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Just if you may be one who still thinks it's a joke.

hakzaw1

Well-known member
Some of you could benefit from joining my LSO Tutorial thread--

here are some pics if the pages on MPE(from the LSO ILDA training manual)
- just FYI I added the part about skin hazards but for pilots , of course , its all about eye exposure-and causeing a pilot vision problems on the job -- problems seeing not getting a hole in their retinas- (& NOT eye damage- there is a diff. )

The MPE is used for laser shows and displays and it not written with pilots in mind but all the same there IS a MPE.. BUT it has nothing to do with distracted pilots--

so here is a quote

'Laser safety calculations rely on a concept called Maximum Permissible Exposure(MPE). This is the highest irradiance or radiant exposure that is considered to be safe. It is expressed in W/cm2 or J/cms. & there is no one number as wavelength and exposure duration are factors..(et al)'

.. 'the is set at 10% of the exposure that has a 50% probability of creating damage. Said another way, a beam that is 10 times the MPE has a 50/50 chance of causing an injury.

nothing to do with distracted pilots --

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BobDiaz

Member
The LSO ILDA training thread is found at:

http://laserpointerforums.com/f51/lso-laser-safety-officer-tutorial-88136.html

I was playing with an online MPE Calculator to see how the numbers would work out assuming that someone had a 2,000mW laser pointed at someone 1,000M (3,280 feet) away. For an aircraft overhead, that would be really close.

Assume the Beam diameter at aperture is 1mm and the Divergence is 1mrad. This would be a very good laser, but I'm using worst case numbers.

According to the calculator the Beam area is 786969.7 mm² and Irradiance is 0.3 mW/cm².

MPE Calculator

Unfortunately this is where my knowledge falls off and I can't say if that's still too high a number or not. However, this was worst case numbers so if someone had a 50mW laser with a wider beam aperture and divergence, I'm guessing that because of the distance, it's a big distraction, but would not blind the pilot.

It's still STUPID and illegal to point the laser at an aircraft or anyone, but because of the distance and divergence, in most cases the power drops to a point it unlikely to blind someone.

Correct me if I'm wrong here, I'll be the first to admit that I don't have any real background here and I'm guessing.

Bob Diaz

hakzaw1

Well-known member
Im with you Bob- the math past of the class went by way too fast. --

So I can't confirm your answer-- But I do know that what is max permissible is way below what is actually dangerous== they always go with the worst case senerio- and at every LEM I have attended audience scanning= mirror balls etc where going on everywhere and there were no glasses/goggles being worn.. but these are closed events and each attendee signs a waiver of liability== no exceptions.

hk