While most early 100mw laser pointer

As seen below, A Green Laser Pointer 10mW begins with an infrared 808 nm laser diode, which pumps energy through a yttrium aluminum garnet (YAG) crystal to further increase the beam's wavelength to 1064 nm. The energy then passes through a second crystal designed to double the radiation's frequency, therefore halving the beam's wavelength to 532 nm (which will produce a green output beam). Only after these changes in wavelength and frequency can a beam finally be emitted. This process is often replicated to produce blue and violet output beams.
Output Power
A laser's output power refers to the strength of its beam and is measured in watts (W) or milliwatts (mW). Specifying a 200mw green laser 's output power not only determines its relative brightness but also determines its safety class as discussed below.

Safety
As high power laser pointers have become widespread and freely available to consumers, manufacturers and industry groups have correspondingly increased awareness of the dangers of such devices. While most early 100mw laser pointer intended for use in classrooms were limited to 5 mW of power or less, inexpensive high power devices — emitting as much as 1000 mW of power — are now easily obtainable. Even a split-second exposure to a 200 mW laser emitting 100 yards away can cause permanent eye damage.
One should never look into the beam of any green 100mw laser pointer - especially if it is collimated. Use an indirect means of determining proper operation such as projecting the beam onto a white card, using an IR detector card or tester (where needed), or laser power meter.
Laser diodes in CD players operate at 780 nm (near IR, virtually invisible). While safely tucked away inside the optical pickup, risks are quite minimal because the output is usually less than 1 mW and the emerging beam is highly divergent. However, if modifications are made to the pickup (such as by removing the objective lens), a 5 mW collimated beam may be produced which can burn holes in the retina of your eye without you even being aware there is a problem.

Common visible red laser diodes, diode laser modules, and laser pointers produce 1 to 5 mW at various wavelengths between 670 and 635 nm. When collimated (as in the case of a module with internal optics or a laser pointer) the entire beam can enter the eye and burn holes in the retina. Note that light at 635 nm appears more than 5 times as intense as light at 670 nm. Therefore, the apparent brightness of a source is not a reliable indication of its actual optical power output.
Currently, green laser pointers are not simple diode lasers but are Diode Pumped Solid State Frequency Doubled (DPSSFD) lasers (this may change in the future, however). For a given power, green appears substantially brighter than red wavelengths but are also limited a maximum power of 5 mW. However, since there is a high power IR laser diode inside a green pointer and not all include an adequate IR-blocking filter, there could be other dangers lurking even if the green output is weak or dead.
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