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: The present invention relates to a multi-layer dielectric bandpass filter having a primary and a secondary passband. A secondary passband outside the reflection zone of the primary passband is optimized to reduce ripple achieving a passband of at least 90% transmission. Optimization comprises modifying the thickness of certain quarter wavelength reflector layers of a single passband filter from true quarter wavelength at the primary passband to non-quarter, or non-integer-multiple quarter wave thickness.

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: An optical filter, which has a predetermined transmittance and a low reflectance at a wavelength .lambda. of, for example, 780 nm, comprises a metal film and a dielectric thin-film deposited adjacent to the metal film, the dielectric thin-film having a refractive index lower than that of the metal film and a thickness of .lambda./40 or less. Also disclosed is an optical filter, comprising a substrate, a plurality of sets of dielectric thin-films (H) with a high refractive index and dielectric thin-films (L) with a low refractive index, and a metal layer. The dielectric thin-films (H) and the dielectric thin-films (L) are alternately deposited on the substrate and the metal film is provided between one dielectric thin-film (H) and the adjacent dielectric thin-film(L). The dielectric thin-film (L) adjacent to the metal film has a thickness .lambda./40 or less.

Abstract: The subject of the invention is a transparent substrate (1), in particular a glass substrate, including a coating (6) of one or more thin films on at least one of its faces, comprising at least one A film containing an aluminum fluoride or aluminum oxyfluoride Al.sub.x O.sub.y F.sub.z, with y.gtoreq.0.

Abstract: A filter for underwater color correction is described which could be characterized by optical transmission exhibiting more attenuation of blue/green light than red light and having a ratio of transmission at 600 nanometers and 700 nanometers substantially less than 50%.

Abstract: The UV blocking coating includes at least eight alternating layers of a first dielectric material and a second dielectric material stacked upon the surface of an optical substrate to thereby form windows, windscreens, lenses or the like. The first dielectric material has a higher index of refraction then the second dielectric material. For example, the first dielectric material can be TiO.sub.2, ZrO.sub.2 and Ta.sub.2 O.sub.5 and the second dielectric material can be MgF.sub.2 or SiO.sub.2. In addition, each layer of the second dielectric material has an optical thickness which is greater than the optical thickness of the underlying layer of the first dielectric material upon which the layer of the second dielectric material is stacked. As a result of the unique construction of the UV blocking coating, the reflectance of the UV blocking coating varies dramatically upon exposure to UV light on the one hand and to visible light on the other hand.

Abstract: It has been discovered that control of the intra-layer stress in layers of high refractive index materials, such as zirconia and titania, permits low net stress multilayer thin film stacks comprising alternating layers of the high refractive index material and silica, a low refractive index material, to be sputter-deposited on glass substrates. In particular, a simple, cost-effective and readily reproducible post-deposition annealing process is used, i.e., an annealing process that can be effected within a broad temperature range and for a brief and substantially open-ended time period, to change the post-deposition microstructure of the high refractive index film layers and create a selected intra-layer tensile stress. The intra-layer tensile stress created during such an annealing process is largely dependent on the post-deposition microstructure of the high refractive index thin film layers.

Abstract: A design for producing bandpass filters with passbands that are centered at the same wavelength for each mode of polarization. Filters are of the all-dielectric type that consist of single and multiple cavities of bandpasses. All of the layers are of the Quarter Wave type for ease of manufacture with the possible exception of the last few layers being modified to reduce reflection into a new media. The basic structure of the multi-layer bandpass filter is as follows: (XY).sup.n (YY)(XX).sup.m (YY)(YX).sup.n where n and m are integers and wherein X is one of a high refractive index layer and a low refractive index layer; and, wherein Y is the other of the high and low refractive index layer, X and Y being opposite indexes of refraction.

Abstract: An optical interference coating on a refractory substrate, the coating being comprised of alternating layers of silicon dioxide and zirconium dioxide. The coating can be in the form of an optical filter where a substrate bearing the coating can be repeatedly cycled between room temperature and a temperature of at least 1000 .degree. C without significant degradation of its optical or mechanical properties.

Abstract: An anti-reflection screen filter is provided that includes four consecutively applied layers to a substrate. A first layer, furthest from the substrate, is arranged on an underlying second layer and comprises an oxide material having a refractive index within the approximating range of 1.46 to 1.50 at a wavelength of 520 nm. The second layer is arranged on an underlying third layer and is formed by a metal having a refractive index within the approximating range of 1.5 to 4.0 at a wavelength of 520 nm. The third layer is arranged on an underlying fourth layer and is formed by a metal having a refractive index within the approximating range of 0.2 to 1.4 at a wavelength of 520 nm. The fourth layer is disposed on the front surface of a substrate and is formed by a metal having a refractive index within the approximating range of 1.5 to 4.0 at a wavelength of 520 nm.

Abstract: An optical filter is provided for use in color projection display imaging systems which utilize liquid crystal light valves for image modulation. The optical filter is a dichroic coating which separates light into different colors. The optical filter is located on a light transmissive surface of a color splitting device such as a Philips prism. The optical filter is formed from layers of at least two different dielectric materials including a high refractive index material, such as zirconium oxide and a low refractive index material such as aluminum oxide. The low refractive index material has an average refractive index of no less than about 1.6. The high refractive index material has an average refractive index which is sufficiently greater than the average refractive index of the low refractive index such that the average refractive index of the high refractive index material divided by the average refractive index of the low refractive index material yields a ratio that is greater than about 1.

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: Several techniques may be used for forming a colored interference filter coating on a substrate such as polyester film. The interference filter has two metal reflective films, at least one of which is semi-transparent. A layer of transparent acrylate polymer dielectric between the metal layers completes the interference filter, which may be sandwiched between protective layers. The dielectric is formed by evaporating an acrylate monomer having a molecular weight in the range of from 150 to 600. Preferably the acrylate monomer has a molecular weight to acrylate group ratio in the range of from 150 to 400. The acrylate condenses on the substrate and is polymerized in situ for forming a monolithic film with a sufficient thickness to produce an interference color. In several embodiments different areas of the film have different thicknesses for producing different interference colors.

Abstract: A process suitable for forming multi-layer (up to at least several hundred layers) monotonic/linear variable/wedge filter coatings on a single substrate surface and for forming monolithic filter assemblies which incorporate such filters, is disclosed along with the designs for such filters. The monolithic process uses radially variable filter fabrication techniques in combination with ion-assisted deposition to form stress controlled, radially variable filter coatings of the desired varied optical profile, preferably using high and low index materials stich as tantala and silica. Stress is minimized by balancing the amount of ion assist and the coating rate. Slices are cut radially from the substrate to form quasi-linear variable filters. Other coatings such as, but not limited to, a wide band hot mirror can be formed on the opposite surface of the substrate from the radially variable LVF method.

Abstract: The present invention relates to an optical filter including a flexible, transparent substrate coated with a novel combination of optical coatings, and a frame system designed for mounting the optical filter to a television or other visual display screen. A neutral density contrast enhancement is included within the composition of a flexible substrate, or is coated on either the front, the rear, or both of the surfaces of the substrate. A silicone anti-glare hardcoat is applied to both the front and rear surfaces of the substrate. An anti-reflection coating is added to the front surface of the substrate, preferably via sputtering, and designed to reflect a specific color at a preferred brightness measurement. The combination of a front surface anti-reflection coating, front and rear surface anti-glare coatings, and a neutral density contrast enhancement, eliminates the need for an anti-reflection coating on the rear surface of the substrate.

Abstract: A coated substrate comprises a transparent substrate, a lower coating on the transparent substrate, a functional layer on the lower coating, and an upper coating on the functional layer. The lower coating has a first layer comprising silicon or a metal, and nitrogen or oxygen, and a second layer comprising zinc oxide and having a thickness of at least 16 nm. The second layer is in contact with the functional layer.

Abstract: An anti-reflective film construction contains an optically transparent polymeric film having a textured surface and an optically transparent adhesive, the film construction configured to exhibit light transmission of greater than about 70 percent and 60.degree. gloss measurement of between about 15 and 100. Methods of producing such film constructions and methods of reducing reflection from a surface are also described.

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: A reflection-preventing layer for a display device includes a transparent insulating substrate, at least one dielectric film formed on the transparent insulating substrate, and an amorphous carbon thin-film layer having a diamond-like carbon film on the uppermost dielectric layer of the dielectric films, so that the reflectance of the reflection-preventing layer is semi-permanently decreased while increasing the surface solidity thereof.

Abstract: A laminate which comprises a transparent substrate, a first oxide layer comprising ZnO which contains at least one metal, a first metallic layer comprising Pd-containing Ag and a second oxide layer comprising SnO.sub.2 or ZnO which contains at least one metal, wherein said layers are formed on the substrate in this order.

Abstract: A narrow-band antireflective coating is comprised of a multilayer dielectric film formed on a dielectric substrate. The antireflective coating is initially formed so that its outer layer has a thickness greater than the thickness required for antireflection. The reflectivity is monitored while outer layer is reduced in thickness to reduce the thickness of the outer layer to reduce the reflectivity.

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 antireflection film is procided on a plastic optical element as follows. An undercoat composed principally of unsaturated silicon exide SiO.sub.x (2>x>1) with a thickness within a range of 200 to 300 nm is formed on the optical element. A multi-layered film of a repeating structure is formed on the undercoat. The multi-layerd film has antireflective characteristics. The undercoat has a refractive index within a range of 1.49 to 1.59. The multi-layered film is composed of alternate lamination of a layer of a material which has a high refractive index and which is composed principally of TiO.sub.2, ZrO.sub.2 or a mixture thereof, and a layer of a material which has a low refractive index and which is composed principally of SiO.sub.x (2.gtoreq.x.gtoreq.1).

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 all have the same number of layers. 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. Multiple half-waves are added to the outer cavity quarter-wave stacks in particular and also may be added to some of the inner cavity stacks, These sharpen the transition from low transmission to high transmission without unduly adding ripple to the high transmission zone. 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: Four kinds of dielectrics in the form of a mixture of ZrO.sub.2 and TiO.sub.2 having a refractive index of 2.07, MgF.sub.2 having a refractive index of 1.37, Al.sub.2 O.sub.3 having a refractive index of 1.61, and TiO.sub.2 having a refractive index of 2.27 are laminated on a transparent glass substrate in twenty layers. Two kinds of unpolarized light beam splitters having ratios of the reflected light to the transmitted light of 7:3 and 8:2, respectively, are thereby obtained. Both kinds of unpolarized light beam splitters have the twentieth layer, that is the outermost layer, formed with MgF.sub.2. The difference between the reflectance of the polarizing P component and the reflectance of the polarizing S component of the reflected light is set to be below 10%.

Abstract: A hard and durable single-layer or multilayer artireflection coating for use with a high refractive-index IR transparent substrate is provided. The coating is prepared by concurrent deposition of TiO.sub.2 and MgF.sub.2 with the reactive ion-assistance on the IR transparent substrate within a single vacuum chamber. The refractive-index of this film is adjustable by varying the relative deposition rate of the two materials (i.e. controlling the ratio of the materials) to optimize the transmittance of the incident IR irradiation. The opitical thickness of each film of the single-layer and multilayer antireflection coatings is one-quarter wavelength of the IR irradiation.

Abstract: A multilayered reflective body which is thermoformable and capable of being fabricated into a number of parts while maintaining a uniform reflective appearance is provided. The reflective polymeric body is formed from at least two diverse polymeric materials which differ in refractive index and which are arranged in substantially parallel alternating layers. The polymeric body is reflective in appearance yet is transparent or, colored if a coloring agent is included, upon illumination from a back light source. The polymeric body has application in variety of areas such as in an automobile lighting lens which is reflective and thereby indiscernible yet transmissive upon exposure to a back light source. Additionally, various parts of consumer appliances, for example a refrigerator door, can be formed from the polymeric body.

Abstract: This specification discloses antireflection film and an exposure apparatus using the same. The exposure apparatus has an optical system, and antireflection film formed on the refracting surface of the optical system, the antireflection film having a high refractive index layer having Al.sub.2 O.sub.3 or Ta.sub.2 O.sub.5 and a low refractive index layer having SiO.sub.2.

Abstract: A beam splitter formed by laminating a plurality of optical films on a glass substrate having a refractive index of 1.51.+-.0.10. The optical films are first, second, third, fourth, and fifth layers laminated in this order from the glass substrate. The first layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.05-0.15; the second layer has a refractive index of 1.68.+-.0.10 and an optical film thickness of 0.01-0.10; the third layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.50-0.60; the fourth layer has a refractive index of 2.23.+-.0.10 and an optical film thickness of 0.25-0.35; and the fifth layer has a refractive index of 1.44.+-.0.10 and an optical film thickness of 0.25-0.35. The optical film thickness means a relative value represented by n.times.d/.lambda. where n denotes a refractive index; d denotes an actual film thickness, and .lambda. denotes a wavelength deciding the center of a wavelength band.

Abstract: An optical filter for providing an enhanced image. The filter may comprise at least one substrate, layers of a low refractive index material and layers of a high refractive index material. The layers are stacked so that the filter blocks passbands at 490 nm and 590 nm as well as other image-confusing radiation. Light which is transmitted by the filter provides an enhanced image for viewing by the human eye as well as nonhuman detectors.

Abstract: An interference filter having 17 coatings of alternating high and low index materials is located on the illumination path of an optical device and provides correction for green color distortion on the observation path and correction for blue color distortion on the photo path in order that both the observed image and photographed image are color neutral.

Abstract: A mirror coating which provides improved performance characteristic to a mirror assembly, and which includes a non-periodic succession of materials which exhibit neutral reflected chromaticity, and which has a luminous reflectance of greater than 50%.

Abstract: A mirror coating which provides improved performance characteristics to a mirror assembly and which includes a non-periodic succession of materials which exhibit neutral reflected chromaticity and a luminous reflectance of greater than 50%.

Abstract: The present invention provides an optical mirror and an optical device in which the mirror is capable of reflecting a light beam having a plurality of wavelengths with the phase matching condition required for nonlinear optical materials being satisfied, so that a decrease in efficiency due to the phase difference does not generate even if harmonic generation, optical mixing or the like is performed, thereby improving conversion efficiency. The optical mirror includes a plurality of reflection films, e.g., multilayer films 2 and 3, formed on one surface of a transparent substrate, each of which films corresponds to each wavelength of a light beam having a plurality of wavelengths to reflect selectively one of said plurality of wavelengths, wherein a phase difference adjusting layer 4 is formed between the two reflection films 2 and 3, reflecting light beams having different wavelengths.

Abstract: A hologram includes an optically transparent base plate having first and second opposite surfaces. A hologram element is provided on the first surface of the base plate, and has a predetermined holographic pattern. An optically transparent member has first and second opposite surfaces. The first surface of the member faces the hologram element. An arrangement serves to prevent light, which successively passes through the transparent base plate, the hologram element, and the member and is then reflected at a boundary between the second surface of the member and an atmosphere, from travelling back to the hologram element.

Abstract: A high-reflectivity surface reflecting mirror is provided by sequentially forming, on a resin substrate, a silicon dioxide first under layer, a chromium sulfide second under layer, a silver reflecting layer and protective layers. According to a second aspect of the invention, a surface reflecting mirror is provided by sequentially forming, on a resin substrate, a silicon dioxide under layer, an aluminum reflecting layer, a silicon dioxide first protective layer, a second protective layer made of at least one of titanium oxide, tantalum oxide and zirconium oxide, and an aluminum oxide third protective layer.

Abstract: A multilayer antireflection coating for a temperature sensitive substrate such as plastic. One layer is a DC reactively sputtered metal oxide which may be deposited quickly and without imparting a large amount of heat to the substrate. Another layer has a refractive index lower than the substrate.

Abstract: A beam splitter having an optical multilayer thin film is disclosed. The optical multilayer thin film is formed by laminating six layers in sequence. The laminated six layers comprise: a first layer, a third layer and a fifth layer each having a refractive index from 1.63 to 1.64; a second layer and a sixth layer each having a refractive index from 1.37 to 1.38, a fourth layer having a refractive index from 1.9 to 2.3; in which light is allowed to be incident upon the first layer of the optical multilayer thin film at the angle of incidence equal to or greater than 40.degree.. The reflectances of S and P polarized components of reflected light are substantially equal to each other over a wide wavelength range and substantially no phase difference exists between the S and P polarized components.

Abstract: A transflective optical filter comprises a single transparent or transluscent substrate; a colored slice made up of a plurality of layers, each corresponding to one color out of at least two colors; a light diffusing layer; and an opaque mask on which the marks to be displayed in color are represented by transparent zones, the colored slice and the mask consisting of photographic emulsions. A method for making that filter involves multiple exposures of a same film having a multi-colored "slice" and a monochrome photosensitive layer.

Abstract: A formable multilayer reflective polymeric body which has a substantially uniform broad bandwidth reflectance over substantially the entire range of the visible spectrum to provide a substantially uniform reflective appearance is provided. The body includes at least first and second diverse polymeric materials, the body comprising a sufficient number of alternating layers of the first and second polymeric materials such that at least 40% of visible light incident on the body is reflected. A substantial majority of the individual layers of the body have optical thicknesses in the range where the sum of the optical thicknesses in a repeating unit of the polymeric materials is greater than about 190 nm, and the first and second polymeric materials differ from each other in refractive index by at least about 0.03.

Abstract: A new optical diode is disclosed that permits unidirectional transmission of light, the direction of transmission depending on the direction of incidence. The diode comprises a stack of alternating layers of a low-index material and a high-index material. The layers are arranged within the stack such that there is spatial anisotropy of optical pathlengths in the stack and at least the low-index layers or the high-index layers have an optical nonlinearity, either inherently or by doping. At sufficiently high incident intensifies and appropriate wavelengths, such a diode exhibits partial transmission of input light incident from one direction while reflecting almost totally input light incident from the opposite direction.

Abstract: A two-wavelength antireflection film is constituted by a multi-layered film provided on a substrate so as to have antireflection characteristics for a wavelength .lambda..sub.1 and a wavelength .lambda..sub.2 different from the wavelength .lambda..sub.1. Each of the materials constituting the multi-layered film has a refractive index not exceeding 1.7 for a central wavelength .lambda..sub.0 which is defined by2/.lambda..sub.0 =1/.lambda..sub.1 +1/.lambda..sub.2.The materials constituting the multi-layered film are Al.sub.2 O.sub.3, SiO.sub.2 and MgF.sub.2, or Al.sub.2 O.sub.3 and MgF.sub.2. Each of plural films constituting the multi-layered film has an optical thickness equal to 1/4 of the central wavelength .lambda..sub.0.

Abstract: A sputter-coated glass layer system particularly useful in insulating glass units ("IGs"), which includes dual layers of silver separated by a layer of Si.sub.3 N.sub.4 having a thickness of about 700 .ANG.-1,100 .ANG. and further including an undercoat and an overcoat of Si.sub.3 N.sub.4 having thicknesses of about 300 .ANG.-550 .ANG. and about 350 .ANG.-700 .ANG. respectively, such that a glass so coated achieves normal emissivity values (E.sub.n 's) of less than about 0.02-0.09 with good durability and very low reflectance.

Abstract: An all-polymeric cold mirror which reflects visible wavelengths while transmitting a substantial portion of infrared wavelengths is provided. The mirror includes a sufficient number of alternating layers of at least first and second diverse polymeric materials such that at least 50% of peak reflecting visible light of a wavelength of between about 380-680 nm incident on the mirror is reflected and at least 50% of infrared light between about 680-2000 nm is transmitted or absorbed. The mirror may be designed so that it either reflects or absorbs ultraviolet light.

Abstract: An anti-reflection coating includes a first layer of a transparent material having a low refractive index a second layer of an absorbing metal, a third layer of a material which may have a high or a low refractive index and a fourth layer of titanium nitride.

Abstract: A mirror coating which possesses properties which are advantageous for the construction of a mirror assembly. The mirror coating has a complex reflective index which is wavelength dependent, and wherein the real component is dominant and the imaginary component is negligible within a predetermined spectral band pass region, and the imaginary component is substantially within a spectral region other than the predetermined spectral band pass region, and wherein the mirror coating exhibits substantially neutral reflected chromaticity as observed with reflected ambient light.

Abstract: The present invention comprises a contrast-improving filter which uses a tri-layer comprising a metal layer, preferably silver, sandwiched between two metal precoat layers. The silver layer is thin so that it is substantially transparent to visible light. Additionally, the contrast-improving filter uses a silicon nitride layer between the tri-layer and further oxide layer to improve the durability and scratch-resistance of the contrast-improving filter.

Abstract: A mirror for reflecting a selected frequency of light includes a plurality of alternating quarter wavelength thick layers of two dielectric materials that are resistive to physical and chemical changes upon exposure to ultraviolet radiation coated upon a substrate. The materials have different refractive indices. The materials preferably are comprised of a mixture of alumina and tantala as the high refractive index layer and alumina as the low refractive index layer.

Abstract: A color filter comprising a transparent substrate and two or more multilayer films of amorphous silicon materials deposited on said substrate, each film being different, each layer of said two or more multi-layer films having a thickness less than the wavelength of the visible light and at least three layers of said two or more multi-layer films of amorphous silicon materials in an alternate arrangement wherein the amorphous silicon materials are selected from a-SiOx and a-SiNx is described. A method of preparing the color filter comprising depositing on the substrate by PECVD method two or more multilayer films is also described. The color filters prepared by PECVD method have a more compact texture and a better environmental resistant. The PECVD method for the preparation of the filters is more efficient than conventional methods.