Abstract: Various embodiments of a hermetic assembly and a method of forming such assembly are disclosed. The hermetic assembly includes a dielectric substrate having a first major surface and a second major surface, a patterned layer connected to the first major surface of the dielectric substrate by a laser bond, and a ferrule having a body and a flange extending from the body. The flange is welded to a welding portion of the patterned layer that is disposed between the flange and the first major surface of the dielectric substrate such that the ferrule is hermetically sealed to the dielectric substrate.

Abstract: During the fire-polishing of a lengthwise extended glass body (3), for example a preform for drawing optical fibers, the glass body (3) is held by a holding device (5, 7), and is heated by a burner (23) moving at a variable advancing speed parallel to the lengthwise axis (19). The surface temperature of the glass body (3) is determined with a temperature measuring device (25). The mechanical stress condition of the glass body (3) is detected with an optical device (29) and can be controlled by varying the burner temperature and/or the advancing speed of the burner. The invention makes it possible to counteract the occurrence of high mechanical stresses in the glass body (3).