Distance measurement system and distance measurement method

A distance measurement method using a distance measurement system, comprising:

• a detection step of irradiating an object with one part of a split light beam as assessment light, and receiving light reflected by the object to detect a target assessment beat signal, while guiding the other part of the split light beam as reference light to a reference optical path serving as a distance reference, and receiving the reference light that has passed through the reference optical path to detect a reference optical path assessment beat signal;
• a distance measurement step of measuring a distance to the object on the basis of the target assessment beat signal and the reference optical path assessment beat signal, including performing an A/D conversion on the target assessment beat signal by using a built-in A/D converter with the reference optical path assessment beat signal as a sampling clock and calculating the distance to the object based on the target assessment beat signal after the A/D conversion;
• a temperature assessment step of assessing a temperature inside a storage box wherein the reference optical path is stored as a temperature in the periphery of the reference optical path;
• and
• a correction step of correcting the measured distance on the basis of the assessed temperature, wherein
• an optical fiber serving as the reference optical path is wound with deflection around a fiber support unit formed inside the storage box such that even if the fiber support unit is deformed due to a temperature change inside the storage box, an influence of deformation on the optical fiber serving as the reference optical path is prevented.

A distance measurement system, comprising:

• a first light-receiving unit configured to irradiate an object with one part of a split light beam as assessment light, and receive light reflected by the object to detect a target assessment beat signal;
• a second light-receiving unit configured to guide the other part of the split light beam as reference light to a reference optical path serving as a distance reference, and receive the reference light that has passed through the reference optical path to detect a reference optical path assessment beat signal;
• a storage box configured to store the reference optical path;
• a temperature sensor configured to assess a temperature inside the storage box as a temperature in the periphery of the reference optical path;
• an information management unit configured to store a calibrated reference optical path length, a temperature at a time of calibration, and a reference optical path length change rate;
• a correction unit configured to calculate a distance to the object on the basis of the target assessment beat signal, the reference optical path assessment beat signal, the calibrated reference optical path length, the temperature at the time of calibration, and the assessed temperature, including performing an A/D conversion on the target assessment beat signal by using a built-in A/D converter with the reference optical path assessment beat signal as a sampling clock and calculating the distance to the object based on the target assessment beat signal after the A/D conversion;
• and
• an optical fiber serving as the reference optical path that is wound with deflection around a fiber support unit formed inside the storage box such that even if the fiber support unit is deformed due to a temperature change inside the storage box, an influence of deformation on the optical fiber serving as the reference optical path is prevented.