Collimator and optical isolator with collimator

The problem addressed by the present invention is, in an optical isolator with a collimator that is used at the tip of a fiber for transferring light from a laser used in processing, isolating returning light from an optical system and preventing heat transfer of optical energy to the fiber making light incident, laser oscillator, collimator, and isolator. As a means for solving the problem, light receiving fibers (22 and 23) that collect light returning from an article being processed after the light exits the isolator and returns to a collimator lens (5) are disposed at light collection points, the light guided into a ceramic pipe (24), converted to heat and dissipated.