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A blue laser is a laser that emits electromagnetic radiation with a wavelength between 360 and 480 nanometres, which the human eye sees as blue or violet.
Blue beams are produced by helium-cadmium gas lasers at 441.6 nm, and argon-ion lasers at 458 and 488 nm. Semiconductor lasers with blue beams are typically based on gallium(III) nitride (GaN; violet color) or indium gallium nitride (often true blue in color, but also able to produce other colors). Both blue and violet lasers can also be constructed using frequency-doubling of infrared laser wavelengths from diode lasers or diode-pumped solid-state lasers.
Diode lasers which emit light at 445 nm are becoming popular as handheld lasers. Lasers emitting wavelengths below 445 nm appear violet (but are sometimes called blue lasers). Some of the most commercially common blue lasers are the diode lasers used in Blu-ray applications which emit 405 nm "violet" light, which is a short enough wavelength to cause fluorescence in some chemicals, in the same way as radiation further into the ultraviolet ("black light") does. Light of a shorter wavelength than 400 nm is classified as ultraviolet.
Devices that employ blue laser pointer light have applications in many areas ranging from optoelectronic data storage at high density to medical applications.
When choosing a laser pointer, it is also important to decide on the right size. Some people choose to carry keychain laser pointers that are easily portable and can be kept at the ready. For instance, some hikers or outdoor enthusiasts keep this type of laser pointer on their person or in an emergency kit. This way, in the event they become lost, they can use the laser to signal people at a great distance who may be searching for them. Pen laser pointers are popular for use in offices since they can easily be stored with actual pens and slip easily into a pocket. However, their slightly bigger size makes them more comfortable to hold during a presentation. Finally, the most powerful laser pointers that are portable and available for the average consumer are the size of a large flashlight and are known as handheld blue laser pointers. These are the higher power lasers that are legally not for use out of doors. The average person would not want to carry around this size of laser pointer, but some laser enthusiasts may not have an issue with the extra bulk. The size of the laser pointer may also affect the type of batteries that are used, so be sure to check that specification before buying a laser pointer.
Blue lasers are actually the same type of lasers that are used in Blu-ray technology. Only recently have blue laser pointers become available. Some laser pointers that appear blue are actually violet and are the last color on the visible spectrum. As far as presentation pointers go, it can be a nice change of pace to use a blue or violet laser pointer, but much more powerful blue lasers are also available.
Depending on the power of a high power laser, these devices can be extremely dangerous causing damage to eyesight, burns on skin, and even starting fires. This is why it is imperative that anyone operating any type of laser exercise proper precautions. The more powerful Class III lasers should only be operated when wearing proper protective gear, and no laser of any strength should be pointed at a person's eyes. As mentioned earlier, a laser beam above 100 mW can cause severe optical damage, and 300 mW laser pointers can cause instant blindness if shined directly into someone's eye. Even a 30 mW beam can cause bad damage to eyes, though that damage is not usually permanent and can heal in time. Reviewing the manufacturer's safety precautions for an individual item, as well as the laws regarding lasers in the local municipality, is an important part of proper laser pointer operation. And almost all of the blue lasers are high power laser pointers, so be sure to pay attention to safety.