Laser safety with lowerpower lasers

J

jazzhutsby

New Member
Hi all,

I feel I may be opening a can of worms with this post, but I was wondering how lower power lasers such as 150mw, 350mw and 500mw laser projectors are effected by Laser Safety Guidelines.

It seems that you can now pick up a laser almost anywhere without so much as a bat of the eyelid. In fact, some retailers have put these small lasers shining out of their window onto the public streets.

This may sound absolutely ridiculous, and I apologise for sounding so green, but at what point is a laser dangerous?

Many of the units I have come across are dmx controlled, sound to light and automatic. The user can trigger on board programs and vary the speed, x and y, etc. using dmx channels. Most of these are Class3b and no more than 500mw (all diodes combined)

I personally find the guidelines slightly difficult to grasp, particularly with crowd scanning, and even more so with respect to the smaller lasers that I come in contact with.

Does anyone have any advice?

Cheers,

Jazz
 
In the US, 5mW is considered the upper limit of "safe" because if someone is hit in the eye with a 5mW laser, the human eye's blink reflex will close the eye before damage will occur to the eye; anything over 5mW is considered unsafe. That is why you need a varience from the CDRH to use any laser above 5mW in a public venue (unless it is a private event where no commerce is occuring). As a matter of fact, it is illegal to import a laser projector that does not already have a CDRH variance into the US that is over 5mW in power. If Customs notices it there is a good chance it will get confiscated.
 
One of my mentors, Jim Rockwell, told me a story of the early days of laser safety research. One of his colleagues wanted to do some exposure tests with a human subject. This involved the researcher himself being exposed. The idea was to determine how much laser power was needed to definitely cause a lesion in the eye (scar tissue).

The exposures were done in the periphery of the eye (so as not to affect main vision), and the results indicated that 20 mW of power would cause scarring to occur.

I don't have the details of the experiment, but I assume they were using either a HeNe or an Argon ion laser (given the timeframe). But when you don't have a lot of data, and need answers, this is what you resort to, and live with the consequences.
 
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