Abstract: A temperature probe has a metal casing, closed at one end and open at its other, in which a temperature sensor is buried in compacted hygroscopic mineral insulation having an exposed end face through which extend wires from the sensor. Such end face is sealed to keep it dry by a metal tube having one end surrounding and brazed to the metal casing, and plugged at its other end by a body of compressed sealant material. Lead wires extend through the sealant body and are electrically joined in a space provided between the exposed end face of mineral insulation and the opposing inner end face of the sealant plug.

Abstract: Electrode material is laser machined from a piezoelectric device (10) to adjust its resonant frequency to a nominal value. At the same time the device (10) is electronically cleaned by overdriving the device at a high current level to prevent loosely adhering lasered particles, which cause the device to be electrically unstable, from accumulating on the device. The simultaneous laser machining and electronic cleaning also eliminates erratic resonant frequency changes in the device (10) which occur if the electronic cleaning is performed after the laser machining. As the nominal resonant frequency value is approached, the device (10) is overdriven at successively lower current levels and the laser machining is carried out at respective successively lower rates.