Patent ID: 7220939

Claim:
Laser beam machine having laser beam generating means for generating laser beam, a first beam guide portion for guiding said laser beam from said laser beam generating means in a first direction, a second beam guide portion for guiding said laser beam from said first beam guide portion in a second direction, and a machining head for radiating said laser beam passed through said first beam guide portion and said second beam guide portion, being moved and driven, on a workpiece, said machining head located adjacent to said second beam guide portion, comprising: a movable first reflecting means located at said first beam guide portion, for adjusting a length of an optical path of said laser beam according to a change of a reflected position of said laser beam; a second reflecting means supported by said second beam guide portion so as to face said first reflecting means, for introducing said laser beam reflected by said first reflecting means into said second beam guide portion; a first opening portion being formed at said first beam guide portion on a side adjacent to said second beam guide portion along said first direction; a first belt member for preventing the entrance of dust and foreign objects into said first beam guide portion and being located along said first opening portion; and said first belt member being located so as to close said first opening portion in a portion excluding a portion adjacent to said second beam guide portion and so as not to close said first opening portion in said portion adjacent to said second beam guide portion in order to allow said laser beam to be entered into said second beam guide portion.