Contact angle and anti reflective coating.

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Discussion Overview

The discussion revolves around the relationship between the contact angle of anti-reflective (AR) coatings and their effectiveness. Participants explore the definitions and implications of contact angle in the context of coatings, as well as the factors influencing AR coating performance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about a potential correlation between the contact angle of an anti-reflective coating and its effectiveness, suggesting that a larger angle might indicate better performance.
  • Another participant seeks clarification on the term "contact angle," indicating it may have a specific meaning in the context of coatings versus the angle of incidence.
  • A participant clarifies that contact angle refers to the angle measured through the liquid at the interface between a liquid and a solid surface, without any special meaning in this context.
  • It is noted that the effectiveness of AR coatings depends on their thickness, and the contact angle relates to how this thickness varies at the edges of the coating application.
  • One participant explains that anti-reflective coatings rely on interference effects, where the path differences of reflections must meet specific conditions for destructive interference, which can be affected by different angles and wavelengths.
  • A participant acknowledges a misunderstanding between contact angle and angle of incidence, indicating a correction in their understanding.

Areas of Agreement / Disagreement

Participants express differing views on the implications of contact angle for AR coatings, with no consensus reached regarding its correlation with coating effectiveness. The distinction between contact angle and angle of incidence is clarified, but the relationship between these concepts and AR performance remains unresolved.

Contextual Notes

There are limitations in the discussion regarding the specific conditions under which the contact angle affects AR coating performance, as well as the dependence on definitions and the lack of empirical data presented to support claims.

Weirdzzl
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Hi all, just want to ask is there any correlation between the contact angle of a anti reflective coating? i.e the bigger the angle, the better the anti reflective coating? Thanks in advance.
 
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I just want to be sure what you mean by "contact angle" here, since it seems to have a special meaning in the context of applying coating to surfaces but you may just mean "angle of incidence".

Note: there is a lot of information online about this stuff.
 
Hi, there is no special meaning. it is the angle, conventionally measured through the liquid, where a liquid/vapor interface meets a solid surface.

http://en.wikipedia.org/wiki/Contact_angle.

I tried to search the web, but could not get any info on the correlation between these 2.
 
Ah - I figured that was what you meant.
AR coating depend on their thickness ... the contact angle between the coating and the surface it coats relates to the way the coating's thickness changes at the edges of the application. You don't use that bit. You want the AR coating to have as uniform a thickness as possible.
 
An anti reflective coating will be relying on interference between the reflections from two (or more) surfaces. For the reflections to interfere destructively, the path differences must be right. For different angles (and different wavelengths) the condition for exact cancellation will be compromised.
But there's lots about this if you Google. You may need to look further than the first hit to find the effect of angle of incidence, though.
 
@Sophiecentaur: that's the mistake I made - in this case, "contact angle" \neq "angle of incidence". (see post #3).
I feel better about my mistake now :)
 

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