Question about AR coatings

[Biblebanger]

I posted in my review of the Planet Ocean(which is new on the reveiw page ) that one of my gripes with the PO was the AR coating. I have two questions.

Has anyone ever had or seen a scratched AR coating? Any pics?

Has anyone ever removed or know of a system of removing it?

I would never try remove it at this stage, but if I ever took a chunk out of it or scratched it badly I would probably consider it.

[padi56]

Originally Posted by Biblebanger

I posted in my review of the Planet Ocean(which is new on the reveiw page ) that one of my gripes with the PO was the AR coating. I have two questions.

Has anyone ever had or seen a scratched AR coating? Any pics?

Has anyone ever removed or know of a system of removing it?

I would never try remove it at this stage, but if I ever took a chunk out of it or scratched it badly I would probably consider it.

Your sapphire crystal is equipped with an AR coating, limiting to a very low level the reflection on the crystal, bringing the glare almost to zero except for a very little purple glare.

For more complex AR coating such as the coatings for watches, multiple layers are deposited in order to create a multiple destructive interference between the waves, bringing the reflected light to almost a zero level.

The main problem of an AR layer is that it is only valid for ONE wavelength (one colour), but sunlight consist of a large variety of visible colours from violet to red, therefore an AR coating could not offer the minimum reflection for ALL colours and that is why you see purple reflection like a quality coating on a camera lens


The drawback of double side AR coating is the scratch resistance - the oxides deposited on the sapphire (DO NOT offer) the same scratch resistance compared to bare sapphire - that is why you CAN scratch a coated sapphire : you do not scratch the sapphire by itself (it can only be scratched by sapphire or diamond) but you simply scratch its coating.Omega only coat the dial side of crystal I believe.But firms like Breitling coat both sides and have a slightly different formula more like a coated camera lens.


Is it scratch resistant??
Yes but not as much as sapphire, something in between glass and sapphire but far better than plastic.

Is it possible to re-coat a scratched sapphire?
Yes but it will cost you a fortune for a single crystal, but when a manufacturer coats them they put hundreds of crystals in the evaporator.It would be much cheaper to replace the crystal.

[JJ Irani]

Originally Posted by padi56

Your sapphire crystal is equipped with an AR coating, limiting to a very low level the reflection on the crystal, bringing the glare almost to zero except for a very little purple glare.

For more complex AR coating such as the coatings for watches, multiple layers are deposited in order to create a multiple destructive interference between the waves, bringing the reflected light to almost a zero level.

The main problem of an AR layer is that it is only valid for ONE wavelength (one colour), but sunlight consist of a large variety of visible colours from violet to red, therefore an AR coating could not offer the minimum reflection for ALL colours and that is why you see purple reflection like a quality coating on a camera lens


The drawback of double side AR coating is the scratch resistance - the oxides deposited on the sapphire (DO NOT offer) the same scratch resistance compared to bare sapphire - that is why you CAN scratch a coated sapphire : you do not scratch the sapphire by itself (it can only be scratched by sapphire or diamond) but you simply scratch its coating.Omega only coat the dial side of crystal I believe.But firms like Breitling coat both sides and have a slightly different formula more like a coated camera lens.


Is it scratch resistant??
Yes but not as much as sapphire, something in between glass and sapphire but far better than plastic.

Is it possible to re-coat a scratched sapphire?
Yes but it will cost you a fortune for a single crystal, but when a manufacturer coats them they put hundreds of crystals in the evaporator.It would be much cheaper to replace the crystal.

Bloody brilliant!! Thanks, Padi!!!

[Biblebanger]

Wow! That is interesting information to know. I guess that is why the camera lenses have the tint to them as well.

Actually the Planet Ocean has the AR on both sides as well. Just like my Breitling Steelfish. It is really noticeable in this pic.

[JJ Irani]

If memory serves me right, all OMEGAs have AR coating on the underside of the crystal, but only the PO and Broad Arrow have it on both sides.

Breitling, on the other hand, have the AR on both sides, giving that bluish tint in certain angles.

Rolex, of course, don't believe in AR coating at all....none of their models have it!!

JJ

[padi56]

Originally Posted by JJ Irani

If memory serves me right, all OMEGAs have AR coating on the underside of the crystal, but only the PO and Broad Arrow have it on both sides.

Breitling, on the other hand, have the AR on both sides, giving that bluish tint in certain angles.

Rolex, of course, don't believe in AR coating at all....none of their models have it!!

JJ

Well thanks for that on the Omega PO coated both sides,have heard a few rumours that Rolex intend AR coat.