LASER BEAM SPOT SHAPE DETECTION METHOD

Disclosed herein is a laser beam spot shape detection method for detecting a spot shape of a laser beam oscillated by laser beam oscillator and collected by a condenser in a laser machining apparatus, the laser beam spot shape detection method including: a concave mirror holding step of holding a concave mirror having a spherical face forming a reflecting face with a chuck table; a focal point positioning step of positioning the focal point of the condenser in a proximity including the center of the spherical face forming the reflecting face of the concave mirror held by the chuck table; a laser beam irradiation step of irradiating a laser beam onto the held concave mirror, and an imaging step of capturing images of reflected light with a camera.