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WO2012101393A1 - Structure de surface ayant des propriétés de réflectance et de transmission de la lumière, et son procédé de fabrication - Google Patents

Structure de surface ayant des propriétés de réflectance et de transmission de la lumière, et son procédé de fabrication Download PDF

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Publication number
WO2012101393A1
WO2012101393A1 PCT/GB2011/050144 GB2011050144W WO2012101393A1 WO 2012101393 A1 WO2012101393 A1 WO 2012101393A1 GB 2011050144 W GB2011050144 W GB 2011050144W WO 2012101393 A1 WO2012101393 A1 WO 2012101393A1
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WO
WIPO (PCT)
Prior art keywords
light
reflector layer
layer
major surface
transparent
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.)
Ceased
Application number
PCT/GB2011/050144
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English (en)
Inventor
Adrian Geisow
Stephen Kitson
Timothy Taphouse
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Hewlett Packard Development Co LP
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Hewlett Packard Development Co LP
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Filing date
Publication date
Application filed by Hewlett Packard Development Co LP filed Critical Hewlett Packard Development Co LP
Priority to PCT/GB2011/050144 priority Critical patent/WO2012101393A1/fr
Publication of WO2012101393A1 publication Critical patent/WO2012101393A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/28—Interference filters
    • G02B5/285—Interference filters comprising deposited thin solid films
    • G02B5/286—Interference filters comprising deposited thin solid films having four or fewer layers, e.g. for achieving a colour effect
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
    • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/02—Diffusing elements; Afocal elements
    • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
    • G02B5/0284—Diffusing elements; Afocal elements characterized by the use used in reflection

Definitions

  • Surface structures have a wide variety of applications. For example, such structures may be used for product casings or product surfaces or may otherwise be incorporated within decorative and utilitarian products and articles. Surface structures may be formed of a single material, or may be formed of different materials, for example in a multilayer structure comprising layers of different materials. The appearance of products and articles, and, in particular, the visible surfaces thereof, under particular illumination conditions can be varied by the choice of a surface structure, including its configuration and materials, according to design requirements.
  • Figure 1 is a schematic side view of a structure according to the present disclosure
  • Figure 2 is a ray diagram showing an optical model of an example structure according to the present disclosure when illuminated with white light from one side thereof;
  • Figure 3a is a graph illustrating a spectral reflectance profile of the example structure of Figure 2 and Figure 3b is a graph illustrating a complementary transmission profile;
  • Figure 4 is a cross-sectional view of an example structure according to the present disclosure.
  • Figure 5 is a cross-sectional view of another example structure according to the present disclosure
  • Figure 6 is a flow diagram of an exam ple method for making a structure according to the present disclosure
  • Figure 7a is a schematic view of a product incorporating a structure according to the present disclosure
  • Figure 7b is a schematic view of an optical device incorporating a structure according to the present disclosure.
  • the present disclosure provides a novel structure which may be used to form a surface in a wide variety of product applications.
  • the structure provides a desired appearance when viewed from one or more of its surfaces, for example under certain lighting or illumination conditions.
  • Use of the structure as a visible surface of a decorative or utilitarian product or article, or a part thereof, enables the appearance of that surface to be selected, controlled or altered, in some cases dependent u pon a particular illumination condition or lighting environment.
  • Methods for manufacturing the structure are also disclosed.
  • the drawings are schematic and not to scale. Like reference numerals in different drawings are used to denote the same or similar features.
  • the term "transparent” means su bstantia lly 100% tra nsm issive of wavelengths within a range of interest, such as visible light, infrared light or ultraviolet light.
  • light means electromagnetic radiation having wavelengths in a nd around the visible spectrum, including ultraviolet and infrared wavelengths.
  • coloured light means light having wavelengths within a particular colour waveband within the visible spectrum.
  • the red waveband generally corresponds to wavelengths of 580 to 650 nm
  • the green waveband generally corresponds to wavelengths of 490 to 580 nm
  • the blue waveband general ly corresponds to wavelengths of 400 to 490 nm .
  • Coloured l ight may have a broadba nd spectrum across wavelengths within the relevant waveband, but typically has a spectral profile with a peak wavelength at or around the centre of the waveband (and thus also called “centre wavelength”), for example a peak wavelength of 620 nm for red light, a peak wavelength of 535 nm for green light and a peak wavelength of 460 nm for blue light.
  • white light means light having a spectral profile across the visible spectrum, so that it is perceived as white by the human eye. Examples of white light include ambient light and light from an incandescent light source.
  • textured when used in relation to a surface/topography of a substrate (or layer(s) thereon), means the local surface area normal to the substrate (i.e., height) varies over lateral distance/area sufficiently quickly to diffuse, scatter or otherwise deviate the light it reflects over a defined angle range, but not so quickly as to diffract it; put another way, the height of the surface is varying (i.e., textured) across distances of an order greater than optical wavelengths, but non-varying (i.e., smooth) across distances of the order of optical wavelengths.
  • smooth when used i n relation to a surface/topography of a substrate (or layer(s) thereon), means the local surface area normal to the substrate does not vary over lateral distance/area so as to diffuse, scatter or otherwise deviate the light it reflects, but may vary at sub-wavelength scales; put another way, the height of the surface is non- varying across distances of the order of optical wavelengths.
  • conformal when used in relation to a layer or stack of layers, means the thickness of the layer/layers, with respect to the surface on which it is formed, is substantially uniform (i.e., constant or only slowly varying over distance) so that transmitted light is not significantly diffused.
  • FIG. 1 schematically illustrates a structure according to the present disclosure.
  • the structure 1 has first and second opposed major surfaces 3, 5.
  • First and second surfaces 3, 5 may have any appropriate surface topography that is smooth, such as planar or curved, according to product design requirements.
  • first and second surface surfaces 3, 5 are generally planar.
  • Structure 1 comprises a transparent substrate 7, having opposed major surfaces 9, 11, of a material having a refractive index
  • Major surface 9 has a smooth topography and forms the second surface 5 of the structure 1.
  • Opposite major surface 11 comprises an area that has a textured topography, and forms an interface with additional layers of the structure 1.
  • an area of the surface 11 has a plurality of peaks and troughs of varying configurations and dimensions. The peaks and troughs may be fully randomized, partly-randomized or periodically arranged, according to design requirements for the application of the structure.
  • Structure 1 further comprises a reflector layer 15 overlying, and substantially conformal with, the major surface 11 of substrate 7.
  • the reflector layer 15 is a non-homogenous (i.e., heterogenous) layer adapted to selectively reflect light with a predefined spectral reflectance profile.
  • a non-homogenous layer enables sufficiently high reflectance of selected wavelengths in accordance with a desired spectral reflectance profile for an application of the structure. Examples of such a non-homogenous reflector layer include a stack of multiple layers, and a single cholesteric layer as discussed in further detail below.
  • the reflector layer 15 may be adapted to selectively reflect light of wavelengths in a selected waveband in the visible spectru m, su ch a s red, gree n or b l u e, a n d to transmit other wavelengths.
  • the reflector layer may be adapted to selectively reflect light of wavelengths in the blue waveband and to transmit light of wavelengths in the red and green wavebands (which combine to produce yellow).
  • the reflector layer 15 may be adapted to reflect a selected proportion of wavelengths across multiple wavebands of, or the whole of, the visible spectrum.
  • the reflector layer 15 may be adapted to reflect a selected proportion of light according to its spectral reflectance profile and to transm it a complementary, non-reflected proportion of light according to its spectral transmission profile.
  • the choice of reflector layer 15 is arbitrary, based on the desired spectral reflectance profile and complementary transmission profile, according to design requ irements of the application of the structure.
  • Structure 1 further comprises a transparent layer 17 having a major surface that forms an interface with reflector layer 15 and has an opposite, smooth major surface that forms first surface 3 of the structure 1.
  • Layer 17 comprises any suitable transparent material having a refractive index n 2 .
  • refractive index n 2 of transparent layer 17 is closely matched to the refractive index ni of the transparent substrate 7.
  • structure 1 is generally symmetrical comprising a conformal reflector layer 15, having a textured topography, sandwiched between transparent substrate 7 and transparent layer 17, which have similar refractive indices.
  • Figure 2 illustrates the optical properties of an area of the example structure 1 of Figure 1, in which the substrate 7 has a textured topogra phy and in wh ich the reflector layer 15 is adapted to selectively reflect blue light.
  • Figure 3a is a graph showing the reflectance profile of the reflector layer 15 of the example structure of Figure 2, in which the maximum/peak reflectivity is about 100% at the centre blue wavelength 460nm
  • Figure 3b is a graph showing the transmission profile of the reflector layer 15, which is complementary to the reflectance profile, in which the minim um transmission is about 0% at the centre blue wavelength 460nm.
  • Figure 2 illustrates the propagation of light rays through the structure 1, when white light is incident on the side of the first surface 3 of the structure, e.g., by projecting a white image thereon.
  • the optica l effects illustrated in Figure 2 also arise when white light is incident on the side of the second surface 5 of the structure.
  • Reflector layer 15 reflects (scatters) rays of blue light R B within a range of different angles (angles i, p 2 p 3 are illustrated, by way of example, in the drawing) to the normal N, by virtue of partial reflection from the textured interfaces formed by the surfaces thereof, to produce blue light of diffuse appearance.
  • the range of different reflection angles is dependent upon the topography of the textured surfaces of the reflector layer 15, and thus the reflected light is scattered over a defined angle range for a given structu re.
  • Reflector layer 15 fu rther tra nsm its non-blue wavelengths (i .e., red a nd green wavelengths), and rays of yellow light T Y are transmitted through second surface 5 of structure 1 at the same angle ⁇ to the normal N as the incident rays I, by virtue of the closely matching refractive indices ni and n 2 of transparent substrate 7 and transparent layer 17, respectively
  • the reflected light when viewed from the side of the first surface 3 of the structure 1, the reflected light appears diffuse (matte) blue to the human eye when ambient (white) light is incident thereon, e.g., the projected white image appears blue, by virtue of the diffusely reflected light.
  • non-diffuse yellow light (formed from red and green wavelengths) is tra nsmitted substantially undeviated through the second surface 5, e.g., the white image incident on the first surface 3 appears yellow when projected through the second surface 5 onto a screen.
  • Other example structures 1 may have a reflector layer 15 having different spectral reflectance and transmission profiles from those shown in Figures 3a and 3b.
  • the reflector layer 15 may be adapted so a s to diffusely reflect any other selected colou r (for insta nce red or green l ight) when illuminated with ambient (white) light and to transmit other colours.
  • the reflector layer 15 may be adapted to diffusely reflect only a proportion of the selected colour (i.e., less than 100% of the pea k wavelength of the spectral profile) when il luminated with am bient (wh ite) light, a nd to transmit the non-reflected light.
  • the reflector layer 15 may be adapted to diffusely reflect multiple selected colours, such that its spectral reflectance profile has corresponding multiple peaks, which each may have different reflectivity values.
  • the m od el of Figure 2 demonstrates that, with such example structures under the described illumination conditions, when viewed from the illuminated side, the structure 1 appears the selected diffuse (matte) colour to the human eye (for instance diffuse blue, red or green) and the other side of the structure 1 projects l ight of a complementary colour (for instance yellow, cya n or magenta) substantially undeviated.
  • a complementary colour for instance yellow, cya n or magenta
  • Further example structures 1 may have a reflector layer 15 with a spectral reflectance/transmission profile to reflect selected wavelengths, or selected proportions of wavelengths, across the whole of the visible spectrum.
  • reflector layer 15 may be designed to reflect a proportion of white light and to transmit the remaining proportion (subject to any losses e.g., due to absorption).
  • the scattering angle range, and thus the diffuse appearance, of the light reflected by the reflector layer 15, is dependent on the topography of the surfaces thereof.
  • light scattering may be selected or controlled according to design requirements. For instance the amount of scattering can be controlled (light being scattered to a greater or lesser extent, as desired), or scattering can be anisotropic (light being scattered more in some directions that others) across the surface topography, according to design requirements for the application of the structure.
  • structure 1 has the combined optical properties of deviated reflection of selected light from an illuminated side thereof, and undeviated transmission of light that is complementary to the reflected light from the other side thereof. This gives rise to multiple possible applications.
  • FIG. 4 illustrates an exam ple structure according to the present disclosure, for use with visible wavelengths.
  • substrate 7 comprises a transparent material having a textured major surface 11 adapted to scatter light.
  • Substrate 7 may be formed of any suitable material, which is transparent to visible wavelengths, according to design requirement for the desired application, including, but not limited to, polyester, polycarbonate, acrylic, glass or fused silica.
  • Substrate 7 may be flexible or rigid and of any desired thickness, according to the design requirements for the application of the structure. The thickness of the substrate is typically 100 to 250 ⁇ , but may be up to 100 mm or more.
  • reflector layer 15 comprises a multilayer stack of layers 15a-15d adapted to reflect light in a particular colour waveband.
  • reflector layer 15 may comprise a multilayer stack adapted to reflect light with a spectral profile having a central/peak wavelength at about 620 nm for the red waveband, at about 535 nm for the green waveband and at about 460 nm for the blue waveband.
  • a suitable multilayer stack may comprise a multilayer dielectric mirror comprising alternate layers of high and low refractive index materials, n 3 and n 4 .
  • reflector layer 15 comprises a multilayer (dielectric) reflector formed from a stack of four substantially parallel layers 15a, 15d, 15c & 15d generally conformal with, and thus with similar topography to, the textured major surface 11 of the substrate 7. Whilst only four layers (i.e., two pairs of layers) are illustrated, typically between 16 and 24 layers (i.e., eight and twelve pairs of layers) are used to form the reflector layer 15, dependent upon the desired spectral reflectance profile. Typically, the percentage peak reflectivity of the multilayer stack increases with an increasing number of layers.
  • the thickness of each layer of the multilayer stack 15 is about a quarter of the centre/peak wavelength of the desired spectral reflectance profile for the reflector layer 15, where the centre/peak wavelength is that wavelength in the med iu m of the layer.
  • the thickness of the layer is 79 nm.
  • multilayer stack comprises alternate layers of: Si0 2 having a relatively low refractive index n 3 of 1.45, and Ti0 2 having a relatively high reflective index n 4 of 2.44.
  • multilayer stack comprises alternate layers of two different metal oxides having refractive indices n 3 of 1.59 and n 4 of 1.83, respectively.
  • the refractive indices n 3 and n 4 of the layers of the multilayer stack are in the range of about 1.3 to 2.7. Many other example implementations are possible and contemplated.
  • the thicknesses, number, order and refractive indices of the materials of the layers 15a-d of a multilayer stack reflector layer 15 are chosen for the desired spectral reflectance profile, including central/peak wavelength and reflectivity/intensity of reflectance.
  • Suitable multilayer mirrors examples of which are described in further detail below, are available through optical filter coating vendors such as Evaporated Coatings Inc of Willow Grove, Pennsylvania, USA.
  • transparent layer 17, formed over the multilayer stack comprises a transparent material having a refractive index n 2 that is substantially the same as the refractive index ni of substrate 7.
  • the material of layer 17 may be different from the material of the substrate (e.g., a transparent optical adhesive) or the same as the material of substrate 7 (e.g., polyester, polycarbonate, acrylic, glass or fused silica).
  • the thickness of the layer 17 is determined according to design requirements but is typically 100 to 250 ⁇ .
  • the configuration of the textured surfaces and interfaces of the multilayer stack 15 have a partly-randomized surface topography, for example with at least 10% variation over in-plane or lateral distances.
  • the configuration of the textured surfaces and interfaces of the multilayer stack 15 have a periodic surface topography.
  • the height is substantially non-varying over lateral distances of the order of visible wavelengths.
  • the textured surface of substrate 7 may be defined by structures having peaks and troughs (e.g., ridges) having a height in the region of 1 ⁇ and width in the region of 10 ⁇ .
  • the period of roughness of the textured surfaces may be selected to provide a predetermined angle over which light is scattered or deviated, and an amplitude of roughness, (i .e., the heights of the peaks/troughs) may be selected to provide a predetermined scattering of light. Selection of a relatively wide range of scattered angles results in more of the available light being reflected within a wide cone, which provides the desired diffuse reflection, with a relatively wide viewing angle.
  • the reflector layer 15 of the structure 1 may reflect light, according to its spectral reflectance profile, with a deviation consistent with the surface topography to achieve an optical function.
  • an optical function may include a magnifying function provided by a surface topography, for example forming a Fresnel lens.
  • the reflector layer 15 exhibits reflectance of substantially 100% of coloured light having the corresponding peak/centre wavelength of its reflectance profile/waveband and transmission of substantially 100% of coloured light outside the reflectance profile/waveband.
  • the reflector layer 15 comprises a multilayer stack of layers that is adapted to reflect a selected proportion of coloured light having the corresponding peak/centre wavelength according to its spectral reflectance profile and to transmit a proportion of light according to its complementary spectral transmission profile.
  • the reflector layer 15 may exhibit reflecta nce of su bstantia l ly 90% of colou red l ight at its spectra l peak/centre wavelength a nd transmission of substantially 10%.
  • the reflector layer 15 may exhibit reflectance of substantially 80% of coloured light at its spectral peak wavelength and transmission of substantially 20% etc.
  • Other examples include a reflector layer having a spectral peak/centre wavelength reflectance in the range of 75 to 100% and complementary transmission in the range of 0 to 25%.
  • the multilayer stack may comprise at least one metal layer comprising silver, aluminium, gold or similar metals and have a thickness to provide the desired reflectance/transmission properties, typically in the region of 30nm.
  • the reflector layer 15 may comprise a stack of birefringent layers having the desired light reflectance and transmission properties, such as is described in Science 31 March 2000: Vol. 287 no. 5462 pp. 2451-2456 "Giant Birefringent Optics in Multilayer Polymer Mirrors" by Michael F. Weber, Carl A. Stover, Larry . Gilbert, Timothy J. Nevitt and Andrew J. Ouderkirk.
  • the multilayer stack may comprise layers of other homogenous materials, and/or non-homogenous layers such as birefringent layers, to provide the desired reflectance and transmission properties.
  • the reflector layer 15 comprises a single, non-homogenous layer having the desired selective reflectance and transmission properties.
  • reflector layer 15 may comprise a single cholesteric polymer layer that selectively reflects, for one polarization, wavelengths of light according to a particular spectral reflectance profile and that transmits non-reflected wavelengths, (i.e., wavelengths outside the particular spectral reflectance profile or all wavelengths with the opposite polarization).
  • a layer is non-homogenous in the sense that the cholesteric polymer self organises into a twisted birefringent layer.
  • the reflector layer 15 may comprise a single layer having sub-wavelength resonant structures embedded therein.
  • the layer may comprise laterally alternate low and high refractive index materials patterned on a sub-wavelength lateral scale across the surface thereof, to provide the desired spectral reflectance and transmission profiles.
  • the non-homogenous layer may comprise a binder material, such as a polymer, containing many small wavelength selective mirrors, such as fragments of the multilayer stack described previously.
  • Figure 6 illustrates a method of making the structure of Figure 1.
  • a transparent substrate having a surface having a textured area is provided at block 100.
  • the substrate may comprise a transparent diffuser film of plastic or other suitable transparent material having a major surface that is textured over the whole or a pa rt of the area thereof.
  • a substrate 7 comprising any suitable transparent material may be provided and treated by embossing, etching or otherwise to form a textured area of the major surface.
  • the textured surface is non-varying (i.e., smooth) across distances of the order of optical wavelengths, but is sufficiently varying to diffuse (scatter) reflected light, and may be fully or partly randomized or periodic.
  • a reflector layer 15 is formed over the textured area of the surface of the substrate 7.
  • reflector layer 15 comprises a multilayer stack formed by laminating layers 15a-15n of material (e.g., metal oxides), with alternate layers having different refractive indices (e.g., 1.59 and 1.83), ove r th e textured surface of the su bstrate using a clea r (tra nsparent) optica l ad hesive therebetween to form a thin film stack.
  • the reflector layer 15 similarly comprises a multilayer stack formed by coating alternate layers of material, in sequence, onto the textured surface of the substrate by deposition, vacuum thermal evaporation, printing, spin-coating or other suitable techniques. The materials and thicknesses of the layers 15a-15n of the multilayer stack are selected to provide the desired colour reflectance and transmission properties according to the desired spectral reflectance profile according to design requirements for the particular application.
  • reflector layer 15 comprises a single non-homogenous layer of material (e.g., a cholesteric layer) formed by laminating, deposition or any other suitable coating technique.
  • a single non-homogenous layer of material e.g., a cholesteric layer
  • a transparent layer comprising a material having a refractive index closely matched to the refractive index of the transparent substrate, is formed over the reflector layer, using any suitable technique such as by lamination using a UV curable, optically transparent adhesive.
  • a 10 degree light shaping diffuser film available from Luminit LLC was provided. Multilayer stacks comprising alternate layers of metal oxides with refractive indices of 1.59 and 1.83, respectively, were formed on the diffuser surface to form red, blue and green coloured reflectors.
  • a zf-16 plastic film available from Zeon chemicals was laminated onto the surface of the reflectors, using a clear optical adhesive, NOA65, available from Norland Products Inc.
  • the smooth outer surface of the diffuser film formed a first surface of the example structure and the smooth outer surface of the plastic film formed a second surface of the example structure.
  • the structure was tested by projecting light from a helium-neon laser of wavelength 632.8 nm onto a surface of the example structure incorporating the blue reflector. Transmission intensity was measured from the other surface of the structure. The angular spread of the red laser beam transmitted through the structure was minimized by matching the refractive indices of the materials on either side of the reflector i.e., the substrate and the plastic film.
  • the structure was further tested by projecting white light forming a text image onto a surface of a front side of the structure incorporating the red reflector.
  • the text image When viewing the illuminated front surface of the structure, the text image was coloured red.
  • the text image When viewing the image projected onto a screen positioned behind the surface of the other, rear side of the structure, the text image appeared sharp and in focus and was coloured cyan.
  • the structure was further tested by projecting white light forming a text image onto a surface of a front side of the structure incorporating the green reflector. When viewing the illuminated front surface of the structure, the text image was coloured green.
  • the text image When viewing the image projected onto a screen positioned behind the surface of the rear side of the structure, the text image appeared sharp and in focus and was coloured magenta.
  • the structure was further tested by projecting white light forming a text image onto a surface of a front side of the structure incorporating the blue reflector.
  • the text image When viewing the illuminated front surface of the structure, the text image was coloured blue.
  • the text image When viewing the image projected onto a screen positioned behind the surface of the other, rear side of the structure, the text image appeared sharp and in focus and was coloured yellow.
  • each of the test structures diffusely reflects selected coloured light and transmits the complementary coloured light without significant deviation.
  • Applications include a product 50 incorporating a structure 1 according to the present disclosure, as shown in Figure 7a.
  • an object 55 such a static image, a hologram or a light source is positioned adjacent a major surface of the structure 1 so that the object 55 can be viewed through the structure 1.
  • the image, hologram or lightsource would be blurred, obscured or otherwise impaired, and would have to be positioned immediately adjacent the diffuse or translucent material to reduce this effect.
  • the image, hologram or light source could be positioned away from the surface without degradation, as least as far as light that is transmitted through the structure is concerned.
  • Further applications include an optical device 60 incorporating a structure according to the present disclosure, as shown in Figure 7b.
  • a device 66 such as a light source or an image forming device (e.g., camera) is positioned behind a major surface of the structure 1.
  • An optically transparent screen which may form a part of, or the whole of, one or more walls of a room, may be formed from the structure disclosed herein.
  • the reflector may be chosen to selectively reflect a narrow set of wavebands such as red, green or blue, and transmit other colours and/or to selectively reflect one polarization. This could provide various possible effects depending upon relative internal and external lighting conditions.
  • the screen would provides diffuse reflection of a selected colour on the external side of the screen, providing an opaque, coloured appearance and thus an obscuring effect to anyone outside the room.
  • the screen would allow substantially broadband transmission of light from the external side through the screen into the interior, providing additional light and allowing occupants to see out of the room through the structure.
  • This arrangement can further allow projection of an image onto the screen, which thereby forms a projection screen, from inside the room for viewing on the walls inside the room, with the colours of projected images adapted to utilize narrowband colours reflected by the screen .
  • a narrowband projector could be used inside the room, with low light levels therein, and the image would be reflected back inside the room by the screen. Outside the room, the screen would appear partly transparent, with only narrow parts of the spectrum blocked.
  • the projected image would be substantially invisible to those outside the room, as substantially all of the project light would be reflected, providing security for the protection of confidential or sensitive information, while still allowing those outside to see the room is occupied.
  • a camera could also be positioned behind the partly transparent projection screen to produce an image of the viewers of the projection screen, for use in video-conferencing.
  • the structure could be used to enhance heads up display of information, for example to drivers or pilots, by reflecting just the narrowband light used to project information, whilst letting the majority of external light in to allow good external vision for the driver or pilot.
  • a casing, surface, or part thereof, of a decorative or utilitarian product or article may be formed from the structure such that a first surface of the structure forms an external, visible surface of the product.
  • the reflector may be selected to diffusely reflect light within a narrow waveband, so that the external surface appears diffusely coloured, and the interior of the product is (partially) obscured (depending upon lighting conditions).
  • the reflector may be selected to diffusely reflect light having a broadband spectral reflectance profile, so that the external surface appears diffuse (matte) white, and the interior of the product is obscured.
  • visible indicator lights such as LEDs, producing coloured light outside the reflected waveband
  • visible indicator lights may be positioned on the interior of the product, which, when on, can be seen from the exterior of the product.
  • a continuous casing or surface of a product can be provided, which accommodates indicator lights, without the need to form openings therein during manufacture. It should be noted that the positioning of indicator lights that provide an image, such as text or an icon, need not be close to the interior surface of the casing in order to be clearly visible, as would be required for conventional diffuse/translucent materials, thus allowing greater flexibility of design.
  • luminaires or lighting fixtures in buildings or vehicles could be designed to present a coloured diffuse appearance when the light is off, yet let light from the luminaire through substantially unimpeded when on.
  • Vehicle stop light casings could be designed to be substantially 100% transmissive of red light, yet diffusely reflective of other parts of the spectrum, perhaps colour-matching the body panels of the vehicle.
  • White light if implemented as e.g., narrow band red, green and blue LED sources, could be arranged to project unimpeded through such a casing when on, whilst still presenting a largely diffuse and optionally coloured appearance when off.
  • the product surface or casing may be provided with a distinctive or decorative a ppea ra nce by design i ng the structu re to have a reas of different light scattering or deviating characteristics, such as a mix of diffuse and specular reflection of light, and/or areas that reflect light having different spectral reflectance profiles.
  • the structure of the present disclosure can be used, e.g., in conjunction with static images/patterns or holograms, as a security feature in products including bank notes. Since the properties of the structure, namely diffuse, selective reflection from one side of the structure, and unscattered transmission from the other, opposite side of the structure, is difficult to achieve without specialist knowledge, such a security feature would be difficult for counterfeiters to replicate.
  • an image may be positioned behind the diffuse reflector of the structure, e.g., in the form of a static printed image or a holographic image.
  • the image When viewed through the structure, the image will appear distinctive by virtue of the diffuse reflection of selected light, e.g., in a particular waveband.
  • the structure may be designed so that the image appears visible only under certain illum ination conditions.
  • the transparent layer and/or substrate may be selected so that the image is only visible under ultraviolet or infrared illumination, or for certain wavelengths, angles or polarization of the illumination light source.
  • the structure may comprise a transparent substrate and reflector layer with a textured surface having an optical function other than that for diffusely reflecting light.
  • a Fresnel lens structure could be coated with a reflective layer such that, in reflection, light is focused or defocused, but, in transmission, light passes through undeviated.
  • the resultant visual effect has a distinctive appearance. This is not only useful as a visually distinctive security feature, but may also be employed to provide a decorative effect.
  • novel surface structure of the present disclosure appears diffuse and allows a suitably illuminated object positioned behind the rear or internal side thereof to be clearly/sharply visible.
  • Objects may include static, moving or holographic images, decorative patterns and icons, and lights such as LEDs.
  • the appearance of the illuminated side of the structure may be made decorative and distinctive by selecting different light scattering characteristics and/or different spectral reflectance profiles of the reflector in different areas of the substrate. This may include areas of specular reflectance mixed with areas of diffuse reflection, and/or transparent areas formed by apertures in the reflector layer as described herein.
  • the spectral reflectance profile of the reflector layer has been defined in terms of a waveband in the visible spectrum, the spectral reflectance profile may be in other parts of the electromagnetic spectrum such as ultraviolet and infrared for some applications.
  • the spectral reflectance profile may be in other parts of the electromagnetic spectrum such as ultraviolet and infrared for some applications.
  • only a part of the surface area of the substrate is textured and/or includes the reflector layer. Accordingly, the examples should not be regarded as limiting the scope of the present disclosure.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

Une structure qui peut être utilisée pour une surface d'un produit ou d'un article pratique ou décoratif comprend : un substrat transparent comportant une première surface principale qui a une zone texturée ; une couche réfléchissante sensiblement conforme au-dessus de la zone de la première surface principale du substrat transparent ; et une couche transparente au-dessus de la couche réfléchissante. La couche réfléchissante conforme est conçue pour réfléchir la lumière de façon diffuse en fonction d'un profil de réflectance spectrale, et pour transmettre la lumière en fonction d'un profil de transmission spectrale complémentaire. L'indice de réfraction du substrat transparent est sensiblement égal à l'indice de réfraction de la couche transparente, de sorte que la lumière qui est incidente sur la zone de la première surface principale et qui est transmise par la couche réfléchissante traverse la structure en n'étant pratiquement pas déviée.
PCT/GB2011/050144 2011-01-28 2011-01-28 Structure de surface ayant des propriétés de réflectance et de transmission de la lumière, et son procédé de fabrication Ceased WO2012101393A1 (fr)

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WO2016153869A1 (fr) * 2015-03-26 2016-09-29 Otoy, Inc. Enregistrement de données holographiques sur des surfaces réfléchissantes
WO2017178299A1 (fr) * 2016-04-15 2017-10-19 Lumileds Holding B.V. Miroir à large bande
CN107924001A (zh) * 2015-08-07 2018-04-17 罗利克技术有限公司 方位调制的散射设备
US10031479B2 (en) 2015-03-26 2018-07-24 Otoy, Inc. Recording holographic data on reflective surfaces
KR20190113867A (ko) * 2017-01-31 2019-10-08 쌩-고벵 글래스 프랑스 방향성 확산 반사를 제공하는 투명 층으로 제조된 층상형 요소

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WO1997005509A1 (fr) * 1995-07-26 1997-02-13 Reflexite Corporation Articles retroreflechissants dont les prismes sont de tailles multiples et situes dans des emplacements multiples
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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016153869A1 (fr) * 2015-03-26 2016-09-29 Otoy, Inc. Enregistrement de données holographiques sur des surfaces réfléchissantes
WO2016153850A1 (fr) * 2015-03-26 2016-09-29 Otoy, Inc. Hologrammes ré-éclairables
US10031479B2 (en) 2015-03-26 2018-07-24 Otoy, Inc. Recording holographic data on reflective surfaces
CN107924001A (zh) * 2015-08-07 2018-04-17 罗利克技术有限公司 方位调制的散射设备
CN107924001B (zh) * 2015-08-07 2021-06-04 罗利克技术有限公司 方位调制的散射设备
WO2017178299A1 (fr) * 2016-04-15 2017-10-19 Lumileds Holding B.V. Miroir à large bande
CN108886076A (zh) * 2016-04-15 2018-11-23 亮锐控股有限公司 宽带反射镜
US11302848B2 (en) 2016-04-15 2022-04-12 Lumileds Llc Broadband mirror
KR20190113867A (ko) * 2017-01-31 2019-10-08 쌩-고벵 글래스 프랑스 방향성 확산 반사를 제공하는 투명 층으로 제조된 층상형 요소
JP2020507121A (ja) * 2017-01-31 2020-03-05 サン−ゴバン グラス フランス 指向性拡散反射をもたらす、透明な層でできた積層要素
JP7163295B2 (ja) 2017-01-31 2022-10-31 サン－ゴバン グラス フランス 指向性拡散反射をもたらす、透明な層でできた積層要素
KR102485161B1 (ko) 2017-01-31 2023-01-06 쌩-고벵 글래스 프랑스 방향성 확산 반사를 제공하는 투명 층으로 제조된 층상형 요소

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