Do you believe an ordinary laser pointer can be transferred 100 miles away in the sound of air in it?
We did it, and I believe you can do it.
A semiconductor laser 1
Generally light source is a laser optical fiber communication, but the atmosphere at the time of communication, incoherent light than the Violet laser pointer pen diode is sometimes useful. The main reason is the change in atmospheric density laser will destroy the phase coherence and lead to random fluctuations in brightness, it is possible to destroy the information contained in the beam. Secondly, when large diameter beams needed telecommunications but coherent light beam expander is not easy, which requires the use of very sophisticated and increases the weight and cost of the camera.
Even with these shortcomings, in optical communication with a common Green Laser Pointer 10mW is still very attractive thing, they are inexpensive, readily available and easy to get, low power consumption, safer, and easier by pwm modulation technique. Finally, and most importantly, how cool laser communication!
Most affordable red laser pointer is ideal collimated beam even if they produce only a few millimeters in diameter, but also in considerable distance observed with the naked eye, when good weather viewing distance can be as far as 100 kilometers.
Mentioned 100mw laser pointer (Laser Pointers), surely we are not familiar with the size of a lipstick little thing, according to what can be emitted from a small red or green. They often will hold a laser pointer, a spot with a laser pointer pointing issued on the screen with the PPT do reports. Even many children's toys will have something similar, such as a variety of cute graphics to draw on the walls. On a famous domestic retail sites found a bit rough, a lot of sellers, prices are mostly between 30 to 50 yuan, can be seen everywhere in daily necessities. But it is such a small thing, feel free to abuse, will stir up big trouble, you believe it?
Examples of 30mw Laser Pen Green abuse, I am afraid we are most familiar with is the football hooligan. Yes, whether at home or abroad, the football game is not difficult to see this little devil's shadow. For example, this year's Super League match in June, in Tianjin TEDA home, Yang Hao to canalblog Guangzhou team members takes the corner at the critical moment, and is irradiated with a laser pointer dazzling fans something happened.