Laser irradiation method for laser treatment and laser treatment apparatus

A laser treatment apparatus for performing treatment for a treatment part of a patient by irradiating the part with a treatment laser beam, the apparatus including:

• a light delivery optical system provided with a laser source for emitting a treatment laser beam, for forming the laser beam emitted from the laser source into a spot beam and for delivering the beam to the treatment part;
• scanning means disposed in the light delivery optical system, for scanning the beam spots of the laser beam within an irradiation area;
• setting means for variably setting at least one of a shape and size of the irradiation area and size of the beam spots;
• determining means for determining a scanning sequence of the beam spots to be scanned by the scanning means based on a predetermined rule;
• and
• control means for controlling laser irradiation within the irradiation area based on the determined scanning sequence,
• wherein the predetermined rule is a rule that the scanning sequence is determined based on the shape and size of the irradiation area and the size of the beam spot, and when the laser irradiation is required of performing on four or more scanning lines, the scanning lines are divided into two groups of alternate scanning lines so that one group includes the 1st, 3rd . . . scanning lines and the other group includes the 2nd, 4th . . . scanning lines, and alternate beam spots on each scanning line of the first group are scanned, alternate beam spots on each scanning line of the second group are scanned, alternately remaining beam spots on each scanning line of the first group are scanned and alternately remaining beam spots on each scanning line of the second group are scanned.