Abstract: An input of an optical interferometer is a periodical optical pulse. A phase of a first half and a latter half of a reference pulse is a 90 degree (independently orthogonal) phase difference. Two interferometric outputs i1 and i2, where the phase difference is 90 degrees from each other, are obtained by interference of the reference pulse and the signal pulse. ? is calculated by referring the amplitude of reference pulse and the signal pulse to remove the light intensity fluctuations. Two values of cos ?1 and cos ?2 are calculated and positions are determined on the cosine curve by obtaining ?1 and ?2 values. ??1 and ??2, which are the phase increment or decrement of both ?1 and ?2 in a T period, are summed and becomes the sensor output signal that removes the measurement range limitation of ±90 degrees (a half wavelength of light) of the light phase.

Abstract: An input of an optical interferometer is a periodical optical pulse. A phase of a first half and a latter half of a reference pulse is a 90 degree (independently orthogonal) phase difference. Two interferometric outputs i1 and i2, where the phase difference is 90 degrees from each other, are obtained by interference of the reference pulse and the signal pulse. ? is calculated by referring the amplitude of reference pulse and the signal pulse to remove the light intensity fluctuations. Two values of cos ?1 and cos ?2 are calculated and positions are determined on the cosine curve by obtaining ?1 and ?2 values. ??1 and ??2, which are the phase increment or decrement of both ?1 and ?2 in a T period, are summed and becomes the sensor output signal that removes the measurement range limitation of ±90 degrees (a half wavelength of light) of the light phase.

Abstract: For effective use of the optical energy and yet proper operation of an automatic gain or threshold control circuit comprised by a receiver of an optical data transmission system, a transmitter of the system produces an optical binary signal with at least one optical pilot pulse inserted between two sequences of optical data pulses only when the two sequences are spaced wider from each other than a predetermined interval that would render the control circuit no more operative and would thereby adversely affect correct reproduction of the data from an electrical binary signal derived from the received optical binary signal through the control circuit.