| 摘要 |
Acoustic frictional resistance comprises a plate having at least one laser-formed hole therethrough. The plate is formed by positioning a plate preferably one having a thickness smaller than one and one-half milimeters alongside a laser and directing the laser beam so that it cuts a hole through the plate. During the process of producing the resistance, the value of the acoustic friction is measured as a pressure drop of a constant air stream or as an expenditure of electrical energy for an electrically excited electroacoustic transducer. This measurement is then used as a variable or as a standard for controlling the process. Advantageously, a coherent beam is emitted by the laser which is deflected by mirror from a horizontal to a vertical direction and focused by means of a lens to work in a contact-free manner on a workpiece supported on a support member such as a movable table. By moving the table in two coordinate directions, a plurality of bores are formed in a pattern in a workpiece. The workpiece may comprise a plate which may be rectangular, circular, annular, etc. |
