Patent ID: 7263297

Claim:
A transmitter for Free Space Optical transmission systems, the transmitter including: at least one convergent lens having a corresponding focal point located at a focal distance (ƒ) from the convergent lens along an optical axis; and at least one source of light situated behind the convergent lens in order to produce a beam of light carrying a signal to be transmitted on air, the at least one source of light being situated at a source distance (ƒ 1 ) from the convergent lens, and means for changing the source distance (ƒ 1 ) for changing the angle of divergence (α) of the beam of light in a corresponding manner, characterized in that said means for changing the source distance (ƒ 1 ) are operable so as to maintain a wide angle of divergence (α) in good visibility conditions of the link, namely in conditions that are sufficient to guarantee the quality of the link, and to reduce the angle of divergence (α) proportionally to worsening of environmental conditions along the link.