Abstract: The invention is directed to a method in which disks, particularly wafers, of brittle material are severed along planned severing lines by a laser by introducing thermal stresses. The temperature gradient required for this and the compressive stresses and tensile stresses resulting from it are generated in that the disk is first cooled proceeding from its underside at least along the planned severing lines toward the upper side of the disk, and the upper side of the disk is then acted upon by a laser beam along the planned severing lines. The description also relates to an apparatus for carrying out the method.

Abstract: The invention relates to a handpiece for radiating light onto a skin surface during a medical or cosmetic skin treatment. An optical coupling element (6) is provided in said handpiece (1). The light entrance surface (8) of said coupling element faces towards a light source, while its light exit surface (5) is in contact with the skin surface (2) during the skin treatment. The invention provides that the coupling element (6) of a handpiece (1) of this type consists of a bundle of light guides which end in the light entrance surface (8) and in the light exit surface (5) and which are in such close lateral contact with each other, at least in their end sections, that there are no optically ineffective intermediate spaces.

Abstract: The invention is directed to a method in which disks, particularly wafers, of brittle material are severed along planned severing lines by a laser by introducing thermal stresses. The temperature gradient required for this and the compressive stresses and tensile stresses resulting from it are generated in that the disk is first cooled proceeding from its underside at least along the planned severing lines toward the upper side of the disk, and the upper side of the disk is then acted upon by a laser beam along the planned severing lines. The description also relates to an apparatus for carrying out the method.

Abstract: The invention relates to a handpiece for radiating light onto a skin surface during a medical or cosmetic skin treatment. An optical coupling element (6) is provided in said handpiece (1). The light entrance surface (8) of said coupling element faces towards a light source, while its light exit surface (5) is in contact with the skin surface (2) during the skin treatment. The invention provides that the coupling element (6) of a handpiece (1) of this type consists of a bundle of light guides which end in the light entrance surface (8) and in the light exit surface (5) and which are in such close lateral contact with each other, at least in their end sections, that there are no optically ineffective intermediate spaces.