theory was introduced to calculate birefringence from the residual stress state. The simulation results were in good agreement with deformation and birefringence distribution in the existing experimental result.

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A Study on the Birefringence Properties of Single Mode Optical Fiber (단일모우드 광섬유의 Birefringence특성에 관한 연구)

  • 김은수;박한규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.7 no.4
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    • pp.161-166
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    • 1982
  • In this paper, the intrinsic birefringence and twist-induced rotation of the single mode optical fiber have been investigated. On the analysis, the optical fiber has been modeled as a linear retarder and the intrinsic linear retardation of the single mode optical fiber is approximately found to be 2.57'/m from the measurement. Theoretically analyzing the twist-induce rotation by the purturbation theory, it is found that the magnitude of the twist-induced rotation varies linearly with the twisted angle. And this theorerical result has been in good accord with the experimental result.

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Measurement of Birefringence Distribution in Optical Disk Substrates Fabricated by Injection-Compression Molding (사출압축성형을 통한 광디스크 기판 성형 및 복굴절의 측정)

  • 김종성
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.218-224
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    • 1999
  • It is necessary to improve mechanical and optical properties in the optical disk substrates as the information storage devices with high storage density using short wavelength laser are being developed. Injection compression molding is regarded as the most suitable process to manufacture optical disk substrates with high is regarded as the most suitable process to manufacture optical disk substrates with high dimensional accuracy low residual stresses and superb optical properties In the present study polycarbonate optical disk substrates were fabricated by injection compression molding and the birefringence regarded as one of the most important optical properties for optical disk is measured. The effects of various processing conditions upon the development of birefringence distribution were examined experimentally. It was found that the value of the birefringence distribution were very sensitive to the mold wall temperature history and the variance of the birefringence distribution in the radial direction was affected by the level of the packing and the compression pressure.

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Flow-Induced Birefringence of Polymers in the Region of Abrupt Thickness Transition (두께가 급격히 변하는 영역에서 고분자 유동에 의한 복굴절)

  • Lee, H.S.;Isayev, A.I.
    • Transactions of Materials Processing
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    • v.18 no.1
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    • pp.20-25
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    • 2009
  • A finite element analysis was carried out for a 4:1 planar contraction die for polymer melts using the viscoelastic constitutive equation of Leonov. Viscoelastic fluids showed significant differences in pressure drop and birefringence in contraction and expansion flows. The pressure drop was higher and the birefringence smaller in expansion than in contraction flow. The difference increased with increasing flow rate. The nonlinear Leonov model was shown to describe the viscoelastic effects observed in experiments.

Differential diagnosis of periapical cyst using collagen birefringence pattern of the cyst wall

  • Ji, Hyo Jin;Park, Se-Hee;Cho, Kyung-Mo;Lee, Suk Keun;Kim, Jin Woo
    • Restorative Dentistry and Endodontics
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    • v.42 no.2
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    • pp.111-117
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    • 2017
  • Objectives: Periapical lesions, including periapical cyst (PC), periapical granuloma (PG), and periapical abscess (PA), are frequently affected by chemical/physical damage during root canal treatment or severe bacterial infection, and thus, the differential diagnosis of periapical lesions may be difficult due to the presence of severe inflammatory reaction. The aim of this study was to make differential diagnosis among PC, PG, and PA under polarizing microscope. Materials and Methods: The collagen birefringence patterns of 319 cases of PC (n = 122), PG (n = 158), and PA (n = 39) obtained using a polarizing microscope were compared. In addition, 6 cases of periodontal fibroma (PF) were used as positive controls. Results: Collagen birefringence was condensed with a thick, linear band-like pattern in PC, but was short and irregularly scattered in PG, and scarce or absent in PA. PF showed intense collagen birefringence with a short, palisading pattern but no continuous band-like pattern. The linear band-like birefringence in PC was ascribed to pre-existing expansile tensile stress of the cyst wall. Conclusions: In this study all PCs (n = 122) were distinguishable from PGs and PAs by their characteristic birefringence, despite the absence of lining epithelium (n = 20). Therefore, the authors suggest that the presence of linear band-like collagen birefringence of the cyst wall aids the diagnostic differentiation of PC from PG and PA.

Birefringence induced by irregular structure of photonic crystal fibers (광결정 광섬유의 불규칙적인 구조로 인한 복굴절)

  • Hwang, In-Gak;Lee, Yong-Jae;Lee, Yong-Hui
    • Proceedings of the Optical Society of Korea Conference
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    • pp.368-369
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    • 2004
  • Birefringence due to structural irregularities in photonic crystal fiber is numerically analyzed. The statistical correlations between the birefringence and the degree of the irregularities are presented, and their behaviors are explained using a perturbation theory.

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Dynamic Behavior of Photoinduced Birefringence of Copolymers Containing Aminonitro Azobenzene Chromophore in the Side Chain

  • 최동훈;강석훈
    • Bulletin of the Korean Chemical Society
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    • v.20 no.10
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    • pp.1186-1194
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    • 1999
  • Photoresponsive side chain polymers containing aminonitro azobenzene were synthesized for studying optically induced birefringence. Four different copolymers were prepared using methacrylate, a-methylstyrene, and itaconate monomer. Two copolymers are totally amorphous and the other two are liquid crystalline in nature. Trans-to-cis photoisomerization was observed under the exposure of UV light with UV-VIS absorption spectroscopy. Reorientation of polar azobenzene molecules induced optical anisotropy under a linearly polarized light at 532 nm. The dynamic parameters of optically induced birefringence let us compare the effect of polymeric structure on the rate of growth and decay of the birefringence. Besides the effect of glass transition temperature on the dynamics of photoinduced birefringence, we focused our interests on the geometrical hindrance of polar azobenzene molecules and cooperative motion of environmental mesogenic molecules in the vicinity of polar azobenzene moiety.

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