The invention discloses a ceramic cooktop comprising a cooking plate made of a glass ceramic or glass. Also, a system and method for evaluating the seal integrity in flexible packaging across a moving web by the use of non-contact optical interferometry is provided. The old laser shutter fin was positioned to engage a laser shutter of the first type of printer, and the new laser shutter is positioned to engage a laser shutter of the second type of printer. A graph is constructed, in which nodes represent the sets of MS, mid each edge between a pair of nodes represents channel interference between the MS represented by the pair of nodes.