Abstract: The invention provides a substantially athermal etalon. In one embodiment, the multi-cavity etalon includes at least one free-standing multi-layer thin film and is rendered thermally stable through the use of the free-standing multi-layer film and spacers having predetermined thermal expansion coefficients. In another embodiment, the multi-cavity etalon is rendered thermally stable through the use of mixed spacers.

Abstract: An image forming element is disclosed which is easy to manufacture, which can form images easily and at a low cost, and which is stable without fear of environmental problems arising at a time of disposal. Also disclosed is an image forming device which utilizes the image forming element and which can form color images. The image forming element contains at least a film in which rod-shaped bodies are oriented and which reflects incident light as colored interference light. The image forming device is equipped with at least the image forming element, and an ability to irradiate light onto the image forming element. The image forming element reflects, as interference light, the irradiated light. The wavelength of the interference light is 300 to 810 nm.

Abstract: The invention provides a tunable filter that can minimize adjacent channel cross talk despite an increase of a number of available wavelengths and quickly switch a wavelength to be used, and manufacturing method thereof, and also an optical switching device comprising such tunable filter. In a tunable filter having a Fabry-Perot etalon structure, not less than two cavity gaps 114 to 116 are provided and separation between the cavity gaps is controlled by any of electrostatic drive, electromagnetic drive or piezoelectric drive. In this case, the cavity gaps can be formed through the steps of forming a sacrificial layer in advance where a cavity gap is to be formed; forming a plurality of optical multilayer films 100 to 103; and removing the sacrificial layer by etching. Substrates 107 and 109 are combined through a supporting column 108.

Abstract: Method of producing a member of a periodic structure having, alternately stacked, a plurality of high refractive index layers and a plurality of low refractive index layers. The method includes alternately superimposing on each other a plurality of first sheet glasses having a high refractive index and a plurality of second sheet glasses having a low refractive index, and heating the stacked member to at least a glass transition temperature. In addition, the method includes applying a pressure to the heated stacked member perpendicularly to a principal surface of the sheet glasses or extending the heated stacked member parallel to the principal surface of the sheet glasses, thereby integrating the stacked member while reducing the thickness of each of the sheet glasses.

Abstract: One-dimensional (1D) photonic crystal prisms can separate a beani of polychromatic electromagnetic waves into constituent wavelength components and can utilize unconventional refraction properties for wavelength dispersion over significant portions of an entire photonic band rather than just near the band edges outside the photonic band gaps. Using a 1D photonic crystal simplifies the design and fabrication process and allows the use of larger feature sizes. The prism geometry broadens the useful wavelength range, enables better optical transmission, and exhibits angular dependence on wavelength with reduced non-linearity. The properties of the 1D plhotonic crystal prism can be tuned by varying design parameters such as incidence angle, exit surface angle, and layer widths. The 1D photonic crystal prism can be fabricated in a planar process, and can be used as optical integrated circuit elements.

Abstract: In the invention, light incident onto an end surface of one-dimensional photonic crystal is phase-modulated in the same period and direction as those of the photonic crystal to thereby propagate only specific high-order band light in the photonic crystal. That is, a phase modulation unit for generating phase-modulated wave having the same period as that of the periodic structure is disposed adjacent or close to a light incident surface of the periodic structure.

Abstract: Disclosed is an optical element comprising in order a light source, air, at least one thin layer having a thickness of 80 to 200 nm, and a thick layer, each layer varying in refractive index (RI) by at least 0.05 from the next adjacent layer, in an alternating manner.

Abstract: An interference filter (10) and a process (100) by which it may be fabricated. A substrate (12, 52, 82) is provided and a working region (56, 84) is defined therein or thereupon. Relative to the horizontal substrate (12, 52, 82), a plurality of vertical layers having differing refractive index are then constructed by applying material into the working region (56, 84) or altering material already in the working region (56, 84). Photo masking and etching processes may be used to selectively remove material in the working region (56, 84) for applying additional material having a differing refractive index. Photo masking and impurity doping processes may be used to selectively change material to have a differing refractive index.

Abstract: The optical device having a predetermined surface profile of the invention is fabricated by forming a multi-layered dielectric film on the surface of a solid composition layer having a glass transition temperature of not lower than 100° C. The solid composition layer is formed by molding and curing a polymerizable organic group-having fluid composition. The curing may be effected through photopolymerization or thermal polymerization of the polymerizable organic group in the composition, and a predetermined surface profile is transferred onto the composition layer from the mold used. The cured composition is released from the mold, and this is coated with a multi-layered dielectric film.

Abstract: Optical bodies, comprising: a plurality of first optical layers comprising a first polymer composition that comprises (i) a polyester portion having terephthalate comonomer units and ethylene glycol comonomer units, and (ii) a second portion corresponding to a polymer having a glass transition temperature of at least about 130° C.; and a plurality of second optical layers disposed in a repeating sequence with the plurality of first optical layers. Also disclosed are optical bodies comprising: (a) a plurality of first optical layers, each first optical layer being oriented; and (b) a plurality of second optical layers, disposed in a repeating sequence with the plurality of first optical layers, comprising a blend of polymethylmethacrylate and polyvinylidene fluoride. Methods of making the above-described optical bodies, and articles employing such optical bodies are also provided.

Abstract: The invention provides a method for fabricating an optical device comprising at least one optical component formed on a transparent substrate. The method comprises determining an area of the substrate that is to be light-absorbing; and fabricating a light-absorbing mask on the determined area prior to fabricating the at least one optical component. The invention also provides an optical device comprising a substrate; and first and second optical components formed on the substrate, wherein the first optical component has two modes, each mode producing a different optical response to light incident thereupon, and wherein the second optical component absorbs light and is formed on the substrate before the first optical component is formed.

Abstract: A reflective measuring scale graduation, as well as a method for manufacturing the same are described. The reflective measuring scale graduation includes first and second subdivisions having different reflection properties, which extend in at least one first direction on a reflecting substrate. The highly reflecting first subdivisions are made of a plurality of partial layers having different indices of refraction and function as an interference filter. The low reflecting second subdivisions are composed of at least one absorber layer on the substrate.

Abstract: An electromagnetic wavelength filter that allows the transmission of electromagnetic energy within a narrow range of wavelengths while reflecting incident electromagnetic energy at other wavelengths. The filter includes at least one cavity region; and at least two reflectors surrounding the at least one cavity region, at least one of the reflectors being an omni-directional reflector. The omni-directional reflector includes a structure with a surface and an index of refraction variation perpendicular to the surface, and the omni-directional reflector is specifically configured to exhibit high omni-directional reflection for a predetermined range of frequencies of incident electromagnetic energy for any angle of incidence and any polarization.

Abstract: According to an exemplary embodiment of the present invention, an optical apparatus includes an optical filter array which comprises a plurality of optical filter elements, wherein at least one of the optical filter elements is adapted for tuning to two or more wavelengths.

Abstract: Multilayer thin film reflectors, such as mirrors and reflective polarizers, are described in which form birefringent optical layers are incorporated into a plurality of optical repeat units in the film. The form birefringent layers exhibit birefringence as a result of microscopic structures that have a dimension that is small compared to the wavelength of light but large compared to molecular distances. The optical layers within the optical repeat units have out-of-plane indices of refraction that are tailored to produce desired effects as a function of incidence angle for p-polarized light. The multilayer reflectors can be made by conventional vacuum deposition techniques using known inorganic optical materials, but can also be made entirely with polymeric materials by co-extrusion or other processes.

Abstract: A distributed Bragg reflector and a method of fabricating the same incorporates a support for supporting the gaps against collapse. The method includes forming a plurality of alternating structure and sacrificial layers on a substrate. The structure and sacrificial layers are etched into at least one mesa protruding from the substrate. A support layer is formed on the at least one mesa leaving a portion of the structure and sacrificial layers exposed. At least a portion of at least one of the exposed sacrificial layers are etched from between the structure layers to form gaps between the structure layers.

Abstract: An interference filter (10, 30, 50, 70, 90, 110, 130, 150, or 190) filters selected wavelengths by dividing an input beam into two or more intermediate beams having different optical path lengths and by recombining the intermediate beams into an output beam that is modified by interference between the intermediate beams. An optical path length difference generator (20, 40, 60, 80, 100, 120, 140, 160, or 200) varies the optical path lengths of the intermediate beams by changing the physical lengths of their paths or the refractive indices of the mediums in which they are conveyed. The optical path length generator (20) of one exemplary embodiment (10) includes a spacer plate (20) that is divided into elements (22 and 24) having different refractive indices for varying the optical path lengths of the intermediate beams.

Abstract: To suppress light loss without deteriorating resolution of a projected image, light is first polarized and separated by a polarizing beam splitter. Green light is separated from a light flux emitted by the polarizing beam splitter by a dichroic mirror having a green light reflection property. A light flux containing blue and red light, which is transmitted by the dichroic mirror, is separated into red light and blue light by a dichroic prism. Resultant color light is modulated and reflected by reflection light valves, returned to the corresponding dichroic mirror or dichroic prism, and combined by the dichroic mirror and the dichroic prism. Resultant combined color light is projected via the polarizing beam splitter and a projection lens. The dichroic prism transmits s-polarized light having wavelengths less than a wavelength substantially within a wavelength band of green light and reflects s-polarized light having larger wavelengths.

Abstract: Optical bodies, comprising: a plurality of first optical layers comprising a first polymer composition that comprises (i) a polyester portion having terephthalate comonomer units and ethylene glycol comonomer units, and (ii) a second portion corresponding to a polymer having a glass transition temperature of at least about 130° C.; and a plurality of second optical layers disposed in a repeating sequence with the plurality of first optical layers. Also disclosed are optical bodies comprising: (a) a plurality of first optical layers, each first optical layer being oriented; and (b) a plurality of second optical layers, disposed in a repeating sequence with the plurality of first optical layers, comprising a blend of polymethylmethacrylate and polyvinylidene fluoride. Methods of making the above-described optical bodies, and articles employing such optical bodies are also provided.

Abstract: A polymeric photonic band gap structure can be defined by a block copolymeric species, a mixture of homopolymers, or a combination optionally with appropriate dielectric contrast enhancing additives. The structure includes periodic, phase-separated microdomains alternating in refractive index, the domains sized to provide a photonic band gap in the UV-visible spectrum.

Abstract: A projection type display device constructed so that light source beams via a polarization beam splitter are separated of colors by a color separating/synthesizing optical system and enter light valves disposed for every color light, the light beams exiting from the respective light valves are synthesized by the color separating/synthesizing optical system, the synthesized light beams exit, the polarization beam splitter analyzes the synthesized light beams and takes out the analyzed light beams, and the analyzed light beams are projected on a screen through a projection lens. A normal line of an outgoing surface of the polarization beam splitter with respect to the light source beams exiting toward the color separating/synthesizing optical system from the polarization beam splitter, has a predetermined angle larger than zero degree with respect to an optical axis of the light source beams.

Abstract: A photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided. A Fabry-Perot delay line device has several regions of periodically alternating refractive material layers which exhibit a series of photonic band gaps and a periodicity defect region, interposed between the regions of periodically alternating refractive material layers. The Fabry-Perot delay line device imparts a predetermined delay to photonic signals that pass therethrough. The introduction of the periodicity defect region into this photonic band gap structure creates a sharp transmission resonance within the corresponding photonic band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size. Variable photonic delays to multiple photonic signals are also generated by this Fabry-Perot delay line device.

Abstract: An improved lithographic process for fabricating articles comprising photonic band gap materials with micron-scale periodicities is provided, the process readily capable of being performed by current lithographic processes and equipment. The process involves providing a three-dimensional structure made up of a plurality of stacked layers, where each layer contains a substantially planar lattice of shapes of a first material, typically silicon, with interstices between the shapes. Each shape contacts at least one shape of an adjacent layer, the interstices throughout the plurality of layers are interconnected, and the interstices comprise a second material, e.g., silicon dioxide. Typically, the second material is etched from the interconnected interstices to provide a structure of the first material and air, this structure designed to provide a particular photonic band gap.

Abstract: The photonic band gap (PBG) dual-spectrum sensor utilizes the frequency-selective properties of a photonic band gap device constructed in accordance with this invention to separate incident electromagnetic wave into two frequency bands. The parameters of the PBG device are chosen so that one frequency band is transmitted through the device with low attenuation while the second band is reflected with low attenuation from the front face of the device. This separation of the two frequency bands allows separate detection processes to be performed to recover the information content of the two signals before the information is fused in subsequent signal processing operation. Such a PBG device would be useful in missile seekers that seek to distinguish a target object from its background.

Abstract: A polymer-based mirror formed from a synthetic thermoplastic or thermoset resin substrate, such as polymethyl methacrylate, which is resistant to warping and distortion from moisture. A composite multi-layer surface-hardening coating is formed on at least the anterior surface of the resin substrate. The mirror further includes a composite multi-layer reflective coating. A protective back-coat layer is deposited on a posterior surface of the mirror. A multi-layer weather-resistant coating may optionally be applied to the anterior surface of the polymer-based mirror in order to increase the weatherability and durability of the mirror. The various layers coating the synthetic resin substrate have their moisture permeabilities selected so that substantially equal amounts of moisture permeate through to both the anterior and posterior side of the synthetic resin substrate.

Abstract: A dielectric interference filter system with at least filter elements of different spectral characteristics on the same carrier substrate is provided. The filter elements have the same height and/or adjoin each other without gaps. The system is used for, inter alia, interference color filter systems in the form of an LCD-display or CCD-arrangement. A process for manufacturing the system includes preparing at least one filter element by coating and subsequent etching, and preparing at least one subsequent filter element by coating and subsequent structuring utilizing lift-off in which the etching mask is used as the lift-off mask.

Abstract: A method for making polymeric reflectors and parabolic reflectors in particular. The reflector is made by forming a series of layers (12, 14, 16, 18, and 20) that are progressively thinner with the final polymeric layer (20) being about one millimeter in thickness. The reflector is then coated with a reflective layer (22) by vapor deposition. To make aparabolic reflector, the layers are spun cast at a constant, preselected rate throughout the process, including during the curing of each layer. Layer formation is made in a controlled, particulate-free environment and additives can be used to increase stiffness, decrease weight, and reduce stresses during curing.

Abstract: A transparent thermoplastic resinous laminate film is disclosed having at least 10 very thin layers of substantially uniform thickness, said layers being generally parallel, the contiguous adjacent layers being of different transparent thermoplastic resinous materials of which one is a naphthalate-based polyester or copolyester resin, the contiguous adjacent layers differing in refractive index by at least about 0.03.

Abstract: A transparent metal structure permits the transmission of light over a tunable range of frequencies, for example, visible light, and shields ultraviolet light and all other electromagnetic waves of lower frequencies, from infrared to microwaves and beyond. The transparent metal structure comprises a stack of alternating layers of a high index material and a low index material, at least one of the materials being a metal. By carefully choosing the thickness of the second material, the transparent window can be tuned over a wide range of frequencies.

Abstract: An electrochromic device is disclosed having a self-cleaning, hydrophilic optical coating. The electrochromic device preferably forms an external rearview mirror for a vehicle. The coating preferably includes alternating layers of a photocatalytic material having a high index of refraction and a hydrophilic material having a low refractive index. More specifically, the coating includes a first layer having a high refractive index, a second layer having a low refractive index, a third layer of titanium dioxide, and a fourth layer of silicon dioxide provided as an outermost layer. The disclosed optical coating exhibits a reflectance at the front surface of the reflective element that is less than about 20 percent, and has sufficient hydrophilic properties such that water droplets on a front surface of the optical coating exhibit a contact angle of less than about 20°.

Abstract: Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system.

Abstract: The present invention relates to multilayered filter films, and in particular, a multilayered filter film not having a substrate and a method for making the same. The method for making the multilayered filter film not having a substrate includes a step for forming a filter frame layer having a window on the substrate, a step for forming a multilayered film on the substrate inside the window and on the filter frame layer, and a step for removing the substrate from the filter frame layer and the multilayered film.

Abstract: Optical devices such as light pipes which incorporate multilayer optical films in which the refractive indices of two adjacent layers in the thickness direction are substantially matched or are small relative to the difference in refractive indices of said two adjacent layers in an given in-plane direction which is at least 0.05.

Abstract: A broad-band multilayer antireflection coating comprising four layers designed for deposition in an inline magnetron sputtering machine. The optical thickness of the third layer from the substrate is less than one quarter of a wavelength in the center of the low-reflection band, and the second and fourth layers are made of silicon dioxide.

Abstract: An elemental mirror having a high luminous reflectance of at least about 60% of incident light at the wavelength region of about 550 nanometers and being acromatic includes a substrate coated with a reflector comprising a multilayer thin film stack. The thin film stack comprises a first thin film layer of an elemental semiconductor which is closest to the first surface of the glass substrate and has a refractive index of greater than 3.0, a second thin film layer which is farthest from the first surface of the glass substrate, and a third thin film layer disposed between the first thin film layer and the second thin film layer, the third thin film layer having a refractive index between about 1.3 and 2.7, the second thin film layer having a refractive index greater than the third thin film layer. A light absorbing coating is included on at least one surface of the substrate and a layer of the reflector, the light absorbing coating absorbing light transmitted by the reflector coated substrate.

Abstract: By applying a photonic signal to a microresonator that includes a photonic bandgap delay apparatus having a photonic band edge transmission resonance at the frequency of the photonic signal, the microresonator imparts a predetermined delay to the photonic signal. The photonic bandgap delay apparatus also preferably has a photonic band edge transmission resonance bandwidth which is at least as wide as the bandwidth of the photonic signal such that a uniform delay is imparted over the entire bandwidth of the photonic signal. The microresonator also includes a microresonator cavity, typically defined by a pair of switchable mirrors, within which the photonic bandgap delay apparatus is disposed. By requiring the photonic signal to oscillate within the microresonator cavity so as to pass through the photonic bandgap delay apparatus several times, the microresonator can controllably impart an adjustable delay to the photonic signal.

Abstract: A novel design for producing bandpass filters with essentially square shapes with little or no ripple in the passband zone. Filters are of the all-dielectric type consist of multiple cavities of bandpasses. Quarter wave thick layers of low index material separate all of the cavities from each other. Multiple half-waves may be added to the outer cavity quarter-wave stacks in particular. This invention provides the addition of half wave to some of the inner cavity stacks to remove ripple that would otherwise be present. Together, these additional half wave layers added to the outer and inner cavities sharpen the transition from low transmission to high transmission without unduly adding ripple to the high transmission zone.

Abstract: Multilayer thin film dichroic filters composed of alternating layers of high (H) and low (L) refractive index have three groups, a lower group next to the substrate having a ratio Ra of high and low index layers Ra1; a second mid group having a ratio Ra of high and low index layers Ra2; and a third upper group having a ratio Ra of high and low index layers Ra3; and the ratios have the relationship Ra1<Ra2<Ra3. Such filters exhibit improved angle sensitivity and wavelength transition values, and are useful for example in color projection displays.

Abstract: A novel design for producing bandpass filters with essentially square shapes with little or no ripple in the passband zone. Filters are of the all-dielectric type that consist of multiple cavities of bandpasses with the first and last cavities consisting of four less layers than the inner cavities. The inner cavities are all identical. All of the cavities are separated from each other by quarter wave thick layers of low index material. Layers of low index material may be added between the filter and the entrance and exit mediums. The thickness of the first few layers and last few layers may be altered to enhance the transmission of the filter by matching the index structure of the passband to the adjacent mediums.

Abstract: In order to provide a multilayer film structure for soft X-ray optical elements in which a high reflectivity can be attained in even a soft X-ray wavelength region of a wavelength of 10 nm or less including the wavelength range of water window zone, in a multilayer film structure for soft X-ray optical elements wherein a first thin film, being a different type of a second thin film, and the second thin film are piled up in layers to form a multi-layer film, at least one of the aforesaid first thin film and the aforesaid second thin film is made to be an oxide thin film.

Abstract: A photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided. A Fabry-Perot delay line device has several regions of periodically alternating refractive material layers which exhibit a series of photonic band gaps and a periodicity defect region, interposed between the regions of periodically alternating refractive material layers. The Fabry-Perot delay line device imparts a predetermined delay to photonic signals that pass therethrough. The introduction of the periodicity defect region into this photonic band gap structure creates a sharp transmission resonance within the corresponding photonic band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size. Variable photonic delays to multiple photonic signals are also generated by this Fabry-Perot delay line device.

Abstract: The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

Abstract: Birefringent multilayer optical films in which the refractive indices in the thickness direction of two adjacent layers are substantially matched have a Brewster angle (the angle at which reflectance of p-polarized light goes to zero) which is very large or is nonexistant. This allows for the construction of multilayer mirrors and polarizers whose reflectivity for p-polarized light decreases slowly with angle of incidence, are independent of angle of incidence, or increase with angle of incidence away from the normal. As a result, multilayer films having high reflectivity (for both planes of polarization for any incident direction in the case of mirrors, and for the selected direction in the case of polarizers) over a wide bandwidth, can be achieved.

Abstract: This invention provides a thermoplastic multilayer resinous film in which two or more resinous materials form a plurality of very thin layers of substantially uniform thickness, the layers being substantially parallel, the contiguous adjacent layers being of different transparent thermoplastic resinous materials differing in refractive index, each of the outermost skin layers being at least 5% of the total thickness of the film and the multilayer film containing a sufficient quantity of a pearlescent pigment in at least one of the interior layers to render it non-glossy.

Abstract: A thin-film color-selective beam splitter and the method of fabricating the same are disclosed. The method includes the steps of: (i) forming a main prism by a pre-selected material, and deciding a first base angle and a second base angle according to the substance and coating characteristics of the pre-selected material; (ii) coating a first multilayer film and a second multilayer film on two slopes of the main prism, in which tilt angles for coating the first multilayer film and the second multilayer film and tilt angles of light entering and emerging the main prism are different, so that spectra of the first multilayer film and the second multilayer film are different, and the first multilayer film can be a red reflective film and the second multilayer film can be a blue reflective film; and (iii) using the pre-selected material to form interface prisms, and adhering the interface prisms to the main prism, so that light can perpendicularly enter and emerge from surfaces of the prism.

Abstract: An optical multiplexing device spatially disburses collimated light from a fiber optic waveguide into individual wavelength bands, or multiplexes such individual wavelength bands to a common fiber optic waveguide or other destination. The optical multiplexing device has application for dense channel wavelength division multiplexing (WDM) systems for fiber optic telecommunications, as well as compact optical instrument design. Multiple wavelength light traveling in a fiber optic waveguide is separated into multiple narrow spectral bands directed to individual fiber optic carriers or detectors. An optical block has an optical port for passing the aforesaid multiple wavelength collimated light, and multiple ports arrayed in spaced relation to each other along a multiport surface of the optical block. A continuous, variable thickness, multi-cavity interference filter extends on the multiport surface of the optical block over the aforesaid multiple ports.

Abstract: A photonic signal is applied to a photonic bandgap structure having a photonic band edge transmission resonance at the frequency of the photonic signal and having a photonic band edge transmission resonance bandwidth which is at least as wide as the bandwidth of the photonic signal. When a photonic band edge transmission resonance is matched to the photonic signal which is being transmitted, a controllable delay is imparted to the photonic signal without significantly altering the photonic signal itself.

Abstract: An optical filter arrangement comprises at least two optical filter elements including a transparent substrate and an optical coating typically comprising at least two overlying optical thin films. The coating defines a first patterned area and a second surround area bordering the first area. The first area has substantially the same optical transmittance characteristics as the second area and different optical reflectance characteristics over at least a portion of the visible spectrum. The distinction between the first area and the second area is visually perceptible when viewed from one side of the optical filter arrangement and is substantially visually imperceptible when viewed from the opposite side of the optical filter arrangement. As a result, a coloured pattern or logo is only visible when viewed from one side of the filter arrangement. The invention extends to a method of forming such an arrangement.

Abstract: A hologram forming layer, transparent evaporated layer, colored layer, adhesion anchor layer, and adhesive layer are sequentially laminated on the under surface of a base member. The laminated body is used as a seal by the presence of the adhesive layer. It is preferable for the base member to have adequate rigidity (flexibility, tensile strength) and surface flatness. The hologram forming layer has a relief type hologram image. The transparent evaporated layer is a multi-layered ceramic layer constructed by alternately laminating high-refractive index layers and low-refractive index layers and the thickness thereof is preferably set to 1 &mgr;m or less. In the transparent evaporated layer, the color of visible light in predetermined wavelength range is changed according to the viewing angle when it is transmitted therethrough or reflected therefrom.