Abstract: Perforations are made at locations spaced about the periphery of a cigarette by conducting separate parts of a laser beam through respective separate light paths which intersect such spaced peripheral locations.

Abstract: A web is electrically perforated at high hole density by applying alternating-current voltage across an electrode pair facing the web while pressurized gas is supplied to the electrode gap. Voltage amplitude level and gas flow level are selected to provide for the striking of multiple arcs per half-cycle, thereby enabling reduction in spacing between adjacent perforations in the web. Perforation practice involving preselection of cigarette filter tipping paper based on chemical composition of the paper is also disclosed as is apparatus for use in implementing the described practices, wherein electrode support members have gas flow conduits formed integrally therewith and wherein webs are taken up by a capstan drive unit resiliently biased into engagement with a web take-up roll.

Abstract: Metal layers of extreme thinness, of the order of fifty Angstroms and greater are detected by use of microwave energy so propagated as to permit determination of the presence or absence of the metal in a detection zone of limited extent outwardly of the issuance location of such propagated energy. Apparatus is provided for propagating microwave energy having a characteristic which changes with propagation distance from a maximum value at the energy issuance location to a minimum value first exhibited at the outward end of the detection zone.