Low Power Laser Projects

I been reading a lot of posts here and on other sites but I am still a little confused on a few things.

First, I am having a difficult time finding any lasers that are under 5mW. I would like to keep them under 5mW 3v (hopefully 1mW). This forum has a thread with a list of trusted sites but all I see are 5mw and over. Laserglow.com was the only one I see with 3-5mW but still higher that what I want. Could someone recommend a trusted site to order from?

Second, I see there is a old rating system and a revised system for classes. Can you determine what class a laser falls under by its output power (mW) if it is not listed on a website? I want to stay within class 1 or 2 to be eye safe.

Third, In this forums experience/opinion using lower power lasers (1mW) will it be strong enough to travel 30 feet? The beam will be refracted once or twice. I am looking to use the wavelength 650nm but color choice is not that important. I will be using a fogger to make the beam visible.

Thanks for any input.

KayBee said:

I been reading a lot of posts here and on other sites but I am still a little confused on a few things.

First, I am having a difficult time finding any lasers that are under 5mW. I would like to keep them under 5mW 3v (hopefully 1mW). This forum has a thread with a list of trusted sites but all I see are 5mw and over. Laserglow.com was the only one I see with 3-5mW but still higher that what I want. Could someone recommend a trusted site to order from?

Second, I see there is a old rating system and a revised system for classes. Can you determine what class a laser falls under by its output power (mW) if it is not listed on a website? I want to stay within class 1 or 2 to be eye safe.

Third, In this forums experience/opinion using lower power lasers (1mW) will it be strong enough to travel 30 feet? The beam will be refracted once or twice. I am looking to use the wavelength 650nm but color choice is not that important. I will be using a fogger to make the beam visible.

Thanks for any input.

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Perhaps try Dragon Lasers. Are you looking for a pointer or a module?

You could buy a 5mW laser and use an ND filter or partial reflect mirror to bring the power down to 1mW. That said, 5mW is considered eye safe so you should be fine to use that much. Is there a reason you want to stick to 1mW?

As for classifications, yes, you can determine what class the laser is by the output power. This Wiki page has definitions for both the old system and the new system: https://en.wikipedia.org/wiki/Laser_safety#Class_1

You'd be looking for Class II by the sound of things. The question was a little ambiguous - did you mean determine the class without knowing the output power? If so - no, not unless either the class or output power is specified.

30ft is doable, but keep in mind the beam will get somewhat wider over that distance. 1mW won't be as visible as you want at 650nm (if at all), it may not even be as visible as you'd like at 532nm. The eye is more sensitive to 532nm and as such it will appear brighter at the same power level. You'd need a lot of fog at 1mW whichever wavelength you pick if you want a highly visible beam - which will attenuate the beam somewhat too.

Also did you mean refract or reflect? There's a big difference

There is no power of laser that is "eye safe." Even a 1 mW laser cannot be looked into while on.That being said, I wouldn't worry about the difference between a 1 mW and a 5 mW laser. As long as the laser is not diverging terribly, it should have no problem travelling 30 ft. I assume you meant reflecting, as off a mirror, as it wouldn't work well to refract the beam.

paul1598419 said:

There is no power of laser that is "eye safe." Even a 1 mW laser cannot be looked into while on.That being said, I wouldn't worry about the difference between a 1 mW and a 5 mW laser, and neither is "refracted" in the air and, hence, not able to travel ore than 30 feet. Even a 1 mW laser should have no difficulty travelling more than 30 feet.

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It is considered eye safe because your blink reflex will kick in faster than the laser can do damage. You'd need to sit and stare into the beam to cause damage at those power levels.

I think OP meant reflected instead of refracted...

With enough fog to make the beam decently visible there will be notable attenuation at 1mW. Although not enough to completely attenuate the beam.

Yes, sorry I meant reflected using mirrors.

I forgot to mention the details of the project. I have been asked to make a team building exercise where one person is completely blindfolded and their teammate verbally guides them through the course. The teammate is outside of the course at all times. One section will have the lasers at 6 inches and 18 inches off of the floor. I am trying to be extremely safe by setting the lasers low. The lasers will get shut off for 2 seconds if the beam is broken. The only person(s) I have to be concerned with is the teammate and instructor and neither will be in the course. The person using the course will have no chance of accidental eye contact unless they remove the blindfold. The reason behind the lasers instead of a physical small walls is that we don't want the user to stumble over and get hurt while blindfolded.

To answer your first question on module or pointer. I am looking for a module but I could use a pointer and take it apart. I need to hook it up to an Arduino so I can control the power to laser.

At 5mW or below do I need to worry about heat if they run for 1 minute?

diachi said:

It is considered eye safe because your blink reflex will kick in faster than the laser can do damage. You'd need to sit and stare into the beam to cause damage at those power levels.

I think OP meant reflected instead of refracted...

With enough fog to make the beam decently visible there will be notable attenuation at 1mW. Although not enough to completely attenuate the beam.

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I get that these low power laser are considered eye safe because of the blink reflex, but I believe that caveat must be included when calling the laser eye safe. Otherwise, it can give rise to confusion over the meaning.

I'd go with 520nm 5mw as it sounds like this project could include assembly and disassebly. 532nm when dropped or bumped can easily break it (look into dpss to see why). 520nm is quite a bit more rugged and could potentially survive a jolt or drop even. The beam will be much brighter at 5mw and likely visible without fog in a very dark room. There is even an up to 10mw 510nm-520nm diode on DTR's website and I'm sure he would be happy to set it at or near 5mw for you based on his tests. If not there are members here that you can ship to who will receive the diode and driver and set it for you with their LPM. I have had this done for several of my lasers as I do not own an LPM.

Thank you all for the input. I will definitely check out DTR's and dragon lasers website. I thought I was getting a grasp on all this then you throw dpss but I love to learn.