US Patent 7220939 Laser beam machine

A laser beam machine can make quality of machining almost constant in such a manner that a first reflecting means in a first beam guide portion is moved and driven so as to maintain a length of an optical path of laser beam to be almost constant in spite of a moved position of a machining head. According to the invention, a second reflecting means for catching laser beam in a second beam guide portion is located at a position facing the first reflecting means, thereby relatively shortening a length of the optical path between the first and second reflecting means and shortening the whole length of the optical path, and maintaining quality of machining with laser beam good.