Patent ID: 8796582

Claim:
A laser welding apparatus comprising a laser welding unit, the laser welding unit comprising: a laser focusing section arranged to focus a laser beam, the laser focusing section comprising: a first lens adapted to focus the laser beam at a focal point, a second lens adapted to diffuse the laser beam to the first lens, and a third lens adapted to guide the laser beam to the second lens; a focus adjusting section comprising a lens-barrel, the lens-barrel being rotatable supported in the laser welding unit such that the lens-barrel is rotatable about a longitudinal axis of the lens-barrel, the lens-barrel including three spiral grooves in an inner peripheral wall of the lens-barrel; and at least one stopping device arranged to restrict rotation of the first lens, the second lens, and the third lens when the lens-barrel is rotated, wherein the first lens, the second lens, and the third lens are engaged with respective ones of the spiral grooves such that the first lens, the second lens, and the third lens move in a direction of the longitudinal axis of the lens-barrel when the lens-barrel is rotated, and wherein the focus adjusting section is arranged to adjust at least one of a focal length of the laser beam, and a focal spot size of the laser beam.