He-Ne Laser Communication

Abstract

Preliminary experiments, demonstrating the feasibility of laser communication, using a He-Ne gas laser of cavity length of about 45 cm. with confocal reflector arrangement and of output power of the order of a milliwatt, have been reported. The amplitude modulation is produced by superimposing the audio signal on the exciting d.c. voltage of the discharge tube and the resulting intensity modulated laser beam (λ = 0·6328 μ) is focused on a PMT/solar cell to detect the audio signal. Without using any sophisticated collimating or receiving optics, communication up to a distance of about 100 ft. has been demonstrated and can easily be extended further.