Laser processing device and laser beam rotating unit for drilling a taper-free through hole on the processed object

The invention realizes taper-free machining by using drill machining. A path of the laser beam from the emission source to the processed object is provided with a beam rotator, a galvanometer scanner, and a f[theta] lens processing device in sequence and therefore, the movement of the laser light displacement is synchronized, in a manner that the scanning trajectory of the irradiation position becomes a closed curve such as a circle through a galvanometer scanner, with the action of tilting the irradiation of the laser light and rotating the irradiation direction by the beam rotator and f[theta] lens. Furthermore, the laser light is made incident on the processed object at the outermost part of the laser light's passing range where the angle of incidence is perpendicular to the processed object.