Abstract: A seismic sensor, has a case, a pre-charged, non-conductive membrane located between two plates that form a capacitor and accommodated inside the case, with one of the plates being immovable relative to the case and the other of the plates being movable relative to the one plate under the action of seismic activity of a medium in which the sensor is located, so that the capacitor produces an electrical signal responsive to the seismic activity, and a mass increasing element associated with the movable plate so as to increase mass of the movable plate and therefore enhance oscillations of the movable plate under the action of the seismic activity.

Abstract: For measuring sizes in a scanning measuring microscope a nominal magnification is selected so that an object image occupies a substantial part of a field of view, an actual magnification is calculated depending on a coordinate on a screen along the direction of measurement, the object is positioned on a microscope table so that a line of scanning coincides with a direction of measurement and scanned by an electron beam to obtain a function of a video signal, points are localized which correspond to left and right edges of the object on a curve, and a size of the object is determined from the coordinates of the left and right edges and the magnification of the microscope changing from one point to the other.

Abstract: A method of calibrating magnification of optical devices includes providing a mask with a predetermined pattern, projecting radiation through the mask so as to form a pattern image, and comparing a pattern of the image with a pattern of the mask to determine deviations of the image of the projected image from the image of the mask.