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A Look at the Hazards of Green Laser Pointers

An appropriate use of a laser during last year's Jupiter-Venus conjunction. (Photo by Author).

An appropriate use of a laser during last year’s Jupiter-Venus conjunction. (Photo by Author).

Those handheld green lasers pointers may not be as harmless as you thought.

A recent study released by researchers at the National Institute of Standards and Technology (NIST) has revealed an alarming trend. Of 122 hand-held laser pointers tested, 44% of red lasers and 90% of green lasers tested failed federal safety regulations.

The primary culprit was overpowered units. The Code of Federal Regulations in the United States limits commercial class IIIa lasers to 5 milliwatts (mW). And yes, lasers above 5 mW are commercially available in the United States, but it is illegal to market them as Class IIIa devices.  Some units in the NIST study  tested as high as 13 times over the legal limit at 66.5 mW. For context, many military grade rifle mounted lasers are rated at 50 mW.

A diagram of a typical diode-pumped solid-state laser. (Credit: NASA/Langley).

A diagram of a typical diode-pumped solid-state laser. (Credit: NASA/Langley).

“Our results raise numerous safety questions regarding laser pointers and their use,” stated NIST laser safety officer in the recent paper presented at the Laser Safety Conference in Orlando, Florida.

Why should backyard astronomers care? Well, since hand-held lasers first became commercially available they’ve become a familiar staple at many public star parties. Reflecting back off of the dust and suspended particles in the atmosphere, a green laser provides a pointer beam allowing the user to trace out constellations and faint objects. Lasers can also be mounted on the optical tube assemblies of a telescope for pointing in lieu of a finder scope.

A typical 5mW green laser pointer. (Photo by Author).

A typical 5mW green laser pointer. (Photo by Author).

An amateur astronomy club based near San Antonio, Texas even coordinated signaling the International Space Station with a pair of powerful searchlights and a 1 watt blue laser in 2012, just to prove that it was possible.

But such devices are not toys. Even a 5 mW laser can temporarily blind someone at short range. Further eye damage can often linger for days or even permanently and can go unnoticed. This is why researchers working around lasers in research facilities such as LIGO (the Laser Interferometer Gravitational Wave Observatory) must submit to routine eye exams.

Its not the Death Star... LIGO engineers practicing proper safety around the gravity wave observatory's  200 watt laser. Credit: NSF/LIGO).

Its not the Death Star… LIGO engineers practicing proper safety around the gravity wave observatory’s 35 watt Nd YAG laser. Credit: NSF/LIGO).

The trouble with green lasers is that, well, they look too much like light sabers.

It’s for this reason I keep mine on a very “short leash” at star parties and NEVER hand it off to anyone, no matter how well meaning, child or adult. I also NEVER point it below the local horizon, (there’s wildlife in them trees). A laser reflected inadvertently off of an optical surface such as a car window or primary mirror can also do just as much damage as a direct aiming.

And also, NEVER aim one at an aircraft. In fact, it’s a federal violation to do so. The Federal Aviation Administration has reported a 13-fold trend in reported aircraft/laser incidents from 2005 to 2011. There has also been an upward trend in individuals being tracked down and prosecuted for such offenses. If it blinks, assume it’s an aircraft and steer clear!

Reported incidents of laser/aircraft violations from 2005-2011. (Credit: Federal Aviation Administration).

Reported incidents of laser/aircraft violations from 2005-2011. (Credit: Federal Aviation Administration).

In a post-9/11 era, the Department of Homeland Security has been concerned with the potential threat posed by laser pointers as well. It’s not yet illegal to fly in the US with a 5mW laser pointer in your carry-on luggage, but and several countries now outlaw them all together, a note for traveling astronomers. Note that the de facto policy often comes down to the particular TSA officer you’re dealing with.

With this sort of news, we wonder if laser pointers might become outlawed entirely in the coming years. 5mW range lasers are generally classed IIIa or 3R systems. By the American National Standards Institute (ANSI) guidelines, such devices under the recent NIST study would fall into the much more hazardous IIIb range for 5-500 mW lasers. Such lasers can cause permanent eye damage with direct exposure for periods of as little as 1/100th of a second.

Safety distances for a 5mW green laser. (Wikimedia Commons graphic under a Creative Commons Attribution-ShareAlike 30 License).

Safety distances for a 5mW green laser. (Wikimedia Commons graphic under a Creative Commons Attribution-ShareAlike 3.0 License).

It’s also worth noting that actual reported cases of laser injuries are fairly rare. A 2004 paper from the Archives of Ophthalmology cites 15 injuries worldwide each year, while a recent 2012 paper in PLoS ONE estimates “220 confirmed laser eye injuries have occurred between 1964 and 1996,” for an average of 6.9 laser injuries per year.

The Code of Federal Regulations limits output for green laser pointers to 5mW in the visible range and 2mW in the infrared. 75% of the tested devices exceed this standard for infrared emission as well. Note that there have been anecdotal reports that even the point source generated by a laser (say, by shining it against a wall) can be excessively bright. This recent NIST study was the first time we’d seen a back up argument for this. Many of the cheaper handheld lasers sold online (think in the 20$ USD range) may forgo the infrared filtering component all together.

So in lieu of an outright ban on laser pointers, what can be done? Joshua Hadler cites the need for a better accountability for laser manufacturers. “By relying on manufacturers’ traceability to a national measurement institute such as NIST, someone could use this design to accurately measure power from a laser pointer.” Mr. Hadler also notes that a simple test bed for laser pointers can be built using off the shelf parts for less than $2,000 USD. We’re surprised there’s not “an App/Kickstarter for that…” already. (Would-be designers take note!)

In the end, we’d hate to see these crucial tools for astronomy outreach  banned just because a very few individuals were irresponsible with them. Through accountability from production to application, we can assure that laser pointers remain a vital part of the amateur astronomer’s tool kit.

Comments on this entry are closed.

  • Raymond Dayton April 4, 2013, 7:33 PM

    It is also possible to cut yourself with a steak knife. Shall we outlaw the sale of steaks next?

    • Woodrow Wotan April 4, 2013, 8:47 PM

      Mmmmm… steak.

    • Jason Major April 4, 2013, 10:09 PM

      If steak knives could be thrown into the cockpits of aircraft, blinding pilots who are responsible with the safety of passengers and crew, yes. http://www.fbi.gov/news/stories/2011/september/laser_092611/laser_092611

      But the real key is 1. making sure people are fully aware of the dangers of a seemingly innocuous item, and 2. prosecuting negligent uses of them harshly. Should those not work, due to the irresponsibility of even a few users, then all would have to be banned to avoid tragedy.

      • newSteveZodiac April 5, 2013, 4:18 PM

        Item 2 is usually what causes things to be banned because it’s cheaper and easier than actually prosecuting and holding idiots to account for their actions. If you look at the arguments for/against you see it’s a) If you ban these we will not be able to point out astronomical things to a group of people or b) if you don’t ban them someone will down an airliner. That’s a no-brainer for any poltician, especially since deterrents don’t work on real idiots. Please, I’m not arguing for a ban but you can see how it will happen, idiots always spoil it for everyone so if you have a gun and know someone who abuses laser pointers shoot them quick and you might get to keep the lasers.

        DISCLAIMER: This reply contains traces of irony and the author accepts no responsibility for misuse of firearms.

        • Ashley April 5, 2013, 6:48 PM

          I believe it is legal for anyone to own very high powered firearms in the USA. Would firing these at a low flying (eg landing) plane cause any damage? If lasers are banned then it is logical that firearms should also be banned. After all, it is just as easy for some nutter to fire a very high powered weapon at a plane (or a person) as it is for them to point a laser.

      • Douglas Dobson April 11, 2013, 5:48 PM

        Really? you’re going to outlaw steaks if steak knives can be used to blind pilots? There’s too many things wrong with that statement for me to even know what to say. . . .

      • Douglas Dobson April 11, 2013, 5:56 PM

        Man I hope you never get into any public office, I’m not giving up my guns or laser pointers or steak knives or anything else because “all would have to be banned to avoid tragedy” Look, a rock can hurt someone if used as a weapon, so now I’m making it your job to ban all the rocks and enforce that ban. Yeah it’s easy to make a bold (and uneducated) statement like that, but a ban across the board on an item because of a few careless people is ridiculous, impractical, and impossible to enforce. . . . . so go start picking up your rocks buddy

    • Douglas Dobson April 11, 2013, 6:21 PM

      no, only Jason Major should be banned from steaks and steak knives and forks and rocks and bat length sections of fallen branches and his car and anything else that can cause “tragedy”, just ban him from everything that can possibly be misused, pencils, pens, eye glasses (can be used to focus the sun and burn someone) all medications, bottles, cans, any kind of rope or strong string especially piano wire and guitar strings, and dress him up in a hockey goalies uniform for his own protection from tragedy. A dollar says Jason is a grade school teacher., and the rest of us are little children who have to sacrifice everything because one or two of us might hurt ourselves. One of the big problems in government is this mentality; oh my, someone might cause harm with these items, lets ban them all from everyone. Let’s just usher in the New World Safety Order under Martial law with bans on everything, even going outside, no one can work, because someone might suffer an injury there, we all have to live in padded homes with straight jackets on “for our own protection” You know who else enforced a ban on firearms? Adolph Hitler, but we’re just talking about laser pointers. If you really are concerned, then make everyone who buys a laser pointer take a course in laser safety and pass a background check with the FBI, and get a special concealed laser certification and permit. . . . no? OK, then lets leave it the way it is

  • WulfBlud April 4, 2013, 8:08 PM

    I have a scar on my back from when my friend shined a laser pointer on me when I was bending over.. I thought it was funny

    • Kevin Frushour April 4, 2013, 10:31 PM

      I still have a mark of graphite in the back of my right hand from when a friend accidentally stabbed me with a pencil when we were horsing around 25 years ago.

      • WulfBlud April 4, 2013, 10:32 PM

        HAHA, funny you should say that.. I have a graphite in my left palm from 1st grade when I had a sharpened pencil in my pocket and went digging through it after school one day.

        • Dav_Daddy April 5, 2013, 9:29 AM

          That is funny I have one in my right hand between my pointer and middle fingers.

          It’s been there since second grade when a friend and I were bouncing our pencils off of our desks and making them stick in the ceiling when the teacher left the room.

          • Douglas Dobson April 11, 2013, 6:45 PM

            I have some scars from broken glass I didn’t see until I dragged my hand across it cutting my hand wide open. . . . . . should we consider banning glass?, and question for WulfBlud, where did that laser come from?, I’ve pointed several lasers at myself to see if I could feel it, I couldn’t even feel them much less get a scar from them, that’s a pretty powerful laser if it left a scar, more powerful than the lasers they use for hair and tattoo removal which are much stronger than any laser pointers. I’d like to have a laser strong enough to leave a scar, are you sure that’s not just a stretch mark?

  • Rob Sparks April 4, 2013, 8:20 PM

    I go one step further than just not pointing at blinking lights…I don’t point at ANY moving object in the sky unless I have confirmed it is a satellite pass. Nice to have cell phones hand that list satellite passes so I can instantly check.

    • DarkGnat April 4, 2013, 9:03 PM

      I always give it a moment to make sure the object I’m looking at isn’t moving. There is an Air-Force base near me, so I want to be extremely careful. From certain angles, planes may not appear to blink. A plane facing you may have its “headlights” on which can be mistaken for a bright star. Shining a laser at the plane would mean the cock-pit would be illuminated, which would not be good. I’d bet such a scenario would account for many of incidents reported by pilots.

  • meekGee April 5, 2013, 12:11 AM

    So wait. The author says he’s using Lasers at star parties, but doesn’t explain how he differentiates a head-on airplane from a star

    Don’t point lasers at the sky. It’s not complicated.

    • Paul W April 5, 2013, 3:12 AM

      I am also a presenter at an observatory and there are a few simple things:
      Planes move – relatively quickly

      Planes tend to have easily observable blinking navigation lights,

      Head on they’re are usually pretty bright and a presenter who notices a ‘new’ bright star not in a known position should have a clue!

      If you are still unsure, try a pair of binoculars first.

      As for don’t point lasers at the sky, try directing the gaze of 50 people who have little knowledge and have come to learn about the night sky in a dark environment to specific objects without a laser!

      Safe use comes down to 2 basic elements – a bit of experience and common sense, and unfortunately green lasers are easily obtained by people who have neither!

      • meekGee April 5, 2013, 4:11 AM

        So a pilot is supposed to trust his eyesight and the safety of his plane on the hope that you won’t make a mistake, ever?

        Don’t point lasers at the sky. How did they direct people’s attention before laser pointers? And even if they couldn’t, what’s more important? this bit of convenience, or aviation safety?

        It’s a real danger, and there’s no way to supervise which of the astronomy enthusiasts out there is making judgement calls like that, and how good they are at it.

        • Paul W April 5, 2013, 5:55 AM

          Interesting point, – do you trust the pilot of your plane? Is his training up to date, did he spend all last night in the bar?

          We trust in each other everyday and make judgement calls, how about the driver in front/next/behind you on the freeway?

          How far do we push the example? should we ban the use of aircraft for civilian use altogether and go back to ships to cross the Atlantic – which we used before aeroplanes? but then there was the Titanic…

          Licensing/registration could be a way forward..

          • meekGee April 5, 2013, 6:04 AM

            That’s easy. There’s a huge deal of effort going into certifying pilots, and there’s the expense of always having two on commercial flights.

            Also, pilot are necessary to fly the plane.

            It is a simple matter of priorities. Shining lasers into the sky is dangerous in a “lives in the balance” sort of way. Helping astronomy enthusiasts direct the attention of other astronomy enthusiasts just doesn’t compare.

            We have an activity that poses real risk to human lives, that’s carried out with no monitoring, supervision, or accountability, and whose upside is basically convenience. Worth it?

            You think you know what you’re doing. But what about the next guy? The one to whom you wouldn’t give your laser? Can he tell the difference between an airplane and a star?

            Here’s a constructive idea. Make a pointer with a large lens, that focuses non-laser light at a distance of 50 m. Will give you a nice bright spot, and not hurt anyone.

            Meanwhile, don’t shine lasers at lights in the night sky. It is a dangerous activity, even if done with the best of intentions.

          • Dav_Daddy April 5, 2013, 9:54 AM

            Not to detract from your point but pilots are most certainly not “necessary” to fly the plane and haven’t been since the late 80’s. The only real purpose of having pilot(s) is strictly psychological because most people are not comfortable flying without there being a human being at the controls.

            They don’t want to know that if the computer and backup both took a dump there is no way any human could make all of the super tiny rapid fire adjustments that are necessary for modern aircraft to stay airborne. Autopilot can taxi, take off, change speed and altitude, avoid weather and other aircraft, enter a landing pattern, land, and taxi to the terminal. At no time does it need input from the cabin, most accidents happen when a bonehead human gets vertigo, takes over and does something stupid.

          • meekGee April 5, 2013, 2:59 PM

            I know. But as you say, it’s irrelevant today. When most planes are automated, go ahead and lase….

          • Nick Langer April 5, 2013, 5:43 PM

            or “tint” the windows of the plane to block the wavelengths that are a problem.

          • meekGee April 5, 2013, 5:46 PM

            In theory, yes. Except the lasers show up on the market a lot faster than you can tint all the airplane windows.
            (Never mind who pays for them).
            So until this is done somehow, wait for it…. here it comes… Don’t point lasers at lights in the night sky. :)

      • maurizio52 April 5, 2013, 9:10 AM

        It is simply immpossible to blind a pilot during flight, the beam cannot pierce the airframe from bottom.

        It is possible to dazzle a pilot near the airfield, but hand held beams aren’t stable enough while the aircraft is moving (pretty fast during landing approach and takeoff) and an airport should be sourveilled enough to prevent such things to happen.

        I’ve seen (via tv) a green laser aimed at a soccer player’s eyes from a stupid man in the public. The green spot was already an inch wide and very unsteady. The player simply ignorate it, maybe for it vasn’t aiming directly in front at him.

        Distance has a key role because the beam disperse it’s energy and nobody should stay within a hundred meters from a runway for safety and security reasons.

        So I strongly agree with mr Daniel Beck’s words: “However making green lasers illegal, or regulated won’t solve anything,
        it will only serve to bloat government and it’s power further, and
        restrict the rights of those who would never have considered breaking
        the law in the first place, and those who don’t care about laws will
        continue to break the laws, both the old ones, and the new ones”

        Here in Italy laser pointers are already illegal, welcome in the dumb club!

  • Daniel Beck April 5, 2013, 1:36 AM

    I love how people who might all be in favor of banning XY or Z (ex Guns), suddenly get all constitutional and pissed off when the ban stick is pointed at something they care about.

    Frankly it is beyond time people woke up and realized the role of government is not to protect us from anything. The TSA mentioned in this article are an affront to the logical arguments that formed the foundation of the USA.

    Thomas Jefferson said, and I quote:

    “I know no safe depository of the ultimate powers
    of the society but the people themselves; and if we think them not
    enlightened enough to exercise their control with a wholesome
    discretion, the remedy is not to take it from them but to inform their
    discretion by education. This is the true corrective of abuses of
    Constitutional power.”

    In other words, when the people abuse their powers and rights, it isn’t the job of the Government to take those rights away like they would from a spoiled wicked little child… Or restrict them to only those who are “Trusted” by the establishment.

    The right ways to use laws is as a penalty in the event that someone missuses their rights and or violates the rights of others.

    Shining a green laser at a plane should be illegal and it is!

    However making green lasers illegal, or regulated won’t solve anything, it will only serve to bloat government and it’s power further, and restrict the rights of those who would never have considered breaking the law in the first place, and those who don’t care about laws will continue to break the laws, both the old ones, and the new ones.

    • DarkGnat April 5, 2013, 3:26 PM

      Which is why UT’s post on the subject is so important.

    • Douglas Dobson April 11, 2013, 5:46 PM

      “spoiled wicked little child”? I hope you don’t have any children of your own. There are no wicked little children unless they’ve already learned the wickedness from their parents who might do such things as beat on, or yell profanities at, or call them “wicked” little children. To call a child wicked is to step back into the 18th century

  • Douglas Dobson April 11, 2013, 6:34 PM

    You’re right, and again we should ban rocks and branches because someone could hurl them at an aircraft taking off or landing and placed just right you could seriously crash the aircraft, especially on takeoff, when a small rock could be thrown into the engine intake of a jet and destroy the entire engine which could explode and kill everyone (I hope no terrorists are reading this) My point is you can ban things like lasers and guns, but only the law abiding citizens will give them up, the criminal element isn’t going to give up their guns, anyone intent on bringing down an airliner with a laser isn’t going to hand over their laser because they’re told to do so, banning stuff isn’t the answer, prosecuting law breakers and idiots severely is the only answer,

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