WO2003019244A1 - Optically coated article and method for its preparation - Google Patents

Optically coated article and method for its preparation Download PDF

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Publication number
WO2003019244A1
WO2003019244A1 PCT/US2002/025378 US0225378W WO03019244A1 WO 2003019244 A1 WO2003019244 A1 WO 2003019244A1 US 0225378 W US0225378 W US 0225378W WO 03019244 A1 WO03019244 A1 WO 03019244A1
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Prior art keywords
coated article
optically coated
layers
substrate
amoφhous
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PCT/US2002/025378
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French (fr)
Inventor
George Theodore Dalakos
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General Electric Co
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General Electric Co
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Publication date
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Priority to JP2003524053A priority Critical patent/JP2005501286A/en
Priority to EP20020768483 priority patent/EP1421414A1/en
Publication of WO2003019244A1 publication Critical patent/WO2003019244A1/en
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/24—Deposition of silicon only
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/40—Oxides
    • C23C16/401—Oxides containing silicon
    • C23C16/402—Silicon dioxide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G02B1/113—Anti-reflection coatings using inorganic layer materials only
    • G02B1/115—Multilayers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31507—Of polycarbonate
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31511—Of epoxy ether
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31652—Of asbestos
    • Y10T428/31667—Next to addition polymer from unsaturated monomers, or aldehyde or ketone condensation product

Definitions

  • This invention relates to articles having optical coatings and a method for their preparation. More particularly, it relates to the provision of optically coated articles having a thermally stable optical response.
  • Optically coated articles are useful as interference filters in such applications as thermal-optical switching. They generally comprise a substrate having a number of coatings, the substrate and coatings being transparent to light in various regions ofthe spectrum, typically the visible and/or short wavelength infrared regions, wherein the coatings having alternating high and low refractive indices.
  • the term "short wavelength infrared” refers to the region in the range of about 700-2,500 nm.
  • An essential feature of the coating system is a substantial difference between the refractive indices of adjacent coatings, typically represented by a ratio of refractive indices (hereinafter "R") of at least about 1.5. Higher ratios are often desirable.
  • Typical optically coated articles known in the art comprise a glass substrate and alternate coatings of silicon oxide (Si0 2 ) and either tantalum oxide (Ta 2 O 5 ) or titanium dioxide (TiO 2 ).
  • the coating systems of such articles have R values of 1.5 and 1.6, respectively.
  • a-Si:H silicon dioxide and amo ⁇ hous hydrogenated silicon
  • the coatings may conveniently be deposited by plasma enhanced chemical vapor deposition (hereinafter referred to as "PECVD"). It has been found that a SiO 2 /a-SiH coating system consisting of 46 coating layers and having a total thickness of about 7.5 microns exhibits optical behavior equivalent to a Si0 2 -Ta 0s coating system consisting of 64 layers and having a thickness of 13 microns.
  • thermo-optic coefficient describes the change of the material refractive index as a function of temperature
  • thermo-mechanical coefficient also known as the coefficient of thermal expansion (hereinafter referred to as "CTE"
  • thermo-optic coefficient ofthe a-Si:H layer Upon heating, therefore, a shift of the interference structure, usually by the center wavelength between the full width at half-maximum (FWHM) of reflected light, is observed. The shift is typically on the order of 7 run over a 75°C variation in temperature.
  • the substrate CTE in some cases can be used to compensate the optical shift ofthe coatings, as just described.
  • Glass has a CTE on the order of 7.8 ppm/°C. Temperature-related effects on optical behavior (as exemplified by the aforementioned wavelength shift) will be minimized if a substrate is chosen such that its CTE is as close as possible to 66 ppm/°C, whereupon the substrate CTE will essentially cancel out the effects of the coatings. This would be highly desirable.
  • the present invention provides optical articles in which temperature-induced variations in optical performance are essentially negligible.
  • a method of producing such articles is also provided.
  • the basis for the invention is the discovery of the effect of coating a resinous substrate having a CTE on the order of 70 ppm/°C.
  • the invention is an optically coated article comprising a polymeric substrate and a plurality of coating layers, the plurality of layers comprising alternate layers of silicon dioxide and amo ⁇ hous hydrogenated silicon, said article being transparent to light in the short wavelength infrared region of the spectrum.
  • Another aspect of the invention is a method for producing an optically coated article which comprises depositing alternate coating layers of silicon dioxide and amo ⁇ hous hydrogenated silicon on a thermoplastic resin substrate, the substrate being chosen so that said article is transparent to light in the short wavelength infrared region of the spectrum.
  • FIGURE 1 is a comparison of the optical response of prior-art Si0 2 /a-Si:H and SiO 2 /Ta 2 ⁇ 5 multilayer coating systems;
  • FIGURE 2 is a plot of the refractive index profile of the prior-art Si0 2 /Si multilayer coating system of Figure 1 as a function of thickness;
  • FIGURE 3 is a plot of the refractive index profile of the prior-art Si0 2 /Ta 2 0 5 multilayer coating system as a function of thickness;
  • FIGURE 4 is a schematic of a quarter-wave optical thickness stack of the present invention.
  • FIGURE 5 is the refractive index profile of the 24 layer design stack of the present invention deposited on polycarbonate plotted as a function of optical thickness;
  • FIGURE 6 is the measured percent transmission plotted as a function of wavelength for the 24 layer stack ofthe present invention deposited on glass; and
  • FIGURE 7 is the measured percent transmission plotted as a function of wavelength for the 24 layer stack schematically shown in FIGURE 4 deposited on a polycarbonate substrate.
  • a prior-art SiO 2 /a-Si:H coating system has the layered configuration shown below:
  • the prior-art SiO 2 /a-Si:H layered configuration consists of 46 alternate layers of a- SiH (designated as "H") and Si0 2 (designated as "L”) and has a total thickness of about 7.5 microns. Each layer unit thickness corresponds to a quarter-wave optical thickness.
  • a prior-art SiO 2 /Ta 2 ⁇ 5 coating system has the layered configuration shown below:
  • the prior-art SiO 2 /Ta 2 Os layered configuration consists of 64 alternating layers of Si0 2 (designated “L”) and Ta 2 O 5 (designated "H") and has a total thickness of about 13 microns. Each layer unit thickness corresponds to a quarter-wave optical thickness.
  • the refractive index profiles of the Si0 2 /a-Si:H and SiO 2 /Ta 2 Q 5 designs are shown in Figure 2 and Figure 3, respectively.
  • thermoplastic resin substrate Any thermoplastic resin substrate may be employed according to the present invention, provided its use can produce an article which is transparent to light in the short wavelength infrared region ofthe spectrum.
  • polymethyl methacrylate and aromatic polycarbonates especially bisphenol A polycarbonate; that is, the polycarbonate derived from 2,2-bis(4-hydroxyphenyl)propane.
  • Bisphenol A homopolycarbonate is especially preferred.
  • the thickness of the substrate is not critical for the purposes of the invention. Illustrative thicknesses are in the range of about 1-50 mm. Excessive substrate thickness, however, can result in high abso ⁇ tion in certain areas within the near infrared region. This abso ⁇ tion may or may not be problematic, depending on the application.
  • a plurality of coating layers comprising alternate layers of SiO 2 and a-Si:H is deposited on the substrate.
  • the identity ofthe layer actually contacting the substrate is not critical, with either Si0 2 or a-Si:H being suitable for this pu ⁇ ose. It is, however, frequently convenient for the first layer to be of a-Si:H.
  • the coating configuration of the present invention may include up to about 500 layers. In one embodiment, between about 10 and about 100 layers may be deposited. In another embodiment, the plurality of coating layers comprises at least one layer and up to about 10 layers.
  • layer thickness is not critical, it is frequently advantageous for the thickness of a single layer to correspond to a quarter-wavelength of light at a single wavelength probe value within the range of light to be transmitted.
  • the thickness of each layer is related to other parameters as follows:
  • L layer thickness
  • ⁇ is the wavelength of the probe
  • n is the refractive index of the layer.
  • a layer thickness in the range of between about 100 and about 300 nm is employed, but this value is based to some extent upon the range of other parameters of interest.
  • Figure 4 shows a stack of these quarter- wave basic unit building blocks on a massive medium substrate material. The layer thickness may be altered from the quarter-wave optical thickness as dictated by the optical coating design.
  • the deposited layers may be arranged either periodically or non-periodically.
  • Non- periodic layers may be useful, for example, in computer-optimized designs or as added layers to a basic design included for anti-reflective pu ⁇ oses.
  • the optical coating may comprise symmetric profiles or variations thereof. Such coatings may be useful, for example, in bandpass, narrow bandpass, long or shortpass filters.
  • the optical coating prefferably comprises a non- homogeneous layered structure.
  • One such non-homogenous design is a sinusoidal periodic refractive index profile commonly referred to as a "rugate" design.
  • the a-Si:H coatings are doped with various elements known in the art, such as, but not limited to, nitrogen, germanium, phosphorous, boron and carbon.
  • the articles of this invention are typically prepared by deposition of the desired coatings on the substrate. Any convenient method of deposition may be employed, with PECVD often preferred by reason of its particular suitability for this pu ⁇ ose. PECVD procedures and apparatus for their performance are well known in the art.
  • Si0 2 and a-Si:H layers may, respectively, be produced by plasma dissociation of suitable precursors, typically silane (S1H ) for a-Si:H and a mixture of silane and nitrous oxide (N 2 O) for SiO , the molar ratio of nitrous oxide to silane in the latter mixture typically being in the range of about 20-100:1.
  • Suitable plasmas include those of noble gases, nitrogen, ammonia and hydrogen, as well as combinations thereof, with argon often being preferred.
  • Deposition time for a layer of the desired thickness can be determined by simple experimental comparison with standards involving various time periods.
  • the invention is illustrated by an example in which a transparent bisphenol A homopolycarbonate substrate was coated with a layer of silicon and then with alternating layers of SiO 2 and silicon to a total of 24 layers, the layer thicknesses being 133 nm for silicon and 263 nm for SiO .
  • the particular design is referred to as a narrow bandpass design.
  • the requirements for such a design include high transmission at the wavelength of interest while reflecting both higher and lower wavelength in that near vicinity.
  • the multilayer configuration 400 for the design is shown in Figure 4.
  • the Si0 2 /a-Si:H layers had the following configuration:
  • H (designated 440 in Figure 4) signifies a layer of a-Si:H and L (designated 460 in Figure 4) signifies a layer of Si0 2 .
  • Each of the unit thickness layers has a quarter-wave optical thickness unit as described above.
  • the refractive index profile ofthe design is shown in Figure 5.
  • the scale is in units of optical thickness; therefore each unit layer thickness is designated by quarter-wave (0.25 ⁇ ) increments.
  • the double unit Si0 2 thickness, designated "LL" allows the transmission at the wavelength of interest while allowing high reflection at the wavelengths outside the center-band wavelength.
  • the silicon layers were deposited by PECVD of silane (provided at a flow rate of 200 SCCM) using argon (provided at a flow rate of 1,000 SCCM) at a pressure of 200 millitorr as the plasma gas and a RF power level of 200 watts.
  • the Si0 2 layers were deposited by PECVD of silane (provided at a flow rate of 200 SCCM).
  • the silane was diluted by argon to 2 mole percent. Nitrous oxide, provided at a flow rate of 200 SCCM, was used as the plasma gas.
  • the SiO 2 layers were deposited using the same pressure and power level. Silicon is deposited according to the reaction:

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Abstract

An optically coated article (400) comprising a polymeric substrate (420), such as aromatic polycarbonate, and a plurality of optical coating layers comprising alternate layers of silicon dioxide (460) and amorphous hydrogenated silicon (440) or variations thereof, produced by plasma enhanced chemical vapor deposition. The article (400) is characterized by essentially constant optical characteristics over a wide temperature range.

Description

OPTICALLY COATED ARTICLE AND METHOD FOR ITS PREPARATION
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT
The United States Government may have certain rights in this invention pursuant to Contract No. DE-AC38-83CH-10093, awarded by the United States Department of Energy.
BACKGROUND OF INVENTION
This invention relates to articles having optical coatings and a method for their preparation. More particularly, it relates to the provision of optically coated articles having a thermally stable optical response.
Optically coated articles are useful as interference filters in such applications as thermal-optical switching. They generally comprise a substrate having a number of coatings, the substrate and coatings being transparent to light in various regions ofthe spectrum, typically the visible and/or short wavelength infrared regions, wherein the coatings having alternating high and low refractive indices. The term "short wavelength infrared" refers to the region in the range of about 700-2,500 nm. An essential feature of the coating system is a substantial difference between the refractive indices of adjacent coatings, typically represented by a ratio of refractive indices (hereinafter "R") of at least about 1.5. Higher ratios are often desirable.
Typical optically coated articles known in the art comprise a glass substrate and alternate coatings of silicon oxide (Si02) and either tantalum oxide (Ta2O5) or titanium dioxide (TiO2). The coating systems of such articles have R values of 1.5 and 1.6, respectively.
It would be desirable to produce optical articles in which the coating systems have a higher R value, for example above 2.0. Such values can be obtained by employing alternate coatings of silicon dioxide and amoφhous hydrogenated silicon (hereinafter referred to as "a-Si:H") on a fused silica (i.e., glass) substrate. The coatings may conveniently be deposited by plasma enhanced chemical vapor deposition (hereinafter referred to as "PECVD"). It has been found that a SiO2/a-SiH coating system consisting of 46 coating layers and having a total thickness of about 7.5 microns exhibits optical behavior equivalent to a Si02-Ta 0s coating system consisting of 64 layers and having a thickness of 13 microns.
The optical response of an optical article depends on the refractive index and thickness of the coating deposited thereon. Both of these properties are a function of temperature. The thermo-optic coefficient describes the change of the material refractive index as a function of temperature; the thermo-mechanical coefficient, also known as the coefficient of thermal expansion (hereinafter referred to as "CTE"), describes physical dimension changes with temperature
In the case of glass coated with alternating layers of SiO2 and a-Si:H, there is a profound change in optical behavior with temperature based on the CTE of the substrate and the CTE and thermo-optic coefficient of the coatings. A principal factor in this change is the relatively high thermo-optic coefficient ofthe a-Si:H layer. Upon heating, therefore, a shift of the interference structure, usually by the center wavelength between the full width at half-maximum (FWHM) of reflected light, is observed. The shift is typically on the order of 7 run over a 75°C variation in temperature. The substrate CTE in some cases can be used to compensate the optical shift ofthe coatings, as just described.
Glass has a CTE on the order of 7.8 ppm/°C. Temperature-related effects on optical behavior (as exemplified by the aforementioned wavelength shift) will be minimized if a substrate is chosen such that its CTE is as close as possible to 66 ppm/°C, whereupon the substrate CTE will essentially cancel out the effects of the coatings. This would be highly desirable.
It is therefore of interest to provide an optical article in which temperature-induced changes in optical performance are minfmized.
SUMMARY OF INVENTION The present invention provides optical articles in which temperature-induced variations in optical performance are essentially negligible. A method of producing such articles is also provided. The basis for the invention is the discovery of the effect of coating a resinous substrate having a CTE on the order of 70 ppm/°C.
In one of its aspects, the invention is an optically coated article comprising a polymeric substrate and a plurality of coating layers, the plurality of layers comprising alternate layers of silicon dioxide and amoφhous hydrogenated silicon, said article being transparent to light in the short wavelength infrared region of the spectrum.
Another aspect of the invention is a method for producing an optically coated article which comprises depositing alternate coating layers of silicon dioxide and amoφhous hydrogenated silicon on a thermoplastic resin substrate, the substrate being chosen so that said article is transparent to light in the short wavelength infrared region of the spectrum.
BRIEF DESCRIPTION OF FIGURES
FIGURE 1 is a comparison of the optical response of prior-art Si02/a-Si:H and SiO2/Ta2θ5 multilayer coating systems;
FIGURE 2 is a plot of the refractive index profile of the prior-art Si02/Si multilayer coating system of Figure 1 as a function of thickness;
FIGURE 3 is a plot of the refractive index profile of the prior-art Si02/Ta205 multilayer coating system as a function of thickness;
FIGURE 4 is a schematic of a quarter-wave optical thickness stack of the present invention;
FIGURE 5 is the refractive index profile of the 24 layer design stack of the present invention deposited on polycarbonate plotted as a function of optical thickness;
FIGURE 6 is the measured percent transmission plotted as a function of wavelength for the 24 layer stack ofthe present invention deposited on glass; and FIGURE 7 is the measured percent transmission plotted as a function of wavelength for the 24 layer stack schematically shown in FIGURE 4 deposited on a polycarbonate substrate.
DESCRIPTION OF INVENTION
In the following description, like reference characters designate like or corresponding parts throughout the several views shown in the figures. It is also understood that terms such as "top," "bottom," "outward," "inward," and the like are words of convenience and are not to be construed as limiting terms.
Referring to the drawings in general and to Figure 1 in particular, it will be understood that the illustrations are for the puφose of describing a preferred embodiment ofthe invention and are not intended to limit the invention thereto.
A prior-art SiO2/a-Si:H coating system has the layered configuration shown below:
Air I 0.5H LHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHL 0.5H I substrate
The prior-art SiO2/a-Si:H layered configuration consists of 46 alternate layers of a- SiH (designated as "H") and Si02 (designated as "L") and has a total thickness of about 7.5 microns. Each layer unit thickness corresponds to a quarter-wave optical thickness.
A prior-art SiO2/Ta2θ5 coating system has the layered configuration shown below:
Air|0.5H
LHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHLHL HLHLHLHLHLHL 0.5H| Substrate
The prior-art SiO2/Ta2Os layered configuration consists of 64 alternating layers of Si02 (designated "L") and Ta2O5 (designated "H") and has a total thickness of about 13 microns. Each layer unit thickness corresponds to a quarter-wave optical thickness.
The layered SiO2/a-Si:H and Si02/Ta20 configurations exliibit almost identical optical performance in terms of reflectance, as shown in Figure 1. The refractive index profiles of the Si02/a-Si:H and SiO2/Ta2Q5 designs are shown in Figure 2 and Figure 3, respectively.
Any thermoplastic resin substrate may be employed according to the present invention, provided its use can produce an article which is transparent to light in the short wavelength infrared region ofthe spectrum.
Among the particularly useful resins of this type are polymethyl methacrylate and aromatic polycarbonates, especially bisphenol A polycarbonate; that is, the polycarbonate derived from 2,2-bis(4-hydroxyphenyl)propane. Bisphenol A homopolycarbonate is especially preferred.
The thickness of the substrate is not critical for the purposes of the invention. Illustrative thicknesses are in the range of about 1-50 mm. Excessive substrate thickness, however, can result in high absoφtion in certain areas within the near infrared region. This absoφtion may or may not be problematic, depending on the application.
A plurality of coating layers comprising alternate layers of SiO2 and a-Si:H is deposited on the substrate. The identity ofthe layer actually contacting the substrate is not critical, with either Si02 or a-Si:H being suitable for this puφose. It is, however, frequently convenient for the first layer to be of a-Si:H. The coating configuration of the present invention may include up to about 500 layers. In one embodiment, between about 10 and about 100 layers may be deposited. In another embodiment, the plurality of coating layers comprises at least one layer and up to about 10 layers.
While layer thickness is not critical, it is frequently advantageous for the thickness of a single layer to correspond to a quarter-wavelength of light at a single wavelength probe value within the range of light to be transmitted. The thickness of each layer is related to other parameters as follows:
L = mλ/4n ,
where L is layer thickness, m is a multiple of the basic quarter-wave optical unit (m=l), λ is the wavelength of the probe and n is the refractive index of the layer. Typically, a layer thickness in the range of between about 100 and about 300 nm is employed, but this value is based to some extent upon the range of other parameters of interest. A typical multilayered structure 400 using these unit layer thicknesses deposited on a substrate 420 is schematically shown in Figure 4. Figure 4 shows a stack of these quarter- wave basic unit building blocks on a massive medium substrate material. The layer thickness may be altered from the quarter-wave optical thickness as dictated by the optical coating design.
The deposited layers may be arranged either periodically or non-periodically. Non- periodic layers may be useful, for example, in computer-optimized designs or as added layers to a basic design included for anti-reflective puφoses. Alternatively, the optical coating may comprise symmetric profiles or variations thereof. Such coatings may be useful, for example, in bandpass, narrow bandpass, long or shortpass filters.
It is also within the scope of the invention for the optical coating to comprise a non- homogeneous layered structure. One such non-homogenous design is a sinusoidal periodic refractive index profile commonly referred to as a "rugate" design.
In another embodiment of the invention, the a-Si:H coatings are doped with various elements known in the art, such as, but not limited to, nitrogen, germanium, phosphorous, boron and carbon.
The articles of this invention are typically prepared by deposition of the desired coatings on the substrate. Any convenient method of deposition may be employed, with PECVD often preferred by reason of its particular suitability for this puφose. PECVD procedures and apparatus for their performance are well known in the art. Si02 and a-Si:H layers may, respectively, be produced by plasma dissociation of suitable precursors, typically silane (S1H ) for a-Si:H and a mixture of silane and nitrous oxide (N2O) for SiO , the molar ratio of nitrous oxide to silane in the latter mixture typically being in the range of about 20-100:1. Suitable plasmas include those of noble gases, nitrogen, ammonia and hydrogen, as well as combinations thereof, with argon often being preferred. Deposition time for a layer of the desired thickness can be determined by simple experimental comparison with standards involving various time periods. The invention is illustrated by an example in which a transparent bisphenol A homopolycarbonate substrate was coated with a layer of silicon and then with alternating layers of SiO2 and silicon to a total of 24 layers, the layer thicknesses being 133 nm for silicon and 263 nm for SiO . The particular design is referred to as a narrow bandpass design. The requirements for such a design include high transmission at the wavelength of interest while reflecting both higher and lower wavelength in that near vicinity. The multilayer configuration 400 for the design is shown in Figure 4. The Si02/a-Si:H layers had the following configuration:
Air I LHLHLHLLHLHLHLHLHLHLLHLHLH | Polycarbonate,
where H (designated 440 in Figure 4) signifies a layer of a-Si:H and L (designated 460 in Figure 4) signifies a layer of Si02.
Each of the unit thickness layers has a quarter-wave optical thickness unit as described above. The refractive index profile ofthe design is shown in Figure 5. The scale is in units of optical thickness; therefore each unit layer thickness is designated by quarter-wave (0.25λ) increments. The double unit Si02 thickness, designated "LL", allows the transmission at the wavelength of interest while allowing high reflection at the wavelengths outside the center-band wavelength.
The silicon layers were deposited by PECVD of silane (provided at a flow rate of 200 SCCM) using argon (provided at a flow rate of 1,000 SCCM) at a pressure of 200 millitorr as the plasma gas and a RF power level of 200 watts. The Si02 layers were deposited by PECVD of silane (provided at a flow rate of 200 SCCM). The silane was diluted by argon to 2 mole percent. Nitrous oxide, provided at a flow rate of 200 SCCM, was used as the plasma gas. The SiO2 layers were deposited using the same pressure and power level. Silicon is deposited according to the reaction:
SiH4(gas)-> Si(solid film) + 2H2(gas) ,
and silicon oxide is deposited by the reaction:
SiH4(gas) + 2N20(gas) -» SiO2(solid film) + N2, H2, NH3 (gases) Due to incomplete dissociation of the precursors and low substrate temperatures, the final compositions are not exactly stoichiometric and contain considerable impurities, most notably hydrogen. This has an effect on the optical properties to a varying degree.
The thermal shift in the optically coated article thus prepared, over a temperature range from ambient to about 100°C, was on the order of 1 nm. By contrast, the thermal shift of a control article in which the coating layers were deposited on a glass substrate was about 7 nm. This is shown by transmission spectra in Figures 6 and 7. Figure 6 shows the 7 nm shift of the multilayer on glass upon heating from 25°C to 100°C, and Figure 7 shows the multilayer performance on polycarbonate where there is a virtual absence of any movement upon heating the device from 25°C to 100°C.
While typical embodiments have been set forth for the puφose of illustration, the foregoing descriptions and examples should not be deemed to be a limitation on the scope of the invention. Accordingly, various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the spirit and scope ofthe present invention.

Claims

CLAIMS:
1. An optically coated article (400) comprising a polymeric substrate (420) and a plurality of coating layers, wherein the plurality of layers comprises alternate layers of silicon dioxide (460) and amoφhous hydrogenated silicon (440), and wherein the optically coated article (400) is transparent in the short wavelength infrared region ofthe spectrum.
2. The optically coated article (400) according to claim 1, wherein the substrate (420) is a thermoplastic resin.
3. The optically coated article (400) according to claim 2, wherein the thermoplastic resin has a coefficient of thermal expansion that is compatible with a coefficient of thermal expansion ofthe plurality of coating layers
4. The optically coated article (400) according to claim 2, wherein the substrate (420) is one of polymethyl methacrylate and an aromatic polycarbonate.
5. The optically coated article (400) accordmg to claim 1, wherein the substrate (420) is a thermosetplastic material.
6. The optically coated article (400) according to claim 4, wherein the thermosetplastic material is one of an epoxy, a cross-linked acrylic, a polyester, a melamine, and a silicone.
7. The optically coated article (400) according to claim 1, wherein the plurality of layers is arranged in a non-periodic array.
8. The optically coated article (400) according to claim 1, wherein the plurality of layers comprises at least one symmetric profile and multiples thereof.
9. The optically coated article (400) according to claim 1, wherein the optically coated article (400) is one of a bandpass filter, a narrow bandpass filter, a long-pass filter, and a shortpass filter.
10. The optically coated article (400) according to claim 1, wherein the plurality of coating layers forms an inhomogeneous layered structure.
11. The optically coated article (400) according to claim 9, wherein the inhomogeneous layered structure has a sinusoidal periodic refractive index profile.
12. The optically coated article (400) accordmg to claim 1, wherein the amoφhous hydrogenated silicon is doped with at least one of nitrogen, germanium, phosphorous, boron, and carbon.
13. The optically coated article (400) according to claim 1, wherein each coating layer is between about 100 nm and about 300 nm thick.
14. The optically coated article (400) according to claim 1, wherein the plurality of layers comprises up to about 500 layers.
15. The optically coated article (400) according to claim 14, wherein the plurality of layers comprises at least one layer and up to about 10 layers.
16. The optically coated article (400) according to claim 14, wherein the plurality of layers comprises between about 10 and about 100 layers.
17. The optically coated article (400) according to claim 1, wherein the layer contacting the substrate (420) comprises amoφhous hydrogenated silicon.
18. The optically coated article (400) according to claim 1, wherein the layer contacting the substrate (420) comprises silica.
19. An optically coated article (400) comprising a bisphenol A homopolycarbonate substrate (420) and between about 10 and about 100 coating layers, wherein said layers comprises alternate layers of silicon dioxide (460) and amoφhous hydrogenated silicon (440), wherein the layer contacting said substrate (420) comprises amoφhous hydrogenated silicon (440), and wherein said article (400) is transparent in the short wavelength infrared region ofthe spectrum.
20. A method for producing an optically coated article (400), the method comprising the steps of depositing a plurality of alternate coating layers of silicon dioxide (460) and amoφhous hydrogenated silicon (440) on a polymeric substrate (420), wherein said optically coated article (400) is transparent in the short wavelength infrared regions ofthe spectrum.
21. The method according to claim 20, wherein said plurality of alternate coating layers are deposited by plasma enhanced chemical vapor deposition.
22. The method according to claim 20, wherein the substrate (420) is poly(methyl methacrylate) or an aromatic polycarbonate.
23. The method according to claim 20, wherein the substrate (420) is an aromatic polycarbonate.
24. The method according to claim 20, wherein the substrate (420) is bisphenol A homopolycarbonate.
25. The method according to claim 20, wherein each coating layer is between about 100 nm and about 300 nm thick.
26. The method according to claim 20, wherein the layer contacting the substrate (420) comprises amoφhous hydrogenated silicon (440).
27. A method for producing an optically coated article (400), the method comprising the step of depositing a plurality of alternate coating layers of silicon dioxide (460) and amoφhous hydrogenated silicon (440) on a bisphenol A homopolycarbonate substrate (420), wherein the layer contacting said substrate (420) comprises amoφhous hydrogenated silicon (440) and wherein the plurality of alternate coating layers comprises between about 10 and about 100 layers, and wherein said optically coated article (400) is transparent in the short wavelength infrared region of the spectrum; wherein the plurality of alternate coating layers are deposited by plasma enhanced chemical vapor deposition, wherein amoφhous hydrogenated silicon is deposited using an argon plasma with silane, and wherein silica is deposited with silane and nitrous oxide.
PCT/US2002/025378 2001-08-24 2002-08-07 Optically coated article and method for its preparation Ceased WO2003019244A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12265239B2 (en) 2018-07-18 2025-04-01 Ii-Vi Delaware, Inc. Wide angle application high reflective mirror

Families Citing this family (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7045558B2 (en) * 2003-08-29 2006-05-16 General Electric Company Method of making a high refractive index optical management coating and the coating
JP4765504B2 (en) * 2005-09-16 2011-09-07 東レ株式会社 Optical filter
JP2008016799A (en) * 2006-06-06 2008-01-24 Mitsubishi Electric Corp Semiconductor laser device
DE102009004251B3 (en) * 2009-01-07 2010-07-01 Ovd Kinegram Ag Security element and method for producing a security element
KR101569406B1 (en) * 2009-08-19 2015-11-17 주성엔지니어링(주) Organic light emitting device and manufacturing method thereof
KR20110061422A (en) * 2009-12-01 2011-06-09 엘지이노텍 주식회사 Capacitive touch panel
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US9835952B2 (en) 2013-03-14 2017-12-05 Taiwan Semiconductor Manufacturing Company, Ltd. Systems and methods for a narrow band high transmittance interference filter
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US10168459B2 (en) 2016-11-30 2019-01-01 Viavi Solutions Inc. Silicon-germanium based optical filter
US10644048B2 (en) 2017-02-01 2020-05-05 Omnivision Technologies, Inc. Anti-reflective coating with high refractive index material at air interface
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US11650361B2 (en) * 2018-12-27 2023-05-16 Viavi Solutions Inc. Optical filter
KR20210132176A (en) * 2019-03-05 2021-11-03 퀀텀-에스아이 인코포레이티드 Optical Absorption Filters for Integrated Devices
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WO2021092425A1 (en) * 2019-11-08 2021-05-14 Viavi Solutions Inc. Optical coating and an apparatus including the optical coating
CN111175873A (en) * 2019-12-27 2020-05-19 光驰科技(上海)有限公司 A near-infrared filter
CN112114402A (en) * 2020-10-12 2020-12-22 东莞市微科光电科技有限公司 CWDM optical filter
US12372701B2 (en) * 2023-03-21 2025-07-29 Vactronics Technologies Inc. Narrow bandpass filtering element

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4166919A (en) * 1978-09-25 1979-09-04 Rca Corporation Amorphous silicon solar cell allowing infrared transmission
EP0173566A2 (en) * 1984-08-29 1986-03-05 Exxon Research And Engineering Company Multi-layered material having graded properties
US4599729A (en) * 1983-02-09 1986-07-08 Hitachi, Ltd. Semiconductor laser device having facets provided with dielectric layers
US4859553A (en) * 1987-05-04 1989-08-22 Xerox Corporation Imaging members with plasma deposited silicon oxides
EP0490613A2 (en) * 1990-12-14 1992-06-17 Ford Motor Company Limited Motor vehicle windshield having an antireflective transparent coating
US5242740A (en) * 1991-03-06 1993-09-07 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Multilayer coating for polycarbonate substrate

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4827870A (en) 1987-10-05 1989-05-09 Honeywell Inc. Apparatus for applying multilayer optical interference coating on complex curved substrates
US5009920A (en) 1990-03-30 1991-04-23 Honeywell Inc. Method for applying optical interference coating
US5694240A (en) * 1994-06-24 1997-12-02 Bausch & Lomb Incorporated Multilayer anti-reflective and ultraviolet blocking coating for sunglasses
US6157503A (en) * 1998-11-10 2000-12-05 Thermo Vision Corporation High performance optical filters suitable for intense ultraviolet irradiance applications
US6164777A (en) * 1998-12-16 2000-12-26 Bausch & Lomb Incorporated Color-imparting contact lenses with interference coating and method for making the same
US6215802B1 (en) * 1999-05-27 2001-04-10 Blue Sky Research Thermally stable air-gap etalon for dense wavelength-division multiplexing applications

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4166919A (en) * 1978-09-25 1979-09-04 Rca Corporation Amorphous silicon solar cell allowing infrared transmission
US4599729A (en) * 1983-02-09 1986-07-08 Hitachi, Ltd. Semiconductor laser device having facets provided with dielectric layers
EP0173566A2 (en) * 1984-08-29 1986-03-05 Exxon Research And Engineering Company Multi-layered material having graded properties
US4859553A (en) * 1987-05-04 1989-08-22 Xerox Corporation Imaging members with plasma deposited silicon oxides
EP0490613A2 (en) * 1990-12-14 1992-06-17 Ford Motor Company Limited Motor vehicle windshield having an antireflective transparent coating
US5242740A (en) * 1991-03-06 1993-09-07 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Multilayer coating for polycarbonate substrate

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12265239B2 (en) 2018-07-18 2025-04-01 Ii-Vi Delaware, Inc. Wide angle application high reflective mirror

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