Laser classification systems

There are two laser classification systems, the old system used before 2002, and the revised system being phased in since 2002. The latter reflects the greater knowledge of lasers that has been accumulated since the original classification system was devised, and permits certain types of lasers to be recognized as having a lower hazard than was implied by their placement in the original classification system. The revised system is part of the revised lEC... 

Laser Classification (old system). There are four classes of lasers for safety purposes, with Class 1 lasers being the least hazardous and Class 4 lasers being the most hazardous. Proper laser classification is very important because it provides the basis for laser safety design. The required safety features for a given laser are based on its classification. The laser safety community has developed this laser classification system based on injury potential. The classification levels are dependent upon the lasers wavelength, power or energy, exposure duration, pulse repetition frequency (PRF), and the size of the laser beam. 

Over the past few years a better understanding of lasers has resulted in an evolution of classification systems for lasers. Before 2002 the older system of classification used Roman numerals with the most hazardous class being Class IV (see Special Topic 7.3.3.1 Old Laser Classification). As experience with lasers grew, the classification system was updated to include new defining specifications. Beginning in 2002 a newly revised classification system was phased in and was fully implemented in 2007. It is based on International Electrotechnical Commission (lEC) Standard 60825-1/ANSI Z136.1—2007 that separates lasers into four classes. Class 1 is the least hazardous, Class 4 is the most hazardous, and there are new subclasses." The classification of lasers is dependent on the dose of radiation that can be received from a laser. A brief description of these laser classes is presented in Table 7.3.3.2. 

A military classification system for laser hazards divides lasers into five categories. Table 21-4 details this... 

These laser classification levels in the old system are shown in Table 2.13. 

Revised Laser Classification (new system). Table 2.14 describes the main characteristics and requirements for the new classification system as specified by lEC 60825-1. 

It is also useful to consider using the Current U.S. Classification system to search for related materials. These numbers are somewhat arbitrary, but can be better understood by searching the USPTO web site. For example, all photochemical patents dealing with microencapsulation are in class 430/138 those involving infrared exposure are 430/944, and those using laser beams 430/945. Class 281.1 contains radiation sensitive composition comprising ethylenically unsaturated compounds. 

Due to the large variety of laser materials and pumping methods, it is almost impossible to catalog all the laser devices that have been demonstrated up to date. However, we can make a classification of the laser systems based on the different types of active media. We will briefly comment on the basis and properties of some specific types of laser systems, which are representative of different laser schemes. 

LIBS has been also successfully applied to the analysis of geochemical samples [1485]. The most accurate information can be obtained for the relative concentrations of different elements in a sample. This is important, for example, for the classification of minerals on earth or in meteroites when it is not clear whether two different samples come from the same source. Also for archeological samples the precise knowledge of elemental composition is very helpful for the exact dating and assignment. The applications of LIBS has benefitted from the use of fiber optics which allows remote sensing, where the laser and detection systems are far away... 

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