Abstract: The present invention relates to an apparatus for calibrating the magnification of a scanning electron microscope. The microscope includes a generator for generating an electron beam, a scanning signal generator for producing a scanning signal and a unit for scanning the beam. The apparatus is comprised of a calibration object which has a plurality of aligned elements thereon which, when scanned by the electron beam produces a signal having a frequency which has a fundamental periodicity dependent on the spacing of the aligned elements. A detector is provided for detecting the signal and producing an output signal having a data content and the fundamental periodicity. A unit is connected to the detector for determining the fundamental periodicity of the output signal from the entire data content of the output signal. A control unit is provided for producing a desired magnification signal.

Abstract: A method and apparatus for making precise measurements as small as in submicron distances of an object or specimen (13) includes a stage (18) which is movable under the control of a microprocessor (20). An instrument, such as a scanning electron microscope (10) scans the object (13) to obtain a first scan representation thereof. The stage (18) is then shifted a precise known distance and a second scan is made thereof. The results of the two scans are stored and compared by the microprocessor (20) to determine the apparent magnitude of the stage shift in arbitrary units. This apparent magnitude is then equated to the known precise shift distance to calibrate the arbitrary units. The microprocessor (20) can then calculate the desired measurement from the data of either of the two scans stored therein.