Patents by Inventor Sadao Nakai
Sadao Nakai has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7502396Abstract: A solid-state laser apparatus which can improve its durability is provide. In the solid-state laser apparatus 1, a main pipe 11 for circulating a coolant through a solid-state laser medium 3 is provided with a heat exchanger 14, whereby the laser medium 3 is prevented from raising its temperature. When the coolant becomes acidic or alkaline, a controller 24 controls a flow regulating valve 23, so as to increase the flow rate of the coolant flowing into a bypass pipe 21 provided with a deionizing filter 22, whereby the acidity or alkalinity of the coolant can be weakened. This can prevent the coolant from deteriorating a predetermined part of the laser apparatus 3, and thus can improve the durability of the solid-state laser apparatus 1.Type: GrantFiled: August 23, 2004Date of Patent: March 10, 2009Assignees: Hamamatsu Photonics K.K.Inventors: Toshiyuki Kawashima, Tadashi Kanabe, Sadao Nakai, Hirofumi Kan
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Publication number: 20070297470Abstract: In the solid-state laser apparatus 1, a main pipe 11 for circulating a coolant through a solid-state laser medium 3 is provided with a heat exchanger 14, whereby the laser medium 3 is prevented from raising its temperature. When the coolant becomes acidic or alkaline, a controller 24 controls a flow regulating valve 23, so as to increase the flow rate of the coolant flowing into a bypass pipe 21 provided with a deionizing filter 22, whereby the acidity or alkalinity of the coolant can be weakened. This can prevent the coolant from deteriorating a predetermined part of the laser apparatus 3, and thus can improve the durability of the solid-state laser apparatus 1. Also, since the bypass pipe 21 connected in parallel to a part of the main pipe 11 is provided with the deionizing filter 22, the flow rate of the coolant circulating through the main pipe 11 can be restrained from decreasing, and the cooling efficiency of the laser medium 3 can be prevented from lowering.Type: ApplicationFiled: August 23, 2004Publication date: December 27, 2007Inventors: Toshiyuki Kawashima, Tadashi Kanabe, Sadao Nakai, Hirofumi Kan
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Publication number: 20070189346Abstract: A solid-state laser apparatus which can cool a solid-state laser medium such that the solid-state laser medium attains a uniform temperature along the propagating direction of light to be amplified is provided. In a solid-state laser apparatus 1, a coolant circulating through flow paths 12a, 12b comes into direct contact with a pair of reflecting end faces 5a, 5b of a solid-state laser medium 3, whereby the laser medium 3 heated by pumping light emitted from semiconductor lasers 9 can efficiently be cooled. Since the coolant circulates through the flow paths 12a, 12b in a direction substantially perpendicular to a propagating surface P of light to be amplified L, the solid-state laser medium 3 can be cooled such as to attain a uniform temperature along a propagating direction of the light L. This can lower the thermal lens effect and thermal birefringence effect in the solid-state laser medium 3.Type: ApplicationFiled: August 23, 2004Publication date: August 16, 2007Inventors: Toshiyuki Kawashima, Tadashi Kanabe, Sadao Nakai, Hirofumi Kan
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Patent number: 7198738Abstract: The present invention provides a cesium-lithium-borate crystal, which can be used as a high-performance wavelength converting crystal, having a chemical composition expressed as CsLiB6O10, and substituted cesium-lithium-borate crystals expressed by the following formula: Cs1?xLi1?yMx+yB6O10 or Cs2(1?z)Li2LzB12O20 (where, M is an alkali metal element, and L is an alkali earth metal element); a method for manufacturing same by heating and melting; and an optical apparatus using such crystals.Type: GrantFiled: December 23, 2005Date of Patent: April 3, 2007Assignee: Research Development Corporation of JapanInventors: Takatomo Sasaki, Akio Hiraki, Yusuke Mori, Sadao Nakai
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Publication number: 20060165578Abstract: The present invention provides a cesium-lithium-borate crystal, which can be used as a high-performance wavelength converting crystal, having a chemical composition expressed as CsLiB6O10, and substituted cesium-lithium-borate crystals expressed by the following formula: Cs1-xLi1-yMx+yB6O10 or Cs2(1?z)Li2LzB12O20 (where, M is an alkali metal element, and L is an alkali earth metal element); a method for manufacturing same by heating and melting; and an optical apparatus using such crystals.Type: ApplicationFiled: December 23, 2005Publication date: July 27, 2006Inventors: Takatomo Sasaki, Akio Hiraki, Yusuke Mori, Sadao Nakai
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Publication number: 20030030039Abstract: The present invention provides a cesium-lithium-borate crystal, which can be used as a high-performance wavelength converting crystal, having a chemical composition expressed as CsLiB6O10, and substituted cesium-lithium-borate crystals expressed by the following formula:Type: ApplicationFiled: August 15, 2002Publication date: February 13, 2003Inventors: Takatomo Sasaki, Akio Hiraki, Yusuke Mori, Sadao Nakai
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Publication number: 20020000541Abstract: The present invention provides a cesium-lithium-borate crystal, which can be used as a high-performance wavelength converting crystal, having a chemical composition expressed as CsLiB6O10, and substituted cesium-lithium-borate crystals expressed by the following formula:Type: ApplicationFiled: July 3, 2001Publication date: January 3, 2002Inventors: Takatomo Sasaki, Akio Hiraki, Yusuke Mori, Sadao Nakai
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Patent number: 6296784Abstract: The present invention provides a cesium-lithium-borate crystal, which can be used as a high-performance wavelength converting crystal, having a chemical composition expressed as CsLiB6O10, and substituted cesium-lithium-borate crystals expressed by the following formula: Cs1−xLi1−yMx+yB6O10 or Cs2(1−z)Li2LzB12O20 (where, M is an alkali metal element, and L is an alkali earth metal element); a method for manufacturing same by heating and melting; and an optical apparatus using such crystalsType: GrantFiled: July 17, 1995Date of Patent: October 2, 2001Assignee: Research Development Corporation of JapanInventors: Takatomo Sasaki, Akio Hiraki, Yusuke Mori, Sadao Nakai
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Patent number: 5872804Abstract: A passive eight-pass solid-state laser amplifier is constructed using a quarter-wave plate (11), a total reflection mirror (12), a polarization beam splitter (5), and a total reflection mirror (6) while input/output faces of a hexagonal zigzag slab solid-state laser medium (15) optically pumped are kept nearly perpendicular to pulsed laser light. Thermal birefringence takes place in the laser medium (15) optically pumped with good symmetry by flash lamps or LDs (9) and is compensated for by a quartz 90.degree. rotator (10). Linearly s-polarized laser light reflected by a polarization beam splitter (3) is output as pulsed laser output light (13) to the outside. Owing to this, saturation laser amplification can be achieved using output laser light from a pulsed laser oscillator of relatively low output, as source light.Type: GrantFiled: July 17, 1997Date of Patent: February 16, 1999Assignees: Hamamatsu Photonics K.K., Institute for Laser Technology, Sadao Nakai, Yasukazu IzawaInventors: Hirofumi Kan, Yasukazu Izawa, Masanobu Yamanaka, Hiromitsu Kiriyama, Takuji Yoshida, Sadao Nakai, Chiyoe Yamanaka
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Patent number: 5587793Abstract: A sample is placed between a circular polarizer and an analyzer in an optical path between a monochromatic light source and a two-dimensional optical receiver. Parallel beams emitted from the monochromatic light source are converted into circularly polarized light by the circular polarizer. After transmitting the sample, the light is guided to the analyzer. While rotating the analyzer about the axis of the beams, image data are detected by optical receiver at a step of a regular rotation angle, and the detected image data are sampled to be sent to an image processing device in the next stage. On the basis of the image data, an operation is conducted on each pixel to obtain a relative phase difference due to birefringence of the sample, the two-dimensional birefringence distribution including the sign of the relative phase difference, and also the principal axis direction.Type: GrantFiled: June 6, 1995Date of Patent: December 24, 1996Assignees: Sadao Nakai, Institute for Laser Technology, Fuji Electric Co., Ltd.Inventors: Sadao Nakai, Yasukazu Izawa, Masanobu Yamanaka, Masato Ohmi, Masanori Akatsuka, Chiyoe Yamanaka, Yoshiyuki Yonezawa
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Patent number: 5582629Abstract: The present invention provides a process for reforming sponge titanium powder into intermediate titanium particles of desirable fluidity and superior bulk specific gravity suitable as a starting material of a titanium or titanium alloy product to be produced by powder metallurgy, comprising the steps of: charging a sponge titanium powder in mill pots of a planetary ball mill together with crushing medium; collapsing the particles of the powder to be consolidated forming a squamation under an inert atmosphere in the mill pots; and adjusting the particle size and particle diameter by cutting the squamated particle under an inert atmosphere in a crushing medium stirring mill.Type: GrantFiled: February 22, 1995Date of Patent: December 10, 1996Assignee: Kurimoto, Ltd.Inventors: Sadao Nakai, Kazuaki Arakawa
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Patent number: 5465178Abstract: The invention is directed to a focusing optical system for semiconductor lasers, which is regulated in terms of magnification power in both its directions normal to the optical axis, so that the back focus of sufficient magnitude can be made equal in both the directions and the magnitude of aberration can be regulated to achieve an improvement in focusing efficiency, and in which a light beam from a semiconductor laser having varying exit angles in the horizontal and vertical directions is focused on a spot having substantially equal diameters in the horizontal and vertical directions. This focusing optical system comprises first lens unit L1 including a rotation asymmetric lens having positive power in the direction defined by a large exit angle at which a laser beam emanates from the laser, a second lens unit L2 including at least one lens of negative power, and a third lens unit L3 that is a rotation asymmetric lens unit having positive power in the directions defined by both large and small exit angles.Type: GrantFiled: September 10, 1993Date of Patent: November 7, 1995Assignees: Olympus Optical Co., Ltd., Sadao Nakai, Kimnon Electric Co. Ltd.Inventors: Sadao Nakai, Masanobu Yamanaka, Koji Ishikawa, Tsuyoshi Sato, Kimiaki Yamamoto, Mikihiko Terashima
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Patent number: 4929847Abstract: A method for determining a sludge content in a heavy hydrocarbon oil and a device therefor are disclosed. The method comprises measuring absorbances of a heavy hydrocarbon oil sample, having an oil film thickness selected form a range of form about 0.01 to 5 mm, at two different wavelengths selected from the visible light region of from 500 to 1000 nm and determining a sludge content of the sample oil by comparing two measured absorbances according to the relationship between known sludge contents and absorbances at the two wavelengths. The device comprises a light source, a cell for a sample oil, a two-wavelength absorbance detector containing two interference filters and two light-current transducers, and a computing means for converting the current values obtained into a sludge content. The method and device provide a means for rapid and precise determination of sludge contents in heavy hydrocarbon oils.Type: GrantFiled: May 4, 1989Date of Patent: May 29, 1990Assignee: Cosmo Oil Co., Ltd.Inventors: Seigo Yamazoe, Sadao Nakai, Yukimasa Fukui