Temperature dependency on magnetic field strength of an electron optical element in an electron beam system due to variation of permeability with temperature of a ferromagnetic pole piece subject to radiant heating from another electron optical element is corrected by measurement of pole piece temperature and closed loop control of excitation current of a correction element which may be provided as a portion of a lens, stigmator, deflector or the like. A correction function may be computed to extrapolate correction values from empirically determined correction values or correction values may be retrieved from a memory such as a look-up table. Performance of the electron beam system is improved and constraints on choice of pole piece materials, mounting geometry, relative positioning of electron optical column elements and electron optical column length are relaxed since temperature dependencies of many electron optical elements can be corrected.

A method for magnetic coupling compensating a rod position indication system having at least two rod position indicators each having induced noise comprising the steps of applying a sinusoidal current to a primary of the first rod position indicator for inducing a voltage on a first secondary of the first rod position indicator; receiving both the first secondary voltage from the first rod position indicator and a second secondary voltage, induced from the noise, of the second rod position indicator; and deriving a difference of the first and second secondary voltage for obtaining the magnetic coupling compensation.

A combined alarm and display belted clinical thermometer being wound on an arm of a user which comprises a thermal sensor to sense the temperature of the user. The sensing signals are converted and the measured value is displayed on an LCD display. The belted clinical thermometer also comprises a comparator which is preset witha reference value to comparing the measured temperature with a reference temperature and; if the measured temperature is significantly larger than the reference temperature, an alarm is triggered to sound. Further to the basic design, the belted clinical thermometer can be equipped with a transmitter which can signal a remote receiver to sound an alarm.

A method for compensating a rod position indication system for non-linearity comprises the steps of applying an excitation current to a primary of a sensor for inducing a generally linear voltage that is representative of the position of a control rod on a secondary of the sensor. The excitation current includes a first frequency which is sufficient to provide the generally linear output for the sensor. The excitation current is then modified to include a second frequency which is sufficient for providing the generally linear output when the first frequency is insufficient to provide the generally linear output.

A method and system for indicating the position of a nuclear reactor control rod which is suspended from a shaft sliding vertically inside a travel housing. Primary and secondary coils are wound around the travel housing and an AC current travelling through the primary coil induces a secondary voltage across the secondary coil and a primary voltage across a secondary coil of an isolation transformer. The primary and secondary AC voltages are low pass filtered, rectified into DC voltages, and low pass filtered a second time. The secondary DC voltage is divided by the primary DC voltage and a ratiometric signal is produced. The ratiometric signal is compensated by decoupled zero and span adjustments and by a temperature compensation adjustment. A linear correction offset is calculated from data stored in an EPROM and summed with the ratiometric signal yielding a module output signal which is a linear representation of the control rod position.