One of the opticians that I work with was explaining to a patient that A/R was imbeded into the lens and is not a coating. After the patient left I explained that it was in fact a coating. Well we got into a heated discussion about A/R . I just want to know how its applied and if it is truely a coating.
It's a coating. It's applied under a vacuum.
You can strip it, so it is a coating. But since it is vacuum sealed it does bond to the surface.
CHRIS? WE need you.
It actually bonds to the base coat/hard coat, it is sealed with a hydrophobic coating.
What about Alize and Carat?
Different base and hydrophobic. Thr AR layer is the same in all brands
This was her point. She said that Essilor reps said that theses coating were baked on and imbeded in the lens. I guess that we will have to ask Pete about this one.Originally Posted by Ryan
I wish Peter Z was here, he makes the AR coating equipment. The only thing thats imbeded in the lenses is Transitions. I think someone is trying to do a fast sales pitch to sell something.
You can order the same lens, with AR or without AR, so the AR is NOT embedded in the lens. Manufacturers love to throw around "molecular bonded" and "substrate matching" to demostrate the adhesion of the coating, but I don't recall anyone saying their AR was embedded.
Anything you apply to a surface, whatever it is, the north wall of your house, the paint on you car, or a spectacle lens is a coating.
Therefore we all know, that coatings can be applied to just about any existing surface by different means from brush to spray or by flowing the liquid, or the newest way is the use of powder coatings. Applied coatings the have to be cured which is usually done with initiation of the process by drying, baking, or the use of UV or now even white light (dentist fillings)
Zeiss discovered in the 1930's that by using a small vacuum chamber they could evaporate silicone dioxide (SIO2, one the purest natural types of glass) onto a microscope or cameras lens surface. This SIO2 layer would form a thin crystal typer layer that would stop light from reflecting of the surface and therefore their instruments would produce much clearer pictures.
Then they went on and and added powdered metal oxydes onto the glass surface which gave the lens the a bluish, greenish, pinkysh or other colored hue.
In the 1950s a italian company in Milan started to coat sunglass colors on spectacle lenses, which of course gave lenses a uniform color dispersed all over the lens . This was the sensation at the time because sunglass lenses had been colored in the mass and had lighter or darker areas depending on the power.
Shrtly after that AR coating came up on a commercial basis on spectacle lenses and this was still all on glass lenses.
When plastic lenses became popular in the 1970's a few companies started to try AR coatings on the plastic. AR coatings on plastic lenses started to become more popular in the 1980's
The SIO2 would not adhere to the CR39 and the AR would delaminate partially in a short time and become unsightly. Unhappy customers would complain about this fact. By 1986 a Chris Ryser discovered a non dangerous way of removing AR coatings in seconds in a way that every optician could do it in house.
Slowly the different AR coating companies found out that by placing a so called hardcoat (easy to understand for opticians), that would adhere to the basic lens and the SIO2 glass layer would also adhere to the hard coat. Now we had a working AR coating.
AR coatings had a big draw back. They smudged and got dirty real fast which drove poeple up the wall and many did not want them anymore. Cleaning was hard to do because dirt and grease got into the gaps of the crystals of the coating layer.
In 1987 Chris Ryser in conjunction with Jack Jew of I-Coat came up with the first hydrophobic treatment which sealed these gaps and made the AR coated lenses easier to clean. This idea along the way has been used ever since in different ways of applications.
A few short years ago some companies started to apply another top coat over the hydrophobic, like the Essilor Alize and Solas Teflon which provides a smooth slippery surface which is even better to clean and just about totally seals the surface of the AR layer.
I hope that I have neen able to give you an idea on the makings of an AR coat in a general and understandable way. Of course it is a lot more complex but the basics are all there.
Progress never stops...............I just had a report Friday from an independent AR coating lab in the US that is conducting test's with a new coating material and claims that it has far better resistance and quality to anything that is presently on the market, like "Alize" and "Teflon" and should be available soon through your local distributors and independent coating labs.
Last edited by Chris Ryser; 06-05-2005 at 04:58 AM.
So, is it a coating or not? :D
perhaps it is an inbedded coating. :bbg:
It would make sense that it is a coating. That is how I have always known it and every thing that I have ever read has said that it is a coating. But what I think some of these companies are trying to say is that "our coatings stay on so well they are practically part of the lens."
Thera are no imbedded AR coatings...............they all are applied on the existing lens and have become part of the lens.
Vacuum applied thin film are coatings. Films applied to achieve A/R coatings are applied to the surface of the substrate (in most cases this is the hardcoat applied to the front and back side of the lens). The degree of adhesion can vary depending on many different parameters. The films at not inbedded or absorbed in the substrate like a tint or dye is.
Thanks Pete and thanks Chris:cheers:
I would like to add to this discussion. I think the term coating is one the industry would like to stay away from if possible. A great AR coating would best be described to the end user something like this:
"The Anti Reflective process that we provide is bonded to a thermally cured, (if your lab uses a thermally cured process), hard bearier bonding to help prevent scratches. Then the Anti Reflective process is applied in a high vacuum. This process produces an very durable surface that is much harder than the underlying lens material yet is optically capable of now letting in 99% of the available light compared to non-AR lenses that will only let in a maximum of about 92% of the available light."
Facts to consider about AR. If applied to glass lenses they are almost impossible to scratch off. Depending on the hard coating process and the surface preparation of the hard coating for AR determines the bonding of the AR to non glass lenses.
From a marketing point of view the work coating can tend to mean something that is easily removable.
Technically this process is a variation of a coating process and depending on the surface preparation you get different degrees of bonding and durability.
Thin film coating which is what the Anti Reflection process is are usually not the cause of reported AR failure. The cause is almost always related to surface preparation before the Anti Reflection is applied.
I hope this explains the Anti Reflection process and the related marketing of this feature.
Allen Weatherby
ICE-TECH Lens Technology
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