Primary Purpose of AR Coating?

[Falstaff]

Parameters which are used to indicate the performance of AR coatings often include values for Bayer Ratios, indications of Adhesion, Resistance to Crazing etc.,(important of course). One parameter which is almost always downplayed though is the Reflectivity. Can anyone enlighten me as to why this may be?

Since the coatings are designed to be anti-reflective, you might expect this to be of paramount importance. It often seems that the reflex colour (a cosmetic property) is more important than the degree of 'antireflectiveness'. It also seems that as long as the average Reflectivity over the visible spectrum is reasonably low, that it is acceptable for there to be a relatively powerful beam of coloured light reflected over a more narrow part of the spectrum.

Am I just being cynical when I am almost dazzled by a flash of green (for example) when someone's 'antireflective' coating just catches the light as they turn their head?

Falstaff (grumpy old man)

[chip anderson]

At many establishements the primary purpose is to add $100 or so to the sale. And a new sale in a year or two when the coating fails.
Other important purposes:
Reduce glare especially from headlights at night.
Allow a greater transmission of light, especially at night and indoors.
Make it seem as though you are more knowledgeable on the science of optics than your previous optician.
Reduce glare seen by others from your spectacles, especially in front of an audience or photographer.

Chip

[Nikolay Angelov]

Am I just being cynical when I am almost dazzled by a flash of green (for example) when someone's 'antireflective' coating just catches the light as they turn their head?

Whew, it's not just me then .

I had to select stock lenses for express service so i ordered plano lenses to compare. The idea was to test abrasion resistance and other properties in controlled tests.
The more lenses i received the more obvious it became that there are difference in the performance of the AR.

How i compared:

1. Clean and dry lenses perfectly (wash)
2. Place two lenses on black surface convex side up (back of a book etc.)
3. Go outside and look at the lenses, from the front and compare the reflection strength and color uniformity.
4. Then tilt the book or whatever is your black lens holder (while holding the lenses :)) and compare the reflection intensity and color uniformity from oblique angles.

I went and compared some plano stock lenses:

1. Zeiss Clarlet 1.5 LotuTec
2. Zeiss Clarlet 1.5 Combi NT
3. Hoya Hilux 1.5 HiVision LongLife
4. Hoya Hilux 1.5 Super HiVision
5. Some budget lenses (different suppliers).

Here are some photos of the lenses in question. Click the images for (mutch) higher resolution.

1. Oblique view on (left to right) Hoya SuperHiVision ; Hoya LongLife:



2. Oblique view on (left to right) Hoya LongLife ; Zeiss LotuTec:



3. Oblique view on (left to right) Hoya SuperHiVision ; Hoya LongLife ; Zeiss LotuTec ; Zeiss Combi NT:



4. Normal view on (left to right) Hoya SuperHiVision ; Hoya LongLife ; Zeiss LotuTec ; Zeiss Combi NT:

One parameter which is almost always downplayed though is the Reflectivity.

On the plus side, this is one of the few parameters at the moment that you can evaluate with no extra equipment (just your eyes).

Since we observed the differences, AR performance and aesthetics became an important factor in selecting lens suppliers/manufacturers. So downplaying it is probably not a good business move.

[nawsman]

geographically speacking, we do not recomend any standard Antireflection coating, do to were are located (Middle of the Mojave Desert) we have constant problem to to the extreme temps we get. We alway recomend premium AR's and we do not get problems associated with Heat.

[chip anderson]

Nawsman:

I have yet to find a "premium" or less than "premium" coating that I have not at one time or another had a problem with heat with. What "premium" coatings are you using that are not so affected? I know it ain't made by Zeiss or Varilux while these are pretty good coatings they sure can be damaged by heat and/or time.

Chip

[mike.elmes]

geographically speacking, we do not recomend any standard Antireflection coating, do to were are located (Middle of the Mojave Desert) we have constant problem to to the extreme temps we get. We alway recomend premium AR's and we do not get problems associated with Heat.

Put them on the dash and see how they last.