Anti-reflective Coating: Guide to Solve Glare Problem on your Product
Are you experiencing some sort of reflection on any of your optical products? Have you ever attempted to resolve it in vain?
If yes then just know you are in the right place.
It is simple!
This ultimate guide will help you solve the annoying glare problem on any of your optical product. From basic definition, working principle, benefits, practical applications, FAQ on anti-reflective coating, etc. – you will certainly be an AR coating expert by the end of this guide.
But before we get an in-depth understanding of anti-reflective coating, let’s first know what anti-reflective coating is.
What is Anti-reflective Coating (AR Coating)?
Ordinarily, only some percentage of light is often transmitted to the eye on your optical product, if at all you use one with lenses.
The rest of the light is lost to the surface reflections. A lot of adverse things can happen to you as a result of these reflections.
Glasses without an AR coating – Photo Credits: QUORA
Glasses with an AR coating – Photo Credits: QUORA
For that reason, an anti-reflective coating was invented to help in reducing and if possible eliminate the effects of these reflections.
So primarily, AR coating refers to a specific dielectric thin film optical varnish that is applied to the lens surface or any other photonic device to reduce reflection and glare.
Some of the surfaces for such applications include spectacles, optical elements like cameras, telescopes and solar cells among others.
This would then allow sufficient light to pass through your lenses, which subsequently increases your quality of vision.
What at times you need is eliminating the glare on your ocular product so that it may enable enough light to pass through.
If a lens is treated with an AR coating, it can transmit light up to about 99.9%. Isn’t that amazing?
Yes, it is because later on, you’ll realize the benefits of applying this coating on your optical elements’ lenses.
What you need at the end of the day is quality vision through the particular optical product you’re using.
So it means that it would be ideal to do whatever you can to attain this particular goal. And luckily, AR coating is available. All you need is ensuring that you get it done by an expert in these matters.
Anti-Reflective Coating Materials
In most instances, we talk of anti-reflective coating being a dielectric material or a substance that alters the refractive index of surfaces.
Well, that alone is not enough.
It is important to state the specific substrates that are responsible for this phenomenon.
This way, it makes it easier for both manufacturers and OEM clients to choose a suitable anti-reflective coating solution.
For a fact, there are many compounds with superior anti-reflective properties for different applications. Let’s review just a few AR coating substrates that you choose from:
2.1. Magnesium Fluoride (MgF2)
This is one of the most popular anti-reflective coatings. With just a single layer, it can reduce reflectance from about 4% to 1.3%.
It is a popular coating for a range of optical products in the market.
Structure of magnesium fluoride – Photo Credits: WIKIPEDIA
Furthermore, when you apply it at high temperatures, it becomes hard and durable.
Normally, you can use a single layer of magnesium fluoride to coat windows, lenses, beam splitters, etc.
Remember, by reducing glare, magnesium fluoride improves image quality while reduces reflectance losses on the surface.
A theoretical reflectance of MgF2 – Photo Credits: Dr. Michael Fink
2.2. Zinc Sulfide as Anti-reflective Coating Substrate
Normally a Zinc Sulfide is available as either low or high transmission coating, depending on the formulation.
Zinc sulfide – Photo Credits: WIKIMEDIA
For effectiveness and efficiency you can apply it on both sides of the surface. In this scenario, you can use it as a broadband anti-reflective coating i.e. from 8 to 12 µm.
Photo Credits: D. Vápenka, J. Václavík and P. Mokrý
2.3. Silicon Nitride Anti-reflection Coating
This is a popular anti-reflective coating in solar cells. As a matter of fact, Silicon Nitride has almost the same characteristics as that of silicon monoxide.
With Silicon Nitride AR coating, a solar panel can collect as much light energy as possible. It aims to boost the output energy of the solar panel.
Zinc Nitride – Photo Credits: WIKIMEDIA
Remember, this is a broadband AR coating. Thus, it is suitable for solar cells that operate within 300 to 1200nm.
2.4. Yttrium Fluoride (YF2) AR Coating
Like the Zinc Selenide, Yttrium Floride is a perfect anti-reflective coating for infrared regions just above the 5µm.
Yttrium Fluoride (YF2 – Photo Credits: WIKIMEDIA
It is also a perfect choice when it comes to eliminating glare on surfaces.
Now, what’s the bottom line here?
There are quite a number of compounds you can use as AR coating substrates. As a general rule, knowing the applications, wavelength and refractive index of the coating are some of the essential aspects you must consider.
Take for example:
- Silicon monoxide is suitable for infrared wavelengths
- Yttrium Flouride and Magnesium Flouride are a perfect choice for visible region
So, the effectiveness and efficiency of anti-reflective substrate on a surface will depend on the ability of the manufacturer to choose a perfect compound. This involves an extensive research and tests.
A reason why you need to consider only reputable companies in this business – otherwise, you will not get value for your money.
But that’s not all:
You can modify this coating for unique anti-reflective applications, just as I have highlighted above. Remember, with the modern advancements in the AR coating compounds, there are unlimited possibilities.
Depending on the nature of the application, you can apply anti-reflective substrates on a range of material such as:
- Glass, etc.
This is irrespective of whether the surface is curved or flat.
With this knowledge on anti-reflective coating materials, we can now move further to explore different classifications of AR coating.
Classification and Types of Anti-Reflective Coating
In the past, people could wear the comparatively large vintage frames without necessarily bothering about glare.
In fact, it is the invention of computers, fluorescents and constant light pollution that necessitated the need for anti-reflective coating.
However, times changed and so did technology. The AR coatings were then introduced to be used in various applications.
In general, we have different types of AR coatings. Let’s look at some of the common ones;
3.1. Single Layer Anti-reflection Coatings
These refer to the comparatively thin layers of a somewhat transparent material. For them to obtain anti-reflective properties, it calls for their reflective index to be the square root of the refractive index of the particular object that they are used to coat.
An illustration of single layer anti-reflection coating – Photo Credits: HYPER PHYSICS
This specific ratio leads to the center wavelength that doesn’t have a reflectivity at all and reduced reflectivity in wavelengths that surround the center.
In such kind of situation, the two reflections of equal degree tend to arise at the two interfaces. The result is that these two reflections cancel one another by destructive interference.
This particular approach has two major limitations;
One is that it is often rare to find a coating material that has an ideal refractive index especially in instances where the bulk medium contains a comparatively low refractive index.
The second limitation is that a single layer anti-reflection coating typically works only in a limited wavelength range.
3.2. Multi-Layer Anti-reflective Coatings
These are the types of AR coatings that can reach to the lowest reflectivity at the center wavelength. They are normally applied to a single laser bandwidth or complex wavelength mechanism that is closely spaced.
Illustrating single layer anti-reflection coating – Photo Credits: HYPER PHYSICS
Obtaining reflectivity for as low as 0.1 percent is possible. This is when you choose to use alternating layers of a comparatively low index material and higher index material.
The essence, in this case, is to warrant the nethermost loss for center bandwidth range. Such kind of coating can be provided for bandwidth range that ranges from 250nm to 2200nm.
It is always fundamental to ensure that you pay close attention to the damage threshold and center wavelength whenever you’re picking an ideal multilayer antireflective coating.
Other than such properties, the aspect of tolerance to growth errors may also be of significant interest. This is because some complicated coating designs tend to get to peak performance only specifically for precise manufacturing.
3.3. Absorbing AR Coatings
This refers to the type of AR coatings that do not substantially transmit light appropriately but can as well provide somewhat low levels of reflectivity.
Ordinarily, the absorbing AR coatings require comparatively few layers. They are often inexpensive and compared to other coatings such as multilayer and other non-standard absorbing AR coatings.
Photo Credits: PHYS
The thickness of the absorbing AR coatings can only be a few nanometers. This is deemed important since any strong imaginary elements of this coating can result in considerable phase changes.
These coatings become handy in circumstances where high transmission via a surface is inconsequential and undesirable, but low reflectivity is needed.
Furthermore, the Absorbing AR Coatings can also be useful in enhancing the contrast as well as replacing the tinted glass.
In most cases, the absorbing ARC’s tend to utilize the unusual optical properties that are displayed in the compound thin films created by sputter deposition.
3.4. Gradient Index Coatings
In these types of coatings, the composition of a layer material is progressively varied. This is to mean that a smooth index changeover between two ocular elements can reasonably suppress well the reflection over an angular range and a broad spectral range.
Photo Credits: OSA PUBLISHING
Apparently, this can be relatively difficult to comprehend precisely for surfaces that are close to air. It is because most of the solid materials tend to have a refractive index that is considerably different from the one of air.
An ideal way of handling this is by using nano-optics in the form of sub-bandwidth range pyramid structures. These types of structures usually duplicate a smooth conversion of the refractive index to 1.
This happens through smooth reduction of the number of solid substances in a plane parallel to the surface.
Nevertheless, there are also solutions that do not primarily utilize nano-optics. This is specifically about the integration of gradient index layers into a multilayer coating.
This essentially enables the ideal broadband anti-reflection properties in a broad angular range without utilizing the materials that need a small refractive index.
3.5. Circular Polarizer
This is a type of ARC often laminated on the surface to help in eliminating the reflections. What happens is that light is transmitted by the polarizer.
After transformation of polarizer into handedness, light is then reflected on the surface. It becomes difficult for this light to pass through the circular polarizer.
Photo Credits: WIKIMEDIA
The reason is majorly because there is a change in its chirality. The major limitation of this AR coating method is that should the input light be unpolarized; the transmission will be less than 50% especially via the assembly.
In addition to these 5 classification criteria, you can also have anti-reflective spray, anti-reflective film and anti-reflective sheet.
Choosing any of these types of anti-reflective products will depend on the nature of the application at hand.
So, what is unique in these three types of anti-reflective products?
3.6. Anti-reflective Spray
This is one of the most efficient ways to apply anti-reflective coating on surfaces. Like other spraying products, the anti-glare spray or anti-reflective sprays come in cans.
You’ll find them in either metallic or plastic cans.
Kenro anti-reflective spray
By pressing the top spraying system, it atomizes the anti-reflective solution. This releases very fine droplets of anti-reflective substrates that are deposited on the surface.
For a fact, this is a simple process that you can do at home. All you need is a high quality anti-reflective spray.
Here, the anti-reflective or anti-glare in this case comes in the form of a solution in a can.
In most cases, you can use anti-reflective spray on numerous surfaces such as glass, polycarbonate or metal surfaces. For instance, there is the anti-reflective spray for goggles and vehicle plates.
Photo Credits: eBay
Remember, it’s only by choosing high quality anti-reflective spray that you will eliminate any possible reflections on the surface. It is the only sure way to improve visibility.
Again, depending on the ingredients of anti-reflective spray, it may have anti-fog and anti-static properties. This implies that, by spraying a surface with such substrates, it will not only eliminate reflections, but prevent accumulation of charges and fog.
You will learn more about consolidating anti-reflective with other coating technologies in chapter 7.
3.7. Anti-reflective Film
This is a thin film made from polycarbonate or acrylic (PMMA) sheet with anti-reflective properties. Depending on the type of film, you may have:
- PMMA anti-reflective film or PMMA anti-glare film
- Polycarbonate anti-reflective film or Polycarbonate anti-glare film
With appropriate substrates, these AR films eliminate any possible surface reflections on various surfaces such as polycarbonate, glass or acrylic.
In most cases, anti-reflective films have a self-adhesive property, allowing it to stick on the surface where you intend to eliminate glare. Whether you need one for solar panels or goggles, anti-glare films diffuse harsh reflections from sunlight or any other source of light.
You can conveniently install the anti-reflective films on windows, TV screens, smartphone screens, glass partitions etc.
A thin film
The good news here is that, an anti-reflective coating may also have anti-scratch and anti-fog properties. Basically, you can consolidate it with other coating technologies.
This makes it a multipurpose accessory in the industry.
Still on anti-reflective substrates, another option is:
3.8. Anti-reflective Sheet
An anti-reflective sheet or anti-glare sheet is basically a polycarbonate, PMMA, glass or any other sheet of material with anti-reflective substrates. Like the anti-reflective spray and film, it eliminates possible reflections and glare on surfaces.
With the current advancement in technologies, you can use anti-reflective sheets as anti-glare screen for laptop, anti-glare windows, anti-glare lenses, etc.
Anti-glare on speedometer
So basically, you can use these anti-glare sheets on numerous optical surfaces.
Now, what’s the bottom line here?
Choosing an anti-reflective spray, anti-reflective film or anti-reflective sheet will depend on your unique applications. As you have also seen, you can consolidate all these anti-glare solutions with other coating technologies to make them multipurpose.
And, even as I conclude this chapter, it is important to note that:
There are a range of anti-reflective solutions that are available for virtually all applications. The choice of a particular coating or substrates will depend on your unique requirements.
With these in mind, let’s go a step further and understand how anti-reflective coating works.
How does the Anti-Reflective Coating Work
With the information you have learnt in chapters 2 and 3, now I want to introduce you to how anti-reflective works.
It is simple and a fascinating technology.
Typically, there is a significant physics behind how AR coating works. However, my interest in this case, is not to put you through some of the scientific phrases and formulae in explaining this phenomenon.
Before that, I want you to have a recap of what you’ve learnt so far. Here is a 2.30 min video for that by John Davis:
Now back to the main subject of this section.
Don’t worry I will make everything simple for you to understand.
When you look at an object, you’ll realize that there is a light reflecting from it.
Photo Credits: END MYOPIA
Any particular object tends to reflect light from it. The moment an object reflects light from the lenses of your eyeglasses, glare is created which inconveniences you from seeing other objects clearly.
So what anti-reflection coating does is enabling the light that is reflected from the object you look at and go through to get rid of the reflection or glare.
In some cases, you’ll realize that when you’re wearing sunglasses, you can notice the reflection of your eyes inside the sunglasses.
However, when you add anti-reflection coating at the back of the glasses, it allows the light to go through and get rid that reflection.
In a simple understanding:
The ARC absorbs apart of the reflected light and reduces or fully eliminates the reflection of light.
It also implies that the anti-glare coated eyeglasses allow more light to get through the lens, which consequently improves your vision.
Most of the AR coatings are designed with transparent thin films structures that contain alternating layers of contrasting refraction.
I hope you remember the discussion in chapter 2. If not, you can go over it again.
4.1. Anti-reflective Coating Thickness Calculator
Essentially, it is critical to understand is that the transmission properties of a coating considerably depend on the wavelength of light that is used.
In addition, it also depends on the angle of the incident light, substrate’s index of refraction, the thickness of the coating and the coating’s refraction index.
The idea behind ARC in this instance is that the manifestation of a double interface by using a relatively thin film that provides two reflected waves.
The coating is formulated in such a manner that the corresponding phase shift between the beam redirected at the lower and upper boundaries of the thin film ranges at 180 degrees.
A caustic interference occurs between the two reflected beams. What follows is cancellation of both beams before they exit the surface.
For this to happen, the optical thickness of the coating needs to be an odd number of quarter bandwidth range.
It is the only way that you can attain the anticipated path difference of one half bandwidth range between the reflected beams, which subsequently results in their cancellation.
Below are links to some calculator that you will find useful when it comes to this:
- Anti-reflective Thickness Calculator – by the Brigham Young University
- Thin Film Optical Coating Calculator – by CALC TOOL
- Reflectance Calculator – by Film Metrics
Now, away from rather a technical aspect, let me take you to what most people would like to hear.
So why do you need an AR coating?
Benefits of Anti-reflective Coating
The essence of the anti-reflective or anti-glare layer is to reduce or eliminate light and ultimately enhance vision. Nonetheless, let’s look at some of the advantages of AR coatings;
5.1. Improves Vision and Reduces Eye Strain
One importance of this is that it protects your eyes from excessive straining. Have it mind that when your glasses do not allow enough light to pass through, your eyes will tend to sprain merely because you’d be struggling to see.
What AR coatings do is primarily to eliminate all the reflections from the back and front surfaces of your eyeglass lenses.
The moment reflections are no more; enough light passes through the lenses of your optical product.
This enables the product to optimize the visual acuity that has less interference more so during the night hours.
Comparing anti-glare lenses at night – Photo Credits: STANTON OPTICAL
The result is that you obtain a clear, sharper natural and brilliant vision that what you’d otherwise get with uncoated lenses.
Significantly, it increases your efficiency and productivity at work even when working on a computer for reasonably long.
The anti-reflective coating will protect your eyes and at the same time reduce glare; which leads to less eye strain. This is irrespective of how long you stare at the computer screen.
5.2. Improves Safety while Driving
Typically, driving at night is often strenuous. Lights from oncoming traffic as well as the street lights can be overwhelmingly blinding.
When you’re wearing glasses, the lights can be o destructive owing to the fact that they are not stationary.
This can lead to serious accidents given that reflection of the streetlamp and or traffic headlights can interfere with your vision.
What to expect without AR coating: Photo Credits: NIGHT VISION
When you get an anti-reflective coating on your glasses, you can be sure that the reflection of these lights will be eliminated.
Consequently, you’ll be able to easily recognize the potential hazards that are on the road and avoid them accordingly.
This is important since it guarantees both your safety and that of other road users so that you avoid unnecessary accidents.
5.3. Enhancing your Appearance
When you consider doing an anti-reflective coating on your optical elements, be sure that your overall impression will also improve.
The ARC tends to make somewhat your glass lenses invisible, which is a considerable way of enhancing your appearance by attracting more attention.
The ARC eliminates all the light reflections that the other people would see in your prescription glasses.
This also makes it possible for you to maintain excellent eye-contact when having direct engagement with other people.
Comparison of surfaces with and without AR – Photo Credits: DAGNYZENOVIA
The significance here is also that it makes conversation relatively easy with others given that they will also not be hindered by disrupting reflections.
5.4. Improves Quality and Durability of Lens
Buying optical glasses and other related elements can be a strenuous and expensive investment.
Therefore, you need something that can also last for a comparatively long duration before thinking of replacing it.
Photo Credits: ALL BOUT VISION
Anti-reflective coating can in a significant way help in enhancing the quality of your lenses. Additionally, it can also make the lenses to be durable, resistant to scratch, dirt, and water.
The overall advantage, in this case, is that you will end up saving a significant amount of money when you consider going for an anti-reflective coating.
5.5. Protects your Eyes from Sunlight
What you ought to realize is that the direct sunlight is dangerous for the skin around your eyes. When you go for AR coating, you’ll be able to protect your eyes from the harmful UV rays.
These UV rays increase the risk of contracting cataracts and also premature aging of the skin that is around your eyes.
So when you get lenses with AR coating, you’ll be preventing such incidences from occurring on your body and eventually improving your wellness.
As you can see, AR coating ensures you’re safe at all time.
Now, how can you apply this coating on a surface to enjoy all its benefits?
How to Apply Anti-reflective Coating
Applying AR coating is a relatively intensive procedure that takes place in an optical laboratory in a process involving vacuum deposition technology.
Below is a video by OPTOTECH GBH showing anti-reflective coating machine:
It essentially involves fusing or baking of special chemical layers in a process that can last for many hours to complete.
Here are a few steps you should follow:
Step 1: Choose the Lens or Surface to Apply the Anti-reflective Coating
The first thing that you need to do in this process is to obtain the copy of your glasses prescription that you currently use.
Or, get the lens you intend to coat.
Step 2: Clean the Surface
The lenses are cleaned meticulously and inspected whether or not they have visible and microscopic surface blemishes.
The law clearly requires that you have to get your prescription from your optician. After that, you can consider ordering the AR lenses from the reliable and recommended optical dealers or online stores.
Note the following:
- An anti-reflection coating can only be applied to new lenses.
- Avoid using anti-glare coating on optical lenses that have already been worn.
The process involves a production line that includes numerous washing and rinsing baths. One of them includes the ultrasonic cleaning. It helps in getting rid of any traces of surface defects.
Step 3: Begging Applying the Anti-reflective Coating
There are different ways of applying the AR coating.
You can spray the coat on and then expose the lens to relatively high temperature.
The process should take some few hours on the heat. What follows is that the high temperature causes the liquid solution to harden somehow and therefore adhering to the lens.
This process is relatively intensive and requires undivided attention given that you have to get it right.
Remember if you fail to observe some little aspects of the procedure, you’ll end up messing your lenses. To an extent, the AR coating won’t be sufficient.
You can adopt a vacuum application system.
In this case, the lens is taken and put inside a comparatively large machine. It is inside this machine that it is then coated using a specific liquid.
The combination of the vacuum process with a high-intensity heat leads to a hard film of anti-reflective coating. This film is resistant to scratch and also adhering to the lens.
Alternatively, you can opt for fabrication process. This ordinarily happens at a particular time when the lens is manufactured.
What happens is that during the production of the lens, the AR coating material is by default built into the lens.
This is then distributed throughout the lens hence creating a uniform anti-reflective layer.
The good thing with this particular method is that in any event that the anti-reflective film becomes defective or scratched, it can easily be removed.
What follows is that the removal of the layer will eliminate any form of discoloration that is caused by scratching or crazing.
In line with the ways of application of ARC to the lenses, two fundamental questions arise;
Is it Possible to add ARC when Purchasing?
The answer is yes. As a matter of interest, it is necessary to apply the anti-reflective coating on your eyewear the moment you’ve settled on the particular product.
The dealer will integrate it during the manufacturing process, which in the long run turns out to be effective and affordable.
It might not inherently require a thorough process since most of the dealers have the frame inventory that enables them to select the respective one.
All you need is prescription from your optician or the relevant eye physician.
Can you apply ARC after Purchasing the Lens?
The answer to this question is also a resounding yes. Expectedly, you could be reading this post already wearing your eyewear that you obtained long time ago.
Ideally, it is always preferable to apply this coating during your lens purchase. Nevertheless, adding the anti-reflective layer is still possible.
The only fundamental aspect that you have to bear in mind while thinking of this is to ensure that your product has never possessed this option before.
So, assuming you’ve never done it before and you’re considering doing it right now. First, you must ensure that;
- The lens is not exposed to skin oils because it might fail to adhere so that it sticks as appropriate as required.
- Ensure that lens dos not have scratches. The essence here is that the coating will end up magnifying the scratches such that it even becomes worse to wear.
I will address more of these questions, in chapter 8 – just keep reading to learn more.
So, what’s the bottom line here?
You need to have the right tools and accessories to apply anti-reflective coating. Besides, it is a delicate process so you must be cautious in every process.
Consolidating Anti-reflective with Other Coating Technologies
The truth is that an anti-glare coating alone on surfaces will not guarantee 100% safety. In fact, the reflection of light is one out of the many phenomena that blur vision.
The good news is:
You can consolidate anti-reflective coating with other coating technologies. By doing so, you can easily have an optical class 1 surface.
Let’s discuss the various coating technologies you can consolidate with anti-glare:
If you expose lenses to the UV lights, millions of photochromic molecules that are contained in the lens start to alter in structure.
Apparently, it is this particular reaction that makes the lens to start becoming dark. So primarily, all the lenses that adapt to light tend to utilize photochromic molecules.
This is what happens on photochromic materials:
Two processes determine the how photochromic becomes an integral element of the lens.
One of these processes is known as imbibing. It is a method that uses heat to induce the photochromic dye into the lens.
When the imbibing process is over, a particular scratch-resistant is smeared on the surface of the lens. You, however, need to understand that several materials do not imbibe easily.
In instances where the imbibing fails, another process known as the photochromic is utilized. This is quite different from imbibing.
Imbibing process puts the photochromic technology below the surface of the lens while photochromic process places the technology on the surface of the glass.
Both the imbibing and photochromic methods offer similar uniform tint irrespective of the thickness variance that can be caused by lens prescriptions.
One element you’ll realize with photochromic and phochromic technologies is that they react to UV light.
It is the reason most of them tend to change especially when you are in the sun, but when you’re indoors, they maintain clarity.
For instance, the car windscreen glass can block up to 99% of the UV light. It thus suggests that most of the photochromic lenses do not offer enough darkening inside the car.
Now, the good news is, you can consolidate this technology with anti-glare coating. This provides better eye safety.
In fact, you don’t have to carry an extra lens with you.
7.2. UV 400 coating
The adverse effects of the sun and UV radiation to the skin are apparent. It thus makes a UV protection one of the essential products that you can buy to protect your skin.
The eyes are ordinarily susceptible to damage caused by the sun. UV 400 shows eye protection that is augmented to prevent exposure of your eyes to UVA and UVB radiation.
One of the outstanding features of the items that are covered with UV 400 is that they can block the light rays as small as 400 nanometers.
It thus implies that UV 400 keeps away close to 99.9% of the sun’s harmful radiation from your eyes. Typically, this makes a significant difference in your eye protection.
UV 400 coating is integrated into a wide range of eye protection products including sunglasses and some safety goggles.
Photo Credits: EYE VISION AMERICA
When purchasing UV 400 coated items, it is always vital to ensure that they have a sticker that indicates they have been tested for UV 400 protection.
At times, you may find they are labeled that they can offer 100% of UV radiation. This, however, depends on particular manufacturers.
Again, the truth is:
The anti-glare coating will only eliminate reflections however it cannot filter all the harmful UV radiations. So, as much as you focus to eliminate glare, it is important to eliminate harmful UV radiations too.
The good news is that you can have the UV 400 protection alongside anti-reflective coating on one surface.
7.3. Anti-Fog Coating
These are also referred to as non-mist coatings. They are essential for eyewear and a number of externally located devices and signs.
If you reside in a comparatively cold type of weather, you can attest that it is so frustrating to have your eyeglasses fog up when you come from the cold.
Apparently, this can also be regarded as a safety concern given that your ability to have a clear vision is limited until the fog clears.
Lens fogging are often formed by tiny water droplets that condense on the eyeglass lenses’ surface. This happens when the lenses become considerably cooler than the immediate air temperature.
So what most of the anti-fog coating manufacturers often do is creating a permanent film designed to get rid of this problem.
One of these fascinating technologies is the WeePro Anti-fog Visor Insert. You can see the product in the video below:
Others include anti-fog sprays and anti-fog coating.
They all get rid of the condensation of moisture that gets into the lenses that tend to cause fogging.
What follows is that you maintain clear vision whenever you transit from a relatively cold surrounding to a warm one.
This technology also prevents your lenses from fogging up during sporting activities as well as during other occasions when you’re perspiring.
Essentially, the role of anti-fog coating technology is to uniformly spread the water droplets across the surface of the lens so that they become invisible. Of course, this is the situation with hydrophilic anti-fog coating (by far it is the most popular).
The anti-fog coating can be applied to a wide range of elements including eyeglass lenses like photochromic lenses. They can also be used on polycarbonate and plastic among others.
Anti-fog coating is often applied to the lenses before they are cut to fit into your frame. They use either flow or dip coating.
Now this is the good news:
You can have an anti-reflective coating on the outer surface of the lens with an anti-fog on the inside section. This way, the surface will not only eliminate glare, but also remains free from any kind of fog.
7.4. Anti-scratch coating
The truth of the matter is that there are no polycarbonate or glass surfaces that are resistant to scratch.
But the good thing is that if you find a lens that is treated back and front using a clear scratch resistant material, it becomes scratch-proof.
The best news in this regard is that presently, most of the lenses including the high index ones have a built-in anti-scratch coating.
Anti-scratch coating is vital because they enhance the durability of the lenses. But you also need to be concious of the fact that even the best anti-scratch coatings don’t guarantee complete lens protection.
Surface with/without anti-scratch coating
They can still wear and tear but to prevent this, you can choose to clean them using a microfiber material and store them in a well-cushioned case.
You also need to be cautious of the products that promise to mend scratched lenses. Most of them only fill in the scratches but can’t necessarily make the scratches to disappear completely.
Again here, you can consolidate anti-glare coating with anti-scratch coating. Such surfaces provide maximum protection from glare while surfaces remain scratch free.
7.5. Optical Coating
It refers to the combination of thin film deposits that produce interference effects and are used to improve reflection or transmission properties within optical component.
The efficiency of an optical coating depends on the number of layers, the thickness of every film deposit and refractive index at the layer edges.
Optical coatings are designed for a particular incident angle and a specific light polarization like the S-polarization or random polarization.
Lens with an optical coating
These coatings are created by depositing metallic and dielectric materials in sporadic thin layers. The thin layers induce the interference effects required by alternating between layers of the high and low index of refraction.
Like the other four coating technologies, optical coating is no exception. You can consolidate it with anti-glare coating.
As you can see, with an anti-reflective coating, you have unlimited options at your disposal. It depends on the kind of features you want the surface to have – obviously to make it optical class 1.
FAQ for all Your Questions about Anti-reflective Coating
Given that anti-reflective coating is regarded as a relatively new post-modern technology, many questions tend to arise about it.
Anti-glare coating – Photo Credits: ALL ABOUT VISION
In this section, I will try to answer some of the commonly asked questions concerning this technology. The answers will be as brief as possible to give you an idea of what you need to know.
8.1. What is the fundamental difference between anti-reflection and anti-glare?
Anti-glare merely tends to deal with the external sources of reflection off a lens surface. However, anti-reflection tends to deal with both the external and internal sources of light reflection.
8.2. How does AR coating work?
By inducing a modern technology into a wide range of optical elements, it eliminates reflection of light that blur vision. Thus, it enhances vision without you necessarily squinting.
8.3. How do you know that a particular AR coating suits me?
This basically depends on your kind of lifestyle. Upon visiting the physician, he/she will be able to determine the ideal ARC brand for you.
8.4. What are the best ways to care for AR-coated glasses?
First, you need to ensure that you’re cleaning the lenses using the recommended products only. Secondly, ensure that you wet the AR-coated lens before washing them because dry cloth can scratch the lens surface.
8.5. What is the ideal lens material for AR coating?
Always ensure that you go for high index lens material. This one is suitable because it can reflect more light than the ordinary plastic lenses.
It is because the lens material that has a higher index of refraction allows more light to be reflected on the lens surface.
Again, you can use the knowledge I shared in chapter 2 of this guide. Having this background information is handy when sourcing for a new anti-glare lens.
8.6. How does anti-reflection coating contribute to eye-strain?
When the eyes are exposed to too much light reflection, they need to work extra hard to adjust to the fluctuating light intensities. It is this constant adjustment that leads to eye fatigue.
8.7. Is it possible to apply AR coatings on glass polarized lenses?
Yes. In fact, you need to know that when you try to remove the coatings once they have been applied, the lenses will be damaged permanently.
8.8. What is the thickness of anti-reflection coating
Ordinarily, the layer is always an extremely thin film. It should not be thick because it can eventually reduce the effectiveness of the lens.
8.9. Must the AR coatings be applied on both sides of the lenses?
No. the coatings can as well be applied on a single side or both. This, however, depends on the type of coating material used and the lens.
8.10. Can I remove the anti-reflection coatings from the lenses?
It is possible to remove the coatings whenever you deem they are unnecessary. However, you should also note that poly, polarized and hi-index glass can only be removed in the event that you as the customer assumes liability for the damage.
8.11. Can anti-reflection be applied to sunglasses?
Yes. It can be applied to sunglasses as a way of reducing the effects of light that light which passes through its lens cause.
It makes it possible for you to see clearly when you are in your sunglasses, especially on a sunny day.
8.12. How long does applying AR coating take?
The duration varies depending on the process used, the type of element that is coated and the type of material used.
But some would take approximately eight hours whereas others would require about three days.
8.13. How do I know that the company offering AR coating services is authentic?
There is a body that is mandated to regulate all the anti-reflection service providers. You need to confirm the name of that particular company to validate its genuineness.
But more importantly, the reputation and experience of the company plays a critical role here.
8.14. How long can an AR coated lens last?
This depends on the condition and the quality of your lenses. But in general, a quality anti-reflection should last for at least two years.
But for the coating to last even longer, you need to ensure that you take good care of the lenses by cleaning the lenses gently using recommended products.
8.15. Is it possible to repair a coating on lenses?
Yes. It can be repaired rather than replacing the entire coating. Nonetheless, whether that would be somewhat economical depends on the actual value of the lens.
8.16. How much would it cost to have an anti-reflection coating?
The price is dependent on various factors. Most specifically, the type of lens is what determines the price.
But in general, the cost would range from $20 to $100 or even more in addition to the basic lens price.
8.17. Is AR coating ideally necessary for glass lenses?
Yes. It is beneficial to have your glass lenses coated with anti-reflection element. It will enhance your vision.
Besides, it will also prevent your lenses from scratching and ultimately extend the overall lifespan of your glass lenses.
8.18. Can I add anti-reflective coating afterward if I purchased my lenses a long time ago?
Yes, you can.
All you need is to ensure that no attempt of the coating has ever done on your lenses before. Again, the lens surface needs to be scratch-free for the ARC to be effective and durable.
8.19. Should I repair or replace anti-reflection coatings after it wears off?
The particular choice depends on the value of your lens or otherwise what you think would be economical from your perspective.
If the lens is considerably expensive, the right approach would be to replace the AR coating. However, it is relatively cheap than it would be if you rather just go for a new anti-glare coating.
8.20. Can anti-reflection coating be applied to plastic lenses?
Of course, yes. As long as the lenses reflect light to the extent of barring your vision, an anti-reflection coating can be applied to it.
Normally, these are the most common questions I came across in different forums.
In case you have any question or inquiry on anti-glare coating, please leave a short comment below. I will respond to it.
Applications of Anti-reflective Coating
If you may not have realized, an anti-reflective coating is nowadays used in various applications. I’m sure you’ve even used some albeit unconsciously.
In this chapter, I want us to look at these various applications and find out whether or not you can relate to some of them.
Let’s get down;
9.1. Anti-Glare Glasses for Computer
If you’ve ever worked on a computer for long hours, probably you’ve at the very least experienced blurred vision and eye strain. These among others are known as computer vision syndrome.
However, nowadays we have anti-glare computer glasses that allow you to obtain the most comfortable vision and prevent the eye strain.
These glasses are relatively different from the typical eyeglasses. They help in optimizing your eyesight when looking at your computer screen for long.
They have often placed within a range of 20-26 inches away from the eyes of the users. This range is what experts regard as the intermediate zone of vision.
It simply implies that the distance is closer to the driving vision and comparatively far away than the reading vision.
Many computer users often tend to suffer from blurred vision when working on computers without the anti-glare glasses.
Photo Credits: EYE DOCTOR
Worse still; the users also on most occasions attempt to for the blurred vision by leaning towards the computer screen.
So it becomes double trouble for you. However, the glasses provide long-term solution to this particular problem.
9.2. Anti-Reflective Coating for Glass
We wear eyeglasses for different reasons. But above all improving vision would be the main reason for putting it on.
Ironically, you’d be wearing the eyeglasses, but instead of enhancing your vision it gets distorted. And that is where the anti-reflective coating becomes handy.
Nowadays, you do not necessarily have to worry about less light passing through your glasses hence hindering your vision.
Several interventions including integration of the anti-reflective coatings have become phenomenal and effective.
Photo Credits: COOLWINKS
Most manufacturers understand the quintessence of this problem. Therefore, they ensure that they produce glasses that can suit different anti-reflection materials that fit an individual needs.
The good thing again is that anti-reflective coating for glass can also be applied even after purchasing the lens.
9.3. Anti-Reflective Coating Touch Screen
The world is changing and so is technology. These days, virtually all mobile phone manufacturers produce smartphones.
These handsets are operated via a touchscreen unlike the previous models that were using keypads.
In fact, the next generation of youth already anticipates most devices to have touchscreen interfaces.
Photo Credits: OPTITUNE
But manufacturers have come up with anti-reflective coatings for touch screen as a means of providing safety and better vision when using such screens.
It simply involves the application of a particular layer of film to the surface of the cover lens. In turn, this film decreases reflection by canceling the wavelength of light.
These coatings enhance the user-experience when operating the device making it easy for you to obtain best results.
9.4. Anti-Reflective Coating on Solar Panels
This is the other area where AR coating is again commonly used. In fact, it’s not only the solar cells alone that nowadays carry anti-reflective coating.
The AR coating can however also be used on the glass surface that is always apparent on the solar panels.
Photo Credits: MITSUBUSHI ELECTRIC
The essence of the AR coatings on solar panels is merely to enhance the transmittance of light. This subsequently improves the overall effectiveness of the PV module.
Additionally, this coating also reduces the glare from the glass. It thus allows the solar panel to blend with the surrounding easily.
Again, these panels can easily be installed in airports given that they do not have the reflective elements that would probably blind the pilots.
9.5. Anti-Reflective Coating for TV
Most of the TV screens, including the LCDs, LEDs, and plasmas have glassy screens designed to enhance the appearance of the picture.
Nonetheless, if you place your TV in a conservatory or somewhat bright room, it’ll be able to display the reflections emanating from windows, indoor lighting, sun and even doors.
The result is that it somehow makes it difficult to watch TV especially during the day or when the lighting on in the room.
But AR coating for TV screen has made it ideal as it helps to eliminate more than 90% of the reflection without necessarily interfering with the quality of your TV picture.
It is a good idea given that TV is often a considerable investment and this coating helps in maintaining its life for as long as you own it.
9.6. Anti-Reflective Coating Windshield
Windshields are essential components, especially on planes and automobiles. AR coatings are applied to the windscreen since they assist in reducing glare and double images.
Anti-glare coating for windshield – Photo Credit: QUORA
Double images are more of a concern in windshield because they tend to form several layers that can easily destruct the driver.
Most manufacturers often produce the windshield while bearing in mind the concern about light reflection.
For that matter, applying the AR coating on the windshield surfaces has become integral as it significantly improves vision especially when driving at night.
It is also helpful when driving in an excessively lit area since the coating decreases invisibility.
9.7. Anti-Reflective Coating Watch
AR coatings are nowadays used in various types of high-end wrist watches. In fact, it is very rare to find most of these types of watches without this kind of coating.
Wath with/without anti-reflective coating
These coatings are essential in the watches because they help in blocking most of the unwanted reflection.
The AR coatings block the colors in a systematic manner such that the eyes do not get irritated by the common reflection shades emanating from the surrounding.
This coating in most of the high-end wrist watches is applied on both the outside and the inside surfaces.
Other than giving these watches enhanced appearance and patency, they also improve their lifespan. The coatings also help to protect the surface from scratching.
9.8. Other Applications of Anti-reflective Coating
Telescopes and cameras are the other areas where AR coatings are commonly used these days. It is expected that the images produced by these optical elements to be of high quality.
However, this is only possible if the stray light is eliminated from getting to the lenses of these devices.
And expectedly, researchers nowadays go for telescopes that have AR coating in most of the planetary centers.
These kinds of lenses do not cause reflection of lights. This coating can also reduce the glint hence preferable.
ARC is again used in microelectronic photolithography. They help in decreasing the possibility of image distortion related to the reflections that generally occur off the surface of the substrate.
What typically happens during this process is that varied types of anti-reflective coatings are applied either before or even after photoresist.
This is essential in reducing the thin film interference, the standing waves as well as the specular reflections.
In short, AR coating technology plays a pivotal role in most optical devices. It is actually for these unlimited applications of anti-reflective coating that the manufacturers work to improve their performance.
WeeTect Anti-Glare Solution
WeeTect anti-glare solutions feature both films and sheets. The anti-glare films and anti-glare sheets have high grade anti-glare substrates.
So far, WeeTect Anti-Glare Sheet (WAGS) is a perfect choice for most applications.
With the ability to consolidate anti-reflective technology with other coatings, WeeTect strives to produce multifunctional accessories. That is, anti-reflective sheet that not only eliminates glare, but is also scratch and fog resistant.
As a result, the WeeTect anti-glare solutions are popular in many applications such as:
- Screen protectors
- Glasses and lenses
- Shields, etc.
At every stage in the manufacturing process, WeeTect anti-glare solution must pass strict quality testing (I’ll cover more on this shortly). This to ensure it meets the dynamic market needs.
Effect of WeeTect anti-glare solution on surfaces
To meet the dynamic market needs, WeeTect works closely with its global partners and OEM clients. This ensures the anti-reflective coating meets the required quality requirements at all times.
So, how does WeeTect controls the quality of anti-glare coating?
10.1. Optical Tests for Anti-reflective Material
Ideally, WeeTect uses the refractive index test as per the ISO 1183 and total light transmittance according to the ISO 13468-1.
Furthermore, it has also adopted the haze tests as per the WGT-2S.
10.2. Physical Properties of Anti-reflective Material
Again, WeeTect tests the following properties:
- Pencil hardness as per the JIS5600
- Wave deflection
- Scratch resistance according to steel wool #0000
- Flexibility test by bending it to 90°
- Ball drop tests to determine the impact strength by dropping a 36g steel ball
- Adhesive strength according to ISO D3359
- Temperature and humidity resistance at 50°C x 95% x 72hrs
- Hot water resistance at 60°C X 72hrs
- Heat resistance at 80°C X 2 hours
In short, a quality anti-glare sheet or anti-glare film should pass all these tests.
But these are not enough. WeeTect goes further to test the chemical properties of its anti-glare materials
10.3. Chemical Tests for Anti-reflective Material
Here, WeeTect conducts 5 different chemical tests using the following:
- Sulfuric acid (10%)
- Sodium hydroxide (10%)
- Ethyl alcohol
In all these chemicals, there is no change on the anti-glare properties of the material.
Don’t worry you will get this information in the product datasheet. It is one document that you must evaluate before buying any anti-reflective coating.
Product data sheet
So, what do all these imply?
It is not about designing and manufacturing anti-glare or anti-reflective coating. The anti-reflective substrate must pass all these quality tests.
At this point, I believe you can certainly make the right decision when it comes to choosing or evaluating anti-reflective coatings.
Now it’s your turn:
Do you have any questions on anti-reflective coating?
Or, is there any point you’d want me to clarify further?
Well, you can leave a quick comment or send me a private message for free consultations on anti-glare solutions.