You can!Originally Posted by skirk1975
Start here:
http://www.optiboard.com/forums/show...nti-reflective
You can!
Start here:
http://www.optiboard.com/forums/show...nti-reflective
The Man, The Myth, The Legend,
Fezz
Rising from the ashes like the great Phoenix
Who cares how time advances?
I am drinking ALE today
-Edgar Allen Poe-
Yes, Trio is Canadian. It is a tealish. In my opinion, ugly.
I have seen some rose/red Ar coats out of the Far East.
The Man, The Myth, The Legend,
Fezz
Rising from the ashes like the great Phoenix
Who cares how time advances?
I am drinking ALE today
-Edgar Allen Poe-
It is a standard AR coating from a large manufacturer, not an in-house lab coating. The exact brand is not really important; if two coatings have the same mean spectral reflectance over the visible spectrum, the blue coating will always "appear" less bright compared to a green coating under daylight viewing conditions because of the difference in the relative sensitivity of the eye for these two colors.Nice photo. That green/yellow "standard" A/R lens is made by who exactly?
Actually, assuming that absorption and scatter are negligible, transmittance is related directly to the reflectance, since any decrease in reflectance results in an increase in transmittance and vice versa (see my post above). Think Conservation of Energy: The light has to go somewhere. Consequently, a lens with a lower reflectance will result in a higher transmittance.However, it seems you're still confusing reflex color with light transmittance though folks. The color you see in the mirror or anyplace else is the reflex - and does not denote anything other than the color chosen by the optical engineers...
Regarding your specific numerical example, a difference in reflectance of 0.4% versus 0.8% should be more obvious to the wearer than a difference in transmittance of 99.6% versus 99.2%, since we are talking about a relative difference in reflectance of 50% (or half as much) compared to a relative difference in transmittance of 0.4%.
That said, while maximizing lens transmittance is important to wearers, the single greatest motivation when purchasing an AR coating is the reduction in reflectance and the associated benefits (better cosmetics, less reflected glare at night, etcetera). So, regardless of whether the wearer will notice a difference in transmittance of 0.4%, they will most likely appreciate a difference in reflectance of 50%, at least at the levels we're discussing.
Darryl J. Meister, ABOM
I'll respectfully disagree. We're not really being given the entire picture here to view, and while some points made above are sound - others...well, let's just say there's a reason we don't use blue A/R. :p *sigh*
Best! :cheers:
100% transmission will have 0% reflection in the mirror will have no reflex, reflection, spots no matter the color. 99.6% will have half that of the 99.2%
lets take it to the extreme, would you buy a lens that has 100% transmittance if available?
if your answer is yes, don't bother saying cause the lens is invisible, they're not related according to your deduction.
I was told by a Zeiss guy once that 100% transmittance was possible, but highly impractical. If you think 99+% shows smudges, try 100%. A 0.25 diopter correction is DOUBLE a 0.125 correction, but the difference is still only an eighth. Same with 99.6% and 99.2%; no practical difference in vision.
92% vs. 100% transmittance is also only a twelveth (an eighth and a half) so technically anyone under 1.5 diopter of correction would appreciate a refraction to .12 more then they would appreciate AR.
I'm not sure whether you're disagreeing with the numerical examples, the photographs, the Law of Conservation of Energy, or perhaps all of it, but I certainly believe that you are entitled to your opinion.I'll respectfully disagree.
You may not use blue AR coatings, yourself, but we happen to sell quite a few lenses with a blue AR coating.well, let's just say there's a reason we don't use blue A/R.
Darryl J. Meister, ABOM
I prefer the blue coating to the green. The blue requires more precision to manufacture and keep consistent and their are slight advantages to the blue optically.
If someone were to say 0% reflectance maybe, but keep in mind if their is a lens their no matter how thin their will be absorption which will never allow 100% transmittance. The formula for the amount of light through a lens is:I was told by a Zeiss guy once that 100% transmittance was possible, but highly impractical.
%transmitance = 100%light entering lens - %absoption - %reflectance
Darryl touched on the absorption in his previous post their are formulas availabel in many of the ophthalmic books that give an estimated absorption for every 2mm thickness, but even lenses less than 2mm are going to experience absorption no matter how negligable the thickness is.
To stabilize AR production you need a dominant color, the most dominant to the eye is green. Unfortunately this goes head on against the nature of AR, to cut down reflection intensity.
I agree with Daryl, shifting this domince out of the green let's say toward blue, offers a solution. I know that moving to the other end, towards red, would not be much of a commercial success. We tried it once and got nasty comments from the more conservative male clientel. For example Teflon was one of the earlier attempts to improve on the green and switch to blue. This makes sense especially from an optical engineering point of view.
Georg Mayer
Better Best then Biggest
Can you explain this a little more?
In the same idea, do somebody can tell me which residual color is better for the eye? blue or green ??
As the eye is more sensitive to the green. Is it better to let more blue pass than green. That maybe why green seem to be a better choice for the eye.
But, in an other way, if the eye is less sensitive to the blue, The reflection will be less apparent with a blue residual color.
Here is the problem with Red. Blue, in my opinion, is a much better colour. In the 90s, Essilor tried to introduce blue with Crizal D to dispensers. Did not work. People wanted green, because green was what they knew. Only Quebec accepted it. When Essilor released Alize, they came with the blue or green. We started using the blue, I think most did not. In stock form, only green is available.
But it is due to creatures of habit. We are used to green, so we want to see only green. Doesn't matter if the other colour is more appealing or not.
It is like trying to convince a 65 year old to use online banking.
Please see also this recent link, more towards the end :
http://www.optiboard.com/forums/show...yer#post318950
If you wanted no Color of Reflection you had to create a perfect balance between residual reflections of the three primary colors (that's why snow is white). This perfect balance of Red-Green-Blue AND to have a low Reflection intensity can not be maintained (there is no way) in production. We are talking of layer thickness variations of a few Angström (1x10E-10 meter) messing up this balance, lens geometry and index of the lens adding variables to the equation.
Therefor it is good practise to choose a color to dominate i.e. stabilize the AR cosmetically to make it reproducable from batch to batch, even from L to R lens within the given technical possibilites of todays AR machines.
Does this explain it ?
Georg Mayer
I like that one !!!! :D
Yes! Thank you!!
Excellent explanation. The bottom line really is that green is more forgiving of slight variations in the manufacturing process and will result in more visual consistency run to run.
OptiBoard Administrator
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OptiBoard has been proudly serving the Eyecare Community since 1995.
So what makes BLUE so much harder to regulate in the batch over GREEN? And would RED be actually better based on it having the highest light transmitence? Is there any research to support the choice of GREEN somehow being most soothing to the eye?
If you wanted no Color of Reflection you had to create a perfect balance between residual reflections of the three primary colors (that's why snow is white). This perfect balance of Red-Green-Blue AND to have a low Reflection intensity can not be maintained (there is no way) in production. We are talking of layer thickness variations of a few Angström (1x10E-10 meter) messing up this balance, lens geometry and index of the lens adding variables to the equation.
Therefor it is good practise to choose a color to dominate i.e. stabilize the AR cosmetically to make it reproducable from batch to batch, even from L to R lens within the given technical possibilites of todays AR machines.
Does this explain it ?
Well how did resolution do "Color-Free" AR ?
They didn't. But their marketing department want's the general public to *think* they did. In reality, it still has a light greenish blue reflex - however, it is reduced from A/R lenses of the past. Most of the premium A/R lenses today are of a similar nature, and generally don't exhibit a large color reflex now.
Another advantage of a "Blue" reflectance A/R is that you are keeping a small amount of short wave blue out of the eye... it could enhance clarity slightly.
Beer is proof that God loves us and wants us to be happy ~Benjamin Franklin
I like this thinking! Though in all reality, I fear the actual effect (if any really) to be far too small to be of any practical benefit. Still....good thinkin! :) :cheers::cheers:
Bri~
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