Abstract: Two parallel cigarette rods are guided in a twin cigarette rod making machine between two stationary ionization chambers of a density measuring apparatus. Two radiation sources are mounted on a carrier between the two rods for movement with the carrier between a first position in which the radiation issuing from the sources penetrates through the adjacent rods and into the respective ionization chambers, and a second position in which the radiation enters the respective chambers by way of passages in the guides for the respective rods.

Abstract: Apparatus for optically scanning a moving cigarette rod for the presence of defects in its external surface has two annularly arranged groups of diodes which emit green light in the wavelength range of between 0.49 and 0.58.mu. and direct such light from the opposite sides of a plane that is normal to the moving rod so that the incident light is reflected by successive annular portions of the external surface of the rod into the aforementioned plane. The reflected light is focused by systems of lenses upon discrete photosensitive transducers through discrete slit diaphragms on the transducers themselves or on a thin metallic ring which is adjustably mounted on the support for the diodes and the systems of lenses.

Abstract: Apparatus for making holes in a running web of tipping paper for filter cigarettes has a carrier for a battery of suitably distributed perforating units each of which has an optical system for focusing upon the running web a discrete beam of coherent radiation which is furnished by a laser. The making of holes entails the development of contaminants, and such contaminants are removed by air streams which are circulated through the perforating units not only to remove the contaminants but also to cool the optical systems of the respective perforating units. The web advances along the convex side of a shroud which maintains the web at an optimum distance from the optical systems of the perforating units. The shroud is installed between the web and the perforating units and has elongated slot-shaped apertures for the beams of radiation. The perforating units form several rows, and the shroud has or can have one elongated aperture for each row of perforating units.

Abstract: Apparatus for perforating a web of wrapping material or tubular wrappers of discrete filter cigarettes of unit length or double unit length in a filter tipping machine has a laser which is energizable at a frequency depending on the speed of the main prime mover of the machine to emit a beam which is reflected by a pivotable reflector to impinge alternately upon different portions of a single optical system or upon several discrete optical systems serving to focus the beam upon the web or upon discrete wrappers whereby the beam forms two or more rows or more complex patterns of perforations in the web or in the wrappers of successive cigarettes. The pivotable reflector can be omitted or is optional if a diffraction grating is placed in front of a single optical system so that the grating splits the beam into several discrete beams each of which is focused upon a different portion of the web or of the wrapper of a cigarette.