What is the issue with fieldmeters?
Fieldmeters are typically limited to large minimum probe-to-surface distance applications, therefore resulting in large spot resolution measurements and compromised accuracy. As all non-contacting measuring technologies measure the weighted-average of all charges contained within the resolution spot, the measurements obtained when using a fieldmeter (with its inherent large-area resolution) are particularly vulnerable to weighted-average measurement errors caused by mixed polarity charge located within the measured spot areas. In the extreme, equal and opposite values of even very high charges will result in a ‘zero’ reading by a fieldmeter. Trek Electrostatic Voltmeters, such as Model 520A or Model 541A with their high resolution (small spot) capabilities, will provide higher accuracy readings by reducing the weighted-average measurement error effect. In addition, fieldmeters are calibrated to be operated at a fixed probe-to-surface spacing and will experience large measurement errors
