The invention discloses a mapping method between an incident
ray coordinate and an emergent
ray coordinate when a collimated elliptical
Gaussian beam is converted into a collimated elliptical flat-topped beam and the size of an elliptical
light spot is changed, and belongs to the field of
laser shaping. The method for calculating the mapping relation between the output light coordinates and the input light coordinates comprises the following steps of: 1, utilizing the law of
conservation of energy to ensure that the energy surrounded in an input surface
ellipse is equal to the energy surrounded in an output surface
ellipse; solving a mapping relation between the
ellipse semi-major axis xiout and the ellipse semi-
minor axis eta out of the emergent
light beam and the ellipse semi-major axis xiin and the ellipse semi-
minor axis eta in of the incident
light beam; 2, solving a mathematical expression of a mapping relation between output light coordinates and input light coordinates: determining an included angle theta between a connecting line between a point (xin, yiin) and the center of an ellipse and an X axis according to the point (xin, yiin) on the ellipse circumferences of a semi-major axis xiin and a semi-
minor axis eta in on an input surface, and solving an emergent point coordinate (xout, yout) corresponding to an incident point (xin, yiin) according to the theta, xiout and eta out; and 3,
light intensity statistical
simulation verification: carrying out
Gaussian sampling on the coordinates (xin, yiin) of one million light rays, and carrying out distribution statistical
simulation on all (xin, yiin) and (xout, yiout) by using
matlab programming, so as to display the conversion from an elliptical
Gaussian beam to an elliptical flat-topped beam.