JP4271727B2 - 光誘導チャンバー用の光反射面 - Google Patents

光誘導チャンバー用の光反射面 Download PDF

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Publication number
JP4271727B2
JP4271727B2 JP51299597A JP51299597A JP4271727B2 JP 4271727 B2 JP4271727 B2 JP 4271727B2 JP 51299597 A JP51299597 A JP 51299597A JP 51299597 A JP51299597 A JP 51299597A JP 4271727 B2 JP4271727 B2 JP 4271727B2
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JP
Japan
Prior art keywords
light
reflector
ultraviolet
reflective
reflective material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP51299597A
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English (en)
Japanese (ja)
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JP2000502489A5 (enExample
JP2000502489A (ja
Inventor
エル. マクグレガー,ゴードン
ビー. マイナー,レイモンド
イー. ハノン,グレゴリー
リオン ヘン,ロバート
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
WL Gore and Associates Inc
Original Assignee
WL Gore and Associates Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by WL Gore and Associates Inc filed Critical WL Gore and Associates Inc
Publication of JP2000502489A publication Critical patent/JP2000502489A/ja
Publication of JP2000502489A5 publication Critical patent/JP2000502489A5/ja
Application granted granted Critical
Publication of JP4271727B2 publication Critical patent/JP4271727B2/ja
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18Manufacture of films or sheets
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21SNON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S41/00Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps
    • F21S41/30Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by reflectors
    • F21S41/37Illuminating devices specially adapted for vehicle exteriors, e.g. headlamps characterised by reflectors characterised by their material, surface treatment or coatings
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21VFUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V7/00Reflectors for light sources
    • F21V7/22Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors
    • F21V7/24Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors characterised by the material
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21VFUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V7/00Reflectors for light sources
    • F21V7/22Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors
    • F21V7/28Reflectors for light sources characterised by materials, surface treatments or coatings, e.g. dichroic reflectors characterised by coatings
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/02Diffusing elements; Afocal elements
    • G02B5/0205Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/0236Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
    • G02B5/0247Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of voids or pores
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/02Diffusing elements; Afocal elements
    • G02B5/0273Diffusing elements; Afocal elements characterized by the use
    • G02B5/0284Diffusing elements; Afocal elements characterized by the use used in reflection
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133553Reflecting elements
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2027/00Use of polyvinylhalogenides or derivatives thereof as moulding material
    • B29K2027/12Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
    • B29K2027/18PTFE, i.e. polytetrafluorethene, e.g. ePTFE, i.e. expanded polytetrafluorethene
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/12Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08J2327/18Homopolymers or copolymers of tetrafluoroethylene
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133504Diffusing, scattering, diffracting elements

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Engineering & Computer Science (AREA)
  • Nonlinear Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Mathematical Physics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Laminated Bodies (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Optical Elements Other Than Lenses (AREA)
  • Treatments Of Macromolecular Shaped Articles (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Road Signs Or Road Markings (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
JP51299597A 1995-12-06 1996-10-09 光誘導チャンバー用の光反射面 Expired - Lifetime JP4271727B2 (ja)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US08/569,411 1995-12-06
US08/569,411 US5689364A (en) 1995-01-06 1995-12-06 Light reflectant surface for photoinduction chambers
PCT/US1996/016142 WO1997020882A1 (en) 1995-12-06 1996-10-09 Light reflectant surface for photoinduction chambers

Publications (3)

Publication Number Publication Date
JP2000502489A JP2000502489A (ja) 2000-02-29
JP2000502489A5 JP2000502489A5 (enExample) 2004-09-16
JP4271727B2 true JP4271727B2 (ja) 2009-06-03

Family

ID=24275338

Family Applications (1)

Application Number Title Priority Date Filing Date
JP51299597A Expired - Lifetime JP4271727B2 (ja) 1995-12-06 1996-10-09 光誘導チャンバー用の光反射面

Country Status (7)

Country Link
US (1) US5689364A (enExample)
EP (1) EP0865460B1 (enExample)
JP (1) JP4271727B2 (enExample)
AU (1) AU712860B2 (enExample)
CA (1) CA2236803C (enExample)
DE (1) DE69606553T2 (enExample)
WO (1) WO1997020882A1 (enExample)

Families Citing this family (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6015610A (en) * 1995-01-06 2000-01-18 W. L. Gore & Associates, Inc. Very thin highly light reflectant surface and method for making and using same
US5982542A (en) * 1995-01-06 1999-11-09 W. L. Gore & Associates, Inc. High light diffusive and low light absorbent material and method for making and using same
US5936727A (en) * 1997-04-24 1999-08-10 Foss Nirsystems, Inc. Wavelength standard
US5982548A (en) * 1997-05-19 1999-11-09 W. L. Gore & Associates, Inc. Thin light reflectant surface and method for making and using same
US5976686A (en) * 1997-10-24 1999-11-02 3M Innovative Properties Company Diffuse reflective articles
US6214362B1 (en) * 1999-11-24 2001-04-10 Darren L. Page Cosmetic pad for removing low tension substances and applying cosmetics
US6437861B1 (en) 2000-02-16 2002-08-20 Expo Photonic Solutions Inc. Compact light integration interface
AU2003293088A1 (en) * 2002-11-27 2004-06-23 Novatron, Inc. Uv flux multiplication system for sterilizing air, medical devices and other materials
US7875247B2 (en) * 2002-11-27 2011-01-25 Novatron, Inc. UV flux multiplication system for sterilizing air, medical devices and other materials
US20050115498A1 (en) * 2003-09-23 2005-06-02 Ingram Michael W. Reflector for UV curing systems
US20070200337A1 (en) * 2006-02-27 2007-08-30 Aaron Henry Johnson Method for creating a decoy exhibiting realistic spectral reflectance
TW200740474A (en) * 2006-04-25 2007-11-01 Bing-Yang Yao Device capable of sterilizing completely
US20080269844A1 (en) * 2007-04-30 2008-10-30 Logslett Kimberly D Reflective Crib Liner
US8490321B1 (en) 2009-11-04 2013-07-23 Scott A. Butz UV reflective fishing lure system
US8854734B2 (en) * 2009-11-12 2014-10-07 Vela Technologies, Inc. Integrating optical system and methods
US8426800B2 (en) 2010-09-09 2013-04-23 Vela Technologies, Inc. Integrating optical systems and methods
US9165756B2 (en) * 2011-06-08 2015-10-20 Xenex Disinfection Services, Llc Ultraviolet discharge lamp apparatuses with one or more reflectors
US9093258B2 (en) 2011-06-08 2015-07-28 Xenex Disinfection Services, Llc Ultraviolet discharge lamp apparatuses having optical filters which attenuate visible light
US11000622B2 (en) 2012-07-27 2021-05-11 Aeroclean Technologies, Llc UV sterilization apparatus, system, and method for forced-air patient heating systems
US20160038624A1 (en) * 2012-07-27 2016-02-11 Mark D. Krosney Uv sterilization apparatus, system, and method for forced-air patient heating systems
EP3718413A1 (en) 2014-09-18 2020-10-07 Xenex Disinfection Services Inc. Room and area disinfection apparatus and methods utilizing pulsed light
WO2019045777A1 (en) 2017-08-31 2019-03-07 Krosney Mark D SYSTEM AND METHOD FOR TREATING AIR
KR102595821B1 (ko) 2018-05-02 2023-10-30 서울바이오시스 주식회사 발광 소자 패키지
CN111200049A (zh) * 2018-05-02 2020-05-26 首尔伟傲世有限公司 发光元件封装件
US11850336B2 (en) 2020-05-22 2023-12-26 Molekule Group, Inc. UV sterilization apparatus, system, and method for aircraft air systems
JP2023544252A (ja) 2020-09-14 2023-10-23 モレキュール グループ インコーポレイテッド 統合された空気殺菌器および表面消毒器
US11779675B2 (en) 2020-10-19 2023-10-10 Molekule Group, Inc. Air sterilization insert for heating, ventilation, and air conditioning (HVAC) systems

Family Cites Families (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE392582B (sv) * 1970-05-21 1977-04-04 Gore & Ass Forfarande vid framstellning av ett porost material, genom expandering och streckning av en tetrafluoretenpolymer framstelld i ett pastabildande strengsprutningsforfarande
US4035085A (en) * 1973-06-29 1977-07-12 Ppg Industries, Inc. Method and apparatus for comparing light reflectance of a sample against a standard
US4096227A (en) * 1973-07-03 1978-06-20 W. L. Gore & Associates, Inc. Process for producing filled porous PTFE products
DE2347015C2 (de) * 1973-09-14 1985-12-12 Schering AG, 1000 Berlin und 4709 Bergkamen Neue Pyrazolyloxyessigsäurederivate, Verfahren zu ihrer Herstellung und diese enthaltende Mittel
JPS5936837B2 (ja) * 1977-04-05 1984-09-06 株式会社東芝 光半導体装置
US4571448A (en) * 1981-11-16 1986-02-18 University Of Delaware Thin film photovoltaic solar cell and method of making the same
FR2530873A1 (fr) * 1982-03-17 1984-01-27 Ozil Maurice Dispositif de reperage de positions de cartes de circuits imprimes par rapport a leurs connecteurs
US4523319A (en) * 1983-05-10 1985-06-11 Brown University Laser tape systems
US4764932A (en) * 1985-12-13 1988-08-16 Continental Laser Corporation Ion laser having direct liquid cooling of segmented discharge tube
US4718974A (en) * 1987-01-09 1988-01-12 Ultraphase Equipment, Inc. Photoresist stripping apparatus using microwave pumped ultraviolet lamp
US4802186A (en) * 1987-07-06 1989-01-31 Hughes Aircraft Company High reflectance laser resonator cavity
US4912720A (en) * 1988-10-27 1990-03-27 Labsphere, Inc. Laser cavity material
DE3840632A1 (de) * 1988-12-02 1990-06-07 Kempf Georg Ulrich Streuscheibe
US4902423A (en) * 1989-02-02 1990-02-20 W. L. Gore & Associates, Inc. Highly air permeable expanded polytetrafluoroethylene membranes and process for making them
US4994673A (en) * 1989-06-06 1991-02-19 Solon Technologies, Inc. Ruggedized scintillation detector
EP0450131B1 (en) * 1990-04-06 1995-08-02 New Japan Radio Co., Ltd. Electrodeless microwave-generated radiation apparatus
US5037618A (en) * 1990-04-13 1991-08-06 Peroxidation Systems, Inc. Oxidation chamber
US5116115A (en) * 1990-05-09 1992-05-26 Wyko Corporation Method and apparatus for measuring corneal topography
KR950006318B1 (ko) * 1990-07-16 1995-06-13 미쓰이세끼유 가가꾸고오교오 가부시끼가이샤 확산반사체(diffusion reflector) 및 그를 이용한 고체레이저 장치
AU644518B2 (en) * 1991-04-29 1993-12-09 Labsphere, Inc. Integrating sphere for diffuse reflectance and transmittance measurements and the like
JPH07235714A (ja) * 1994-02-23 1995-09-05 Mitsubishi Electric Corp 固体レーザ装置
US5596450A (en) * 1995-01-06 1997-01-21 W. L. Gore & Associates, Inc. Light reflectant surface and method for making and using same

Also Published As

Publication number Publication date
EP0865460A1 (en) 1998-09-23
DE69606553T2 (de) 2000-09-14
CA2236803A1 (en) 1997-06-12
EP0865460B1 (en) 2000-02-02
AU7262296A (en) 1997-06-27
CA2236803C (en) 2001-04-03
US5689364A (en) 1997-11-18
JP2000502489A (ja) 2000-02-29
DE69606553D1 (de) 2000-03-09
AU712860B2 (en) 1999-11-18
WO1997020882A1 (en) 1997-06-12

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