Measurement system and measuring method

A ranging apparatus comprises:

• a light source configured to transmit an optical input signal to an optical signal input/output unit of a measurement target;
• a light receiving unit configured to receive an optical output signal as the optical input signal applied with an optical change, from said optical signal input/output unit;
• and
• a measuring unit configured to measure a propagation distance of the optical signal from said light source to said light receiving unit through said optical signal input/output unit based on the optical output signal, and measure a relative position of said optical signal input/output unit based on the propagation distance.

A measuring method comprising:

• transmitting an optical input signal from a ranging apparatus to an optical signal input/output unit mounted on a measurement target;
• receiving the optical signal from said ranging apparatus by said optical signal input/output unit and transmitting an optical output signal as an optical input signal applied with an optical change, to said ranging apparatus;
• receiving the optical output signal as the optical signal from said optical signal input/output unit by said ranging apparatus;
• measuring a propagation distance of the optical signal from a transmission point of the optical input signal to a reception point of the optical output signal applied with the optical change based on the optical signal applied with the optical change, by said ranging apparatus;
• and
• measuring a relative position of said optical signal input/output unit based on the propagation distance.