Method for measuring profile of beam spot and recording medium storing program of the same

PURPOSE: A method for measuring a beam spot profile and a record medium for recording a program for executing thereof are provided to simply compute aberration of a beam spot at a focal point using the zernike polynomial without additional device. CONSTITUTION: A method for measuring a beam spot profile is as follows. A beam spot forming a focal point is defocused(S210). Energy distribution of the defocused beam spot is measured(S220). The zernike polynomial at the defocused beam spot is computed by measured energy distribution of the beam spot and ideal energy distribution of the beam spot at the defocused position(S230,S240). The energy distribution of the beam spot at the focal point is computed by the zernike polynomial(S250).