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Polarized glass?
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Author:  nickzac [ Sun Oct 28, 2012 7:18 pm ]
Post subject:  Polarized glass?
Any idea if any maker has used a polarized glass? Breitling's double-sided AR is awesome in looks (a huge step above anything else) but too fragile relative to the rest of the watch IMO. Sapphire is stupidly hard but you really don't get the advantage of it because the AR coating gets messed up so much easier. My Maui Jims have a polarization that is unreal in reducing glare. Theoretically, polarization wouldn't wear off like an AR coating, and wouldn't be exposed on the external portion of the super hard sapphire...but I say that theoretically as I haven't a clue how it would work with watches.
Author:  Kodiak [ Mon Oct 29, 2012 6:35 pm ]
Post subject:  Re: Polarized glass?
I'm sure it can be done, but then don't try and tell the time with polarized sunglasses (dial will black out). A lot of aircraft instruments have polarized glass and one cannot wear polarized sunglasses when flying for this reason (I wore high quality real glass non-polarized lenses).
Author:  nickzac [ Mon Oct 29, 2012 10:02 pm ]
Post subject:  Re: Polarized glass?
Kodiak wrote:
I'm sure it can be done, but then don't try and tell the time with polarized sunglasses (dial will black out). A lot of aircraft instruments have polarized glass and one cannot wear polarized sunglasses when flying for this reason (I wore high quality real glass non-polarized lenses).


Woah...I never knew that! I am guessing that is why guys who fly seem to like the Mosley Tribes with their sort of photogenic but non-polarized coating?
Author:  RJRJRJ [ Wed Oct 31, 2012 2:41 pm ]
Post subject:  Re: Polarized glass?
Also, im pretty sure polarized glass will be completely blacked out at certain angles.
Author:  Scuba Mike [ Mon Dec 17, 2012 1:29 am ]
Post subject:  Re: Polarized glass?
Light reflected (any electromangentic wave) off a surface will be polarized, hence polarized glasses block the glare. Having polarized glass would not be able to replace AR coatings (work by destructive interference). If you were to wear polarized glasses with a watch with polarized glass you may not see anything (depends on the orientation of the polarizer in the glasses and angle of polarised reflected light).... think about using polarized sunglasses and an LCD screen....
Author:  nickzac [ Mon Dec 17, 2012 4:14 am ]
Post subject:  Re: Polarized glass?
Damn. It was a thought. I guess there really isn't anything better than the AR coating as far as function/durability is concerned? While I hate how easily the outer AR is damaged, I love how it increases the watch's functionality.
Author:  Scuba Mike [ Mon Dec 17, 2012 4:19 am ]
Post subject:  Re: Polarized glass?
I have to admit I hate the double ARC from Breitling especially for someone who uses them as everyday watches... I know some people who just buff the top AR coating off to make the watch more functional.
Author:  nickzac [ Mon Dec 17, 2012 4:26 am ]
Post subject:  Re: Polarized glass?
I can understand...you really can't get your money's worth for the sapphire crystal with the coating. It looks so good at first but it wears quite easily if the watch is an every day wearer. Some people hate the purplish tint...I really don't mind that personally but I'm not a fan of how it takes 10x more effort to clean than a non-ARd coating and how you're talking $350+ each time you scratch it and want it to look like new again. I like the added angle of viewing but it comes at a price.

I'm guessing by your username you do a lot of scuba stuff...do you think it has any value for diving? I've never had an issue reading my Seikos or Citizens underwater, and I dont think they had a coating at all...and I don't believe the Rolex divers do either.
Author:  Scuba Mike [ Mon Dec 17, 2012 4:38 am ]
Post subject:  Re: Polarized glass?
unfortunately I have not any diving for a few years due to work commitments :(.. though I seem to have time at work for watches

AR coating would not really do anything under water. The reason for this is that the coating would be designed to work for specific refractive indexes, i.e. glass/air. Having a glass/water interface means that coating would not be of much use well at least the coating on the top.

Rolex being the super conservative company they are dont put AR coatings on their crystals. However, on my GMT they have decided to put an AR coating on the cyclops, which is the only place I have a scratch on the crystal. So i think its best to have the AR coating on the inside, else it really defeats the purpose of having sapphire....
Author:  nickzac [ Mon Dec 17, 2012 5:29 am ]
Post subject:  Re: Polarized glass?
They only put it on the cyclops? That is interesting...is the date hard to read on it? The other complaint I have about AR is that once a glass is coated in it, it cannot be recoated without imperfections and lesser durability (hence Breitling has to replace scratched ones). I'd assume Breitling's decision to use it was based on the need for anti-reflective properties for pilots, whom would only have a second to take a cursory glance at the watch and may be in very sunny conditions, when the properties of the double AR really shines. Also, removing it is a lot simpler than getting it done by someone else if it did not have it, so I guess that played into their decision as well?
Author:  Scuba Mike [ Mon Dec 17, 2012 5:50 am ]
Post subject:  Re: Polarized glass?
no issue reading the date at all, just rolex being rolex....

Yes thats correct, there will be imperfections. They would need to completely remove the initial coating before reapplying a new one. This would be the case if they were using a sol gel or evaporation deposition methods for applying the coating (I would guess they are using evaporation deposition method - for a previous project we were developing an AR coating as a solgel but solgel give bad yield and not as good results as evaporation)... The joys of opitcs and the issues with optical engineering... Prefer working with electronics for obvious reasons
Author:  Scuba Mike [ Thu Dec 20, 2012 1:35 pm ]
Post subject:  Re: Polarized glass?
Any idea if any maker has used a polarized glass? Breitling's double-sided AR is awesome in looks (a huge step above anything else) but too fragile relative to the rest of the watch IMO. Sapphire is stupidly hard but you really don't get the advantage of it because the AR coating gets messed up so much easier. My Maui Jims have a polarization that is unreal in reducing glare. Theoretically, polarization wouldn't wear off like an AR coating, and wouldn't be exposed on the external portion of the super hard sapphire...but I say that theoretically as I haven't a clue how it would work with watches.
---------------

It depends if the polarizing is due to the material of the crystal or a polarising film. If the film is on the inside it will be protected from scratches. However, if its a film like lets say the top polarizer on an LCD screen (Laptop, ANY LCD display) which is made from cellulose acetate then it may degrade due to UV exposure, so being out in the sun may not be good for it.... however I am sure that its possible to add UV stabalizers to it....

I have a pair of Cartier glasses which have a great polarized lens. However, I find that it gets annoying when using my phone or an atm (anything with an LCD screen) as you get that rainbow effect, same as car windows. For those of you interested in the basic physics behind this is called birefringance, I will let Wikipedia fill you in on the theory . It has a useful effect as the rainbow effect you see is due to internal stress in the opitcal medium (glass, plastic). I have used this phenomenon in the past when working on a project where we were making clear optical parts out of polycarbonate for an infrared military application and we needed to be able to quickly see the amount of internal stress in the molded parts and how different molding parameters (temperature, pressures) effected the amount of internal stress... the pic below shows a plastic part placed infront of my laptop screen then the part and then my sunglasses (any polarizer would work).

Image

for those still reading... this part was molded under about 120T of pressure, this amount of pressure is so high that any air trapped can cause the plastic around it to ignite... basically same principle as a diesel engine... sorry for getting a bit technical... I'm new to the forum and being an engineer with a physics background I just love knowing how things work and why....
Author:  nickzac [ Sat Dec 22, 2012 12:14 am ]
Post subject:  Re: Polarized glass?
Very interesting! (and a little over my head)! So does that mean if Breitling were to use a polarized coating that they would need to change the pressure the sapphire crystal is under itself?

I have a pair of polarized regular glasses (called Feather Weights Plus) which are polarized and have a scratch resistant coating. In real world usage, they have been very durable. If the viewing issue was not a problem, woud that be an improvement over the AR? From what I've read it sounds like the AR coating itself is pretty hard but watches simply get banged up a lot and often with a lot of force.
Author:  Scuba Mike [ Sun Dec 30, 2012 10:57 am ]
Post subject:  Re: Polarized glass?
nickzac wrote:
Very interesting! (and a little over my head)! So does that mean if Breitling were to use a polarized coating that they would need to change the pressure the sapphire crystal is under itself?

I have a pair of polarized regular glasses (called Feather Weights Plus) which are polarized and have a scratch resistant coating. In real world usage, they have been very durable. If the viewing issue was not a problem, woud that be an improvement over the AR? From what I've read it sounds like the AR coating itself is pretty hard but watches simply get banged up a lot and often with a lot of force.


The internal stress would depend on the manufacturing process for the crystal. I am sure that it would be annealed as part of the manufacturing process for that exact reason to get rid of stress. As far as the crystal being under pressure it should not be under any significant pressure at the surface, being under water would apply pressure but I have not seen any divers with sunglasses on (though its been a few yrs) so should not be an issue.

AR coatings are generally "robust" on watches compared to some other opitcal coatings, but I have accidentally scratched the coatings on my Lings and its the most annoying thing to look at the time and see those damn scratches. But then again, I have managed to scratch the sapphire crystal twice on my gmt
Author:  P51 [ Sun Dec 30, 2012 5:01 pm ]
Post subject:  Re: Polarized glass?
I don't think its a good idea to use Polarising glass on a watch if you wear polarising lens in your glass or sun glasses. One contributes to the other and all you see is black. Found that with the instrument cluster on my vehicle. Centre cluster uses a polarising lens for bright sunny days, and I can't see a darn thing with my polarised sun glasses on. Unless I tilt my head 90 degress in the straight on axis. Useless.

Jim
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