SparkFun Forums

[zeus_the_mighty]

Hi everyone, I'm thinking about doing this project:
http://www.instructables.com/id/Framele ... /?ALLSTEPS
I'm a bit unsure on which laser to buy and what precautions to take when using them. I have never used a laser before but I know they can be very dangerous. For this project they specify a green laser under 50mW. Is that safe to view without safety glasses? If it isn't, what sort of safety glasses do I need to purchase. I need the laser to be strong enough to see a beam in the dark. I've read about lasers with IR filters, why is that necessary if the wavelength isn't is the IR band? Also, with one of these lasers do I need to set up a heat sink? I've not used a heat sink before so advice with that would be helpful too! Finally, if anyone has used a stepper motor for a similar application I'm trying to price some if you have any suggestions. I know there's a lot of questions, but I was unable to find any sort of "basic laser" manual page. Thanks for the help!

[jremington]

Sam's Laser FAQ is a good introduction to lasers: http://www.repairfaq.org/sam/lasersam.htm

Many inexpensive green lasers use an IR laser diode and a frequency doubling crystal to generate the green light. The process is inefficient so there is lots of IR in the beam. Therefore, eye protection for green laser light should include filters that remove IR and green light.

You should never allow the direct or reflected beam from any laser, no matter what size, to enter your eye as damage is likely to occur. The more powerful the laser, the higher the chance of permanent blindness in that eye. A "joke sign" is often posted in laser labs: "Do not stare at the laser beam with your remaining good eye", but it is not a joke.

[Mee_n_Mac]

I have no idea why anything near 50 mW is needed, other than, perhaps, the reflection off your hand is so weak that you need a lot of beam power to start with. 50 mW is not eye-safe ! Perhaps a better detector would help.
http://en.wikipedia.org/wiki/Laser_safety