A microwave oven, in which a motor for rotating a turntable has an improved structure. The method involves providing an optical scanning system supporting baseline classes of features and functionalities, and having an extended feature class programming mode for programming extended classes of features and functionalities, in addition to the baseline classes of features and functionalities. In general, each of these methods may operate over a specific frequency band in various embodiments. The rear module is releaseably attached to the rear of the front module and supported by it. The second metal is substantially converted to a metal oxide dispersed in the matrix during or prior to a first phase conversion heat treatment but after formation of the composite, creating an ODS matrix. The method utilises two measurements of OMA, each measurement being related to the slope in a specific portion of the operating region of the powercurrent characteristic curve of the laser diode.