Talk:Anti-reflective coating
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[edit] Merge #1
Should this page be merged with Optical_coating#Antireflection_coatings? They seem to have extremely similar contents.
- The contents of that section should be merged here, and then that section should be reduced to a summary, with the "main article" template linking to the broader description here. Antireflection coatings are an important enough special case to have their own article.--Srleffler 17:12, 30 April 2006 (UTC)
I agree with Srleffler on keeping the Anti-reflective coating article. myth 00:52, 7 January 2007 (UTC)
Merge complete--Srleffler 05:41, 18 January 2007 (UTC)
[edit] Merge #2
I also think Anti-reflection lens should be merged here. An "anti-reflection lens" is just a lens with an anti-reflective coating. Besides this, though, that term is AFAIK not used at all in optics. From the content of the article, it is presumably used in the consumer eyewear industry. I don't see why opthalmic uses of antireflection coatings can't be covered in a section here instead.--Srleffler 00:36, 18 January 2007 (UTC)
Pro merge and redirect Dr Lind 11:44, 30 January 2007 (UTC)
- Merge complete. --Srleffler 13:15, 30 January 2007 (UTC)
[edit] Nanostructure?
I recall reading some time ago that certain insect eyes have a natural AR coating that works completely differently to the types described in the article. It was a type of nanostructure involving pillars of material on the surface. Scientists were studying the structure with an eye to using it for engineered coatings. Anybody know anything about this? It would make a good addition to the article.--Srleffler 05:41, 18 January 2007 (UTC)
- I found some articles on it and added a section.--Srleffler 06:02, 18 January 2007 (UTC)
[edit] One case where quantum mechanics makes things more intuitively understandable
The current text has:
If this is the case, the incident beam I, when reflected from the second interface will travel exactly half its own wavelength further than the beam reflected from the first surface. If the intensities of the two beams, R1 and R2, are exactly equal, then since they are exactly out of phase, they will destructively interfere and cancel each other. Therefore, there is no reflection from the surface, and all the energy of the beam must be in the transmitted ray, T.
This way of explaining things implies that part of the incident light is reflected and then "destroys" itself. The average well-informed reader may imagine two photons being reflected, one from each surfact, and then "canceling each other," resulting in the loss of two photons. An electrical analogy might be that pairs of electrons and protons would emerge from the two surfaces and that their electrical charges would balance each other so that their charges would not be detectable, but the original lens would thereafter be short the equivalent of a hydrogen atom.
As I understand it, it is a single quantum mechanical probability wave that propagates backwards from surfaces and also propagates forward through the lens. If there is no anti-reflective coating then there is a certain probability that the photon will be manifested on the reflected path, and another probability that it will be manifested on the forward part of its path(s). With the anti-reflective in place, the sum of the probabilities on the merged two reflected paths is zero or thereabouts, and the probability going forward through the lens is enhanced. (If a photon can't be manifested on the reflected path it will have to be manifested on the forward path.)
This kind of anti-reflectivity is correctly distinguished in the article from anti-reflective surfaces that just ensure that, e.g., the image of the sun is not reflected off a glass surface into the eyes of an observer at a certain point but is dispersed so widely that the glass surface is effectively very similar to the bark of a tree or some other such matte surface. P0M (talk) 03:14, 14 March 2008 (UTC)
- I just noted an addition that was reverted. The person who added the misinformation probably did not understand the quantum mechanical explanation for why an extra coating actually increases transmission. If you think about light as a wave phenomenon, it's easy to imagine part of the waves of light heading back toward the source. If that happens it doesn't matter whether the reflections are visible to somebody looking at the lens from the front side. If you think about light as a particle phenomenon, it matters very much whether the particles go through or bounce off the first surface of the lens. If a particle is reflected from the first surface of the lens coating, or it is reflected from the second surface of the lens coating, it is in either case heading back toward the source. But the quantum mechanical explanation is that the waves both go forward and go back, but they are probability waves that determine the likelihood that a photon will be detected at one place or another. If they interfere with themselves so that the probability of a photon being detected in front of the lens goes to zero or thereabouts, the probability that it goes forward is increased. So more photons get through.
- There may be a concise statement of this consequence of QM somewhere that could be cited. P0M (talk) 07:16, 21 April 2008 (UTC)
[edit] odd term
What does the term used in the text, "light deep," mean? Is this a mistake? P0M (talk) 06:23, 28 March 2008 (UTC)
