# User talk:Srleffler

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Hi, feel free to leave me a message. Kindly leave messages on new topics at the bottom of this page. Srleffler

## transmitting data using other parts of EM spectrum

This was something I was wondering, instead of using just radio waves, what about using microwaves, infrared, ultraviolet, X-rays, visible light (there's something called li-fi we might have soon) x-rays and gamma rays? The snare (talk) 03:21, 6 April 2018 (UTC)

Microwaves, infrared, and visible light are certainly used for data transmission. The others could be, but aren't as far as I know.--Srleffler (talk) 02:11, 7 April 2018 (UTC)

## M squared

Hi, I absolutely agree with your interpretation of focus size vs M2. Why don't you put this explanation in the article? The way it is presented now is misleading: it is not clear that the comparison is between the multimode beam and the embedded Gaussian, rather than the Gaussian of the same size. Actually, most people working on laser applications are looking for a simple answer to the question: "I have a beam of a given size and a given M2. What is the minimum size I can focus it to with a given lens?". And the answer they get in the "Applications"(!) section of the article is "M times larger than a Gaussian at same wavelength". So they calculate the size of the focus of a same-size Gaussian and multiply it by M. — Preceding unsigned comment added by Mpolyanskiy (talkcontribs) 23:10, 11 January 2018 (UTC)

Good idea. Done.--Srleffler (talk) 16:30, 13 January 2018 (UTC)

Great! Thank you! --Mpolyanskiy (talk) 00:32, 14 January 2018 (UTC)Mpolyanskiy

## Question

Hi Srleffler,

I had an optics-related question for you, hoping with your expertise you may have some insight, but it's not really Wikipedia related so I sent it to your email. Just thought I'd give you a heads-up (if you're anything like me then you may not check it everyday.) Thanks. Zaereth (talk) 19:21, 19 January 2018 (UTC)

Got your message. Usually you get the gradient constant from the GRIN lens vendor. The GRIN lenses I've worked with have index profile of the form:
${\displaystyle n(r)=n_{1}\left(1-{\frac {(r{\sqrt {A}})^{2}}{2}}\right)}$ ,
where ${\displaystyle n_{1}}$  is the index at the center axis of the lens, r is radial position, and ${\displaystyle A}$  is the gradient constant. The focal length is then
${\displaystyle f={\frac {1}{n_{1}{\sqrt {A}}\sin(z{\sqrt {A}})}}}$ .
Some more details can be found at https://spie.org/publications/tt48_55_gradient_index_lens?SSO=1
Thanks. I have those equations, although I've been trying to figure out how to rearrange to solve for A. (Math is not my strong suit.) What I really need is the mathematical definition of A. It's difficult to ask the vendor since I'm the manufacturer. For example, NA is defined by n0 times the square root of 1 - sech2(Ad/2), but no clue how to turn that around. (Note, NA for these is dependent on the radial distance from the axis.) Anyway, thanks for trying.Zaereth (talk) 06:01, 20 January 2018 (UTC)
Hey Srleffler, I think I figured it out (with a little help from Symbolab and a paper titled Some first-order properties of radial gradient lenses compared to homogeneous lenses). Since the numerical aperture is know, working the above problem to solve for A (or g, or k, or whatever notation used) Yielded a number. When I plugged it into the equation for focal length, the answer exactly matches my measurements. From that number I was able to deduce that A = gradient divided by diameter. (Who would've guessed it would be so simple.) I'll have to try it with other sizes and see if the results match. Anyhow, thanks again for your help. Zaereth (talk) 06:30, 21 January 2018 (UTC)
Great. I'm glad you managed to work it out.--Srleffler (talk) 17:44, 21 January 2018 (UTC)
Wasn't as easy as I thought. The math wasn't repeatable with other sizes and gradients. Turns out, A = the square root of gradient divided by the square root of diameter, divided by 2. Live and learn. Zaereth (talk) 01:51, 10 February 2018 (UTC)

## Gaussian beam width

Hi Srleffler,

Re: The article on Gaussian beams.

You reverted the correction to the width of a Gaussian beam that I put and gave as reference the the book of Svelto. This book gives two formulas for the width, one is eq. 4.96 where the width grows linearly with z for large z as you seem to prefer. However, eq 8.18 gives a different formula for the width of a Gaussian beam, and this one grows like the root of z for large z. This was the formula I prefer. Since chapter 8 deals with Gaussian beam propagation while chapter 4 deals with a con-focal resonator, it seems to me that the formula from chapter 8 is more appropriate for this entry.

Let me know what you think --Avronj (talk) 21:52, 20 February 2018 (UTC) Yosi

I don't have Svelto's book, but Yariv's equation matches what is in the article, and that is consistent with my experience as well: Gaussian beams expand linearly with distance in the far field. I have to conclude that you are somehow misinterpreting Svelto's book. --Srleffler (talk) 12:22, 21 February 2018 (UTC)
Looking at the table of contents, I see that section 4.7 in Svelto is about Gaussian beam propagation, while Chapter 8 is about transient laser behaviour. The equation that is relevant to the Gaussian beam article is going to be in section 4.7.--Srleffler (talk) 12:28, 21 February 2018 (UTC)
The book by Svelto cited in the article doesn't number equations the way whatever you looked at does—the relevant equation is 4.7.17a. Were you looking at some other book by Svelto??--Srleffler (talk) 12:38, 21 February 2018 (UTC)
As a general rule, in physics you don't get to pick the formula you "prefer". If you have two different, incompatible formulas for the same thing, then you are misunderstanding one of them or are unaware of the context in which each of the formulas is applicable. --Srleffler (talk) 12:47, 21 February 2018 (UTC)

Hi, I am the one who edited the Gaussian beam width relation to the FWHM which you reverted. Here are my thoughts.

While I agree, of course, that the 1/e width of the field is the same radius as the 1/e^2 width of the intensity, I do not agree that the relations to the their respective FWHM is the same. Allow me to clarify:

If one starts with the simple equation for the field, the exponential is [-r^2 / w(z)^2]. If this is squared, the exponent becomes [-2r^2 / w(z)^2]. Substituting 0.5 for E and I respectively, with E_0 and I_0 being 1 respectively, and (FWHM/2) for r in both cases, the extra factor of two in the equation for the intensity means that the relations for the field and the intensity to their respective FWHM cannot be the same as each other. This is further evidenced by the fact that, for a normalised (to 1) Gaussian field, squaring it does not produce the same FWHM value - see the second diagram on the Guassian Beam page. Therefore, for the 1/e radius for the field to be the same value as the 1/e^2 radius for the intensity, their relations to their respective FWHM values must be different on account of the different FWHM values for each case. — Preceding unsigned comment added by Jwoodsy (talkcontribs) 22:49, 16 July 2018 (UTC)

When talking about the width of a beam, "FWHM" refers to full-width at half maximum intensity. There is only one FWHM, and only one relationship between FWHM and w. See Beam diameter for more information on measures of beam width.--Srleffler (talk) 05:04, 17 July 2018 (UTC)

## Polarity

Thank you for reviewing my recent edits concerning polarity. The background is that all incoming wikilinks to Polarity (physics) were actually about a more specific concept such as electrical polarity. I'm confident of most of my changes but I have doubts about these six links and would welcome a second opinion. If you have time, please could you take a look at and check whether the wikilink or the text could be improved? Thanks, Certes (talk) 01:17, 24 April 2018 (UTC)

I went through all of the edits. Most were good. Some I either fixed to point elsewhere or returned to Polarity (physics). It does appear to me that we need that page, to provide an explanation of the concept when no more specific link will do. In particular, the common use of "polarity" to refer to a phase inversion isn't well covered by any of the articles at polarity.--Srleffler (talk) 03:30, 24 April 2018 (UTC)

## SI photometry quantities table

Hello. Just wanted to say thank you for fixing the mess I made to the table. I'm new to Wikipedia and couldn't figure out how to undo my edits, so then I was making new edits to fix the first ones and it became a mess. Well I figured out how the system works now and will be adherent of the "no original research" principle for the future.

On a side note, the reason I had stumbled on the page is because I am trying to verify the [cd] rating of an LED. I have a sprectrometer, which detects through a fiber optic cable and gives me a [cd/m2] measurement. Would it be accurate to multiply my [cd/m2] measurement by the area of the LED in order to get a [cd] number? — Preceding unsigned comment added by 134.134.139.75 (talk) 21:10, 30 May 2018 (UTC)

Glad you figured it out. Let me know if you have other questions about how things work. I'm happy to help.
If you're just putting the fiber in front of the LED with no collecting optics, I think multiplying by the area of the LED should work. I'm not sure how accurate that will be, though. Let me know how close you get to the manufacturer's value; I'm curious.--Srleffler (talk) 02:21, 1 June 2018 (UTC)

## Good point on Ambient light sensor

Please see if you find a better way to include some numbers for the lux range. I agree the current wording is vague, but I think it's better than what was there before, and I've updated to more sensible numbers. Dicklyon (talk) 02:43, 9 September 2018 (UTC)

## Removed external link on Lighting

Hi Srleffler, thank for the feedback. I added the link because I thought it's useful and as per "Good links are as specific as possible" :) Could you advise a better place for that link? Thanks. — Preceding unsigned comment added by AlexVeliko (talkcontribs) 07:25, 19 September 2018 (UTC)

## Spanish Inquisition

Why did you revert my correction to this? Here is a link to the Video proof of the facts I stated! https://www.youtube.com/watch?v=Ixgc_FGam3s Time Index 8:32

You didn't include an edit comment on your edit, and you deleted material without explaining why. That's sufficient grounds for a revert. Edit comments help other editors to understand what you're doing. In the absence of an edit comment, the rest of us have to try to guess whether your edit is correct, or even whether it is constructive, without anything to go on. It's particularly important when you are removing something from an article, or writing something that contradicts facts already presented. In those cases, I always give the benefit of the doubt to the original author, if the person making the change doesn't explain what they are doing.
Thanks for the link. I agree that the courtroom is clearly not empty.--Srleffler (talk) 06:17, 17 December 2018 (UTC)

## Adding Content to Mirror TV

Hello, Srleffler Greetings of the day! Hope you are doing well.

Dear I have more updated information about the mirror TV. The information you have provided is very less and earlier was wrong or incomplete. (reference - HD & 4K Resolution)

Since the technology is updated time to time i just wanted to update the latest source of information with the external link that i know: http://www.aerodigitalworld.com

My purpose are two - 1. Update all the useful information about Mirror TV - as for example the sizes available - pictures - types of mirror TV - What is dielectric glass - how to clean it - what can you view on mirror TV - as its a smart TV not a regular TV. 2. To update the source of new content as a latest reference - http://www.aerodigitalworld.com/mirror-tv

This is not a paid activity but yes the owner is my uncle and i know them that is why i am aware of the Mirror TV Technology its features and specifications. I dont want to fall under any - Conflict of interest neither Spam

Kindly suggest how to Edit and add on the useful information which i have. Do you want me to share it here over this talk ?

Regards : Puneet Tandon PuneetTandon (talk) 06:01, 26 December 2018 (UTC)

I copied this to your talk page, and replied there. It's better to keep conversations together in one place.--Srleffler (talk) 08:39, 26 December 2018 (UTC)

## Merger discussion for Computation of radiowave attenuation in the atmosphere

An article that you have been involved in editing—Computation of radiowave attenuation in the atmosphere—has been proposed for merging with another article. If you are interested, please participate in the merger discussion. Thank you. Pierre cb (talk) 14:15, 3 March 2019 (UTC)

## Metre

Thanks for the undo. Don't know how I misread that source. Meters (talk) 21:40, 23 March 2019 (UTC)

## Encyclopedia of Laser Physics and Technology

Thanks for the hint concerning COI on my user talk page. Although I think I have always properly taken into account my COI, I will be even more careful. I have now placed on the talk page for the encyclopedia the request for others to update the article because of substantial changes (particularly of the title - now "RP Photonics Encyclopedia" - and the substantial expansion of content into the area of general optics). Maybe with your industrial optics background you would be a particularly appropriate person to do that.

You might also want to think about an external link on the encyclopedia (https://www.rp-photonics.com/encyclopedia.html) in the articles on optics and photonics. I think it would definitely be more appropriate than the majority of other links there.

RPaschotta (talk) 07:33, 6 May 2019 (UTC)

I moved the article and made some other updates. I haven't added anything on the new non-laser content yet, since I haven't had time to go and review the site. --Srleffler (talk) 04:53, 8 May 2019 (UTC)

## Atomic units disamb

Hi, I object to your redirect of Atomic units system and Atomic units to Hartree atomic units. The first two terms are not synonymous with the third one. They could mean either Hartree or Rydberg atomic unit systems, and the latter is not defined or discussed in that article. As it is now, the reader would be lead to think that there is only one system of "atomic units", wich is not correct.
The redlink should be fixed by writing the article, even if it is just as stub.
All the best, --Jorge Stolfi (talk) 05:02, 9 July 2019 (UTC)

Normally we do not create disambiguation pages for cases where there are only two ambiguous terms. Instead, the term points to one article, and that article will contain a hatnote directing readers to the other article. See WP:ONEOTHER.--Srleffler (talk) 05:10, 9 July 2019 (UTC)

## Jackson

I just noticed Jackson's Classical Electrodynamics on your list of favorite references. As it happens, a couple years ago I was looking over the WikiProject Physics quality scale, and I saw that it listed Jackson as an example of a mid-importance physics publication, but the link was red! So, I created the page for it, all the while feeling quite surprised that nobody had done so before. Further improvements would, of course, be welcome! XOR'easter (talk) 06:52, 16 July 2019 (UTC)

## Unnecessary edits

I saw this discussion after the same thing happened at Rainbow Canyon (California). I reverted a couple of changes, but after seeing your discussion I feel I'd be on stronger ground to revert them all. I've never heard of wikitidy before but I always lowercase templates like {{cvt}} and is seems pointless for someone to change them to {{Cvt}} let alone remove them from the lead. MB 15:46, 9 August 2019 (UTC)

The next step would probably be to take it to some kind of dispute resolution. The problem is fundamentally that Hydrargyrum is using a script to semi-automate edits that do not have consensus (WP:MEATBOT). Some of it is just blanket imposing personal preferences like uppercase template names, and some of it is mass violation of guidelines like WP:NOTBROKEN. A lot of the trouble seems to be driven by him tailoring articles to show up well in tooltip previews, even when that produces less desirable formatting of the article itself.
I don't have time to pursue this right at this moment, but if you do ping me and I'll join in.--Srleffler (talk) 17:53, 9 August 2019 (UTC)
I started putting something together here. MB 23:14, 13 August 2019 (UTC)
Just wondering if you have any further comment on this issue? MB 01:02, 7 September 2019 (UTC)
I would focus more on the fact that this editor is using a script to automate enforcement of his/her style preferences, even when those are contrary to the Manual of Style. It's not just the arrogant attitude that is the problem, but the fact that these edits are being churned out using an automated tool.--Srleffler (talk) 20:23, 7 September 2019 (UTC)

## Don't arbitrarily bypass redirects

Re this edit: See WP:NOTBROKEN. Links to redirects should not be arbitrarily bypassed. A link to a redirect is often preferable to a direct link to the target article. --Srleffler (talk) 00:29, 30 August 2019 (UTC)

This was not an arbitrary bypass. Polarity is a disambiguation page, and WP:NOTBROKEN lists "Links on disambiguation pages" under "Good reasons to bypass redirects". It points to Wikipedia:Manual_of_Style/Disambiguation_pages#Piping_and_redirects which says "Apart from the exceptions listed below, piping and redirects should generally not be used on disambiguation pages." -- Beland (talk) 00:35, 30 August 2019 (UTC)
This is one of the listed exceptions. From MOS:DABREDIR: "Linking to a redirect can also be helpful when [...] the redirect target article contains the disambiguated term; and the redirect could serve as an alternative name for the target article, meaning an alternative term that is already in the article's lead section."--Srleffler (talk) 00:49, 30 August 2019 (UTC)
In such cases, I prefer to see the title of the actual article, to make it easier for readers to know whether or not they have already navigated to it, as long as it can be worked into the description line without awkwardness. -- Beland (talk) 03:16, 30 August 2019 (UTC)
I see your point, and in this case the redirect title isn't really better than the actual article title. I undid my revert.--Srleffler (talk) 11:27, 30 August 2019 (UTC)
Cool, thanks for keeping an eye on this page. -- Beland (talk) 00:39, 31 August 2019 (UTC)

## Micro symbol

I notice that you are converting the micro symbol µ to the "small Greek letter mu" symbol μ in many articles, and in particular you are doing this in cases where semantically the character is intended to be a micro symbol and not a Greek letter. Is there a reason why you are doing this? Is there a policy or a bot approval that authorizes you to make this change on a broad scale, or a consensus decision somewhere?--Srleffler (talk) 02:49, 7 September 2019 (UTC)

In general, when there are two ways to write the same thing in Unicode, Wikipedia prefers general-use characters. For example, we write "II" instead of using Unicode Roman numerals. This translates to a preference for Greek letters over semantically specific characters, like "sigma" instead of "sum". For this particular character, I have in my notes that Wikipedia:Manual_of_Style/Dates_and_numbers#Specific_units explicitly says to use mu for micrometer, and that aligns with the general preference. (And actual usage follows the preference, in the sense that mu appears much more frequently than micro.) I'm not sure why this preference has developed, though it makes sense to me for two reasons. First, editors just generally don't know or don't care that the Unicode standard has assigned different meanings to the two codepoints "mu" and "micro", and the glyphs look exactly the same, so for most people they are impossible to tell apart. Anyone relying on the Unicode definitions would find that those definitions are in practice simply not being followed, and it would be quite a bit of work to manually correct all instances of wrong usage. And arguably, using "mu" to mean "micro" isn't even incorrect, in the sense that the Greek letter is being used as an abbreviation to mean "micro", as well as being used in Greek words, as a variable, and even artistically as a funny way to write "y". Second, having two codepoints representing the same character in more or less free variation creates problems for searching and data reuse. Depending on how you access Wikipedia data, a search for micro won't include results that use mu, and vice versa, even though in some situations they are used interchangeably. In my case, this has caused problems for a spell checking project I'm working on, which is why I'm fixing it systematically. I think doing so will make life easier for other data users, and should be invisible to readers since the two glyphs look exactly the same. -- Beland (talk) 04:18, 11 September 2019 (UTC)
Thanks for the explanation.--Srleffler (talk) 22:24, 11 September 2019 (UTC)

Wikipedia:Manual_of_Style/Layout#"See_also"_section: "The links in the "See also" section might be only indirectly related to the topic of the article because one purpose of "See also" links is to enable readers to explore tangentially related topics." Perhaps we could annotate a link to Pigeon Point Lighthouse to say it is a noted example of the Fresnel lens in use. I have not reverted your revert as I am not emotionally invested in including the link, but I do think you are being pedantic. Cheers Elinruby (talk) 03:47, 13 September 2019 (UTC)

My concern was that there are a lot of lighthouses that use Fresnel lenses, and I don't know of anything that makes this one more relevant to the article than any of the others. It would clearly be bad if the See also section were to be filled with a list of every lighthouse that uses a Fresnel lens, so I have to conclude that we should not list any such articles. If there is something that makes this one lighthouse more relevant than all the others, that would be a different matter, of course.--Srleffler (talk) 17:27, 13 September 2019 (UTC)

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## Gyro motion machine

I have added new sources for gyro motion machine plus video run proof by other professional Walter Eugene Wood (talk) 04:22, 25 November 2019 (UTC)

I have added another new sources for gyro motion machine-a very detailed study. Walter Eugene Wood (talk) 00:20, 27 November 2019 (UTC)

Would affidavits from other engineers and expert witness's, that were not published on-line, qualify as a peer-reviewed journal? These were several signed detailed engineering analysis. I have the original hard copies, but I am not sure how to load them into Wikipedia as references. Please advise. Walter Eugene Wood (talk) 09:37, 27 November 2019 (UTC)

## Merry Christmas!!

Hi Srlefler, thanks for all you do on Wikipedia, and for all your help with optics-related articles. You've always been an inspiration to me. My you have a wonderful Christmas and a Happy New Year. (and if you don't celebrate Christmas please feel free to take that as a Happy Hanukkah, a great Dhanu Sankranti, a blessed Hatsumode, or whatever holiday you want to insert there.) Zaereth (talk) 08:55, 25 December 2019 (UTC

Thanks Zaereth. Merry Christmas to you too! Srleffler (talk) 13:46, 25 December 2019 (UTC)

## Brewster angle

Hello, I noticed that you have reverted by edit to Brewster's angle. Being a research physicist but not an expert in optics, I would like to understand this issue better, therefore may I ask you for an explanation please? Considering that the transmittance for both S and P polarizations tends to zero when the incidence angle tends to 90 degrees (by Fresnel's laws), i.e. all incident light reflected, how is it possible that the reflected light is polarized?

Thank you very much.

Goudzovski (talk) 11:26, 15 January 2020 (UTC)

Reflectivity for glass.
The reflectivity rises very steeply to 1 as the angle of incidence approaches 90°, and the s reflectivity is much higher than the p reflectivity for angles a little less than 90°. Saying the Sun is "low in the sky" is not the same as saying the angle of incidence is 90°. At 80° incidence the light is quite significantly polarized.
This effect is of some practical importance. The reason why many sunglasses are made of polarizing material is because it selectively blocks reflections from the ground when the sun is low in the sky, to reduce glare when you are driving toward sunrise or sunset. I believe this effect was also how polarization of light was first discovered.--Srleffler (talk) 13:00, 15 January 2020 (UTC)
Thank you very much for the detailed answer, I understand now. Apologies for the misleading edit to the article. Goudzovski (talk) 13:12, 16 January 2020 (UTC)

## Oscillator

Hey. I've recently been doing lots of work on synthesizer articles (such as synthesizer and Moog synthesizer). These often involve the discussion of oscillators, which in the synthesizer world mean something kind of specific. I think for people in the synthesizer world, "oscillator" refers to a common synthesizer component, and in fact they might not be aware of other kinds of oscillator (I wasn't - I'm not technical at all). That's why I added a link to voltage-controlled oscillator to the disamb page. Do you have any suggestions here? Popcornduff (talk) 21:33, 15 January 2020 (UTC)

This seems like a straightforward partial title match issue. From the guideline, "Add a link only if the article's subject ... could plausibly be referred to by essentially the same name as the disambiguated term in a sufficiently generic context—regardless of the article's title." I don't think synthesizers are a generic enough context to justify adding it to the dab page. The right way to achieve your goal is to make sure that in synthesizer articles the term oscillator is a piped link to Voltage-controlled oscillator (i.e. oscillator). Someone looking at synthesizer articles should be able to find the information they are looking for by following links within the articles. They should never end up at a dab page, because articles should never link to dab pages.--Srleffler (talk) 01:20, 16 January 2020 (UTC)
Srleffler, thanks for the reply. But I don't think I'm following the argument. I guess synthesizers are not a super-generic context, but are they any less generic than everything else currently mentioned in the disambig page? And is the situation any different from string and string (music), neck (music), bridge (instrument), etc, all of which are listed on their respective disambig pages? Popcornduff (talk) 12:14, 16 January 2020 (UTC)
A VCO is a specific type of oscillator. We don't usually list specific types of things on the dab page unless it is common to refer to the specific thing with the generic name alone. There are dozens of different kinds of oscillator, and probably as many fields where it would be common for people to refer to the type of oscillator they are most familiar with as simply an "oscillator". We don't clutter dab pages by listing all of them.--Srleffler (talk) 05:08, 17 January 2020 (UTC)
We don't usually list specific types of things on the dab page unless it is common to refer to the specific thing with the generic name alone. But VCOs are overwhelmingly referred to simply as "oscillators" in the synth world. I strongly suspect that someone looking for information about VCOs on Wikipedia would search for "oscillator", not "voltage-controlled oscillator". It then wouldn't be obvious how to find the article unless they happened to know the specific terminology. Popcornduff (talk) 01:42, 20 January 2020 (UTC)
I see your point. Frankly I don't know whether this case is strong enough to justify an exception. It would clearly be bad if the dab page had separate entries for every type of electronic oscillator. If you want to put it back in I won't revert you, but make it an indented bullet ("**") under Electronic oscillator.--Srleffler (talk) 02:10, 20 January 2020 (UTC)
Srleffler, thanks for seeing it my way - a rare treat on Wikipedia. I'll put it back in. Popcornduff (talk) 02:15, 20 January 2020 (UTC)

## Thin-film interference

Hi Srleffler. Thanks for your edits on the TFI article. I agree that the edit should have some sourcing. I looked and couldn't find any reference to coherence length. In my own experience, with white light you get those beautiful colors when the thickness is at λ/2, as shown in the upper-right photo, but the thicker it gets the more random the interference becomes until, around 12 to 14 wavelengths out, the colors seems to disappear entirely. That doesn't appear to be the case with monochromatic light, which I've seen work at 30 to 50 wavelengths away, possibly more. But I don't have any actual sources that say either way, so I'm with you. Zaereth (talk) 21:25, 21 January 2020 (UTC)

That is what the other editor was alluding to as well. In general, interferometers work with white light only when the paths are almost exactly equal, differing by less than the coherence length of the light. With monochromatic light with a large coherence length, the interferometer works even if the path lengths are quite different. He or she is at least mostly correct.--Srleffler (talk) 04:17, 22 January 2020 (UTC)

## Category:Wireless communication systems

Why have you emptied Category:Wireless communication systems? It's creation was a good idea in my opinion. There are many articles that can be put in this category which will help to reduce the size of the main Category:Wireless. There are a lot of systems that could go in there which don't currently get categorized in Wireless by any subcat. Examples: DECT, CT1, CT2. You should have at least opened a WP:Categories for discussion before doing that to an inexperienced user. SpinningSpark 15:35, 8 April 2020 (UTC)

I see your point. If Category:Wireless communication systems had been created as a subcat of Category:Wireless I probably would have ended up there myself, but since it wasn't I took it as a redundant creation of someone who was unaware of the latter category.--Srleffler (talk) 18:31, 8 April 2020 (UTC)
Thanks for the fast response, and doing the work of putting those suggestions in the cat. SpinningSpark 23:15, 8 April 2020 (UTC)

## Direct quotes in Dot-matrix printer

Hi! You reverted my removal of all the quotation marks from the lede of the article, on the basis that these are direct quotes from the sources. I can't find these quotes in the sources! Let's go step-by-step.

"dot matrix printers"
That's not a quote, it's the name of the article ;-).
"the most common type still sold as of October of 2012,"
The word sold does not occur in any of the sources. In fact, I think this statement isn't even supported by the source!
"a vertical column of pins which fire"
The word vertical does not occur in any of the sources. Neither does fire.
"an ink-soaked ribbon"
The word soaked does not occur in any of the sources. It is called an ink-coated ribbon in the Britannica. Besides, it's three or four words of which one is an article, it's not even a phrase.

I checked all the sources linked in the lede. Is it perhaps the case that you assumed these are direct quotes even though they appear not to be? Cheers! Digital Brains (talk) 08:57, 24 April 2020 (UTC)

Thanks for researching that. Yes, I assumed that they were in quotation marks because they were direct quotes. Apparently that was a bad assumption.--Srleffler (talk) 18:06, 25 April 2020 (UTC)

## Magnifying glass

The explanation to remove an image because it does not fit into the layout is very interesting. ;-) I suppose that your revert represents pure actionism.--Fornax (talk) 07:33, 31 May 2020 (UTC)

An article can only accommodate a limited number of pictures. If there are too many, it starts to interfere with good layout. When an article has enough pictures, we need to scrutinize each to decide whether they really add value to the article. The octoscope seemed like an oddball device; not sufficiently common to include. It wasn't even common enough to be mentioned in the text of the article.--Srleffler (talk) 15:50, 31 May 2020 (UTC)
The presentation of an exceptional magnifying glass cannot be an argument for not depicting it. Particularly with this magnifier, the effort is shown (e.g. 5 elements), which is necessary to achieve a very high magnification. This problem has already been described in the article and is made clear best by the Octoscop. This would obviously improve the article. Of course I will not insist on this improvement. It was just a suggestion...--Fornax (talk) 05:28, 1 June 2020 (UTC)

## Optics: formatting

Hello, thanks for reviewing my changes to optics here. I agree the author's name shouldn't be in italics, but my change didn't affect that. I think the current version is still misleading, as it reads

"Lucky Exposures: Diffraction limited astronomical imaging through the atmosphere" Archived 2008-10-05 at the Wayback Machine by Robert Nigel Tubbs

which sounds like the named person isn't the author. I've changed it to use the "cite thesis" template instead.

Eelworm (talk) 06:21, 9 October 2020 (UTC)

Thanks, yes the cite templates are better. I would have done that as well, but I didn't have time. The cite templates also allow you to pull the archive url into the citation so that it becomes the primary link, which is easier for the reader.--Srleffler (talk) 16:36, 10 October 2020 (UTC)