There are numerous 532nm green laser pointers in the market, while the price varies differently. Many customers are always attracted by low price, but according to an investigation carried out by physicists in the US, cheap green laser pointers can emit dangerous levels of infrared radiation.
532nm Green laser pointer (http://www.laserto.com/green-laser-532nm.html) is produced in three steps. Firstly, a standard laser diode generates near infrared light with a wavelength of 808nm. Then, it is focused onto a neodymium crystal that converts the light into infrared with a wavelength of 1064nm. Finally, the light passes into a frequency doubling crystal that emits green light at a wavelength of 532nm.
For cheap/shoddy laser pointer, manufacture always use second-hand diode, inferior optical filter and other rough material in order to gain much profit. Second-hand diode would reduce using time, while inferior optical filter can’t stop useless laser when it operates. One 100mW green laser pointer, maybe only includes 10 mW green laser, but 90mW infrared laser.
We all know the laser beam of infrared laser is invisible to human’s eyes, one would not aware of it when it emits. And this is quite harmful to one’s health.
However, there is a simple way for anybody to detect these infrared emissions. The method is to reflect the the beam off a standard CD which acts as a diffraction grating, and so separates light of different wavelengths. The diffracted light is reflected onto a piece of paper which displays the diffraction pattern. Many webcams are sensitive to infrared light or can be easily modified to detect it. So photographing the paper using such a camera shows the diffraction pattern of the green light and any infrared light produced too.
532nm laser pointer’s beam is very shining and pure, which is called forest green. The beam would seems a little bit dim once there is mixed with infrared beam. It is better that customers buy from reliable supplier and notice genuine laser pointer have CE or FDA certificate.
