Details of a Researcher - Koike, Yasuhiro

Papers - Koike, Yasuhiro

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Gradient-Index Polymer Lens and Optical Waveguide

KOIKE YASUHIRO, OHTSUKA YASUJI

応用物理/応用物理学会誌 (The Japan Society of Applied Phisics) 第56 ( 第11 ) 1447-1452 1987.11

Research paper (scientific journal), Joint Work

有機ポリマーは、無機ガラスに比べ、いろいろな分布屈折率パターンを形成しうることから、今まで得られなかった新しいGRIN光デバイスが試作されはじめており、興味深い。軸ずれ収差が原理的に存在しない低収差GRIN球レンズ、立体GRIN光導波路素子、レンズアレーなどである。これらの光デバイスならびに、広伝送帯域GRIN光ファイバーの開発について述べる。（解説）

GRIN '87会議に参加して

KOIKE YASUHIRO

光学/日本光学会誌 (Optical Society of Japan (An Affiliate of the Japan Society of Applied Optics)) 第16 ( 第5 ) 220（40）-221（41） 1987.05

Research paper (scientific journal), Single Work

屈折率分布型球レンズ

KOIKE YASUHIRO, OHTSUKA YASUJI

高分子/高分子学会誌 (The Society of Polymer Science, Japan) 35 ( 12月 ) 1102 1986.12

Research paper (scientific journal), Joint Work

Spherical Gradient-Index Sphere Lens

KOIKE YASUHIRO, SUMI YUJI, OHTSUKA YASUJI

Applied Optics Vol.25 ( No.19 ) 3356-3363 1986.10

Research paper (scientific journal), Joint Work, Accepted

Plastic Gradient-Index Optical Fiber and Optical Devices

KOIKE YASUHIRO

繊維と工業/繊維学会誌 (The Society of Fiber Science and Technology, Japan) 第42 ( 4 ) 122-129 1986.04

Research paper (scientific journal), Single Work

光学プラスチック

KOIKE YASUHIRO

第12回　冬期講習会テキスト「結像光学用の材料と加工」 (応用物理学会、光学懇話会) 1-39 1986.01

Research paper (other academic), Single Work

Plastic Axial Gradient-Index Lens

KOIKE YASUHIRO, HIDAKA HIROSHI, OHTSUKA YASUJI

Applied Optics Vol.24 ( No.24 ) 4321-4325 1985.12

Research paper (scientific journal), Joint Work, Accepted

An axial GRIN lens, where the refractive index varies along the optical axis of a convex lens, can reduce the spherical aberration compared with the conventional homogeneous lens. The transparent plastic axial GRIN material was successfully fabricated by chemical copolymerization and diffusion technique. The depth of the gradient index was 〜20 mm with the refractive-index change Δn=0.07. By carrying out the ray tracing of the axial gradient index, the optimum refractive-index distribution reducing the spherical aberration was determined. If we assume that the axial GRIN lens was constructed from the sample experimentally obtained, it was theoretically confirmed that the spherical aberration of this lens would be remarkably improved.

Studies on The Light-Focusing Plastic Rod.18: Control of Refractive-Index Distribution of Plastic Radial Gradient-Index Rod by Photocopolymerization

OHTSUKA YASUJI, KOIKE YASUHIRO

Applied Optics Vol.24 ( No.24 ) 4316-4320 1985.12

Research paper (scientific journal), Joint Work, Accepted

The refractive-index distribution patterns obtainable by the photocopolymerization of ternary monomer systems were predicted with the help of the mechanism for forming a radial gradient index reported by Ohtsuka and Koike. On the basis of this prediction, we successfully fabricated a convex lens, a concave lens, and a fiber with the W-shaped index distribution expected of an optical fiber with low modal dispersion. It was theoretically and experimentally confirmed that the index distribution of the rod by the photocopolymerization of a ternary monomer system could be widely controlled.

Light Scattering and Local Structure in Low-Loss Poly(Methyl Methacrylate)Glasses

大塚保治、小池康博、淡路治子、谷尾宣久

Kobunshi Ronbunshu,Japanese Joumal of Polymer Science and Technology Vol.42 ( No.4 ) 265-271 1985.04

Research paper (scientific journal), Joint Work

The attenuation of light transmittance through a POF in the range of visible light is governed by light scattering loss. In this paper, the possibility of decreasing scattering loss in PMMA, which is one of the core materials of POF, is discussed. The light scattering loss of the PMMA glass prepared from a contaminant-free monomer depended on the conditions of polymerization and heat-treatment. We succeeded in preparing the PMMA glass with a light scattering loss lower than the value, 14 dB/km, which was reported as the theoretical limitation at 633 (nm)-wavelength in the fluctuation theory for structureless liquids. The angular dependence of light-scattering intensity suggested the existence of heterogeneous regions (several hundreds Å) with the order of 10-5 of refractive-index differences. This fluctuation would be caused by the stress-strain due to volume-contraction during tacticity nor by the small amount of remaining monomer.

Studies on The Light-Focusing Plastic Rod.17: Plastic GRIN Rod Lenz Prepared by Photocopolymerization of A Ternary Monomer System

KOIKE YASUHIRO, HATANAKA HIDEYUKI, OHTSUKA YASUJI

Applied Optics Vol.23 ( No.11 ) 1779-1783 1984.06

Research paper (scientific journal), Joint Work, Accepted

Plastic GRIN rod lenses have been fabricated by photocopolymerization of ternary monomer system. To select the monomer appropriate to photocopolymerization, we developed a computer program to predict the physical constants of homopolymer from the chemical structure. Furthermore, according to the model of the gradient-index formation, MMA-VB monomer system and MMA-benzyl acrylate-VB monomer system were chosen as suitable systems. In both monomer system, plastic GRIN rods with good lens functions up to the periphery were successfully obtained.

Studies on The Light-Focusing Plastic Rod.16: Mechanism of Gradient-Index Formation in Photocopolymerization of Multiple Monomer Systems

OHTSUKA YASUJI, KOIKE YASUHIRO

Applied Optics Vol.23 ( No.11 ) 1774-1778 1984.06

Research paper (scientific journal), Joint Work, Accepted

The Plastic GRIN Rod Prepared by The Photocopolymerization Process-Control of The Refractive-Index Distribution

OHTSUKA YASUJI, KOIKE YASUHIRO

日本光学会誌「光学」/　日本光学会第８回光学シンポジウム (Optical Society of Japan, An Affiliate of the Japan Society of Applied Phisics) 第12 ( 第6 ) 470(58)-475(63) 1983.12

Research paper (scientific journal), Joint Work

Plastic GRIN Rods with various profiles of refractive-index distributions were successfully obtained by the photocopolymerization process. We propose a mechanism to form radial GRIN by photocopolymerization in multimonomer systems. By developing the computer program which calculates the physical conditions of polymer from the chemical structure, and which predicts the index profile of the GRIN rods on the basis of the above mechanism, the index profile of the GRIN rods fabricated were tightly controlled.

Studies on The Light-Focusing Plastic Rod.15: GRIN Rod Prepared by Photocopolymerization of A Ternary Monomer System

KOIKE YASUHIRO, OHTSUKA YASUJI

Applied Optics Vol.22 ( No.3 ) 418-423 1983.02

Research paper (scientific journal), Joint Work, Accepted

Plastic GRIN rod and fiber lenses have been fabricated by photocopolymerization of a ternary monomer system, methyl methacrylate-N-vinyl carbazole vinyl acetate. We now propose the general mechanism for forming radial GRIN in the ternary monomer system using computer simulation. The relationship between the preparation condition and the optical characteristics was clarified. The region having quadratic-index distribution and the numerical aperture were remarkably improved by the ternary monomer system.

Studies on The Light-Focusing Plastic Rod.XIII: Photocopolymerization of Methyl Methacrylate-Vinyl Esters of Aromatic Carboxylic Acid

KOIKE YASUHIRO, KIMOTO YOSHIHIKO, OHTSUKA YASUJI

Journal of Applied Polymer Science Vol.27 ( No.9 ) 3253-3264 1982.09

Research paper (scientific journal), Joint Work, Accepted

The light-focusing rod (LFR) was prepared by the photocopolymerization of MMA with VPAC and VB, using BPO, BN, and BME as an initiator. The LFR with high transparency and steep refractive-index distribution was obtained using MMA-VPAc pair and BME. The difference in the index distributions under BPO, BN, and BME initiations was clarified in terms of the photoinitiation rate and the accompanying thermal polymerization during the photocopolymerization process. The light scattering intensity from the LFR was related to the heterogeneity of the copolymer composition and the compatibility between the M1 and M2 polymers. The comparison of the light scattering theory with the experimental data indicated that the much less scattering intensity from the MMA-VPAc LFR than the MMA-VB LFR should be attributed to the good compatibility between MMA and VPAc polymers, and scarcely attributed to the index difference between the VPAc and VB polymers.

Studies on The Light-Focusing Plastic Rod.12: The GRIN Fiber Lens of Methyl Methacrylate-Vinyl Phenylacetate Copolymer

KOIKE YASUHIRO, KIMOTO YOSHIHIKO, OHTSUKA YASUJI

Applied Optics Vol.21 ( No.6 ) 1057-1062 1982.03

Research paper (scientific journal), Joint Work, Accepted

The light-focusing plastic rod (LFR) and fiber (LFF) were fabricated by Photocopolymerization of MMA with VPAc. The MMA-VPAc LFR has much higher clarity than that of the MMA-VB LFR reported previously. Using the BME as the initiator, which initiates photopolymerization preferentially, led to a much steeper index distribution than using BPO, which initiates thermal- and photochemical polymerization simultaneously. The relationship between preparation condition and optical characteristics were clarified in terms of the index distribution, light scattering, lens function, and attenuation of light transmission.

Studies on The Light-Focusing Plastic Rod.7: Estimation of The Refractive-Index Profile of The Doubly Imaging Fiber-Lens

OHTSUKA YASUJI, KOIKE YASUHIRO

Journal of Society of Fiber Science and Technology Vol.37 ( No.11 ) 439-447 1981.11

Research paper (scientific journal), Joint Work

A doubly-imaging fiber-lens (DIF) was fabricated by the Photocopolymerization of MMA with VB. The core and the outer portions of the DIF form two refractive-index distributions with different gradient-indexes from one another. The DIF, assuring a meridional ray under paraxial condition, led to a simple and feasible method estimating the index-profile of DIF on a basis of its lens function. The validity of this method was verified by the measurement in various conditions and the comparison with the index-profile determined interferometrically.

Studies on The Light-Focusing Plastic Rod.10: A Light-Focusing Plastic Fiber of Methyl Methacrylate-Vinyl Benzoate Copolymer

OHTSUKA YASUJI, KOIKE YASUHIRO, YAMAZAKI HIROTAKA

Applied Optics Vol.20 ( No.15 ) 2726-2730 1981.08

Research paper (scientific journal), Joint Work, Accepted

A light-focusing plastic fiber (LFF) with a parabolic refractive-index distribution was obtained by the continuous heat drawing of the preform prepared from the Photocopolymerization of MMA with VB. The relation between the preparation conditions and the optical and mechanical properties of the LFFs was clarified. The index profile of LFFs is found to be scarcely affected by the continuous heat drawing process compared with that of original preforms. The resulting LFF would be suitable for short-distance communication system due to its attenuation being higher than 103 dB/km.

Studies on The Light-Focusing Plastic Rod.6: The Photocopolymer Rod of Methyl Methacrylate with Vinyl Benzoate

OHTSUKA YASUJI, KOIKE YASUHIRO, YAMAZAKI HIROTAKA

Applied Optics Vol.20 ( No.2 ) 280-285 1981.01

Research paper (scientific journal), Joint Work, Accepted

Determination of The Refractive-Index Profile of Light-Focusing Rods: Accuracy of a Method Using Interphako Interference Microscopy

OHTSUKA YASUJI, KOIKE YASUHIRO

Applied Optics Vol.19 ( No.16, ) 2866-2872 1980.08

Research paper (scientific journal), Joint Work, Accepted

Two analysis procedures to determine the refractive-index profile using Interphako interference microscopy are compared for accuracy: (I) express the profile as a five-nominal equation; (II) considering ray bending due to the index gradient and using Abel inversion. Computer simulation indicate that the errors of both procedures are comparable except for mismatching between the specimen periphery (np) and immersion oil (n2) where Analysis (I) is more accurate than Analysis (II). The partial splitting method is more practicable than total spotting for a rodlike specimen. In addition, improved partial splitting procedure facilitates reduction of error. The index profiles of the two selected light-focusing plastic rods (LFR) were calculated with these two procedures in various conditions. It is concluded that Analysis (I) is preferable to Analysis (II) when np≠n2 and that the improved partial splitting procedure is a practicable method for determining the index profile of LFR.

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