All the manufacturers recommend only backside AR on polarized lenses. Anybody know the reason for this? Is it technical, or just cosmetic? Does frontside AR do some kind of dammage to the lens?
I am really baffled by this issue.
AR coating of polarized lenses
All the manufacturers recommend only backside AR on polarized lenses. Anybody know the reason for this? Is it technical, or just cosmetic? Does frontside AR do some kind of dammage to the lens?
I am really baffled by this issue.
AR on a sunlens is used to prevent backside reflections. This is only beneficial on the backside. (you won't see the reflection of the your eye in the lens). Since AR increases light transmission it is a disadvantage on the front of a sunlens.
On a clear lens AR is used to increase light transmission. Both side help.
Usually on Backside A/R is used due to the fact that fingerprints and dirt are more visible on a polarized dark surface that has A/R. You can see smudges very easily. The same goes for any Sun Tinted lens.
Most sun lenses are subject to more abrasion than other glasses and don't need AR on the front as the polarisation takes care of reflected glare from the front. AR's are more subject to scratches, etc. so why put them on the front where they will abrade in a short time?
I disagree. I have yet to see an AR lens that has more scratches than a non-AR lens. I have seen many crazed AR lenses.Originally Posted by chip anderson
griffin said:What do you base the above statement on? Fingerprints become easier to see with AR, but this is not the primary reason it is not recommended for the front of a sunlens.Usually on Backside A/R is used due to the fact that fingerprints and dirt are more visible on a polarized dark surface that has A/R. You can see smudges very easily. The same goes for any Sun Tinted lens.
There is not a good reason to put AR on the front.
AR is to increase light transmission. Tinting is to decrease light transmission.
I have AR on both sides of my polarized sunglasses.I think that the additional 3% light transmittance is not significant enough to offset the higher performance of the polarization. Plus, they clean easier.
DragonlensmanWV N.A.O.L.
"There is nothing patriotic about hating your government or pretending you can hate your government but love your country."
DragonLensmanWV said:The AR cleans easier due to the hydrophobic, not due to the AR. Hydrophobic can be applied to the front of the lens without AR.Plus, they clean easier.
I know there is some confusion about this topic but when you, "peel away the onion", AR is not needed on the front of polarized lenses.
Many AR facilities are not experts in polarized lenses, that is why the AR on the back only was not offered by many.
You are abolutely correct.....but, when applying a/r to the front side of an sunglass tinted lens you increase the smudges that appear (kind of a reflection) same as with the dark polarized. At our facility we process approximate 400 prescription sunglases each day. When an order is placed with a/r on both sides from our accounts it is usually an error or a misunderstanding. We acknowledge this with a phone call to confirm that this is what is needed......make sense????????
AW is on target: what purpose would a front side AR have on sunlenses? None. What negatives? Durability decrease and increased light transmission.
Agreed: hydrophobic is nice on all glasses, even/especially sunwear.
Just going by what I have read - and a lot of that is on OptiBoard - I think that there could only be three solid reasons for having sunglasses AR backside only and not back and front - and they are all cosmetic:
1. AR on the front side would tend to highlight or amplify the appearance of smudges or fingerprints on the front of the lenses, as seen by others; as stated (above).
2. The residual or reflectance (green for Crizal; blue for Teflon; etc.) would tend to alter the apparent color of the sunglass lenses, as seen by others, if there was AR on the front; as stated (above). But a gold AR on the front of brown lenses ... not bad from a cosmetic viewpoint, I would think.
3. AR on the front would tend to make the wearer's eyes visible to others - which many seem not to want. (I think that For-Life posted that a few days back ...)
Vulnerability to abrasion and scratches on the front of the lenses, where it is most likely? Seems like a quality AR and informed lens cleaning habits would obviate this point.
Light transmission? I am puzzled by this comment. Is it not merely a few percent light transmission, one way or the other, that could be attributed to AR? And if it is just a small percentage, compared to something like 50% or even 30% transmission for dark sunglasses - would that make any practical difference to the wearer? I don't "see" that AR on the frontside (or not) would make a noticeable difference to the wearer, regardless of whether they have tinted, polarized, Transitions, or Transitions and polarized lenses like Drivewear. It might even be an improvement in terms of visual acuity for the wearer, as it is on clear lenses, without any other drawbacks - aside from the cosmetic drawbacks.
I think I understand that AR on both sides would be a visual acuity plus, in terms of light transmission, when the lenses are clear. Particularly at night. And for lens materials like the higher index plastics that have somewhat lower percentages of light transmission.
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Last edited by rinselberg; 03-28-2007 at 05:47 AM.
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