A method and apparatus are provided. In an example, a volume portion of the solid body is exposed to light waves of different wavelengths, wherein the light waves are partly reflected at surfaces of the solid body. Light parameters of the reflected light waves are at least partly acquired using a sensor device. Distance information and/or intensity information are/is ascertained from at least a portion of the acquired light parameters. A thickness and/or a transmittance of the solid body in the volume portion are/is determined based upon the distance information and/or the intensity information. Laser radiation is introduced into the volume portion to produce a modification in the interior of the solid body, wherein at least one laser parameter of the laser radiation is set at least depending on the thickness and/or the transmittance such that the modification is at a predefined distance from a surface of the solid body.