Abstract: A system for adjusting the scanning pattern of an electron beam in a scanning electron microscope to decrease image sensitivity to vibrations. In the system, a seismometer is connected to sense displacement velocity caused by vibrations, an integrator is provided for integrating signals from the seisometer, and a phase compensation system is provided for operating upon the integrated signals to provide phase compensated signals that are substantialy 180 degrees out of phase with the sensed vibrations. The phase-compensated signals are used for adjusting the normal scanning pattern of the electron beam microscope to reduce the effects of the sensed vibrations on images provided by the microscope.

Abstract: A method and system to reduce the sensitivity of instruments such as scanning electron microscopes to vibrations and similar disturbances. In the preferred embodiment, the system includes at least two velocity sensors connected to the specimen stage of the microscope to detect vibrations in two independent directions, integrators to integrate output signals from the velocity sensors to indicate displacement of the specimen stage in the two directions, and a beam steering device that receives signals from the integrators and adjusts the normal scanning pattern of the electron beam of the microscope to reduce the effect of vibrations.

Abstract: Method and apparatus for downhole seismic exploration employing vibration emanating from a point deep in a well. An elastic steel column has an upper end extending above the top of the well. A reaction mass is attached vertically thereabove through a vertically mounted compression spring system, in parallel with it a vertically mounted servo-controlled hydraulic cylinder-piston assembly. The displacement of a spear or bit on the lower end of the column relative to earth develops a displacement signal. The piston in the hydraulic cylinder is under reciprocated servo control to apply vertical vibration to the upper end of the column and thereby to the spear, while developing an electrical, pressure-differential signal corresponding to the pressure across the cylinder-piston assembly.

Abstract: Method and apparatus for improving oil production in oil wells. The lower end of an elastic steel column is attached to the upper end of a liner. The upper end of the column extends above the top of the well and is attached to a reaction mass lying vertically thereabove through (1) an accelerometer and (2) vertically mounted compression springs in parallel with a vertically mounted servo-controlled hydraulic cylinder-piston assembly. A substantially constant upward load is applied to the reaction mass, and the piston of the hydraulic assembly is reciprocated under servo control to apply vertical vibration to the upper end of the column. This vertical vibration is adjusted through the servo control to an appropriate resonant frequency for the column in the range of 5 Hz to 25 Hz, and the frequency is maintained at resonance by a feedback system relying on maintaining a phase difference of 90.degree.

Abstract: Method and apparatus for recovering a stuck element from deep in a well. The lower end of an elastic steel column is attached to the upper end of the stuck element. The upper end of the column extends above the top of the well and is attached to a reaction mass lying vertically thereabove through (1) an accelerometer and then (2) vertically mounted compression springs in parallel with a vertically mounted servo-controlled hydraulic cylinder-piston assembly. A substantially constant upward load is applied to the reaction mass, and the piston of the hydraulic assembly is reciprocated under servo control to apply vertical vibration to the upper end of the column. This vertical vibration is adjusted through the servo control to an appropriate resonant frequency for the column in the range of 1/2 Hz to 25 Hz, and the frequency is maintained at resonance by a feedback system relying on maintaining a phase difference of 90.degree.