Multi-path interference light measuring method and apparatus

A multi-path interference light measuring method inputting pulse-modulated signal light to a target to be measured, and measuring multi-path interference light from pulse signal light output from the target to be measured, comprising

• setting a cycle of pulse modulation on an input side in correspondence with a measurement result of time until an optical pulse input to the target to be measured is output from the target to be measured.

A multi-path interference light measuring apparatus inputting pulse-modulated signal light to a target to be measured, and measuring multi-path interference light from pulse signal light output from the target to be measured, comprising:

• a cycle setting unit setting a cycle of pulse modulation on an input side in correspondence with a length of an optical medium of the target to be measured;
• and
• a modulating unit modulating the pulse signal light output from the target to be measured by using a modulation signal that has a same cycle as the set cycle, and can arbitrarily set a phase difference from the output pulse signal.

An optical signal inputting apparatus inputting pulse-modulated signal to a target to be measured in order to allow multi-path interference light to be measured from pulse signal light output from the target to be measured, comprising

• a cycle setting unit setting a cycle of pulse modulation on an input side in correspondence with a length of an optical medium of the target to be measured.

A multi-path interference light measuring apparatus measuring multi-path interference light from pulse signal light output from a target to be measured to which pulse-modulated signal is input, comprising

• a modulating unit modulating the output pulse signal by using a pulse signal for modulation, which has a same cycle as a pulse signal input to the target to be measured, and whose delay time from a rising time of the input pulse light is determined according to the cycle, a duty ratio of the input pulse signal, and a delay time of an output pulse from the input pulse.

A multi-path interference light measuring apparatus inputting pulse-modulated signal light to a target to be measured, and measuring multi-path interference light from pulse signal light output from the target to be measured, comprising:

• a cycle setting means for setting a cycle of pulse modulation on an input side in correspondence with a length of an optical medium of the target to be measured;
• and
• a modulating means for modulating the pulse signal light output from the target to be measured by using a modulation signal that has a same cycle as the set cycle, and can arbitrarily set a phase difference from the output pulse signal.

An optical signal inputting apparatus inputting pulse-modulated signal to a target to be measured in order to allow multi-path interference light to be measured from pulse signal light output from the target to be measured, comprising:

• an obtaining means for obtaining a length of an optical medium of the target to be measured;
• and
• a cycle setting means for setting a cycle of pulse modulation on an input side in correspondence with the length obtained from said obtaining means for.

A multi-path interference light measuring apparatus measuring multi-path interference light from pulse signal light output from a target to be measured to which pulse-modulated signal is input, comprising:

• a signal generating means for generating a pulse signal for modulation, which has a same cycle as a pulse signal input to the target to be measured, and whose delay time from a rising time of input pulse light is determined according to the cycle, a duty ratio of the input pulse signal, and a delay time of an output pulse from the input pulse;
• and
• a modulating means for modulating output pulse signal by using the pulse signal for modulation.