Measurement apparatus and measurement method

A measurement apparatus comprising:

• a light source unit configured to generate probe light;
• a splitting unit configured to split Brillouin backscattered light into two branches of first light and second light, the Brillouin backscattered light arising owing to the probe light in a propagation medium which propagates light;
• a first optical frequency shifter unit which is provided in the first light path configured to propagate the first light and configured to give a frequency shift of a first frequency;
• a second optical frequency shifter unit which is provided in the second light path configured to propagate the second light and configured to give a frequency shift of a second frequency;
• a delay unit provided in any one of the first light path and the second light path;
• a multiplexer unit configured to multiplex light propagating through the first light path and the second light path to generate multiplexed light;
• a coherent detection unit configured to perform heterodyne detection on the multiplexed light to output a difference frequency as a first electrical signal;
• an electrical signal generating unit configured to generate a second electrical signal having the same frequency as a frequency of the first electrical signal;
• a frequency shift amount obtaining unit configured to perform homodyne detection on the first electrical signal and the second electrical signal to obtain a frequency shift amount;
• a signal intensity obtaining unit configured to generate intensity information of the first electrical signal as an intensity signal;
• and
• a signal processing unit configured to obtain strain δε and a temperature change δT separately from the frequency shift amount and the intensity.

A measurement apparatus comprising:

• a light source configured to generate continuous light;
• a probe light generator configured to generate probe light from the continuous light;
• an optical fiber into which the probe light is launched;
• a splitting unit which is connected directly or indirectly to the optical fiber on an input side and is connected to two split optical paths of a first light path and a second light path on an output side;
• an optical frequency shifter unit provided in any one of the first light path and the second light path and configured to give a frequency shift of a beat frequency;
• a delay unit provided in any one of the first light path and the second light path;
• a multiplexer unit configured to multiplex light propagating through the first light path and the second light path to generate multiplexed light;
• a coherent detection unit configured to perform heterodyne detection on the multiplexed light to output a difference frequency as a first electrical signal;
• an electrical signal generating unit configured to generate a second electrical signal having the same frequency as a frequency of the first electrical signal;
• a frequency shift amount obtaining unit configured to perform homodyne detection on the first electrical signal and the second electrical signal to obtain a frequency shift amount;
• a signal intensity obtaining unit configured to generate intensity information of the first electrical signal as an intensity signal;
• and
• a signal processing unit configured to obtain strain δε and a temperature change δT separately from the frequency shift amount and the intensity.

A measurement method comprising:

• generating probe light;
• deriving, after the probe light is launched into a propagation medium which propagates light, Brillouin backscattered light from the probe light in the propagation medium;
• splitting the Brillouin backscattered light into two branches of a first light and a second light;
• giving a frequency shift of a beat frequency to any one of the first light and the second light;
• giving a delay to any one of the first light and the second light;
• multiplexing the first light and the second light to generate multiplexed light;
• performing heterodyne detection on the multiplexed light to output a difference frequency as a first electrical signal;
• generating a second electrical signal having the same frequency as a frequency of the first electrical signal;
• performing homodyne detection on the first electrical signal and the second electrical signal to obtain a frequency shift amount;
• generating intensity information of the first electrical signal as an intensity signal;
• and
• obtaining strain δε and a temperature change δT separately from the frequency shift amount and the intensity.

A measurement method comprising:

• generating probe light;
• deriving, after the probe light is launched into a propagation medium which propagates light, Brillouin backscattered light from the probe light in the propagation medium;
• splitting the Brillouin backscattered light into two branches of first light and second light;
• giving a frequency shift of a first frequency to the first light;
• giving a frequency shift of a second frequency to the second light;
• giving a delay to any one of the first light and the second light;
• multiplexing the first light and the second light to generate multiplexed light;
• performing heterodyne detection on the multiplexed light to output a difference frequency as a first electrical signal;
• generating a second electrical signal having the same frequency as a frequency of the first electrical signal;
• performing homodyne detection on the first electrical signal and the second electrical signal to obtain a frequency shift amount;
• generating intensity information of the first electrical signal as an intensity signal;
• and
• obtaining strain δε and a temperature change δT separately from the frequency shift amount and the intensity.