Talk:Laser safety

Missing information in laser safety ratings (missing power values)

Looking through the Laser ratings, the article seems to missing a great deal of information on power ratings for the various types of lasers and operating parameters

Missing info:
Class 1 max power output (MPE value?)
Class 1B max power output (MPE value?)
Class 3R max power output (pulsed visible, pulsed and non-pulsed non-visible)
Class 3B max power output (non-pulsed visible, and pulsed non-visible)
Class 4 min power output (dependent upon class 3 ratings)

68.0.234.210 (talk) 14:04, 1 September 2011 (UTC)

What is safe?

There seems to be considerable disagreement on reasonable safety guidelines. The initial version of this article seemed to justify (or try to justify) practices which include systematic breaching of laser safety regulations. In particular, it was considered safe to routinely work without safety glasses, even when dealing with class-IV lasers, provided that some guidelines are followed. Surely such practices would be allowed by safety regulations if it could be convincingly shown that they are safe. However, for many reasons (some of which are now given in the modified article), they are not safe. A former colleague of mine worked exactly in this style (no glasses, but keep out of the experimental plane) with a 500-mW Nd:YAG laser. He was later told by a doctor that peripheral regions of both his retinas are burned. He had not noticed that, but with somewhat less luck it could have hit the central portion of the retina, blinding him for ever. He then changed his style; at earlier times, I had been unable to convince him to use his glasses.

Even though most laser operators have probably at least sometimes breached some safety regulations, there is an important difference between occassionally breaching a rule oneself and publicly recommending such breaches to others as allegedly reasonable practices. The latter can hardly be considered responsible. Therefore, I strongly recommend not to return to a relaxed version before laser safety experts can be convinced to include such practices into official rules and guidelines.

RPaschotta 13:38, 30 Oct 2004 (UTC)

I do not believe the picture "Green laser – class IIIb compared to class IIIa" has any meaning compared to the issue of safety and should be removed. It contributes nothing of value to the topic. Prof Gall 22:14, 14 April 2010 (UTC) —Preceding unsigned comment added by ProfGall (talk • contribs)

---

I think that after your edit, the article is reasonably NPOV, discussing both common practice and objections against it. (As opposed to earlier versions that could be read as promoting dangerous behaviour and then as moralizing).

By the way, I think most operators are actually more careful with class 4 lasers. I haven't found a table that lists the exact tresholds for the different classes at various wavelengths, but the treshold for class 4 seems to be around 500 mW. Diffuse reflections from pieces of paper with 500 mW visible light are definitely unpleasant to have within your field of view -- and likely harmful as well, so people tend to be more careful with those.

More philosophically, one could wonder where one should put the boundary between acceptable and unacceptable risks. The chance of dying from head injury is about the same for an hour of car driving as for an hour of cycling (quite low compared to other risks in either case). However, few find it reasonable to recommend helmets to car drivers. Laser accidents happen, but are not very common, and I have not heard about anyone who actually completely lost sight in an eye. The worst I know of is someone who damaged 30% of the central view area of one eye due to a reflection from a mixing crystal.

Han-Kwang (talk) 15:54, 30 Oct 2004 (UTC)

It appears to me that the recommendations made in 2004 have not been implemented. The text still appears to condone unsafe behavior. Eyewear must be worn when engineering or other controls are inadequate to eliminate the potential exposure in excess of the applicable MPE. There have been dramatic improvements in eyewear coatings in the past few years. Eyewear can now be tailored to block only the harmful wavelengths produced by a given laser. The eyewear is also lightweight and comfortable, so the old excuses no longer apply. In the US, your employer is mandated by law to provide you with the safety equipment mandated by the ANSI Z136.1-2000 standard. In the case of Class 4 lasers, this applies to the purchase of eyewear, signage, viewing aids and laser access control systems.

1sciguy 18:25, 6 April 2007 (UTC)

It's an open encyclopedia: go ahead and edit it. However, if you update it, make sure that it's NPOV - something that already lacks now. The article is really not supposed to tell the reader what to do and what not to do - but rather explain what are common practices and what official regulations are. Han-Kwang 19:23, 6 April 2007 (UTC)

disputed

It says most laser pointers are class II. Where's the evidence for this? They're class IIIa or IIIb. Class II lasers have minimal output intensity, like that from an LED. Also see my counterclaims at Talk:Laser. lysdexia 21:25, 21 Dec 2004 (UTC)

Agreed. In the UK and parts of Australia laser pointers are advertized as 1mW, or if you read the fine print "<1W" thus class 2. In the US and most other countries they are advertized as 5mW and have a sticker on them that says, "<5mW" and "CLASS III LASER PRODUCT." Zyxwv99 (talk) 02:50, 8 August 2013 (UTC)

Laser proof curtain is necessary

Blink reflex does not work when you look at sun behind a curtain. It also applies when we exposed to a laser behind a curtain however, it is still dangerous it will burn points where the picture of light holes focus in the retina. All fabric curtains have these direct holes. --Mahdig 31 October 2006 (UTC)

I'm not sure what you mean. Of course, a laser curtain should be made of a material that doesn't transmit any light, but not for the reason you mention. The images of the holes on your retina are too low in intensity to cause harm (For the record, I regularly hold pieces of tissue paper into multi-watt beams and watch them without any harmful effects). However, typically part of the beam will propagate into the same direction after going through the tissue or open fabric. If your eye is in that beam path, it will of course be very unhealthy, since that beam will be focused onto a single spot on the retina. Han-Kwang 23:59, 31 October 2006 (UTC)

You said, "The images of the holes on your retina are too low in intensity to cause harm". It will be true only when the harm of light is thermal. However, in visible light region, the harm of laser to retina is photochemical and the size of picture in retina does not change harm effect. about the test you have done that I think you mean that when you look at a lamp behind a tissue the flash blindness does not occur however it occurs but in the points with distance to each other so it is not so noticeable. The problem exists with ordinary plastic curtain, too. Because you can see bright light behind them that it means that, it has holes. --Mahdig 14:06, 1 November 2006 (UTC)

I still have no clue what you are talking about. I see that you created an article Cutains and The blinking reflex containing the above comment. I strongly suggest that you add a diagram, remove the two spelling errors in the article, and add some context. As the new article is now it is non-encyclopedic and a very likely candidate for WP:AFD. Also please remember WP:NOR. Han-Kwang 14:42, 1 November 2006 (UTC)

May be you understand what I am saying if you use a cloth instead of a tissue (tissue holes is very small) and with dark color and put it in front of your eye when looking to a lamp. Mahdig 18:52, 26 November 2006 (UTC)

OK, you mean that a laser-shielding curtain should be absolutely light-tight. Agreed. But that doesn't have anything to do with the blinking reflex. Han-Kwang 19:36, 26 November 2006 (UTC)

Assenment scale

I'd say that this article definately needs an A-class or at least a GA-class rating on the assesment scale. I have nominated it for one of these ratings. G man yo 09:55, 28 February 2007 (UTC)

What do these classes mean? Pzavon 15:24, 28 February 2007 (UTC)

Reasons for GA Failure

Unfortunately I have failed this article as there are a few areas in which I would like to bring to attention to the editors of this article in order to hepefully bring it up to standaeds in the future.

1. The name of the article (Laser safety) is not mentioned in the introduction and not emboldened as mentioned in WP:MOS
2. Secondly, there are very few interwikis is the second half of the article, therefore once again it is not up to the standards of WP:MOS.
3. The different classes for the old system and the revised system should be in subcategories instead of just emboldened as mentioned in WP:MOS.
4. There are only 2 categories, I'm sure they could be a few more added.

If this article was improved in the ways mentioned above and any other areas in which editors bring to attention then it may pass in future months/weeks.Tellyaddict 13:00, 3 March 2007 (UTC)

Leakage of high-power IR pump beam from DPSS laser pointers?

Anything authoritative on this issue?

• [1] (scroll down to "Yet Another caution note on DPSS laser pointers")
• [2] "It's also possible for a misaligned green pointer to let out IR while still throwing a green beam; that can happen if you drop them and their internal alignment goes bad."

"(From The Physical and Theoretical Chemistry Laboratory Oxford University)"

Which makes the whole section a copyvio... ed g2s • talk 13:30, 9 August 2007 (UTC)

I'll try to rewrite the section one of these days. Han-Kwang 10:04, 10 August 2007 (UTC)

Excellent in general, but lacking some necessary details

The Class 1 and Class I limits are clearly stated in the abstract ==> laser exposure may not exceed the MPE. However, while Class 2 and Class II limits are correctly expressed the for *visible* light (which Class 2 and II are specific to) Class 3x and Class IIIx and higher classifications continue to assume visible light. For instance, I work with lasers which regularly emit powers greater than 10 mW but which are still Class 1 - according to this page they would only possibly be Class 3b and Class IIIb due to the clear statement for each that lasers emitting greater than 5 mW radiation are such. There is also a serious problem with an earlier statement (section titled Classification) that the relevant units for MPE are W or J, and switch to W/m^2 at wavelengths greater than 4 um. This is just wrong. The relevant units are always, specifically, radiant exposure (in J/cm^2) or irradiance (in W/cm^2) for both MPE evaluation and classification. Statements like, "output may not exceed 5 mW" are rules of thumb for point-source lasers (in this case for visible Class IIIa lasers) which have implicit assumptions about beam diameter, ocular aperture, aversion response time, etc. built in. Looking first for response. If I have time perhaps I'll try to improve this. 64.32.245.242mjd 2007-10-29 16:42 EDT

You don't indicate where you are located and which jurisdiction's laser safety regulations you are working with. On the issue of whether a 10mW laser could be Class 1, I believe the US FDA/CDRH regulations are structured so that such a laser could not be Class 1. Pzavon 02:16, 30 October 2007 (UTC)

According to IEC60825-1, the accessible emission limits (AEL) for class 1 are 0.39 mW for visible light (-700 nm), 10 mW for 1400-4000 nm, and 1 kW/m2 above 4000 nm. In the range 700-1400 nm, there is a wavelength dependence. However, the wavelength and pulse duration dependence is -not surprisingly- just as complicated as for the MPE plots, and I don't think it is very meaningful to specify it in so much detail. In principle, classifying a laser and sticking the correct warning labels on a laser is the duty of a manufacturer, who surely has a copy of the regulations. The user of the laser just has to read the label "class 1" and understand that it is safe to use without eye protection, or "class 3B" and understand that it is dangerous. The article just gives a few example AEL values for common types of lasers. I will clarify that a bit, although it is for example clearly mentioned that the 5 mW limit for Class 3R is for visible, continuous lasers. I don't have access to the old classification (the IIIa description in the article does not mention the wavelength range.) Pzavon, do you have a copy of the US and/or old regulations? Are the MPE/AEL numbers the same as in the IEC standard (I have the 2007 revision)? Han-Kwang (t) 15:42, 30 October 2007 (UTC)

Harm through eyelids

I removed this: **When picking up something from the floor, closing the eye may not give sufficient protection against multi-watt laser beams, as the eye's lid is partially transparent, particularly for infrared light. Closing both eyes when kneeling becomes second nature and automatic for workers in such fields.. Not only is the remark about the second nature a bit strange, but also the first part is not correct. Although the eyelid may not absorb near-IR light, it still scatters the laser light which prevents the light from being focused onto the retina. Of course, a 10 W beam with a 3 mm diameter will probably burn the eyelid and possibly damage the cornea underneath as well, but this is not a very likely situation in a research lab, where the smell of burning clothes, skin, and wall painting would have drawn attention before. Han-Kwang (t) 22:24, 1 November 2007 (UTC)

Burning sweater in my case. ;) --Chuck Sirloin 17:15, 2 November 2007 (UTC)

Suggestion for additional reference

I suggest to insert the following additional reference, which is a page of my own "Encyclopedia of Laser Physics and Technology": article on laser safety in the Encyclopedia of Laser Physics and Technology

RPaschotta 16:34, 5 Nov 2007 (UTC)

Edits on class 4 and treatment lasers

Regarding these edits, I think I agree with Pzavon, both on how a class 4 laser can damage skin and on the suitability of therapy lasers for this article (i.e., not suitable). Therapy laser treatment seems to be an interesting topic though, that would probably be suitable for an article of its own with a bit more background on what kind of medical conditions this laser treatment would deal with. Han-Kwang (t) 00:46, 16 December 2007 (UTC)

Old/new classification

I think the sections on the old and new classifications should be merged. Most of the specifications overlap. I think there should be a small intro about the differences between the schemes, and then Class 1/I can be discussed together. IN the current version there's too much duplicate info. Han-Kwang (t) 18:01, 12 February 2008 (UTC)

I disagree. The systems are distinct and separate in that the old system has regulatory force in the US and not elsewhere. The "new" system is a revision developed primarily in the EU and being adopted elsewhere, including the US. The purpose of two sections is to make it clear and easy to see the range of each system and to recognize the differences. In the US, symbols and phrases from both can be encountered at the same facility. Even the use of Arabic vs Roman numerals is easier to show clearly with a separate listing. And the new classes (1M, 2M, and 3R) do not have a precise one-to-one relationship with the replaced classes (IIA and IIIB). Perhaps some text can be combined, but the Hazard Class numbers should be displayed as two separate sequences. Pzavon (talk) 03:28, 13 February 2008 (UTC)

I will think about how to combine some text. The problem is that I am not familiar with the details of the old system to really be able to give an overview of the philosophies behind the two systems.

Something else: your recent edit summary: The definition of Class 4 is based upon determinations of what will damage skin. I looked it up, thinking that it was "skin damage OR dangerous diffuse reflectios", but indeed, The IEC standard says about class 4: "...for which intrabeam viewing and skin exposure is hazardous and for which the viewing of diffuse reflections may be hazardous. (emphasis added) Apparently, also from the description of class 3B, a laser can be dangerous in diffuse reflections without causing skin damage, and vice versa. I'll clarify this. Han-Kwang (t) 13:05, 13 February 2008 (UTC)

Your assessment of the basic criteria for Classes 3B and 4 is correct. Pzavon (talk) 03:21, 14 February 2008 (UTC)

The "old system" (quotes from article) has no information about when that classification system was in use, nor when the classification scheme changed. It also has a very old citation needed tag. The section should be fixed or removed. 134.29.231.11 (talk) 17:36, 24 February 2011 (UTC)

Problem with Class 2 Caution label text provided at line 90

This illustration of a label claims that eye damage could result if a Class 2 beam is directed at the eye for more than 10 seconds. such a label seems "off" to me. I am not aware of any labels containing explicit time limits. Can anyone really familiar with practice in the EU say whether such a label is actually in wide use? Pzavon (talk) 23:42, 16 March 2008 (UTC)

I didn't notice this Talk message before, but indeed that was not correct. The text was modified here, and I undid it a while ago. Case closed. Han-Kwang (t) 18:41, 6 July 2008 (UTC)

Laser pointer safety

I have edited the laser pointer section to reflect that, although red laser pointers appear to be safe and this shouldn't be denied, the overall tone of the article should still emphasise laser safety and the dangers of lasers in general. The paragraph removed consisted solely of an implication that people who complained over laser pointer exposure were liars, fraudsters or crybabies, which isn't too value adding above a simple statement of the fact that damage is unlikely to occur.217.154.66.11 (talk) 19:41, 14 April 2008 (UTC)

In research enviroments

I just rewrote the section about conventional practice in research labs because I felt it was too much POV-, essay- and howto-like. Unfortunately, this is a subject that everybody who works in this area seems to know, but nobody writes down, probably because of legal consequences, so it still looks a bit like original research. I know many people who have had laser-related eye injury in a lab. The worst case is someone who damaged 30% of one fovea, meaning he can't use that eye for reading. And then there are many people who have a small burn. I did once have the opportunity to visit the R&D department in a laser factory, and the procedures were pretty similar to what I've seen in many university labs (goggles are available but only worn during very specific high-risk procedures). Any suggestions for references? Han-Kwang (t) 18:07, 6 July 2008 (UTC)

Re-nomination for GA article

Now, I'm no expert, but the reasons for this article failing at getting "good article" status seem to have been fixed. "Laser Safety" in bold is the first phrase in the whole article, there seem to be alot of links to other articles, the classes and class levels are now sections, and it has 7 categories.G man yo (talk) 11:41, 2 November 2008 (UTC)

Okay, I've re-decided, this article is not necessarily a "good article" yet, however has the potential to soon be. It needs more sources cited inside of the text, and it needs to cover a couple more topics in the lead, even if just briefly (such as protective eyewear). If these things are fixed, then I think it could pass. G man yo (talk) 14:50, 10 November 2008 (UTC)

The section on research environments is problematic. I actually wrote a large part of it and I am pretty sure that the conventions there are common place (also indicated by the absence of objections despite 400 page views per day[3]), but for liability reasons they are not written down anywhere. Following Wikipedia policy, this section should really be removed per WP:OR, but I'd rather have that section in for education of the world and have an article without GA status. Han-Kwang (t) 19:00, 10 November 2008 (UTC)

I can understand that desire, but that is not what the Wikipedia is for (not a How-to manual, etc.) I'll try to look more closely later this week and see if I can rework it, but otherwise I support removal. Pzavon (talk) 22:34, 10 November 2008 (UTC)

It seems that I was too pessimistic when I thought nobody writes these things down. Googling for "laser-safety horizontal beams" and "laser safety jewellery" brings up a lot of links, most of them indeed university institutes. I added a number of references which seem to roughly cover what is in the article, but there might still be a couple of unsupported statements. Unfortunately the new references don't really prove that these guidelines are commonplace, only that there are a couple of institutes that use them. We really need a secondary source that claims that "most university laser labs do such-and-so". Han-Kwang (t) 09:00, 11 November 2008 (UTC)

Actually, I think this is an important section, it's main problem being that it is a little biased (especially the first sentence). Really, the main problem with this article is the lack of citations, especially in the classification sections. Also, the difference between classes 1 and 1M and between 2 and 2M are hard to find. G man yo (talk) 11:59, 11 November 2008 (UTC)

Thanks for noting that there wasn't a reference for the classification system. It is all in the IEC 60825 standard, which was cited somewhere else in the article. Han-Kwang (t) 19:39, 11 November 2008 (UTC)

I would like to see a few changes before considering this a "good article":

• More comprehensive coverage of the typical safeguards required by regulations, for example assignment of a laser safety officer (probably deserves a whole section), use of beam stops, training requirements.
• Clear description of the mechanisms for injury.
• Each laser class (especially for the "old system") doesn't need a section heading taking up room in the TOC.
• WP shouldn't make recommendations, even behind the veil of the passive voice ("is recommended").

I disagree with this, and it's not policy. See WP:HOWTO. WP would not be able to discuss the treatment of any disease, in that case. Nor even ISO 9000 standards. Recommendations exist in the real world as objective facts with reliable sources. SBHarris 19:18, 7 May 2010 (UTC)

I can work on some of this, but unfortunately don't have access to the actual regulations to be able to know I'm being complete and to give references. The Photon (talk) 03:21, 12 November 2008 (UTC)

Does wearing Glasses or Contact Lenses Increase Laser Damage to the Eye?

Since glasses and contact lenses are meant to focus light, do they increase the damage by lasers to the retina? I heard someone one time wearing contact lenses the she was more sensitive to daylight light when she first put them on.70.79.50.5 (talk) 09:03, 7 May 2010 (UTC)BeeCier

Yes, wearing corrective lenses for near-sightedness (myopia) would be expected to focus any light more narrowly, including laser light. I suppose in marginal cases, that extra might be enough to make a difference between damage and not. But the relative effect is so small compared with safety eyewear, it's not worth discussing much, I think. SBHarris 19:15, 7 May 2010 (UTC)

No. Corrective eyewear, only serves to correct the eye's native inability to do exactly the same job. 86.166.66.12 (talk) 13:20, 9 March 2011 (UTC)

class of laser product VS class of laser

It seems that the class of a laser product can be lower than the class of the laser it contains (e.g. a DVD burner is a class 1 laser product but IIRC tends to contain a class 3b laser). Does anyone have any more details on this? 86.1.116.158 (talk) 07:20, 15 June 2010 (UTC)

The class applies to the radiation that escapes to the outside world. Since the laser radiation is wholly contained within the DVD burner, there should be no external radiation, thus the burner is a class 1 laser product. However, if you open the casing such that the laser radiation can escape, then it would indeed be a class 3b laser. I have seen DVD video players that have a label inside the casing stating that the laser is a class 3 laser, but this does not seem to be the norm. DieSwartzPunkt (talk) 14:47, 17 February 2011 (UTC)

Hazardous LEDs???

Can someone comment on the following label found (on of all things) a weather forcasting gadget.

It shows the laser hazard symbol (as at the head of the article) with the following words.

CAUTION
LED RADIATION
CLASS 2 LED PRODUCT
POWER: <100MW
WAVELENGTH: 470 nm

The product has 3 LEDs on it but the label seems to apply only to the blue one. I assume that the power should have read "<100mW" as a 100Megawatt blue LED is going to take a heck of lot of power to drive it. It seems odd to put such a label on a product where the blue LED is positioned such that it's only purpose is to be seen. AFAICT, there are no lasers in it whatsoever. DieSwartzPunkt (talk) 14:43, 17 February 2011 (UTC)

From http://en.wiki.x.io/wiki/Light-emitting_diode

Safety and health

The vast majority of devices containing LEDs are "safe under all conditions of normal use", and so are classified as :"Class 1 LED product"/"LED Klasse 1". At present, only a few LEDs—extremely bright LEDs that also have a tightly :focused viewing angle of 8° or less—could, in theory, cause temporary blindness, and so are classified as "Class 2".[81] In general, laser safety regulations—and the "Class 1", "Class 2", etc. system—also apply to LEDs.[82]

24.127.93.76 (talk) 18:59, 29 October 2011 (UTC)

Consolidate Systems

I don't think the old and new system headings need subheadings for each class within them. They should probably be consolidated, most notably the old system. The Photon mentioned this in an earlier section. In fact, the organization of the entire article is rather arbitrary. It seems like things could be grouped better and reorganized. G man yo (talk) 07:35, 27 January 2012 (UTC)

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Correction of plot MPE versus wavelength

Someone pointed out (over email, after 11 years) that there was an error in File:IEC60825 MPE J nm.png in the wavelength range 315-400 nm for exposure times > 1 ns. I have corrected the plot. I'm posting it here so that editors watching this page are aware of the change. Han-Kwang (t) 10:55, 17 October 2018 (UTC)

Indirect laser light can damage camera sensors: https://www.reddit.com/r/photography/comments/ayua7d/tip_dont_record_laser_tattoo_removal/?limit=500 --94.21.11.150 (talk) 19:08, 10 March 2019 (UTC)

class rename and 2 missing classes

Class 4 should be renamed to class 4a.

class 4b: Small part reflections, like dust, which still looked fairly dim at 460 milliwatts, are the next eye hazard.

class 5: The beam's appearance from the side in clean dry air, which still looked dim at 5.5 watts and with a black background, is the last eye hazard. 94.31.84.138 (talk) 19:34, 21 April 2024 (UTC)