VOLTAGE MEASURING APPARATUS

摘要

PURPOSE: To provide a voltage measuring apparatus which enables a user to measure a voltage of an object to be measured on a frequency axis in a short time and moreover, without containing calculation errors. CONSTITUTION: Measuring light emitted from a CW laser 21 is reflected on a reflection film on the bottom surface of an E-O probe 25 and returned to a PBS22 back through the incident path. The measuring light is outputted to a fast photodetector 28 and converted into electricity to be inputted to a narrow band amplifier 29. A fundamental frequency extractor 30 picks up a basic clock f0 of an electrical signal to be measured. The basic clock f0 is inputted to a frequency multiplier 31 and a frequency multiplied by integer thereof is generated as measuring frequency. A narrow band amplifier 29 brings the measuring frequency thereinto to amplify output components having these measuring frequencies obtained in a narrow band from among outputs of the fast photodetector 28. A resulting amplification output is inputted to an analyzer 32 to measure the amplitude and the phase is measured with the basic clock f0 as reference.