Talk:Opacity (optics)

message: The formula for the brem. opacity may be fine for a hydrogen plasma, however needs to be different for a general plasma - dependent on Z squared. Equation (31) on pg. 58 of the NRL Plasma Formulary might be better?  —Preceding unsigned comment added by 155.198.208.38 (talk) 14:17, 15 May 2011 (UTC)
replies: text: Sounds fine to me. I think you should go ahead and change it and add the new footnote. See WP:T or ask me if you're confused about how to edit the article. :-) --Steve (talk) 18:39, 15 May 2011 (UTC)
thread_title: Opacity formulae

message: I moved the contribution from 'Dinesh Pathak Ph D student GND University Asr' into the main body of the text as a new 4th paragraph and cleaned up some of the spelling. Mattgrommes 21:30, 3 August 2006 (UTC)
thread_title: Moved text

message: IUPAC recommends that ε be called the molar (decadic) absorption coefficient.  See , , and especially .
— DIV (128.250.204.118 08:20, 7 September 2007 (UTC)
thread_title:  Molar (decadic) absorption coefficient 

message: I have made a somewhat feeble attempt to clarify and tighten up the lead paragraph; I also changed the section title, "Numerical definition", to just "Definition".  
There remains some confusion about the consistency of the units and the terminology, which I need to refer to my textbooks to straighten up (is it per meter, or per gm/cm^2, etc?)  Someone more expert about the terminology and the whole field of radiative transfer is really needed to do this better.  Improved  co-ordination between this page and the article on radiative transfer, within the general subject of which opacity is just one important concept, also needs to be addressed.  
The actual calculation and tabulation of opacities, generally of plasmas and stellar atmospheres, is a major field of endeavor in itself in astrophysics (& I suppose in many other fields), and may deserve separate treatment, or a section here with references to the literature.
As it is the article seems fragmented and disorganized, though I see many good chunks.  Needs TLC from someone, I think.  Wwheaton (talk) 17:59, 19 February 2008 (UTC)
thread_title: Definition (renamed from Numerical definition) 

message: Substituted at 01:52, 30 April 2016 (UTC)
thread_title: Assessment comment

message: This is a very nice article. I just wanted to point out something I found a little confusing, or, maybe it's just a misunderstanding on my part about the distinctions between these three terms. To my understanding, "transparency" means more than just "all light gets through". Rather, it more means that the light waves get through while retaining their original curvature and vergence. In other words, not only does the light get through, but so does the "image". (I put that in quotes because the image doesn't actually form until the light waves are focused through a lens, but the waves needed to form the image pass through unaltered.) Even in the best glass, there is always some absorption, and colored glasses may only pass certain wavelengths, so all light does not necessarily have to get through to be transparent.
Then there's translucence. A translucent material, such as frosted glass, may transmit almost as much light as clear glass. The difference is that is diffuses the light, scattering the waves in all directions. In this case, like being in a fog, a material can be totally translucent, or anywhere between translucent and transparent.  Like transparency, it can also have varying degrees of opacity depending on things like absorption, color, and haze.
Then there's opacity. An object like a mirror can be totally opaque, where no light gets through the metal coating, or, if the coating is thin enough, some light may get through and the rest reflects, making it partially opaque. The image still gets through, so it is also partially transparent, although different objects may be partially translucent and partially opaque. Laser dyes are another example. They're completely transparent to the desired wavelength for about a microsecond, and then they start absorbing the laser wavelength, making them partially opaque.
So, while I think it's a good article, it seems that this could probably use a little clearing up. Zaereth (talk) 02:34, 6 March 2021 (UTC)
thread_title:  Partially opaque vs translucent