Method of positioning an electrooptic probe of an apparatus for the

Abstract

An method of positioning an E-O probe applied to an apparatus for the measurement of voltage. In the first step, the relative position of the E-O probe against the magnifying optical system in the first condition of being focused the magnifying optical system on the base of the E-O probe, and the focal point difference between the focal plane of the magnifying optical system in the second condition that the E-O probe is substantially out of the optical path for observation of the surface of the device and the focal plane in the first condition are stored. The relative position and the focal point difference are fixed in the apparatus for the measurement of voltage regardless of the device to be measured. Next, in the second step, the focus of the magnifying optical system is adjusted to the observation position of the surface of the device in the second condition, and then in the third step, the magnifying optical system, the E-O probe, and the probe stage are separated from the device by the focal point difference stored in the first step by the Z-axis stage, and in the fourth step, the E-O probe is moved to the relative position of the E-O probe stored in the first step relative to the magnifying optical system by the probe stage.