Temperature measurement method, temperature measurement device, medical device system, and laser treatment method

A temperature measurement device that measures an ambient temperature of a long-length medical device, comprising:

• a first optical fiber and a second optical fiber that are positioned in the medical device and extend in parallel with each other, the first optical fiber having a distal end serving as a measurement unit extending beyond a distal end of the second optical fiber along a longitudinal direction of the first and second optical fibers;
• an optical path length difference measuring unit that measures an optical path length difference between a first optical path including the first optical fiber and a second optical path including the second optical fiber;
• and
• a processor comprising hardware configured to calculate a temperature of the measurement unit based on the optical path length difference,
• wherein when temperatures of the first optical fiber and the second optical fiber are uniform, an optical path length of the first optical path and an optical path length of the second optical path are equal.

A laser treatment method comprising:

• preparing a medical device equipped with a first optical fiber and a second optical fiber, the first optical fiber and the second optical fiber extending in parallel with each other and the first optical fiber having a distal end serving as a measurement unit extending beyond a distal end of the second optical fiber along a longitudinal direction of the first and second optical fibers;
• positioning the medical device with respect to a treatment target;
• projecting a laser beam from the medical device to the treatment target;
• and
• measuring an ambient temperature of the medical device,
• wherein the measuring comprises:
• measuring an optical path length difference between a first optical path including the first optical fiber and a second optical path including the second optical fiber;
• and
• calculating a temperature of the measurement unit based on the optical path length difference, and
• when temperatures of the first optical fiber and the second optical fiber are uniform, an optical path length of the first optical path and an optical path length of the second optical path are equal.