Abstract: A device for measuring polymer build-up on plasma chamber walls provides a cooled window on which a film may form. Light passing through the window outside the chamber may be measured by interferometric techniques to determine change in film thickness and thus indicate when cleaning is required and the success of cleaning operations. A sapphire window may be used to allow for air cooling and to reduce etching by the plasma. A fiber optic cable may communicate the light between the window and measurement electronics.

Abstract: A method and apparatus is provided for testing dissipative mechanical phenomena, including fretting wear. An actuator (54) effects frictional oscillatory slip motion between a stylus (32) and a workpiece (30) in contact. A displacement transducer (62) detects the amplitude of the slip motion, and a control loop (60) responds to the displacement transducer controls the actuator to provide constant amplitude slip motion under changing frictional fretting wear conditions of the workpiece as the workpiece wears during the oscillatory slip motion. The oscillator is driven at its resonant frequency, and the power required to maintain constant amplitude slip motion at resonant frequency is monitored (64).