Verfahren zur kontaktlosen Messung elektrischer Spannungen in einem Messobjekt mit einer Isolatoroberflaeche und Vorrichtung zum Durchfuehren des Verfahrens

In a process and a device for the non-contact measurement of electrical voltages in an object under test having an insulator surface, a primary electron beam is trained on the insulator surface of the object under test. The energy of secondary electrons of a secondary electron flow generated on the insulator surface of the object under test is measured in order to derive the potential of a conductive zone located under the insulator surface of the object under test. To increase measurement accuracy, an electrical resonant field above the object under test is designed as an alternating field in the invention, and the energy measurement of the secondary electrons is performed in synchronization with the alternating field.