Patent ID: 6297651
Filing Date: 2001-10-02
Classification: G01R

Abstract:
An electro-optic sampling probe comprising:an electro-optic element having a reflective face to physically contact wiring on an IC wafer to measure a voltage, the refractive index of the electro-optic element being changed according to the variation of an electric field generated by the variation of the voltage being measured;an optical system for transmitting a laser beam received from an external source to the electro-optic element and to be outputted from a reflective surface of the electro-optic element;an electro-optic sampling optical system module, including;a first optical system having a polarized beam splitter, and a wave plate for isolating a first portion of the laser beam outputted from the electro-optic element and outputting the remaining portion, anda first photodiode for receiving and converting said first isolated portion into an electric signal;a second optical system having a polarized beam splitter and a wave plate for isolating said remaining portion of the laser beam outputted from said first optical system, anda second photodiode for receiving and converting said remaining isolated portion into an electric signal,wherein the difference between the electric signal outputs from the first and second photodiodes corresponds to a change of the refractive index of said electro-optic element; anda unit for attenuating the quantity of light of the laser beam from the external source that is received by said optical system, said unit comprising a device for rotating the polarization direction of the light from the external source and a polarizing device, and said unit being between the external source and the electro-optic sampling optical system module.