WO1999050691A1 - Element optiquement actif et son procede de production - Google Patents

Element optiquement actif et son procede de production Download PDF

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Publication number
WO1999050691A1
WO1999050691A1 PCT/DE1999/000945 DE9900945W WO9950691A1 WO 1999050691 A1 WO1999050691 A1 WO 1999050691A1 DE 9900945 W DE9900945 W DE 9900945W WO 9950691 A1 WO9950691 A1 WO 9950691A1
Authority
WO
WIPO (PCT)
Prior art keywords
optically active
active element
microstructuring
element according
fresnel
Prior art date
Application number
PCT/DE1999/000945
Other languages
German (de)
English (en)
Inventor
Heidrun JÄNCHEN
Werner Hofmann
Andreas Gombert
Volker Wittwer
Original Assignee
Fresnel Optics Gmbh
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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 Fresnel Optics Gmbh, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. filed Critical Fresnel Optics Gmbh
Publication of WO1999050691A1 publication Critical patent/WO1999050691A1/fr

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G02B1/118—Anti-reflection coatings having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/26—Moulds
    • B29C45/37—Mould cavity walls, i.e. the inner surface forming the mould cavity, e.g. linings
    • B29C45/372—Mould cavity walls, i.e. the inner surface forming the mould cavity, e.g. linings provided with means for marking or patterning, e.g. numbering articles
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/12—Optical coatings produced by application to, or surface treatment of, optical elements by surface treatment, e.g. by irradiation

Definitions

  • the invention relates to optically active elements made of a plastic material that is transparent to electromagnetic waves, and to methods for their production.
  • Interference layers or interference layer systems are applied to the surfaces in order to reduce the reflected light component. It should be noted that this possibility is not practical in every case and in particular with the various optically active elements, such as Prisms or Fresnel lenses cannot be used easily.
  • the adhesion of the layer to the substrate can be critical, so that the layer peels off with the slightest mechanical stress.
  • the Anti-reflective treatment of strongly structured surfaces such as Fresnel lenses or prisms with interference - layer systems with the current state of the art only possible in special cases.
  • the anti-reflective effect of interference layer systems depends heavily on the angle of incidence of the radiation, which is problematic in applications with a wide range of angles.
  • protrusions are created in transparent panels made of plastic materials by embossing them in such panels in order to reduce the light losses on the roofs of greenhouses, which normally occur due to reflection.
  • a carrier layer is provided on at least one surface side with a microstructuring superimposed on a macrostructure.
  • the macro structuring looks similar to a diffusing screen, but it does
  • the contrast ratio is reduced.
  • This disadvantage in particular should be avoided in optically active elements in order not to correspondingly impair the desired images.
  • the microstructuring superimposed on the macro structuring in turn only has the task of reducing the reflection on the surface.
  • This solution aims to eliminate disturbing reflections and less to increase the transmission.
  • the macro structure is used to convert clearly recognizable to diffuse reflections; the micro structure reduces the diffuse reflections in order to improve the contrast.
  • a diffuse reflex is generally not an improvement over a clear reflex, because the light yield is reduced and the stray light remains in the optical system (especially in the case of objects with many refractive surfaces) and the contrast deteriorates.
  • adhesion problems which must also be taken into account in the interference layer systems, can occur in particular in the plastic materials.
  • optically active elements such as lenses, prisms, or lenticulars with a small thickness and large opening
  • optical elements With such optical elements, their thickness is almost constant, at least over the optically effective area.
  • active flanks are used, which are arranged concentrically or parallel to one another and due to the formation of the active flanks. Corresponding interfering edges separating these from one another must be present, which cause more or less light losses.
  • Such optical elements have one-sided structuring and the corresponding opposite side, which in this case is normally designed as a flat surface.
  • Such optical elements can also be structured on both sides with active and interference edges.
  • the electromagnetic waves emerge at large angles (up to 70 °) either through the flat surface and / or the existing active surfaces (due to the structuring). Due to increased reflection, there can be at least partial polarization of the light. In addition, the proportion of reflected light at the next interface can be totally reflected or can emerge from interference edges. Due to the high level of complexity, all of these possibilities cannot be taken into account or precalculated, so that interference light can concentrate on the optical axis or on concentric rings (aberrations) in Fresnel lenses, the position of which depends on the distances in the optical system is.
  • the optically active element according to the invention made of a plastic material that is transparent to electromagnetic waves in the visible and invisible wavelength range, is designed in such a way that at least the surface areas on which the undesired reflections are to be avoided have a planar microstructuring directly on the surface, in which the distances between the individual structural elements are each smaller than the smallest wavelength of the electromagnetic waves to be influenced by the element.
  • the undesired reflections can at least be greatly reduced, since an almost continuous transition of the refractive index between the environment, usually air, and the actual surface of the optically active element can be recorded, since the proportion of, for example, air within the microstructuring decreases continuously towards the optically active element.
  • This is favored or achieved by the design of the microstructuring in which the free volume filled with the surrounding medium (air or another gas) decreases continuously with increasing depth within the microstructuring.
  • the microstructuring can be designed periodically and, on the other hand, the individual structural elements of such a microstructuring can also be stochastically distributed on the corresponding surface areas.
  • the shape of the structural elements can also be stochastic, e.g. Pyramids with a size distribution.
  • the periods between the structural elements and, in the case of stochastic structures, the individual structural elements and the distances between them should in each case be smaller than the shortest wavelength of the electromagnetic radiation to be influenced by the optical element.
  • mixed forms of periodic training and stochastic arrangement can also be used if the spacing requirement for the structural elements is at least predominantly fulfilled.
  • the microstructuring should advantageously be formed on the surface of the optically active elements with a depth of up to a maximum of 1.5 ⁇ m, preferably up to 1 ⁇ m, if e.g. to work in the wavelength range of visible light.
  • the structure can also be a few ⁇ m wide and deep.
  • optically active elements can: Prisms, lenticulars, beam splitters, concave or convex-shaped lenses, cylindrical lenses, Fresnel mirrors, if used as rear-view mirrors, or Fresnel lenses.
  • such lenses can also be provided with other structures which are superimposed on the microstructuring to be used according to the invention.
  • Influencing factors for the spectral bandwidth of the reflection-reducing effect are, in the short-wave range, the distances between the individual structural elements or the width of the respective period, and this is limited in the long-wave range by the depth of the microstructuring, which means that for must emboss larger wavelengths deeper.
  • Diffraction occurs if the structure size is too large compared to the wavelength for which the component is used.
  • the microstructuring can be formed on surfaces of the respective optically active element into which the light enters or exits, the reflection-reducing effect occurring in each case.
  • Possible plastic materials for the production of the optically active elements according to the invention are polymethyl methacrylates, polycarbonates and other suitable polymers which are inexpensive to produce and are processable.
  • the optically active elements according to the invention can be produced in such a way that the microstructuring, during the actual production process, is such that elements are formed by injection molding or hot stamping. Tools can be used for this purpose, on the surface of which a negative image of the microstructuring to be formed directly on the surface of the optically active element is formed. This procedure has the advantage that no additional process steps are required for the production of those optically active elements which are necessary in other processes to be described, with which such elements can be produced.
  • Plastic are taken into account, since at least the surface areas to be provided with the microstructuring must be sufficiently softened.
  • a further possibility for producing the optically active elements according to the invention is to form the microstructuring by means of a laser on the surface of such an element.
  • a laser Eximer lasers and, to a limited extent, NdYAG lasers are particularly suitable for this.
  • the laser beam one Such a laser is preferably deflected in two planes over the surface to be provided with the microstructuring, it also being possible to influence the focusing of the laser beam if a non-flat surface is to be microstructured.
  • the laser beam can be directed onto the surface through a mask which specifies the microstructuring and is designed accordingly in order to ensure the required spacing of the individual structural elements.
  • the laser beam treatment has a more cost-effective effect, in particular in the case of small quantities, than is the case with the other production method mentioned.
  • optically active elements according to the invention do not represent a composite material, but rather consist of a single homogeneous plastic material, the disadvantages known from the prior art do not occur, so that long-term use is readily possible even at strongly fluctuating temperatures. In addition, these elements have sufficient mechanical strength, reduce the amount of false light and improve contrast and light efficiency.
  • n 1.496 (at 500 nm)
  • There 10 is a Fresnel lens which has the known structure of active and interference edges on one side, while the other side is planar.
  • the negative image of the desired microstructuring is formed on the counterplate, which specifies the shape of the planar surface of the Fresnel lens.
  • the PMMA is applied in the form of granules, powder or a plate-shaped semifinished product to the Fresnel embossing die located in the embossing device and by heating the Fresnel embossing die and the counterplate up to the softening temperature of 108 ° C., typically to about 180 ° C. warmed up.
  • the Fresnel structure on one side and the anti-reflective micro structure on the other side are simultaneously embossed into the flowable plastic.
  • the Fresnel lens is removed from the mold at a temperature below 98 ° C, the limit temperature for the dimensional stability of the PMMA.
  • planar side of the Fresnel lens produced in this way is characterized by a reduced reflection compared to a planar surface without a microstructure.
  • the surface with the microstructure reflects only about 1.5% of the incident light in the visible wavelength range, while an ordinary planar surface reflects about 4% of the incident light. This improves the light output in optical systems and effectively suppresses the formation of disturbing reflections.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Shaping Of Tube Ends By Bending Or Straightening (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)

Abstract

L'invention concerne des éléments optiquement actifs réalisés dans une matière plastique transparente aux ondes électromagnétiques. L'invention concerne également leur procédé de production. De tels éléments optiques doivent présenter, sur leur interface avec le milieu environnant, une réflexion au moins réduite. Pour ce faire, de tels éléments sont dotés au moins partiellement d'une microstructure surfacique réalisée directement sur leur surface. De plus, les largeurs et les distances des différents éléments structurels doivent être inférieures aux plus petites longueurs d'ondes des ondes électromagnétiques sur lesquelles on agit avec l'élément.
PCT/DE1999/000945 1998-03-27 1999-03-23 Element optiquement actif et son procede de production WO1999050691A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19813690A DE19813690A1 (de) 1998-03-27 1998-03-27 Optisch aktives Element und Verfahren zu seiner Herstellung
DE19813690.0 1998-03-27

Publications (1)

Publication Number Publication Date
WO1999050691A1 true WO1999050691A1 (fr) 1999-10-07

Family

ID=7862643

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE1999/000945 WO1999050691A1 (fr) 1998-03-27 1999-03-23 Element optiquement actif et son procede de production

Country Status (2)

Country Link
DE (1) DE19813690A1 (fr)
WO (1) WO1999050691A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6356389B1 (en) 1999-11-12 2002-03-12 Reflexite Corporation Subwavelength optical microstructure light collimating films
US6570710B1 (en) 1999-11-12 2003-05-27 Reflexite Corporation Subwavelength optical microstructure light collimating films
WO2002012927A3 (fr) * 2000-08-09 2003-10-09 Fraunhofer Ges Forschung Procede et dispositif pour produire une surface optiquement antireflechissante
US6888676B2 (en) * 2003-03-20 2005-05-03 Nokia Corporation Method of making polarizer and antireflection microstructure for mobile phone display and window
DE10153663B4 (de) * 2000-11-03 2005-05-25 Agilent Technologies, Inc. (n.d.Ges.d.Staates Delaware), Palo Alto Mikroanalytische Vorrichtung zum Erfassen von Nahe-Infrarot-Strahlung emittierenden Molekülen

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004026585B4 (de) * 2004-05-28 2006-11-09 Jenoptik Automatisierungstechnik Gmbh Lichtverteiler mit einer lichtverteilenden Struktur bestehend aus Mikro- und Makrostrukturen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013465A (en) * 1973-05-10 1977-03-22 Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Reducing the reflectance of surfaces to radiation
GB1529021A (en) * 1977-03-24 1978-10-18 Secretary Industry Brit Double glazed windows
US4668558A (en) * 1978-07-20 1987-05-26 Minnesota Mining And Manufacturing Company Shaped plastic articles having replicated microstructure surfaces
GB2198279A (en) * 1986-10-23 1988-06-08 Nec Corp An optical storage medium

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4114983A (en) * 1977-02-18 1978-09-19 Minnesota Mining And Manufacturing Company Polymeric optical element having antireflecting surface
DD151827A1 (de) * 1980-07-01 1981-11-04 Joerg Neumann Streuscheibe fuer einen durchprojektionsschirm
DE3831503A1 (de) * 1988-09-16 1990-03-22 Ver Glaswerke Gmbh Transparente deckschicht mit reflexionsvermindernder eigenschaft fuer durchsichtige glas- oder kunststoffsubstrate
JPH09152504A (ja) * 1995-11-29 1997-06-10 Hayashi Telempu Co Ltd 表面レリーフ型光学素子とその成型法
DE19708776C1 (de) * 1997-03-04 1998-06-18 Fraunhofer Ges Forschung Entspiegelungsschicht sowie Verfahren zur Herstellung derselben

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013465A (en) * 1973-05-10 1977-03-22 Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Reducing the reflectance of surfaces to radiation
GB1529021A (en) * 1977-03-24 1978-10-18 Secretary Industry Brit Double glazed windows
US4668558A (en) * 1978-07-20 1987-05-26 Minnesota Mining And Manufacturing Company Shaped plastic articles having replicated microstructure surfaces
GB2198279A (en) * 1986-10-23 1988-06-08 Nec Corp An optical storage medium

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6356389B1 (en) 1999-11-12 2002-03-12 Reflexite Corporation Subwavelength optical microstructure light collimating films
US6570710B1 (en) 1999-11-12 2003-05-27 Reflexite Corporation Subwavelength optical microstructure light collimating films
US6891677B2 (en) * 1999-11-12 2005-05-10 Reflexite Corporation Subwavelength optical microstructure light-redirecting films
WO2002012927A3 (fr) * 2000-08-09 2003-10-09 Fraunhofer Ges Forschung Procede et dispositif pour produire une surface optiquement antireflechissante
DE10153663B4 (de) * 2000-11-03 2005-05-25 Agilent Technologies, Inc. (n.d.Ges.d.Staates Delaware), Palo Alto Mikroanalytische Vorrichtung zum Erfassen von Nahe-Infrarot-Strahlung emittierenden Molekülen
US6888676B2 (en) * 2003-03-20 2005-05-03 Nokia Corporation Method of making polarizer and antireflection microstructure for mobile phone display and window

Also Published As

Publication number Publication date
DE19813690A1 (de) 2000-05-04

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