Line Laser Safety

[tefeari]

How safe/dangerous are line lasers?

Let's take 100mw to be the example output power. Let's also suppose the laser is spread out using a lens (or some other standard optical piece that is used for non-scanning line lasers).

If a 5mw dot laser is the safety threshold with a spot size of 1cm, then wouldn't a 100mw line laser spread out over than more than 20cm be be safe in theory?

I imagine that in reality the line won't have a perfectly uniform power density, so it seems like it would be best to be a bit further than 20cm away. It seems reasonable to believe the distribution must be roughly even though (please correct me if I'm wrong here). So could we stand at the distance where the beam is spread out over 1 meter and call it a sure bet?

 

[HIMNL9]

Hmmmmm, yes, a line can be less dangerous that a spot, for the eyes, but personally, i suggest you to always considerate lasers as not toys ..... managing and using them with safety in mind, is always the better thing to do, cause, after all, are still lasers, and are still "potentially dangerous".

I know, maybe i look a bit over-cautious, but remember always that you only have 2 eyes, and there's no spare parts for them ..... after all, always better safe than sorry, right ? .....

 

[davidgdg]

How safe/dangerous are line lasers?
...

If a 5mw dot laser is the safety threshold with a spot size of 1cm,
...

The U.S. regulations are by reference to the radiant power detectable via a 7mm circular aperture (this figure is obviously by reference to the diameter of a fully expanded pupil). The Class 3A limit (indoor lecture theatre limit) is 5mw.

It is then easy to calculate equlvalence figures as long as you know the initial beam diameter, power and the divergence. If you assume divergence of 1mrad and an initial beam diameter of 1mm (fairly typical figures for high quality units), then rougly speaking:

A 25mw laser will be equivalent to a Class 3A at a distance of >14.5 meters (~50 feet)

A 50mw laser will be equivalent to a Class 3A at a distance of >21 meters (~70 feet)

A 125mw laser will be equivalent to a Class 3A at a distance of >34 meters (~ 120 feet)

A 500mw laser will be equivalent to a Class 3A at a distance of >70 meters (~250 feet)

David

 

[lasersbee]

That's good info for standard round beam Lasers David....
but he was asking about Line Lasers.. Like they use to
line up cuts in a saw mill or the hardware variety for lining
up a shelf with a level in it that projects a line rather
than a dot...

@ OP...Line Lasers that use Optics to create the line project
a line that is not linear in power across the line... The power
is greatest in the middle getting weaker as you go out from
the center of the line.
Scanning line lasers on the other hand... will have the same
power anywhere on the line since it is scanned across a
surface..


Jerry

 

[davidgdg]

That's good info for standard round beam Lasers David....
but he was asking about Line Lasers.. Like they use to
line up cuts in a saw mill or the hardware variety for lining
up a shelf with a level in it that projects a line rather
than a dot...
Jerry

Hi Jerry. I was just commenting on the sun versus laser comparison. I'd guess that a line laser will rarely if ever pose an eye hazard. If you reckon on the line being 1mm by length of say 1m, then the radiance is down by a factor of 1000, compared to a spot .....