Making Sure Green Lazers dont get "Banned"

[Garyh]

Hry leets ban eroplaens instaed!
LOL!

Seriously any new technology can be used for purposes they were not intended for and some uses are just plain criminal...
lets not go backwards guys..
They are a great pointing/educational tool that has its place when used responsibly.

[dugnsuz (Doug)]

Despite all the spelling errors, looks like it could be all over Rover!

http://au.news.yahoo.com/080402/21/16c36.html

[Omaroo (Chris Malikoff)]

Originally Posted by Iemma

"It is an extreme measure, these lasers are used for quite legitimate purposes," he said.

Maybe it'll come down to licensing. Still - much easier to blanket-ban.

[mark3d]

heh sorry no need to argue amongst ourselves is there

it sounds like the issue is the importation of them. restricting that might meet their objectives meaning no need for licenses etc.

i want to buy one but it might become a white elephant if i got the wrong one

[astronut (John)]

Chris,
Whilst I agree with licensing lasers for legitimate use, I'm not prepared to pay for the license (an inevitable addition, when pollies are involved) for a $50 laser.

Originally Posted by Omaroo

Maybe it'll come down to licensing. Still - much easier to blanket-ban.

[Peter Ward]

Just got back from the USA, but cannot believe the media hype and hysteria associated over this.

Having been "laser flashed" myself a couple of times I am totally perplexed as to why this is even an issue. These brightish green flashes from the ground are certainly no where near as bad as, say, the flash that goes off while having your photo taken by a traffic camera....(clearly this doesn't distract motorists enough to cause vehicle accidents...after all there is a revenue issue here!)...and are at worst an annoyance to aviation.

But to suggest this would bring down a heavy jet in the 'burbs beggars belief!

Utter bilge and a total and complete over-reaction....and yet (likely) another freedom lost in the land of Oz.

[mark3d]

not sure if anyone is a Crikey.com.au subscriber but this article looks interesting:

Today’s laser abuse summit in Canberra convened by Customs faces much tougher issues than fools pointing bright beams of light at aircraft

not being a subscriber thats all i can see ;-)

[Ric]

Hi Peter, as a person who works in this area I was wondering if you know if there is a film or tint that could be used to coat the inside of the cockpit windows and block out any laser flash.

I'm sure in this world of amazing technology there must be something that can do the job.

Just a thought I had this morning.

Cheers

[Suzy_A]

According to ARPANSA (Australian Radiation Protection and Nuclear Safety Agency):

Lasers are classified according to the hazard associated with their emissions, as defined in the Australian/New Zealand Standard AS/NZS 2211.1:2004 Safety of Laser Products Part 1: Equipment classification, requirements and user's guide:

• Class 1 and 1M (magnifier) lasers are considered safe under reasonably foreseeable conditions of operation;
• Class 2 and 2M (magnifier) lasers emit visible light at higher levels than Class 1, but eye protection is provided by aversion responses such as the human blink reflex. Class 2M lasers can be hazardous if the beam is viewed directly with optical instruments;
• Class 3R (Restricted) lasers produce visible and invisible light that are hazardous under direct viewing conditions;
• Class 3B lasers produce visible or invisible light that is hazardous under direct viewing conditions; either they are powerful enough to cause eye damage in a time shorter than the human blink reflex (0.25 seconds) or the blink reflex is by-passed due to the invisibility of the beam. Laser products with power output near the upper range of Class 3B may also cause skin burns;
• Class 4 lasers are high power devices capable of causing both eye and skin burns, their diffuse reflections may also be hazardous and the beam may constitute a fire hazard.

For ALL lasers of class 3R, 3B and 4 in ALL Australian states and territories, a licence and registration is required.

This is what the law says in WA (where I am):
All lasers (including laser pointers) in Western Australia must comply with the Australian Standard AS2211; this includes both correct labelling and classification. Any laser pointer in Western Australia of power output greater than 1mW should not be used or possessed by members of the general public."

A friend who is the laser safety officer at a university wandered around the uni recently with a laser power meter and ended up confinscating about 90% of the laser pointers he came across. Most were red and a few green and most were 3 - 5 mW, although some were over 20 mW.

A 20 mW shone into someone's eye will cause instant and permanent damage to their vision.

What has happened in the past has been that, while illegal to sell or possess one of these laser pointers without the appropriate licence, the relevent State and Federal authorites have generally not worried about it. Hell! I can buy a 50 mW laser from a well-known Australian website! That will poke your eye out no problems!


However with the various knee-jerk reactions resulting from various jerks mis-using laser pointers, they are starting to enforce the laws that have been around since the 1970's.

How many times have you seen a 6 yo kid playing with a laser pointer while their parent(s) ignore them.

Unfortunately there are too many kids with impaired vision around these days...

Please note that I am also upset about all this - I have ... um quite a HeNe and diode lasers around the place - but I use them responsably and would be very upset if I am suddenly classified as a 'crim' because of my illegal lasers...

But hey, the same thing has happened lots of other times - a lot of law-abiding firearm owners became instant crims when the law changed, so did most people making biodiesel in their back yard when the excise law changed.

[Peter Ward]

Originally Posted by Ric

Hi Peter, as a person who works in this area I was wondering if you know if there is a film or tint that could be used to coat the inside of the cockpit windows and block out any laser flash.

I'm sure in this world of amazing technology there must be something that can do the job.

Just a thought I had this morning.

Cheers

Many windscreens on commercial jets already have a thin gold coating which is used for windshield heater system. That said, a tertiary would probably not be a viable solution.

Most cheap laser pointers diverge quite quickly due their not so good optics and atmospheric dispersion, hence after several thousand feet they loose the potentially retinal damaging effect they may have at just a few metres.

In effect they become cheap searchlights. Nothing more.

To suggest they... as one poorly...no...make that stupidly...advised NSW Premier stated... they could bring down an aircraft is just nuts.

There have been over 300 document laser events yet there has been not one subsequent aircraft safety "incident". The SMH even reported an "infrared" laser attack on an aircraft....wow! those guys must have had very keen vision!!

As an aside....Police use I/R lasers in their LIDAR's (speed guns). Maybe they'll be banned too!

[Sausageman (Mike Boggan)]

The Professional Pilots rumour network (PPrune), has quite a few posts on this subject, some not so good, but a majority of them are as confused as us over the damage they can do and get confused over mW and MW.

There are some interesting posts on the power of lasers also.

You will have to register to view the posts though.

I don't want to see the lasers banned, just limited like firearms, vehicles, alcohol and such.

Mike.

[programmer]

Hi Susan

Some good info, thanks. But I think it's reality it is quite hard to cause 'instant and permanent' damage with a 20mW laser. You'd have to hold them down as the blink reflex would kick in. You'd also have to focus it in the one spot for maybe half a second (guesstimate) and be up very close, say < 1m. The NOHD (Nominal Ocular Hazard Distance) would probably be 30-40m, but focusing it at any more than a couple of meters would be very hard.

Also a true laser pointer (1mW) is almost impossible to cause eye damage with so probably harmless for the kids, but still not a great idea to let them loose.

Without doubt however, leaving a higher-power laser around for kids to get hold of is a BAD thing.

This is a good read (DansData WickedLasers laser review)

Take care

[Ric]

Thanks for the point of view Peter.

It make me wonder exactly who is advising our wise politicians and what other agendas do they have.

Cheers

[Suzy_A]

Originally Posted by programmer

Some good info, thanks. But I think it's reality it is quite hard to cause 'instant and permanent' damage with a 20mW laser. You'd have to hold them down as the blink reflex would kick in. You'd also have to focus it in the one spot for maybe half a second (guesstimate) and be up very close, say < 1m. The NOHD (Nominal Ocular Hazard Distance) would probably be 30-40m, but focusing it at any more than a couple of meters would be very hard.

Also a true laser pointer (1mW) is almost impossible to cause eye damage with so probably harmless for the kids, but still not a great idea to let them loose.

About 90% of laser pointer sold ARE well over 1 mW. Having actually tested many with a laser power meter, most are 3 - 5 mW and it is not hard to find a 10 - 20 mW laser pointer for $5 - $10 in a shop, although it almost certainly will be labelled "<1 mW".

As for eye damage - it doesn't happen very often as the 0.25 second blink reflex is the worst case - most people will blink and divert their eyes much faster than this, so even a 5 mW will usually not cause damage. However a 10 mW probably will and a 20 mW certainly will.

While these are very low power, their power density is actually very high.

A 1 mW laser may have a beam width of 1 mm or 0.78 mm2. This equates to a power density of (1 mW x ((1000mm*1000mm)/0.78mm2)) = 1274,000 mW/m2 or 1274 W/m2. This is almost exactly the same as the sun at it's zenith and which will cause permanent damage after about 10 seconds exposure - which of course doesn't usually happen as most people have the common sense not to look directly at the sun that long or to blink and divert before there is any damage.

The eye will focus 1 mm beam down to about 20 um, giving about a 400 x increase in power density.

A 20 mW is about 20 x brighter than the sun and will usually cause permanent eye damage before the blink reflex can work.

While not that rigorous, http://en.wikipedia.org/wiki/Laser_safety has some quite a good info.

Incidentally, a number of RAAF (and probably other military) aircrew have suffered permanent eye damage while flying past foreign military naval vessels, particularly those of a former (current?) world super-power, although they would not have been using run-of-the-mill laser pointers...

Susan
Radiation Safety Officer
Senior Physicist

[Peter Ward]

Originally Posted by Suzy_A

A

A 1 mW laser may have a beam width of 1 mm or 0.78 mm2. This equates to a power density of (1 mW x ((1000mm*1000mm)/0.78mm2)) = 1274,000 mW/m2 or 1274 W/m2. This is almost exactly the same as the sun at it's zenith

Susan
Radiation Safety Officer
Senior Physicist

Susan...interesting analysis...but you might want to check your math. The sun is a broad spectral source and its approx 1Kw per sq m flux is spread over a very large spectral range.

Lasers are spectrally very pure, and sure, in their particular frequency, can rival old Sol...but in terms of total power are not very energetic....hence to get the same flux over a *very* narrow band they need to be rated in 10's (if not more) of watts rather than milliwatts....


Cheers
Peter

[Suzy_A]

Originally Posted by Peter Ward

Susan...interesting analysis...but you might want to check your math. The sun is a broad spectral source and its approx 1Kw per sq m flux is spread over a very large spectral range.

Lasers are spectrally very pure, and sure, in their particular frequency, can rival old Sol...but in terms of total power are not very energetic....hence to get the same flux over a *very* narrow band they need to be rated in 10's (if not more) of watts rather than milliwatts....

Cheers
Peter

Hi Peter,

As you are probably aware, in SI units, Power (in watts) is defined as energy (in Joules) over time (seconds). Similarly, watt per square meter or a joule per second per square meter is power per unit area (m2).

A beam of photons at 1250 watts per square meter will carry the same amount of power per unit area and hence energy per unit time and area irrespective of the wavelength, spatial or chromatic coherence.

What is different of course is how the energy is absorbed (or not) when it strikes some surface. At both far ends of the spectrum, gamma and radio, the energy in the photons are not well absorbed by tissue and so quite high flux levels can be tolerated, although with gamma radiation the small proportion of energy that is absorbed does cause severe damage - only 3 joules per kilo whole body exposure (ie total 200 joules wb) can kill someone by wiping out their bone marrow. Drinking a cup of hot coffee will deposit more energy than that... RF radiation tends to cause thermal heating and the human body can absorb a MJ or so of evenly distributed heat without too much damage.

In the case of incoherent sunlight, certainly the UV part of the 1000 W/m2 (about 50 W/m2 I think?) is absorbed in the cornea and lens (causing in extreme cases short term things like snow-blindness and in the long-term cataracts etc) and the IR part is also largely absorbed before it gets through the eye. Even so, something like 850 - 900 J/s/m2 will be absorbed by the retina by looking at the sun - and this is independent on the coherence and wavelength apart from the UV and IR that I mentioed above. Obviously the energy will be much less than this as the aperature, ie pupil, is only a few mm across. Also due to chromatic, spherical etc aberations in the eye as well as the angular size of the source (the sun) which results in a fairly large image, the energy per unit area will be relatively low.

In the case of a coherent (or relatively) source like a diode laser, the energy per time per unit area for a 1 mW laser is, as I said, about the same as the sun, but due to lower aberations and aperture not being an issue, the energy per time per area will be somewhat higher, but still within the same order of magnitude or so, of for looking at the sun for the same time.

In the case of a 20 mW laser pointed at a pilot or even at just anyone at a distance (probably at more than anything more than a dozen metres or so), the time that the beam is in their eye would probably be too brief to cause permanent damage, not due to their blink reflex, but rather as it would be almost impossible to hold the laser steady enough and aim it well enough at the target, ie 3 - 7 mm pupil. Also of course at a few hundred metres the beam will have diverged up to a few cm across, thereby reducing the energy per unit area.

Am I still coherent or has the red wine and late night got to me?

[KG8]

From the mainstream story we have the political "spin" designed to convert public opinion toward a certain perception.

"There has been a sharp increase in the number of laser attacks on planes"

"authorities say it is hard to stop the weapons being brought into Australia"

The key words, the trigger words, are "attack" and "weapons" and when such stories are run long enough and from enough sources public opinion turns. This is why it is important to watch as little TV as possible because regardless of what we think, our perception about the world will be progressively altered, bit by bit, until we are believing all sorts of crap that has no basis in reality.Most people think they are too smart to be fooled but the truth is these saturation techniques work. In the example of the lazers we know it's crock, from personal experience and our common sense knowledge of the technology. But 99.5% of the people have no such knowledge and will eventually view anyone with a lazer as a potential mass murderer.

What other lies have we been told that we take for granted as truth?

[asterisk (Geoff)]

From today's Sydney Morning Herald (somewhat edited):

"THOUSANDS of high-powered laser pointers are already circulating in Australia, making efforts to ban them problematic despite concerns that they are highly dangerous when directed at aircraft. ...

Customs will make recommendations to the Minister for Home Affairs, Bob Debus, tomorrow that are likely to pave the way for stricter regulations and increased penalties for using laser pointers in a destructive fashion but stop short of a ban. ...

Peter Somerville, of the Australian and International Pilots Association, said the new regulatory regime should put the onus on those found in possession of powerful lasers to prove they are being used for legitimate purposes, such as astronomy."

From our point of view, a much more satisfactory resolution of the issue.

[Omaroo (Chris Malikoff)]

Originally Posted by asterisk

From today's Sydney Morning Herald (somewhat edited):

"THOUSANDS of high-powered laser pointers are already circulating in Australia, making efforts to ban them problematic despite concerns that they are highly dangerous when directed at aircraft. ...

Customs will make recommendations to the Minister for Home Affairs, Bob Debus, tomorrow that are likely to pave the way for stricter regulations and increased penalties for using laser pointers in a destructive fashion but stop short of a ban. ...

Peter Somerville, of the Australian and International Pilots Association, said the new regulatory regime should put the onus on those found in possession of powerful lasers to prove they are being used for legitimate purposes, such as astronomy."

From our point of view, a much more satisfactory resolution of the issue.

Excellent pick-up here Geoff.

KG8 - I agree. There is a underlying current of social engineering that the media owners feel they need to be in charge of. It is the ultimate in power. Worrisome, no?

[erick (Eric)]

Originally Posted by Suzy_A

Am I still coherent or has the red wine and late night got to me?

Making sense to me - many thanks Susan!