laser health risks
Discussion
Just a point, I am sure its been raised before on here but thought I would ask.
I am really not happy about the idea of a 2 mile range ultra high power laser being shone into my eyes. Though we cannot see it, and therefore have no real idea that its shining into our precious eyes, I am very worried about the long term effects to my retina. Our eyes are very sensitive, looking into the sun can make you go blind, so can looking into the beam of a personal CD player for a length of time – what about plods lasers?
A 2 mile range high power laser into the eye, though beyond our visible spectrum surely is not doing us any good.
I am really not happy about the idea of a 2 mile range ultra high power laser being shone into my eyes. Though we cannot see it, and therefore have no real idea that its shining into our precious eyes, I am very worried about the long term effects to my retina. Our eyes are very sensitive, looking into the sun can make you go blind, so can looking into the beam of a personal CD player for a length of time – what about plods lasers?
A 2 mile range high power laser into the eye, though beyond our visible spectrum surely is not doing us any good.
ahem!!
laser classifications.
Class 1. Inherently safe as laser cannot come into touch with eyes (fibre optics systems, CD players and the like, though with no power limitation (or there certainly wasn't some time ago)
Class 2. Laser can come into contact with eyes, but is of such low power that no damage can result.
Class 3a. Laser than is powerful enough to damage your eye, but the eyes natural aversion reflexes (blinking, turning your head etc) can prevent this damage occuring.
Class 3b. Laser powerful enough to damage your eye before your aversion reflexes can avoid it.
Can't remember the exact figures, but my 2mW helium neon laser is class 3b due to the exit diameter of the beam (a tenth of a millimeter) which would blind you almost immediately. It 'turns' into a 3a as the beam diverges, and is 3a at about (I think) 40 meters.
A Lastec LTI2020 is 30mW, and is in the infrared at 905nM wavelength, so your aversion reflexes never get used. It is however pulsed at <>44 pulses every 300mS, so not sure if 30mW is the peak power, or RMS power.
Your eyes don't focus infrared very well by the way, but even so, I don't like the idea of high energy IR light being flashed into them.
laser classifications.
Class 1. Inherently safe as laser cannot come into touch with eyes (fibre optics systems, CD players and the like, though with no power limitation (or there certainly wasn't some time ago)
Class 2. Laser can come into contact with eyes, but is of such low power that no damage can result.
Class 3a. Laser than is powerful enough to damage your eye, but the eyes natural aversion reflexes (blinking, turning your head etc) can prevent this damage occuring.
Class 3b. Laser powerful enough to damage your eye before your aversion reflexes can avoid it.
Can't remember the exact figures, but my 2mW helium neon laser is class 3b due to the exit diameter of the beam (a tenth of a millimeter) which would blind you almost immediately. It 'turns' into a 3a as the beam diverges, and is 3a at about (I think) 40 meters.
A Lastec LTI2020 is 30mW, and is in the infrared at 905nM wavelength, so your aversion reflexes never get used. It is however pulsed at <>44 pulses every 300mS, so not sure if 30mW is the peak power, or RMS power.
Your eyes don't focus infrared very well by the way, but even so, I don't like the idea of high energy IR light being flashed into them.
oh, by the way, the Lastec LTI2020 has a vertical preferential astigmatism lens on the front of the laser, so it's top to toe (as cars rarely drive one above the other)to aid selectivity of vehicle, without making it too difficult to aim. So yes, it certainly does get in your eyes. You windscreen refracts pratically nothing, and only really attenuates light when you get into the ultra violet (which is why you generally don't tan through glass, but god is it warm in the summer)
bryan35 said:
ahem!!
laser classifications.
Class 1. Inherently safe as laser cannot come into touch with eyes (fibre optics systems, CD players and the like, though with no power limitation (or there certainly wasn't some time ago)
Class 2. Laser can come into contact with eyes, but is of such low power that no damage can result.
Class 3a. Laser than is powerful enough to damage your eye, but the eyes natural aversion reflexes (blinking, turning your head etc) can prevent this damage occuring.
Class 3b. Laser powerful enough to damage your eye before your aversion reflexes can avoid it.
Slightly out of data on the classification see www.nrpb.org/faq/laser/laser9.htm
Your 3a is actually class 2. It is true to say the class are based on normal usage so a class 1 CD player could have a class 2 laser if engineering prevents eye contact in normal use and therefore becomes class 1
There are power limitations on all but class 4 lasers, class 1 is <MPE hence no damage.
thanks bryan35
I am confused by ^Slider^'s comments about none of the laser making it past the windscreen.
A friend has a Snooper RLD unit, it sits on the dash, behind the windscreen - and that very deffinetly picks up plods laser.
Could you explain what is setting off the snooper laser alert if the laser doesn't hit anything but the number plate.
I am confused by ^Slider^'s comments about none of the laser making it past the windscreen.
A friend has a Snooper RLD unit, it sits on the dash, behind the windscreen - and that very deffinetly picks up plods laser.
Could you explain what is setting off the snooper laser alert if the laser doesn't hit anything but the number plate.
) Rule of thumb we used to assume was a damage threshold for the eye ball of 10mW fully coupled. Why? Because that is equivalent to looking straight at the sun and, not surprisingly, the eye has evolved to be able to withstand that energy density for short exposures with no ill effect.
The further you are from a torch the dimmer it appears to be. This is because the beam is diverging. The energy density on your eye reduces the further you are from a torch as your eye is catching less and less of its total output. The same is true with lasers, although the amount by which their beams diverge is much, much smaller. It nonetheless reduces the energy density entering the eye drastically. For example, we had a lab quality argon ion laser running at about 200mW shining down a 2000m range. (The lad quality stuff means that the beam doesn't diverge much at all.) The beam at the laser's aperature probably had a radius of about 1mm. 2km later the beam had a radius of about 50cm. The energy density was therefore reduced by a factor of at least 1^2/500^2 = 1/250,000 ... assuming the radius of the pupil of you eye is 2mm, then the effective attenuation would be at least 4^2/500^2 = 1/15,625 which if you like reduces the laser's output from 200mW to 0.013mW.
With a 20mW laser, I wopuldn't want to stare into the beam for any length of time at point blank range. But anything more than 50m from the gun for short exposures would be absolutely fine.
The further you are from a torch the dimmer it appears to be. This is because the beam is diverging. The energy density on your eye reduces the further you are from a torch as your eye is catching less and less of its total output. The same is true with lasers, although the amount by which their beams diverge is much, much smaller. It nonetheless reduces the energy density entering the eye drastically. For example, we had a lab quality argon ion laser running at about 200mW shining down a 2000m range. (The lad quality stuff means that the beam doesn't diverge much at all.) The beam at the laser's aperature probably had a radius of about 1mm. 2km later the beam had a radius of about 50cm. The energy density was therefore reduced by a factor of at least 1^2/500^2 = 1/250,000 ... assuming the radius of the pupil of you eye is 2mm, then the effective attenuation would be at least 4^2/500^2 = 1/15,625 which if you like reduces the laser's output from 200mW to 0.013mW.
With a 20mW laser, I wopuldn't want to stare into the beam for any length of time at point blank range. But anything more than 50m from the gun for short exposures would be absolutely fine.
must be out of date. It was a long time ago.
Had to read up on laser classifications for the use of display lasers at work.
3b's were 'laser must be x number of meters above anywhere the audience may stand, must have an operator with an emergency off button, must use a 5 lever key to disable laser'. That sort of stuff.
YOu could get a lens which would turn your 3b into a 3a,.
Having visited a few clubs with lasers, I don't think they are aware of these regulations.
To give those who are a bit confised with power rating, did you know that if you have a 30w YAG (ytrium aluminium garnet - spelling!!!) laser, and you were to point it at the moon (during a new moon), you can actually get a glint from the mirror the astronauts left there. Watch those aeroplanes though - don't want to blind any pilots - oh, and you've looking at a 5 year stretch if you get caught!
Had to read up on laser classifications for the use of display lasers at work.
3b's were 'laser must be x number of meters above anywhere the audience may stand, must have an operator with an emergency off button, must use a 5 lever key to disable laser'. That sort of stuff.
YOu could get a lens which would turn your 3b into a 3a,.
Having visited a few clubs with lasers, I don't think they are aware of these regulations.
To give those who are a bit confised with power rating, did you know that if you have a 30w YAG (ytrium aluminium garnet - spelling!!!) laser, and you were to point it at the moon (during a new moon), you can actually get a glint from the mirror the astronauts left there. Watch those aeroplanes though - don't want to blind any pilots - oh, and you've looking at a 5 year stretch if you get caught!
s a m said:
thanks bryan35
I am confused by ^Slider^'s comments about none of the laser making it past the windscreen.
A friend has a Snooper RLD unit, it sits on the dash, behind the windscreen - and that very deffinetly picks up plods laser.
Could you explain what is setting off the snooper laser alert if the laser doesn't hit anything but the number plate.
I said it was difracted light,.,, never said it wouldnt make it past the windscreen.
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