Abstract: A spot shape detection apparatus for detecting the spot shape of a laser beam oscillated from a laser oscillator includes: a focusing leans for focusing the laser beam oscillated by the oscillator; a rotary body (mirror holder) in which a plurality of mirrors for reflecting the laser beam having passed through the focusing lens are disposed on concentric circles; a drive source (motor) for rotating the rotary body at a predetermined period; a beam splitter for branching return beams of the laser beam reflected by the plurality of mirrors of the rotary body; an imaging unit which is disposed in a direction in which the return beams are branched by the beam splitter and which images spot shapes of the return beams; and a display unit for displaying images obtained by imaging by the imaging unit, in relation with the plurality of mirrors.

Abstract: A spot shape detection apparatus for detecting the spot shape of a laser beam oscillated from a laser oscillator includes: a focusing leans for focusing the laser beam oscillated by the oscillator; a rotary body (mirror holder) in which a plurality of mirrors for reflecting the laser beam having passed through the focusing lens are disposed on concentric circles; a drive source (motor) for rotating the rotary body at a predetermined period; a beam splitter for branching return beams of the laser beam reflected by the plurality of mirrors of the rotary body; an imaging unit which is disposed in a direction in which the return beams are branched by the beam splitter and which images spot shapes of the return beams; and a display unit for displaying images obtained by imaging by the imaging unit, in relation with the plurality of mirrors.