Safety with lasers

D. Sliney and M. Wolbarsht, Safety with Lasers and Other Optical Sources, Plenum Publishing Corp., New York, 1980. 

The book Safety with Lasers and Other Optical Sources by David Sliney and Myron Wolbarsht, published in 1980, remains a very valuable resource on matters of safety in laser use. 

Asrani S, D Anna S, Alkan-Onyuksel H, Wang W, Goodman D, Zeimer R. Systemic toxicology and laser safety of laser targeted angiography with heat sensitive liposomes. J Ocul Pharmacol Ther 1995 11 575-584. 

Capillary electrophoresis with laser-induced fluorescence detection, detect, limit 500 pM, assay time < 10 min Medicine/safety, detect, limit 1 uM, lin. range 1 to 400 uM... 

The above-mentioned results demonstrate the high effectiveness of the laser-assisted technique. Although no clearly significant improvement in success rate was observed compared with mechanical dilatation, procedural time was reduced. Concern was raised by the slightly higher incidence of major complications, mainly due to venous or myocardial wall injury, but mortality was very low. The latest reports suggest that highly experienced centers and operators increase the safety of laser-assisted lead extraction. 

When working with lasers, the main issues to identify are the wavelength and power of a laser since these two factors will guide the necessity for and selection of safety equipment and procedures. Since eye damage is the most likely hazard when working with lasers there is likely little immediate first aid procedures to use if an exposure occurs. Labs should have a plan to transport someone to an ophthalmologist or emergency room. 

The development of small solid state lasers used in consumer products may be compatible with lab-on-a-chip concepts. Zeev (2003) proposes in a patent to use optical irradiance to activate chemical reactions, with laser energy taken along optical fibres to one or more irradiators that are in contact with the reagents of chemical reactions. There are, of course, safety benefits in taking energy into sealed containers this way. The theory behind laser catalysis is explained in Vardi and Shapiro (1998). 

A new laser was set up in a laboratory. In preparation the laboratory personnel gathered three pairs of protective eyewear for working with lasers. One of the personnel noticed that one pair looked different from the others. The Laser Safety Officer (LSO) was called upon to evaluate the eyewear for protection against the new laser - the project was put on hold while this was done. The LSO found that this particular pair of eyewear did not protect again the wavelength of the new laser. It was pointed out that while laser lens come in various colors depending on the filter media, that lens color alone should never be used to evaluate protection and further verification of the adequacy of the lens is needed. 

The most relaxed regulations pertain to the wavelength region above 1.4 JUn where only the heat deposition in the cornea sets the hmit. As a rule of thumb, safety limits are relaxed by at least a factor of 1000 when operating outside the 400—1.4 xm window. For detailed accounts of the medical use of the thermal energy in laser beams we refer the reader to [10.159, 10.161-10.163]. The somewhat related field of material processing with laser is covered extensively in [10.164]. 

Laser safety with respect to the sample, damage to product, ignition, or explosion hazard... 

Laser safety with respect to operator, fiber breakage leading to an unintended exposure hazard with possible skin, or ocular damage the need for operator training in regular operating conditions, under process maintenance conditions and emergency shutdown procedures... 

This standard provides guidance for optical measurements associated with laser safety requirements. The information contained in this document will help users who conduct hazard evaluations and ensure the use of appropriate control measures. It contains clearly written definitions, examples, and other practical information for manufacturers, LSOs, technicians, and other trained laser users. 

Often Zo f which gives Wf Wkwq. As an example, with f = 10 mm, X = 0.5 pm, and Wq = 0.5 mm, Wf 3 pm. If P = 1 W, this yields a power density at focus of 3 MW cm or 3 kW cm if P = 1 mW (e.g. a small HeNe laser). In view of these high power densities, laser safety is an important concern. Eye protective goggles matched to the laser s wavelengths should be worn when working with lasers. 

The beam from a laser can inflict damage on various parts of the human body. In addition, there are other ha2ards associated with the use of lasers. Therefore, a weU-conceived and well-organised safety program is required for the use of lasers, particularly those of high power. 

The U.S. Eood and Dmg Administration (EDA) adopted a legally binding standard, which took the form of a performance standard for laser products (56,57). The standard provides a classification scheme for lasers similar to the ANSI classification. AH lasers sold after August 2, 1976 must comply with its provisions. The standard requires incorporation of safety-related labeling and protective equipment according to the class of the laser. The primary impact of the EDA standard is on laser manufacturers and scientific supply firms. 

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