Talk:Diffraction grating: Difference between revisions

Content deleted Content added

Inline

Revision as of 16:39, 18 November 2007

Physics B‑class High‑importance

	Physics portal This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.PhysicsWikipedia:WikiProject PhysicsTemplate:WikiProject Physicsphysics articles
B	This article has been rated as B-class on Wikipedia's content assessment scale.
High	This article has been rated as High-importance on the project's importance scale.

History section?

A possible starting point for cleanup would be to make a new section 'History' which might start with this sentence about Fraunhofer and Rittenhouse (that IMHO doesn't belong to the introduction). further possible contents:

first blazed grating by Wood 1910
Echelle, Echelette gratings 1940s/50s (?)
recent developments and today's applications (?)

i could try to do this section, but someone would need to correct spelling errors as i'm not a native speaker :) Joerglwitsch 21:04, 7 February 2007 (UTC)[reply]

....and no article on "Fiber Bragg Gratings".

There should be link between grating and diffraction...i do not know how to do thi

Gratuitous Science Jargon

The dimension and period of the grooves must be on the order of the wavelength in question.

Why can't we just say "The size and spacing of the grooves must be the same as the light"? What purpose does explaining something with complicated terms serve?

echelle gratings

??? No link, no article, nothing. Only someone who already knows what these echelle gratings are would benefit from this comparison.Allywilson (talk) 16:39, 18 November 2007 (UTC)[reply]

A fundamental property of gratings is that the angle of deviation of all but one of the diffracted beams depends on the wavelength of the incident light.

Lost us with "angle of deviation", "diffracted beams", "incident light". Seems like 2-3 words per sentence need links to their own article.

Therefore, a grating separates an incident polychromatic beam into its constituent wavelength components, i.e., it is dispersive

"beam"? How is anything being a beam important to the fact that it is light? Is there a single instance in this article where you could not replace the word "beam" with "light"? "Constituent wavelength components" - colors. Just say colors. Then link "colors" to an article that explains how colors work, for those who need a more precise definition.

When groove spacing...

Groove spacing finally makes an appearance, SIX or SEVEN paragraphs later! This should have been used in the first place. Now look what we have, two terms meaning the same thing, in the same article. Now we have inconsistency in addition to gratuitous jargon.

Booo science club! Hooray understanding! Viva la understandionne!

"Why can't we just say "The size and spacing of the grooves must be the same as the light"? What purpose does explaining something with complicated terms serve?"

Because it isn't correct. 'Dimension' is easy to understand. 'Period' and 'order' in the context of science are also straightforward, anyone with any interest whatsoever in diffraction gratings will understand these.

"echelle gratings"

Agreed. I'll put up an article or expansion request.

"Lost us with "angle of deviation", "diffracted beams", "incident light". Seems like 2-3 words per sentence need links to their own article."

It would take a few minutes of research for any half-intelligent person to get up to speed here. Again, if you're anything to do with science, you should know these.

""beam"? How is anything being a beam important to the fact that it is light? Is there a single instance in this article where you could not replace the word "beam" with "light"? "Constituent wavelength components" - colors. Just say colors. Then link "colors" to an article that explains how colors work, for those who need a more precise definition."

Good grief, just do your homework. Nothing in this article is difficult to understand. Sojourner001 22:54, 18 January 2007 (UTC)[reply]

Incorrect Diffraction Equation

According to http://scienceworld.wolfram.com/physics/GratingEquation.html and some supplier's catalogs (www.thorlabs.com) the diffraction equation should be dsin(theta_incident)+dsin(theta_reflected)=m(lambda). There should be no minus sign. I'm not sure how to edit the equations, so I'll trust that someone else will do this. --128.196.213.163 21:59, 30 October 2006 (UTC)Anon[reply]

I think it's just a problem with the sign of the angles. I tried to explain that in the article. -- Pgabolde

Unclear relation in equation

How are groove period and groove density related? Are they inverses of one another? The article leaves this unclear, but an inverse relation is implied when the units are compared... —The preceding unsigned comment was added by MyOwnLittlWorld (talk • contribs) 16:39, 27 February 2007 (UTC).[reply]

Yes it's just the inverse. I clarified the article. -- Pgabolde

Incorrect Example?

I don't think an LCD can cause a diffraction pattern, and pretty sure if it could it wouldn't look like that. Is the picture instead an example of Newton's rings, caused by the close but imperfect separation between the LCD surface and the protective plastic screen? Atropos235 19:12, 18 February 2007 (UTC)[reply]

Agreed. The color pattern in the photograph, is in no way reminiscent of the pattern created by a periodic structure (like the pixels of an lcd in this case.). Also the spacing of the pixels is too large to produce significant diffraction effects with visible light. I would guess what we are seeing has to do with the polarization of light, passing through the polarizer in the LCD screen. Transparent plastics have the property that they can rotate the polarization of light with a degree depending on how much stress is applied to the material, this effect is also wavelength dependent. This could cause different regions to reflect different colors of light. --V. 03:36, 3 March 2007 (UTC)[reply]

Since it's not clear whether the cell phone picture exhibits grating diffraction or not, I removed it for now. It looks like a thin-film effect to me. -- Pgabolde

lines-per-inch of a CD or a DVD

What is the lines-per-inch of a CD or a DVD?-69.87.204.209 21:02, 1 June 2007 (UTC)[reply]

Intro sentence too hard

Does anyone feel up to the challenge of writing something easier to understand? If I didn't already know what to expect I wouldn't understand it. RJFJR 17:16, 14 June 2007 (UTC)[reply]

Better now? Han-Kwang 18:30, 14 June 2007 (UTC)[reply]

Much better. Thank you. RJFJR 22:23, 14 June 2007 (UTC)[reply]

Example of the cd/dvd

It is my understanding that it isthe thin film effect that causes interference patterns in reflected light from the dataside of cd's and dvd's and that the example on teh page needs to be removed.

@@ Line 17: / Line 17: @@
 ''echelle gratings''
-:??? No link, no article, nothing. Only someone who already knows what these echelle gratings are would benefit from this comparison.
+:??? No link, no article, nothing. Only someone who already knows what these echelle gratings are would benefit from this comparison.[[User:Allywilson|Allywilson]] ([[User talk:Allywilson|talk]]) 16:39, 18 November 2007 (UTC)
 ''A fundamental property of gratings is that the angle of deviation of all but one of the diffracted beams depends on the wavelength of the incident light.''