[SGVHAK] Laser Safety

[James McDuffie]

And more more thing. Here is a very long and actively maintained FAQ
full of laser diode information:
http://repairfaq.ece.drexel.edu/sam/laserdio.htm

On Wed, Dec 4, 2013, at 08:30 PM, James McDuffie wrote:
> I've talked with a couple people recently about laser safety. Especially
> troubling to me is the fact that some visible laser diodes have
> resonances in the IR wavelength range. For instances, the following
> article talks about how cheap Chinese manufactured green laser diodes
> were emitting excessive amounts of IR. Sometimes more IR than visible
> light!
> 
> http://www.technologyreview.com/view/420214/the-danger-of-green-laser-pointers/
> 
> A good way to check this is to use a CDROM as a diffraction grating and
> then photograph it with a camera sensitive to IR light. The problem is
> due to the fact that laser diodes have resonance emissions and many of
> the cheaper diodes have no IR filtering. 
> 
> This link also has some more safety tips related to people using DVD
> laser diodes:
> 
> http://www.laserist.org/DVD-laser-caution.htm
> 
> Now you'd think, I will just buy laser protective goggles. That might
> not be enough. You might buy goggles that cover the wavelength range in
> the laser diodes's spec, but there will still be spurious out of band
> emissions. One source told me that the laser protective goggles use very
> narrow band filters. So if it doesn't list protection in certain
> wavelength range you should assume it is transparent to other
> wavelengths.
> 
> Now you might say, as I did, what about those commercial laser cutters
> that have a large window on top and apparently a simple protective film.
> Well, these are industrial products and their lasers are most likely
> crystal based and not using cheaper diode lasers. They are tuned and
> tested for a narrow wave length range. That is part of their expensive
> price tags.
> 
> So what could happen? Well with visible and near IR wavelengths you
> could damage your retina. For IR and above, even though your eye lens is
> opaque to it, the radiation can damage your outer lens and cause
> cataracts. 
> 
> Not all lasers are completely dangerous, the class 3 and 4 ones are what
> you have to worry about:
> 
> http://www.ipgphotonics.com/company_service_safety.htm
> 
> tldr: Be extra careful with higher power lasers you have pulled out of
> equipment or bought off eBay.
> 
> <insert "the more you know" rainbow here>
>