A laser system including: a laser source operable to emit a first laser beam having a first operating wavelength and a second laser beam having a second operating wavelength; a fiber optic cable to guide and homogenize the first and second laser beams; an expander to increase the diameter of the first and second laser beams; a cylinder to guide the first and second laser beams and limit respective diameters of the first and second laser beams, wherein the cylinder is positioned after the expander on an optical path of the laser beam; a first optical system to collimate the first and second laser beams, wherein the optical system is positioned after the cylinder on the optical path of the first and second laser beams; a spot-size selector comprising a plurality of apertures, wherein the spot-size selector is positioned after the first optical system on the optical path of the first and second laser beams; and a second optical system to focus the first and second laser beams on a tissue of the patient.