Contact angle and anti reflective coating.

[Weirdzzl]

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.

 

[Simon Bridge]

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.

 

[Weirdzzl]

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.

 

[Simon Bridge]

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.

 

[sophiecentaur]

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.

 

[Simon Bridge]

@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 :)