PROTECTED ITEM INCLUDING A PROTECTIVE COATING

Abstract

There is disclosed a protected item including an item that needs protection and a protective coating having a hardness of at least about 8 on the Mohs scale. The protected item includes a light transmission in part or all of the visible wavelength of at least about 60% and a light reflection in the visible wavelength of about 4% or less.

Description

FIELD OF THE INVENTION

The present disclosure generally relates to a protective coating. The protective coating can be applied to any surface, including an optical filter.

BACKGROUND OF THE INVENTION

Today, most of the displays for portable electronic devices like smartphones, digital cameras, wearable devices, e.g., watches, fitness tracker devices, etc., do not include an anti-reflective coating. However, because of the optical interference created by the displays of these products, the displays without an anti-reflection coating can be difficult to see or read, especially on a sunny day. Anti-reflective coatings are not as durable as a substrate (e.g., “gorilla” glass or sapphire windows) on which it is coated. Therefore, the displays with anti-reflective coatings for the visible spectral range are cosmetically degraded by even small blemishes.

SUMMARY OF INVENTION

In an aspect, there is disclosed a protected item comprising an item that needs protection and a protective coating having a hardness of at least about 8 on the Mohs scale, wherein the protected item includes a light transmission in the visible wavelength of at least about 60% and a light reflection in the visible wavelength of about 4% or less.

In a further aspect, there is disclosed a method for making a protected item comprising providing an item that needs protection; and depositing a protective coating having a hardness of at least about 8 on the Mohs scale onto the item that needs protection to form a protected item, wherein the protected item includes a light transmission in the visible wavelength of at least about 60% and a light reflection in the visible wavelength of about 4% or less.

Additional features and advantages of various aspects of the invention will be set forth, in part, in the description that follows, and will, in part, be apparent from the description, or may be learned by the practice of various aspects. The objectives and other advantages of various aspects will be realized and attained by means of the elements and combinations particularly pointed out in the description herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention in its several aspects can be more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a cross sectional view of a protected item including a protective coating and an item that needs protection according to an example of the present disclosure;

FIG. 2A is a cross sectional view of an item that needs protection according to an example of the present disclosure;

FIG. 2B is a graph illustrating reflection of light at various angles of incidence for a substrate of an item that needs protection;

FIG. 2C is a graph illustrating reflection of light at various angles of incidence for an item that needs protection;

FIG. 3A is a cross sectional view of a protected item according to another example of the present disclosure;

FIG. 3B is a graph illustrating the reflection of light at various angles of incidence for the protected item of FIG. 3A according to an example of the present disclosure;

FIG. 3C is a graph illustrating the transmission of light at various angles of incidence for the protected item of FIG. 3A according to an example of the present disclosure;

FIG. 4A is a cross sectional view of a protected item according to another example of the present disclosure;

FIG. 4B is a graph illustrating the reflection and the transmission of light for the protected item of FIG. 4A according to an example of the present disclosure;

FIG. 5A is a cross sectional view of a protected item according to another example of the present disclosure;

FIG. 5B is a graph illustrating the reflection and the transmission of light for the protected item of FIG. 5A according to an example of the present disclosure;

FIG. 6A is a cross sectional view of a protected item according to another example of the present disclosure;

FIG. 6B is a graph illustrating the reflection and the transmission of light for the protected item of FIG. 6A according to an example of the present disclosure;

FIG. 6C is a graph illustrate the reflection and the transmission of light for an item that needs protection;

FIG. 7A is a cross sectional view of a protected item according to another example of the present disclosure;

FIG. 7B is a graph illustrating the transmission of light for the protected item of FIG. 7A according to an example of the present disclosure;

FIG. 8 illustrates relative hardness of different protective coatings according to an example of the present disclosure;

FIG. 9 is a graph illustrating the effects of varying hydrogen flow on the transmission of light after deposition of a protective coating; and

FIG. 10 is a graph illustrating the effects of annealing of a protective coating on the transmission of light.

Throughout this specification and figures like reference numbers identify like elements.

DETAILED DESCRIPTION OF THE INVENTION

For simplicity and illustrative purposes, the present disclosure is described by referring mainly to examples thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures readily understood by one of ordinary skill in the art have not been described in detail so as not to unnecessarily obscure the present disclosure.

For purposes of the present disclosure, the words “bandpass filter properties” or “bandpass properties” can be defined as an optical filter that can pass wavelengths or frequencies within a certain range and can reject or attenuate wavelengths or frequencies outside that certain range. Furthermore, “infrared blocking properties” can be defined as an optical filter that is capable of reflecting or blocking at least near-infrared wavelengths while passing visible light. “Antireflection properties” can be defined as an optical filter that is capable of at least reducing reflection and/or stray light.

Furthermore, numeric values and ranges herein, unless otherwise stated, are intended to have associated with them a tolerance and to account for variances of design and manufacturing. Thus, a number is intended to include values “about” that number. For example, a value X is also intended to be understood as “about X”. Likewise, a range of Y-Z is also intended to be understood as a range of from “about Y-about Z”. Unless otherwise stated, significant digits disclosed for a number are not intended to make the number an exact limiting value. Variance and tolerance is inherent in mechanical design and the numbers disclosed herein are intended to be construed to allow for such factors (in non-limiting e.g., ±10 percent of a given value). Example numbers disclosed within ranges are intended also to disclose sub-ranges within a broader range which have an example number as an endpoint. A disclosure of any two example numbers which are within a broader range is also intended herein to disclose a range between such example numbers. Likewise, the claims are to be broadly construed in their recitations of numbers and ranges.

Aspects of the present disclosure relate to a protected item 10 including an item 20 that needs protection; and a protective coating 30, as shown in FIG. 1. The protective coating 30 can be used on any item 20 that needs protection to reduce or substantially inhibit the likelihood of the item scratching or breaking. Additionally, the protective coating 30 would not change the effects, i.e., the optical property or optical properties, of the item 20 that needs protection, for example, reflection, transmission, etc. Some examples of items 20 that need protection include, but are not limited to, smart phones, tablets, touch screen computers, camera lenses, eyeglasses, touch screens or panels, and finger print readers.

As shown in FIG. 2A, the item 20 that needs protection can be, for example, a substrate 40 with an optical filter 50 disposed thereon. The substrate 40 can include, but is not limited to, glass (e.g., gorilla glass, borosilicate glass), silicon, polymer, or wafers such as sapphire windows, photodiode, photodiode array, complementary metal-oxide semiconductor (CMOS) sensors, and charge-coupled device (CCD) sensors.

The substrate 40 can reflect light at various angles of incidence (AOI). For example, as shown in FIG. 2B, a sapphire substrate 40 can reflect light from about 7.5% to about 9% at various angles of incidence (AOI at 0°, 15°,30°, and 45°). The inclusion of an optical filter 50 on the substrate 40, as shown in FIG. 2A, can change the ability of the substrate 40 to reflect and/or transmit light. For example, an anti-reflection coating, as the optical filter 50, on the sapphire substrate 40 from FIG. 2B should reduce the reflection of light at various angles of incidence. As shown in FIG. 2C, an optical filter 50, such as an anti-reflection coating ending with a silicon dioxide layer, can greatly reduce the reflection of light in the visible wavelength at various angles of incidence (AOI at 0°, 15°, 30°, 45°, and 60°). In particular, an item 20 that needs protection can have a light reflection in the visible wavelength of about 4% or less. In an aspect, the inclusion of a protective coating 30 would not, or a de minimis manner, change the effects wrought by the optical filter 50, i.e., the anti-reflection coating of the optical filter 50 would still reduce the reflection of light.

The substrate 40 can include a thickness of from about 0.1 mm or less to about 20 mm or more, for example, from 0.1 mm to 10 mm, from 0.2 mm to 7.5 mm, from 0.3 mm to 7 mm, from 0.4 mm to 6.5 mm, from 0.5 mm to 6 mm, from 0.6 mm to 5 mm, from 0.7 mm to 4 mm, from 0.8 mm to 3 mm, from 0.9 mm to 2 mm, and from 1 mm to 1.5 mm.

As shown in FIG. 2A, the optical filter 50 can include at least one layer (50-1) including up to n layers (n is an integer>1) (50-n), for example, two layers, three layers, four layers, etc. In an aspect, the optical filter 50 can include an even number of layers or can include an odd number of layers. The number of layers present in the optical filter 50 can be determined by various factors, such as the compound included in each individual layer, and/or the optical property to be exhibited by the optical filter 50, and/or the thickness of each layer in the optical filter 50. The optical filter 50 can exhibit any optical properties such as absorptive, interference, monochromatic, dichroic, ultraviolet blocking, infrared blocking, anti-reflection, bandpass, neutral density, longpass, shortpass, guided-mode resonance, metal mesh, polarizer, arc welding, low-reflection, optically-variable, color-shifting, optical interference, transparent conductive, high-reflection, etc. Compounds that can be used in the at least one layer of the optical filter 50 include, but are not limited to, one or more of Si, silicon dioxide (SiO₂), silicon nitride (Si₃N₄), aluminum oxide (Al₂O₃), ZrO₂, Y₂O₃, tantalum pentoxide (Ta₂O₅), niobium pentoxide (Nb₂O₅), NbTa₂O₅, NbTiO_x, wherein x is an integer ranging from 1 to 6, SiC, and titanium dioxide (TiO₂). Additionally, the thickness of each layer of the optical filter 50 can each independently be from 1 nm or less to 2000 nm or more, such as from 3 nm to 300 nm, from 10 nm to 180 nm, from 20 nm to 160 nm, from 30 nm to 140 nm, from 40 nm to 120 nm, from 50 nm to 100 nm, from 60 nm to 90 nm, and from 70 nm to 80 nm.

In an aspect, the optical filter 50 can include alternating layers of two different compounds, for example, alternating layers of SiO₂ and NbTa₂O₅, wherein the number of alternating layers is n (n is an integer>1), for example from about 2 to about 66, for example from about 2 to about 48, and as a further example from about 2 to about 35. An optical filter 50 exhibiting anti-reflection properties can include, for example, 35 alternating layers of SiO₂ and NbTa₂O₅ (FIG. 3A); four (4) alternating layers of Si₃N₄ and SiO₂ (FIG. 4A); or six (6) alternating layers of NbTiO_x and SiO₂, (FIG. 5A). An exemplary optical filter 50 exhibiting an infrared blocking property can include, for example, sixty-six (66) alternating layers of NbTa₂O₅ and SiO₂, as shown in FIG. 6A. An exemplary optical filter 50 exhibiting a bandpass filter property can include, for example, 48 alternating layers of Ta₂O₅ and SiO₂, as shown in FIG. 7A. The optical filter 50 can exhibit at least one of an anti-reflection property, an infrared blocking property, and a bandpass filter property.

A protective coating 30 can be applied to the item 20 that needs protection to form the protected item 10, as shown in FIG. 1. The protective coating 30 can have a hardness of at least about 8 on the Mohs scale, and can be present in a thickness ranging from about 1 to about 2000 nm. An example of a protective coating 30 can be silicon carbide (SiC) because it is a very durable material. Alternatively, or in addition to the silicon carbide, another material can be included in the protective coating 30, including but not limited to titanium carbide, boron, boron nitride, rhenium diboride, stishovite, titanium diboride, diamond, diamond-like carbon (DLC) and carbonado. The other material should not negatively impact the attributes of the protective coating 30 and should also not negatively impact the optical properties associated with the optical filter 50 of the item 20 that needs protection.

Moreover, the protective coating 30 can have a hardness of at least about 8 on the Mohs scale, for example from about 9 to about 9.5. FIG. 8 illustrates the relative hardness of different materials, such as sapphire, SiC, silicon dioxide, silicon, and fused silica, in which a lower indentation depth is understood to reflect a higher relative hardness and thus a higher resistance to scratches. According to FIG. 8, at a load of 77 μN, SiC has an indentation depth of approximately 3.5 nm, and sapphire has an indentation depth of approximately 2.5 nm. Silicon dioxide, silicon, and fused silica all have an indentation depth of over 8 nm. At a load of 91 μN, SiC and sapphire have an indentation depth of approximately 3.8 nm. Silicon dioxide, silicon, and fused silica all have an indentation depth of over 8 nm. Furthermore, at a load of 105 μN, SiC has an indentation depth of approximately 4.1 nm, and sapphire has an indentation depth of approximately 4.7 nm. Silicon dioxide, silicon, and fused silica all have an indentation depth of over 10 nm. Accordingly, at higher loads, SiC has a higher resistance to scratches than sapphire, silicon dioxide, silicon, and fused silica. Sapphire has a hardness of about 9, fused silica has a hardness of about 5.3 to about 6.5, and silicon has a hardness of about 7 on the Mohs scale. One of ordinary skill in the art would know that the Mohs scale is not linear, but is instead exponential.

The protective coating 30 can include a thickness of from about 1 nm to about 2000 nm, for example from about 2 nm to 1000 nm, such as from about 3 nm to about 20 nm or from about 5 nm to about 2.0 nm. This range of thickness can provide ideal light transmission, light reflection, and provide ideal hardness/scratch resistance. In particular, a protective coating 30 can be absorbing in the visible range wavelength, so a reduced thickness can be applied to avoid too much light loss.

In an aspect, the protected item 10 can have a light transmission of at least about 60% in part or all of the visible wavelength and a light reflection of about 4% or less in the visible wavelength. The light transmission in part or all of the visible wavelength can be at least about 65%, 70%, 75%, 80%, 85%, 90%, 95%, or even about 100%. Additionally, the light reflection in the visible wavelength can be about 3.5%, 3%, 2.5%, 2%, 1.5% and below, such as 1.4%, 1.3%, 1.2%, 1.1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or even about 0.1% or lower.

The method of making a protected item 10 can include depositing the protective coating 30, and in particular, a method of depositing the protective coating 30 including SiC, onto an item 20 that needs protection. The deposition of the protective coating 30 can play a part in the performance of the protected item 10. The method of making a protected item 10 can include providing an item 20 that needs protection and depositing a protective coating 30 onto the item 20. The method can further include a method of making the item 20 that needs protection including providing a substrate 40 and depositing an optical filter 50 onto the substrate 40. The deposition of the optical filter 50 onto the substrate can include known deposition techniques, such as magnetron sputtering, direct current sputtering, pulsed sputtering, alternate current sputtering, radio frequency sputtering, ion beam sputtering, and assisted ion beam sputtering; thermal evaporation, electron beam evaporation, ion assisted evaporation, chemical vapor deposition, and plasma-enhanced chemical vapor deposition. The protective coating 30 can be deposited on the optical filter 50 using similar deposition techniques, such as sputtering deposition techniques, and can include the addition of hydrogen. In this manner, the protective coating 30 can be applied in a reduced thickness. The method can further include annealing the protective coating 30 to the item 20 that needs to be protected to form the protected item 10. The protective coating 30 can be deposited onto the item 20 that needs protection, in particular, onto the optical filter 50 of the item 20, using a dual cathode or a single cathode sputtering process. The optical properties of the protective coating 30 can depend on the hydrogen content and, therefore, on the hydrogen flow rate during the deposition step. Additionally, the optical properties of the protective coating 30 can also be influenced by other parameters, such as the flow rate of the inert gas, the PAS (plasma activation source) power level, the cathode power level, and the deposition rate.

The process parameters and values can vary depending on the coating process, chamber size, and many other factors. Generally, the temperature of the deposition process can be from 10° C. or less to 150° C. or more, such as from 15° C. to 100° C. or from 20° C. to 90° C. Furthermore, the pressure can be from 1×10⁻⁶ mtorr to 1×10⁻² mtorr, such as from 5×10⁻⁴ mtorr to 5×10⁻³ mtorr. Moreover, the hydrogen gas flow can be from 10 SCCM or less to 200 SCCM or more, such as 20 SCCM, 40 SCCM, 60 SCCM, 80 SCCM, 100 SCCM, 120 SCCM, 140 SCCM, 160 SCCM, 180 SCCM, and 200 SCCM. Furthermore, the inert gas, such as argon gas, flow can be from 50 SCCM to 500 SCCM, for example, 150 SCCM or more, such as 200 SCCM, 204 SCCM, 295 SCCM, and 390 SCCM.

The method of making the protected item 10 can further include annealing the protective coating 30. In an aspect, if a single cathode sputtering process is used, the protective coating 30 can be annealed. In another aspect, if a dual cathode sputtering process is used, the protective coating 30 does not have to be annealed. The annealing temperature can be at any temperature greater than 90° C. For example, the annealing can take place at a temperature of 100° C., 200° C., 250° C., 240° C., 300° C., 350° C., 400° C., or more. The annealing process can take anywhere from 30 minutes to 24 hours. For example, the annealing process can take from 40 minutes to 10 hours, from 45 minutes to 5 hours, from 50 minutes to 2 hours, such as an hour. In one example, the annealing process takes place at a temperature of about 280° C. for about 1 hour. In another example, the annealing process takes place at a temperature of about 400° C. for about 1 hour.

EXAMPLES

To determine the effects of using a protective coating 30 on an optical filter 50, such as an anti-reflection coating, an infrared blocker, and a bandpass filter, the following protected items 10 were made.

FIG. 3A illustrates a protected item 10 including a sapphire substrate 40 with an optical filter 50. The optical filter 50 included 35 alternating layers of silicon dioxide and NbTa₂O₅. A protective coating 30 of silicon carbide was deposited onto the optical filter 50 at a thickness of 6 nm. The reflection of light in the visible wavelength was 4% or less (FIG. 3B) and the transmission of light in the visible wavelength was at least about 60% (FIG. 3C). As can be seen from a comparison of FIGS. 2C and 3B, the inclusion of a protective coating 30 of SiC does not substantially alter the effects of the optical filter 50, an anti-reflection coating.

FIG. 4A illustrates a protected item 10 including a sapphire substrate 40 with an optical filter 50. The optical filter 50 included 4 alternating layers of Si₃N₄ and silicon dioxide. A protective coating 30 of silicon carbide was deposited onto the optical filter 50 at a thickness of 6 nm. The reflection of light in the visible wavelength was 4% or less and the transmission of light in the visible wavelength was at least about 60% (FIG. 4B).

FIG. 5A illustrates a protected item 10 including a sapphire substrate 40 with an optical filter 50. The optical filter 50 included 6 alternating layers of NbTiO_x and silicon dioxide. A protective coating 30 of silicon carbide was deposited onto the optical filter 50 at a thickness of 6 nm. The reflection of light in the visible wavelength was 4% or less and the transmission of light in the visible wavelength was at least about 60% (FIG. 5B).

FIG. 6A illustrates a protected item 10 including a borofloat substrate 40 with an optical filter 50. The optical filter 50 included 66 alternating layers of NbTa₂O₅ and silicon dioxide. A protective coating 30 of silicon carbide was deposited onto the optical filter 50 at a thickness of 6 nm. The reflection of light in the visible wavelength was 4% or less and the transmission of light in the visible wavelength as at least about 60% (FIG. 6B). In the infrared wavelength (700 nm to 1100 nm), there was a de minimis amount of light that was transmitted. FIG. 6C illustrates the reflection of light and the transmission of light for an item that needs protection 20, i.e., it does not include a protective coating 30. As can be seen from a comparison of FIGS. 6B and 6C, the inclusion of the protective coating 30 (FIG. 6B) does not, or in a de minimis manner, change the effects wrought by the optical filter 50, e.g., an infrared blocker. The infrared blocker property is exhibited by the protected item 10 while also yielding the scratch-resistance, for example, properties of the protective coating 30.

FIG. 7A illustrates a protected item 10 including a borofloat substrate 40 with an optical filter 50. The optical filter 50 included 48 alternating layers of Ta₂O₅ and silicon dioxide. A protective coating 30 of silicon carbide was deposited onto the optical filter 50 at a thickness of 10 nm. The transmission of light in certain areas of the visible wavelength was at least about 60% (FIG. 7B).

To determine the effects of adding hydrogen during the deposition of the protective coating 30 to the item 20 that needs protection, the hydrogen flow was varied to provide a 2 μm SiC protective coating on a fused silica. The transmission of light was measured for each varied flow rate over the visible and infrared wavelengths. The data is shown in FIG. 9. As can be seen, an increased flow rate of the hydrogen during deposition resulted in a greater percentage of light that was transmitted thereby improving the optical property of the protective coating 30.

To determine the effects of annealing of the protective coating 30 after its deposition to the item 20 that needs protection, the temperature was varied. During deposition the hydrogen flow was 120 SCCM to provide a 2 μm SiC protective coating on a fused silica. FIG. 10 illustrates a control without annealing (U07342 AD), an annealing temperature at 280° C. for 1 hour (U07342 2808), an annealing temperature at 400° C. for 1 hour (U07342 4008). The transmission of light was measured for each over the visible and infrared wavelengths. The data is shown in FIG. 10. As can be seen, annealing the protective coating 30 resulted in a greater percentage of light that was transmitted thereby improving the optical property of the protective coating 30.

From the foregoing description, those skilled in the art can appreciate that the present teachings can be implemented in a variety of forms. Therefore, while these teachings have been described in connection with particular aspects and examples thereof, the true scope of the present teachings should not be so limited. Various changes and modifications may be made without departing from the scope of the teachings herein.

This scope disclosure is to be broadly construed. It is intended that this disclosure disclose equivalents, means, systems and methods to achieve the devices, activities and mechanical actions disclosed herein. For each device, article, method, mean, mechanical element or mechanism disclosed, it is intended that this disclosure also encompass in its disclosure and teaches equivalents, means, systems and methods for practicing the many aspects, mechanisms and devices disclosed herein. Additionally, this disclosure regards a coating and its many aspects, features and elements. Such a device can be dynamic in its use an operation, this disclosure is intended to encompass the equivalents, means, systems and methods of the use of the device and/or article of manufacture and its many aspects consistent with the description and spirit of the operations and functions disclosed herein. The claims of this application are likewise to be broadly construed.

The description of the inventions herein in their many aspects is merely an example and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. A protected item comprising:

an item that needs protection; and

a protective coating having a hardness of at least about 8 on the Mohs scale,

wherein the protected item includes a light transmission in part or all of a visible wavelength of at least about 60% and a light reflection in the visible wavelength of about 4% or less.

2. The protected item of claim 1, wherein the item that needs protection includes a substrate and an optical filter.

3. The protected item of claim 2, wherein the substrate comprises glass, silicon, polymer, or wafers.

4. The protected item of claim 3, wherein the wafers comprise sapphire windows, a photodiode, a photodiode array, complementary metal-oxide semiconductor sensors, and charge-coupled device sensors.

5. The protected item of claim 2, wherein the optical filter exhibits at least one of an anti-reflection property, an infrared blocking property, and a bandpass filter property.

6. The protected item of claim 2, wherein the optical filter includes at least one layer of at least one of Si, SiO2, Si3N4, Al2O3, ZrO2, Y2O3, Ta2O5, Nb2O5, NbTa2O5, NbTiOx, SiC, and TiO2, wherein x is an integer from 1-6.

7. The protected item of claim 2, wherein the optical filter exhibits an anti-reflection property and includes alternating layers of SiO2 and NbTa2O5.

8. The protected item of claim 2, wherein the optical filter exhibits an anti-reflection property and includes alternating layers of Si3N4 and SiO2.

9. The protected item of claim 2, wherein the optical filter exhibits an anti-reflection property and includes alternating layers of NbTiOx and SiO2, wherein x is an integer from 1-6.

10. The protected item of claim 2, wherein the optical filter exhibits an infrared blocking property and includes alternating layers of NbTa2O5 and SiO2.

11. The protected item of claim 2, wherein the optical filter exhibits a bandpass filter property and includes alternating layers of Ta2O5 and SiO2.

12. The protected item of claim 1, wherein the protective coating comprises at least one of silicon carbide, titanium carbide, boron, boron nitride, rhenium diboride, stishovite, titanium diboride, diamond, diamond-like carbon, and carbonado.

13. The protected item of claim 1, wherein the protective coating comprises silicon carbide.

14. The protected item of claim 1, wherein the protective coating includes a thickness of from about 3 nanometers to about 20 nanometers.

15. The protected item of claim 1, wherein the protective coating is annealed to the item that needs protection.

16. A method for making a protected item comprising:

providing an item that needs protection; and

depositing a protective coating having a hardness of at least about 8 on the Mohs scale onto the item that needs protection to form a protected item;

wherein the protected item includes a light transmission in part or all of a visible wavelength of at least about 60% and a light reflection in the visible wavelength of about 4% or less.

17. The method of claim 16, further comprising providing a substrate; and depositing an optical filter onto the substrate to form an item that needs protection.

18. The method of claim 16, wherein the protective coating is deposited at a thickness of from about 3 nanometers to about 20 nanometers.

19. The method of claim 16, further comprising annealing the deposited protective coating to the item that needs protection.

20. The method of claim 16, wherein the step of depositing a protective coating is performed using a sputtering deposition technique and includes the addition of hydrogen.