Hirokuni Nanba
Sumitomo Electric Industries
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Featured researches published by Hirokuni Nanba.
CO2 Lasers and Applications II | 1990
Isamu Miyamoto; Hirokuni Nanba; Hiroshi Maruo
Change of focus length due to CO2 laser beam absorption in ZnSe lens was analyzed by the thermal conduction theory and the physical optics. Temperature distribution was calculated in ZnSe lens where the thermal conductivity varies with temperature. Transient focus position was determined within an accuracy of by a diagnostic system where laser beam passing through a rotating slit probe moving along the beam axis is detected by a pyroelectric detector. Focus length was found to be shortened quickly in the initial 10-20 sec, reaching steady state in 60-90 sec in ZnSe lens of 2 inch-diameter. At absorbed power density wab<5 W/cm2, the focus shift is proportional to wab, and increases more rapidly at wab>S W/cm2 with accompanying aberration. The measured focus shift was found to agree well with calculated values. Effect of lens-to-holder contact on the transient focus shift are also discussed.
International Congress on Applications of Lasers & Electro-Optics | 1993
Keiji Ebata; Manabu Shiozaki; Tatsuya Kyotani; Fuminori Higuchi; Hirokuni Nanba
The focussing properties of 45 degree-off-axis parabolic mirrors were examined using a Prometec Laser Scope, with comparison to those of 90, 60 and 30 degree-off-axis parabolic mirrors. These mirrors are all SPDT (Single Point Diamond Turning)-treated, Mo-coated surface and their focal lengths are 254mm. We examined (1) The focussing properties (focal spot size, spot elliptical shape and ellipticity) differ depending on misalignment and mode (Power). (2) With attention to the fact that ZnSe window is frequently used with parabolic mirrors, and the affect on focussing properties of parabolic mirror by the thermally induced optical distortion of this window. And (3) The condition of the parabolic mirrors under irradiation of 5kw laser was simulated.The focussing properties of 45 degree-off-axis parabolic mirrors were examined using a Prometec Laser Scope, with comparison to those of 90, 60 and 30 degree-off-axis parabolic mirrors. These mirrors are all SPDT (Single Point Diamond Turning)-treated, Mo-coated surface and their focal lengths are 254mm. We examined (1) The focussing properties (focal spot size, spot elliptical shape and ellipticity) differ depending on misalignment and mode (Power). (2) With attention to the fact that ZnSe window is frequently used with parabolic mirrors, and the affect on focussing properties of parabolic mirror by the thermally induced optical distortion of this window. And (3) The condition of the parabolic mirrors under irradiation of 5kw laser was simulated.
Proceedings of SPIE, the International Society for Optical Engineering | 2001
Keiji Ebata; Manabu Shiozaki; Takeshi Okada; Keiji Fuse; Hirokuni Nanba
CO2 laser material processing is now being used increasingly in the area of electronics, specifically, for drilling micro holes (min. (phi) 50 micrometers ) in printed circuit. This has become possible through the use of galvanometer mirrors and Aspheric ZnSe f-theta lenses. ZnSe is a good infrared material because of wide transmission. We have succeeded in producing aspheric lenses by using a Single Point Diamond Turning (SPDT) lathe. Distribution of laser beam intensity mainly based on Gaussian distribution is non- uniform. Therefore, the rise great demand for uniform intensity distribution in the fields of heat processing. To obtain higher uniformity, attempts have to be made to convert non-uniform Gaussian distribution into top-hat shaped uniform intensity distribution for smoothly bending laser beams. In this study we propose it is possible to allow the surfaces of a lens to perform more than one function (the center portion functions as a concave lens and the rim portion functions as a convex lens). The Aspheric ZnSe beam shaper consists of two aspheric lenses. First one converts Gaussian profile to uniform irradiation, Second one performs phase matching (compensation). We design this optical component with our special method based on the optical ray tracing. The most important optical property, wave front distortion were measured by infrared interferometer. And we also show the intensity distribution through after beam shaper with high power CO2 laser (>100 W).
LAMP 2002: International Congress on Laser Advanced Materials Processing | 2003
Hiromi Iwamoto; Keiji Ebata; Hirokuni Nanba
We have developed an anti-reflection (AR) coating technique designed for high power carbon dioxide (CO 2 ) lasers that has low absorption and high resistance to humidity. This was achieved by performing ion-assisted deposition (IAD) using a Xe ion beam to apply BaF 2 and ZnSe used as coating materials with extremely low bulk absorption coefficients. It was found that to achieve highly compact BaF 2 thin films with low absorption on polycrystalline ZnSe substrates, both a surface flatness treatment using Xe ion bombardment and an optimized IAD condition of relatively low ion energy up to 200 eV are required. The absorption of the new (BaF 2 /ZnSe) AR coated ZnSe lens is 0.10 to 0.12%, approximately half that of conventional (ThF 4 /ZnSe) AR coated lenses. The new lens has both excellent anti-aging performance and a high resistance to humidity.
Proceedings of SPIE, the International Society for Optical Engineering | 2001
Keiji Ebata; Keiji Fuse; Kenichi Kurisu; Takeshi Okada; Takayuki Hirai; Hirokuni Nanba
We have developed a new design of advanced optics for processing high-power laser material. We introduce the concept of DOE for high power CO2 lasers. The superior functionality of DOE means that it could become the new standard in optics for next generation devices. Here we describe the design of our DOE technology using scalar theory and micro fabrication using photolithography and RIE. We also present results of our ZnSe-DOE technology, mainly focusing on a novel spot-array generator.
International Symposium on Optical Science and Technology | 2001
Keiji Ebata; Keiji Fuse; Kenichi Kurisu; Takeshi Okada; Takayuki Hirai; Hirokuni Nanba
We have developed a new design of advanced optics for processing high-power laser material. We introduce the concept of DOE (Diffractive Optical Elements) for high power CO2 lasers ((lambda) =10.6micrometers ). The superior functionality of DOE means that it could become the new standard in optics for next generation devices. Here we describe the design of our DOE technology using scalar theory and micro fabrication using photolithography and RIE (Reactive Ion Etching). We also present results of our ZnSe-DOE technology, mainly focusing on a novel spot-array generator.
Archive | 1989
Tsunemasa Taguchi; Hirokuni Nanba
Archive | 1988
Tsunemasa Taguchi; Isao Kidoguchi; Hirokuni Nanba
Archive | 2001
Hiromi Iwamoto; Hirokuni Nanba
Archive | 1991
Tsunemasa Taguchi; Hirokuni Nanba