Safety of ~5mW line laser

[lsrnoob]

Hey all,

First off, I'm new. I tried looking for this, but I'm couldn't find anything that answers my question.
Me and a couple of co-students are looking into getting a linelaser for our schoolproject. It will be equipped in a RC controlled vehicle, but it would be a prototype for something driving around in hospitals or a factory environment. We want a line to show up at up to 2m distance, that we'll pick up with a camera and process. Looking into lasers and safety, we are at a loss. We thought LFL635-5-6 or LFL650-3-4.5 would both be safe for use (german class 1 DIN), but also found sources to say anything bigger than 1mW would potentially be dangerous. So our questions are: are the mentioned line lasers dangerous? How long would you have to look into them for them to be dangerous? At what distance?
Thanks in advance!

 

[zyxwv99]

Just from what I've read, an average 5mW laser pointer (pen-style) with 2mm beam and fairly narrow divergence is safe if it accidentally hits you in the eye for a split second. In one study people who were about to have an eye surgically removed due to eye disease (usually cancer) has such a laser shined in their eyes for 15 minutes continuously at close range. None went blind, some suffered only minimal eye injury. In another similar study, one woman suffered very significant eye damage after 60 seconds.

In the archives of case histories, one youth (17 years old) shined a 5mW green laser pointer into his own eye for 60 seconds, although no information is available on the actual power of the laser (most cheap greenies are 2-3x overspec). After a 2-year follow-up exam, he still had residual bleaching, but his vision was 20-20.

An 11-year-old who did the same thing for about 10 seconds had no measruable eye damage after 3 months.

On the other hand, there have been case histories of people suffering permanent and significant eye injury after 1-second exposure to such lasers.

Whatever kind of laser you use, you should have it measured with a laser power meter.

This one has a pretty narrow beam. I'm not expert enough on beam divergence to even discuss it, except to know that it's an important factor. Personally I think 5mW is powerful enough that safety could be a concern. In other words, you can't just automatically assume that it's safe. Further investigation is needed.

 

[lsrnoob]

Thanks for taking the time to reply. You've been talking about laser pointers though, don't they differ significantly from a line laser, where the intensity gets spread out over a line?

 

[zyxwv99]

Right. I was just sharing what little I know about laser eye safety in general. I seems like a line should be safe so long as there are no hot spots, and so long as the viewing distance is sufficient. However, since I have no experience with line lasers, I wouldn't want to extrapolate from what I know to what I don't know.

 

[lsrnoob]

Ah, thanks anyway It does help!

 

[Aleksa]

Any type of laser beam is bad for eyes. Eyes aren't used to see a single spectrum light. Exposing your eyes to a 5mW laser beam will not damaged them instantly,but after a couple of years you will feel the consequences. I cant tell you more,cause my friend has a friend that studies lasers and their effects on human eyes. So basically,never look directly at laser,ever. Always wear protection glasses and you should be good

 

[OzLasers]

It really depends on so many different things. If you're concerned about safety, have you considered using a less powerful laser?

You should make yourself aware of the reflective surfaces in your testing area, and avoid or remove them if possible. Even though it's not overly powerful, some people have different reactions low powered lasers.

As Aleksa said above, it's unlikely that short exposure will leave you with any damage, but this risk grows exponentially with continued exposure.

Use safety goggles if you have any serious concerns. You can never be too cafeful with laser equipment, and you only get one set of eyes.

My basic rule is: If you don't trust it, wear protection. (Can be applied to all walks of life)