Initial alignment method for free space optics laser beam

Abstract

The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

Analysis using multiple free space optic channel with amplification to mitigate haze attenuation

“…Although wireless LAN is a common mobile communication service, it has a weak point in security [5] even if any encryption is applied such as WPA/WPA2-PSK. FSO is a substitute wireless communication method, which transmits a collimated laser beam from a transmitter to a receiver through lenses and mirrors [7][8]. FSO is easier to set up compared to optical fiber cables as FSO laser beam is transmitted between two collimator lenses of the transmitter and receiver without using the transmission cables.…”