Lasers Overview

                                     Lasers Overview

Everyone using lasers needs to understand that lasers are dangerous, irrespective of their power levels. In general, low power, Class I, II, and IIa lasers, with output power levels less than 1 mW (a milliwatt is a unit of power equal to 1/1000th of a watt), pose very little hazard, albeit there is a possibility of eye damage if the laser is shined into the eye too long.  The millions of bar code scanners in use around the globe are proof, however, that low power lasers pose little hazard.  Medium power, Class IIIa lasers, from 1 mW to 5 mW, can cause permanent eye damage from only seconds of direct beam exposure, but in general they too pose little danger, according to most ophthalmologists.  But lasers always carry an element of danger: A scientist tells of a painful incident while checking for dust on the lens of a 4.5 mW laser. As he was looking down the barrel of the laser with a otoscope, he accidentally hit the laser’s power button. He recalls that it felt like someone put a fist in his eye and for the next twenty minutes or so all he could see (out of that eye) was red.

Sometime later, after an exhaustive eye exam, it was shown that he had no permanent damage, but this anecdote illustrates why it is so important never to shine any laser toward people’s faces, or toward surfaces which can reflect beams toward their faces. Dangerous or not, common courtesy and respect should always guide laser users to be mindful of the safety and feelings of others, or, paraphrasing an ancient Biblical admonition, “treat others in the same way you would like them to treat you.” For more on the debate of low-power laser dangers, here are some websites well worth visiting:

http://bjo.bmj.com/cgi/content/full/83/10/1164 
http://vision.about.com/gi/dynamic/offsite.htm?zi=1/XJ&sdn=vision&cdn=health&tm=9&gps=184_1055_827_571&f=00&su=p284.21.140.ip_p284.2.420.ip_&tt=2&bt=0&bts=0&zu=http%3A//www.uni-duesseldorf.de/WWW/MedFak/LaserMedizin/hering/laserpointer/laserpointer_engl.html 
http://www.mayoclinic.org/news2005-rst/2800.html 
http://www.eschoolnews.com/news/showStory.cfm?ArticleID=929 
http://laser.physics.sunysb.edu/~wise/wise187/2005/reports/deb/report.html

Medium power, Class IIIb lasers, which output from 5 mW to 500 mW, such as the OEM laser modules sold by Warn Laser, should be considered extremely dangerous and be given the same respect - and handled in the same manner - as a loaded firearm. They are designed to be the heart of laser systems used for research, education, rescue, and police and military purposes, and must never be aimed at people, animals, occupied buildings, cars, boats, or airplanes. Not only do they have the potential to do damage to unprotected skin and eyes, our more powerful modules have been known to accidentally ignite flammable objects. Even momentary specula or diffuse reflections from such powerful laser modules can do permanent retinal damage in some people, and prolonged exposure may cause cataracts and other eye disorders.

Because of this potential danger, we strongly encourage everyone working with lasers to protect themselves and their co-workers with proper laser eyewear. Eyesight is too precious to lose!!! We sell professional grade laser goggles and safety glasses, and to encourage use, we sell them at our cost.  While this policy generally means that our goggles are the least expensive available, there are many sources for quality laser eye protection, including numerous internet sites, and even online auctions like eBay. Whatever brand eye protection you decide to use, make sure that it is a high quality product which meets appropriate military and industrial specs for the frequency laser you are using.  It does little good to wear laser goggles or laser safety glasses which only attenuate green laser light if you are using a red or infrared laser!!  And remember to use laser goggles only for their designed purpose.  Using them as welding goggles, or for viewing solar eclipses and other intense light sources, may cost you your vision.

Before using any laser goggles, inspect them for scratches in the coating which could allow a harmful amount of light to enter your eyes; and when cleaning them, always follow the manufacturer’s cleaning instructions carefully.  When using laser goggles, never look directly into a laser beam. Laser eyewear is not designed to totally block any given frequency of light, just reduce reflected light intensity to a relatively safe level. Also, never try substituting sunglasses or similar eyewear for real laser goggles. The attenuation provided, even by dark sunglasses, does little to reduce laser beam intensity. Even polarized sunglasses are not a safe substitute. Laser light is polarized, and thus can be greatly reduced in intensity with a polarizing filter. However, unless orientation of the light in the laser beam - direct or reflected - is exactly perpendicular to the polarization of the glasses, there won’t be enough attenuation to provide adequate protection. Trying to maintain the necessary orientation while moving and doing laser experiments is virtually impossible.  Your eyes and the eyes of your friends and co-workers are worth far more than the cost of quality laser eyewear, so don’t be stingy or you might spend the rest of your life regretting it. In commenting on the importance of using quality safety equipment, the book “RAPPELLING,” by Tom Martin, perhaps says it best: “If you are too poor - or too cheap - to go first class, then don’t go at all.” If you are going to work with lasers, always wear quality laser eye protection - that’s the Warn Laser philosophy!

Warning: Powerful lasers must always be used and stored in the same manner as firearms.  They must never be allowed into the hands of children or irresponsible or inebriated adults.  When using any laser, always treat the people around you in the same way you would like to be treated.