Talk:Ray (optics)

message: Perhaps this article could use diagrams illustrating some or all of the named rays.--Srleffler 06:14, 9 December 2005 (UTC)
thread_title: Diagram request

message: I'm concerned about this edit. The editor appears to be trying to clarify or correct the definitions, but the new material is not so clear to me. I'm not sure what he/she means by "starts at the object". Assuming the object is not a point, to define a ray you have to specify where on the object the ray starts. The old text did so (although it also made some assumptions and was not so clear). It is not clear to me that these new changes are correct.  --Srleffler 06:28, 29 November 2007 (UTC)
thread_title:  Questionable edit 

message: As far as I can tell, only principal rays (= chief rays?) are used in diagrams related to image perspective; including angle of view, entrance pupil, etc whereas diagrams showing how the image is focussed use marginal rays (?) as well. Please could someone explain / elaborate on this ? If I'm on the right lines this should be quite an important "key" to avoiding misinterpretation of ray diagrams. Redbobblehat (talk) 14:33, 2 September 2008 (UTC)
replies: text: I don't know about "only" such rays being used, but you're correct that there is a connection. The perspective of a lens is controlled by the entrance pupil, and ultimately by the aperture stop. As noted in this article, the chief ray identifies the locations of the lens's pupils—it crosses the axis at each pupil location. The marginal rays identify the location where the the image will be formed.--Srleffler (talk) 03:46, 3 September 2008 (UTC)
replies: text:  "The marginal principal ray begins at the edge of the covered object and travels through the centre of the aperture stop and the edge of the field stop." (Reidl 2001 Optical design fundamentals for infrared systems p.1-2). This could be interpreted as contradictory to the article's current definition of "marginal ray" ... can anyone clarify ? (The significance, BTW, of this special principal ray is it traces the edge of the field of view.)  —Preceding unsigned comment added by 83.100.248.38 (talk) 20:41, 30 January 2011 (UTC)
replies: text: Not contradictory, just slightly different. Riedl's "marginal principal ray" is what this article calls simply the "principal ray". Riedl also has a "marginal axial ray", which is what this article calls just the "marginal ray". Riedl's formalism allows every object point to have a "principal ray", which is useful for detailed modeling of optical systems. In simpler analysis, one is concerned mainly with the principal ray from the edge of the object.--Srleffler (talk) 01:11, 31 January 2011 (UTC)

text: I added Riedl's definitions to the article. Thanks for providing a reference!--Srleffler (talk) 01:21, 31 January 2011 (UTC)

text: Definitive difference between chief ray and principal ray : "One exception is the case in which the aperture stop is at the lens, so that the chief ray is, in effect, the principal ray (i.e., it passes through the principal points, here coalesced at O) .... The point at which the ray crosses the axis is the optical center of the system, but since this is a chief ray, it is also the center of the aperture stop. " (Hecht 2003 Optics p.266-7 - see "Fig 6.34"). That's been bugging me for ages - woot! --Redbobblehat (talk) 20:50, 5 February 2011 (UTC)
thread_title:  principal rays 

message: I came across this definition of a third conjugate ray :
*Rays from object points at the of the object field which limit these ray bundles are called pharoid rays (PR). They are in analogy with the marginal rays (for object points on the optical axis) and thus determine the image brightness for points at the edge of the field of view. Note: By our definition, the pharoid rays are conjugate rays, that means corresponding to the same ray pencil. Sometimes rays ... which characterize the totality of all rays passing through the optical system are called pharoid rays. In that case these rays are of course not conjugate rays... It passes from the edges of the object to the edges of the aperture stop up to the edges of the image. . 
From the diagram on p238, a pair of PRs flank the chief ray through the system - diverging from the same object point and converging to the same image point as the chief ray, but passing through the edges of the aperture instead of the centre. Something similar is depicted (but unnamed) in Fig.2 of van Walree's on Distortion  ...?
Google can find no other reference to a "pharoid ray", and "pharoid" (or similar) does not appear in any of the dictionaries I checked. Is this concept - possibly going under a different name - familiar to anyone ? --Redbobblehat (talk) 16:57, 14 August 2009 (UTC)
replies: text: Another reference to the same definition of "pharoid rays" : -p.17. --Redbobblehat (talk) 20:02, 14 August 2009 (UTC)
thread_title:  Pharoid ray ? 

message: It seems that the term "finite ray" is commonly used to describe rays which are traced without the paraxial approximation : ,,, . --Redbobblehat (talk) 12:35, 18 August 2009 (UTC)
thread_title:  Finite rays 

message: I think we need to get rid of the figure and caption that refers to light as "oscillating in amplitude" as it travels. First of all, it doesn't. It oscillates in phase. The electric field oscillates, but when one refers to "amplitude" in optics, it's understood to mean something other than the instantaneous magnitude of the electric field. Second, that figure adds absolutely no information, and is meaningless and confusing. Why does it help one understand ray optics? The wave nature of light doesn't even come into account in ray optics, so why is this even here?
If nobody objects, I'll delete it. Birge (talk) 22:20, 23 September 2009 (UTC)
thread_title:  Oscillation figure 

message: I added a link to this question in the section "See also". It is mentioned at the end of the section on boundary value problem of the article Computation of radiowave attenuation in the atmosphere
--Thuytnguyen48 (talk) 15:08, 18 October 2010 (UTC)
replies: text: I removed the link. An article on radio wave attenuation is not relevant to a general article on rays in geometric optics, even if that article does happen to mention propagation of rays.--Srleffler (talk) 02:12, 19 October 2010 (UTC)
thread_title: Rays bending in the atmoshere

message: A significant proportion of optical engineers (especially those trained at the University of Rochester) and optical texts refer to marginal rays as a rays and chief rays as b rays. I am tentatively going to plug these names as parenthetical notes in to the main article, unless anyone sees a reason not to. I'll provide a textbook reference when I have one in front of me. Most of them acknowledge a ray and b ray as alternative terms.
128.151.226.73 (talk) 19:32, 20 October 2010 (UTC)
replies: text: Sounds fine. I'm not familiar with that usage myself. Please do provide a textbook reference to support it.--Srleffler (talk) 02:36, 21 October 2010 (UTC)
thread_title:  Alternate Ray Names 

message: Light beam seems to describe the same thing, but artificial. The terms are interchangeable, right?--عبد المؤمن (talk) 18:36, 1 March 2014 (UTC)
replies: text: Oppose. Did you bother to read even the first sentence of each article? They are not at all the same thing. A light beam is a physical, narrow beam of light, like from a spotlight or a laser. A ray is an abstract mathematical object used in analyzing how light propagates.--Srleffler (talk) 07:27, 2 March 2014 (UTC)

text: 'Oppose'  I also disagree. If anything it should be merged with Geometrical optics.Tomgee (talk) 18:25, 9 December 2014 (UTC)

text: Oppose. A beam is real, a ray is an abstract concept. I think it would be quite helpful, however, to explicitly address the fact that many people, not just the original poster, conflate the two. I think this is important because the confusion is deeply embedded; prominent scientists, Newton and Faraday come to mind, have used the term "ray" when they were describing a beam of light. --AJim (talk) 00:33, 10 December 2014 (UTC)
replies: text: It's not wrong to use the word "ray" when describing a physical beam of light. It's just that that's not what we are referring to when we talk about "rays" in optics, and such physical rays are not the subject of this article. Some of the confusion may be caused by problems with the redirects and dab page that link to this article, which I am fixing.--Srleffler (talk) 03:43, 10 December 2014 (UTC)
thread_title:  merge with light beam 

message: Out of incident, reflected, and refracted rays, only "angle of incidence" currently has its own article. The article is just a definition of "angle of incidence" and "glancing angle". I think it would be better explained in context, as a part of this overview article on the ray formalism. They're both pretty short, and there's some repetition of content. Main concern is WP:DICT. Forbes72 (talk) 21:32, 22 March 2016 (UTC)
replies: text: It's a fair point about accessibility, but sounds like support for the advantages of a dictionary entry. What purpose does the angle of incidence article fulfill that is not served by the wiktionary entry? I agree on the importance of the term: we can always set up a "critical angle" subsection to link to directly from the search bar. Forbes72 (talk) 19:34, 23 March 2016 (UTC)
thread_title: Merger proposal