Laser Safety

I need to know what the proper eye protection is, or the standard that could tell me, for laser protection. Also what has to be kept as far as record keeping goes for class III and IV lasers?

Laser-protective eyewear is required to be worn by all staff in an area where a class 3b or 4 laser is operating unless the beam is totally enclosed and inaccessible or an individual is outside the nominal hazard zone (NHZ; an NHZ delineates where the exposure is below permissible levels).

The proper type of eyewear protection for a specific laser beam must be calculated using the laser output, wavelength, beam divergence, type of optics through which the beam is viewed, and distance of the person being exposed. The American National Standards Institute has laser standards that show how these calculations are performed. The reports also contain the safety requirements required for different classifications of laser systems. ANSI Z136.1 is the general standard but there some that are specific to applications, for example, ANSI Z136.3 is for health care uses. These standards have some excellent information not only regarding eyewear but also record keeping and training information and some sample standard operating procedures.

Some states also have regulations or guidelines for safe use of lasers. A copy of the Suggested State Regulation can be obtained from the Conference of Radiation Control Program Directors. There also are vendors/consultants who can assist in choosing the right eyewear (they do all the calculations for you!). I use Rockwell Laser Industries but there are several and a search on the Web would generate a list for you.

We have a new manufacturing line which will have a laser station. What training does someone at our company require? Do we have to have a certified laser safety officer, and from where would training be provided?

The standard ANSI Z136.1 - Safe Use of Lasers will provide guidance in this area. Since you'll be using a Class IV laser, a laser safety officer (LSO) and training for LSO and users is required. At this time, there is no specific requirement for a certified laser safety officer although certification exams are available.

We have a CO₂ 30W class 4 laser with a wavelength of 10.6 micrometers for purposes of marking a rubber product. How do we determine the NHZ and do we need to require operators to wear laser goggles? This system has an interlock system and an automatic enclosure but I am concerned about the safety of our operators.

If the enclosure contains the entire beam path, you have a "reclassified" class 1 laser product and the operator, if following prescribed protocols, would not need protective eyewear from the laser radiation. The nominal hazard zone (NHZ) generally falls into two modes-one for direct exposure (where the distance in your case could be between 20 and 50 meters) or for a diffuse reflection (which could be less than 1 meter). Insufficient information was presented to perform a calculation, such as, is the laser pulsed (which in your application I imagine it might be) or continuous? If pulsed, pulse rate, pulse duration, beam diameter, etc., all affect the NHZ. I strongly suggest you obtain a copy of the ANSI Z136.1 Standard Safe Use of Laser; it contains all the information you need to calculate NHZ.

30 W of CO₂ laser power is sufficient to cause major damage to eyes and skin, but also is easy to shield. Polycarbonate panel should work well for diffuse reflections.

Are lasers that are used for medical or dental treatments safe?

The Food and Drug Administration (FDA) approves lasers for medical and dental uses. So, in general, yes, lasers used for medical or dental treatments are safe. The following is information from the FDA site.

Several manufacturers have received clearance for argon and carbon dioxide lasers to activate tooth-bleaching solutions and to treat gum disease. Several lasers have clearance for hard tissue use on teeth. On May 7, 1997, FDA cleared the first laser system for treating tooth decay, an erbium YAG laser. Recently, FDA clearance was provided to market a laser for caries removal. Studies conducted by the manufacturers showed that the laser is as safe and effective as a high-speed drill for removing dental decay and preparing a cavity for a filling. The manufacturer's study indicated that fewer patients needed anesthetic for pain.

Lasers may be used to remove tissue in eye surgery as well. This may include removing tumors, cataracts, or proliferating blood vessels common to diabetic retinopathy. Several manufacturers have lasers cleared for photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK), two procedures for correcting nearsightedness, farsightedness, and astigmatism. The laser is used to reshape the cornea and focus images correctly on the retina. For information on eye surgery and which lasers have received clearance, you can access FDA's website.

Some lasers have been cleared for medical uses such as removing tissue. Because heat from lasers cauterizes blood vessels, there is less bleeding compared to scalpel use. Usually, FDA gives manufacturers general surgical clearances; in order to promote the laser for a specific surgical procedure, manufacturers must first provide FDA with clinical evidence that their lasers are safe and effective for that specific procedure.

States regulate who can use lasers for various therapeutic procedures. Medical lasers are prescription devices available for sale only to licensed practitioners.