Page 108 - Lasers and IPLs in Medical/Aesthetic Applications v1.2
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Chapter 1 – Fundamentals of Medical/Aesthetic Lasers and IPLs v1.2
 Examples of Class 3B lasers include laserlipo devices, laser light shows, industrial lasers.
Class 3B lasers can output up to 500mW of power.
Class 4 Lasers (AEL > 500 mW)
These are high power devices that exceed the AELs for Class 3B devices (i.e. greater than 500 mW, or 0.5 Watts) and are hazardous to the eyes and skin from direct viewing and from specular reflections (i.e. from reflective surfaces such as jewellery, watches etc). Diffuse reflections (from non-polished objects) may also be hazardous. Note that there is no upper limit on Class 4 lasers!
They can also have sufficient energy to ignite materials and produce hazardous fumes or plume. Their use requires extreme caution. They may be visible or invisible beams. The ‘blink response’ may not be fast enough to prevent ocular damage to these lasers (invisible beams will not trigger the blink response).
Class 4 lasers are capable of igniting materials, especially clothing. Even a relatively small 30 watt CO2 laser can ignite fabrics, with ease.
The skin reflects between 4 and 7% of all light which falls on it. So, for a 100 megawatt laser (definitely Class 4!!!), the skin can reflect between 4 and 7 million watts per pulse, every time. If you are not wearing the appropriate safety glasses, you WILL damage your eyes with such lasers. These may be Q-switched or picosecond devices! Remember, invisible laser light can damage your eyes just as easily as visible light energy!
Many medical/aesthetic lasers are Class 4 and, as such, must be used carefully to minimise any stray light energy. ALL Q-switched and picosecond lasers are Class 4.
Some ‘laser pointers’ fall into the Class 4 category – these are NOT toys. They are potentially dangerous devices. An American company currently sells 10 watt green lasers, as ‘pointers’ (Class 4). These do not come with the proper safety glasses – they can cause retinal damage if viewed directly or by reflections. Some laser pointers have been deliberately mis-labelled to circumvent regulations. These lasers have been found to be 10 times more powerful than the label indicated!
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Chapter 1 LEVEL A Fundamentals of Lasers/IPLs
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