Patent ID: 7369775

Claim:
An apparatus for wireless duplex communication, comprising, a first optical transceiver having a first optical transmitter and a first optical receiver, a second optical transceiver having a first optical transmitter and a first optical receiver, the first and second optical transceivers being located at opposite ends of an optical communication line formed thereby, wherein the output of each of the optical transmitters is a diverging beam of incoherent electromagnetic radiation arranged to have a cross sectional diameter which is larger than the cross sectional diameter of the respective optical receiver at that point on the communication line at which the respective optical receiver is situated, wherein each of the optical receivers includes an optical condenser lens having a focal plane, a photodiode, and a diaphragm having an aperture and situated in the focal plane of the optical condenser lens between the optical condenser lens and the photodiode, wherein the distance Δ between the diaphragm and the photodiode is defined by Δ=bF/Dc, where b is the diameter of a light-sensitive site of the photodiode, Dc is the diameter of the optical condenser lens, and F is a focal distance of the optical condenser lens, and wherein a beam angle θ characterizing the first transmitters and the first receivers is defined by Tan 2θ=a/F, where a is the aperture of the diaphragm.