Abstract: A system is used to excite an object at a vibration frequency, in order to induce stationary or travelling waves having the vibration frequency on the surface of the object. An optical interferometer is configured to use optical interference to determine vibration amplitude and phase data of the stationary or travelling wave at each of a plurality of points on the surface, relative to a reference phase. A processing system is used to apply a spatial derivative filter to the vibration phase data, and the resulting spatial-derivative-of-phase data is processed to determine a property of the object, and is further processed to generate graphical-representation data for outputting on a display device.

Abstract: A system is used to excite an object at a vibration frequency, in order to induce stationary or travelling waves having the vibration frequency on the surface of the object. An optical interferometer is configured to use optical interference to determine vibration amplitude and phase data of the stationary or travelling wave at each of a plurality of points on the surface, relative to a reference phase. A processing system is used to apply a spatial derivative filter to the vibration phase data, and the resulting spatial-derivative-of-phase data is processed to determine a property of the object, and is further processed to generate graphical-representation data for outputting on a display device.

Abstract: An optical interferometer (1) is used to determine information about the position, gradient or motion of a surface of an object (2) at each of a plurality of points on the surface. An image is projected onto the surface of the object (2), such that, for each of the plurality of points, the intensity or spectrum of the projected image at that point depends on the determined information about the position, gradient or motion of the surface at that point.

Abstract: An optical interferometer (1) is used to determine information about the position, gradient or motion of a surface of an object (2) at each of a plurality of points on the surface. An image is projected onto the surface of the object (2), such that, for each of the plurality of points, the intensity or spectrum of the projected image at that point depends on the determined information about the position, gradient or motion of the surface at that point.

Abstract: Method and system for measuring vibration in two or three directions in objects (12) by using three illumination light beams (11A-C) for measurement of in-plane vibrations in two directions, where one of the three illumination light beams (11A-C) is common for the two in-plane measurements, and where the three illumination light beams (11A-C) are configured to provide free space at one side of the object (12) for easier access to the object. The method and system is further arranged for using two illumination light beams (30A-B) for measuring vibrations in the object (12) in a third direction, which third direction is out-of-plane direction, where one illumination light beam (30A) is illuminating the object (12) through an imaging objective (16) and one illumination light beam (30B) is used as reference beam.

Abstract: Method and system for measuring vibration in two or three directions in objects (12) by using three illumination light beams (11A-C) for measurement of in-plane vibrations in two directions, where one of the three illumination light beams (11A-C) is common for the two in-plane measurements, and where the three illumination light beams (11A-C) are configured to provide free space at one side of the object (12) for easier access to the object. The method and system is further arranged for using two illumination light beams (30A-B) for measuring vibrations in the object (12) in a third direction, which third direction is out-of-plane direction, where one illumination light beam (30A) is illuminating the object (12) through an imaging objective (16) and one illumination light beam (30B) is used as reference beam.

Abstract: A interferometer apparatus for studying the surface of an object, the apparatus comprising a source producing an object beam of coherent light, a source producing a reference beam which is coherent with the object beam, and a detector or a plurality of detectors arranged in a line or array, wherein the apparatus is arranged such that the object beam is diverging or substantially collimated, and wherein, in use the diverging or substantially collimated object beam is directed towards the surface of the object to produce a reflected object beam reflected from the surface of the object, the detector(s) is/are focused to a point beneath the surface of the object, and the reflected object beam is combined with the reference beam and detected by the detector(s). Also provided is a corresponding method for conducting an interferometric study of the surface of an object.

Abstract: A method and apparatus for carrying out a seismic exploration. A seismic event is applied to the earth's surface, particles at the earth's surface move in response to the event and the response to the event is detected using an interferometer. The earth's surface and the interferometer move with respect to each other. The detectors of the interferometer may be arranged in an array. The detected response may be analyze.

Abstract: A interferometer apparatus for studying the surface of an object, the apparatus comprising a source producing an object beam of coherent light, a source producing a reference beam which is coherent with the object beam, and a detector or a plurality of detectors arranged in a line or array, wherein the apparatus is arranged such that the object beam is diverging or substantially collimated, and wherein, in use the diverging or substantially collimated object beam is directed towards the surface of the object to produce a reflected object beam reflected from the surface of the object, the detector(s) is/are focused to a point beneath the surface of the object, and the reflected object beam is combined with the reference beam and detected by the detector(s). Also provided is a corresponding method for conducting an interferometric study of the surface of an object.

Abstract: A method of studying a surface using an interferometer, in which there is relative motion between the surface and the interferometer, the motion having a total velocity Vtot which includes a transversal or traversing component Vt and a longitudinal component Vl.

Abstract: An instrument for studying an object (12) comprising a movable interferometer having a laser source and a plurality of detectors (24) arranged in an array. The laser source is expanded and arranged to direct a converging object beam (21) towards a point (22) or line beyond the object (12) whereby a speckle pattern of light reflected from the object (12) is detected by the detector or detector array (24). The point (12) or line at which the laser source is arranged to converge the object beam (21) is approximately the same distance beyond the object (12) as the object is spaced from the source. The speed of movement of the instrument, the sampling rate of the detectors (24) and size of the area (23) of the object illuminated by the converging laser object beam (21) are arranged so that sequential areas (23) of the object (12) studied overlap.

Abstract: A method and apparatus for carrying our seismic exploration which comprises generating a seismic event; applying the seismic event to the earth's surface; detecting a response to the event, using an interferometer, in which there is relative motion between the earth's surface and the interferometer, the detected response including P-waves and S-waves in the earth's surface; and analysing the detected response; and in which: the detecting step comprises monitoring and recording the response to the seismic event in the form of movements of particles at the earth's surface, from a position spaced from the earth's surface, the detecting step being carried out over a response period, the response period being a predetermined period of time after the seismic event; and the analysing step comprises analysing the movements of particles at the earth's surface in the recorded response to the seismic event during the response period; the said relative motion having a total velocity Vtot which includes a transversal or t

Abstract: A method of studying a surface using an interferometer, in which there is relative motion between the surface and the interferometer, the motion having a total velocity Vtot which includes a transversal or traversing component Vt and a longitudinal component Vl.

Abstract: An instrument for studying an object (12) comprising a movable interferometer having a laser source and a plurality of detectors (24) arranged in an array. The laser source is expanded and arranged to direct a converging object beam (21) towards a point (22) or line beyond the object (12) whereby a speckle pattern of light reflected from the object (12) is detected by the detector or detector array (24). The point (12) or line at which the laser source is arranged to converge the object beam (21) is approximately the same distance beyond the object (12) as the object is spaced from the source. The speed of movement of the instrument, the sampling rate of the detectors (24) and size of the area (23) of the object illuminated by the converging laser object beam (21) are arranged so that sequential areas (23) of the object (12) studied overlap.

Abstract: A Method for measuring vibrations in small and microscopic objects is disclosed. The method includes the steps of vibrating the object at a frequency, illuminating the object with a light source which is phase modulated at the same frequency, collecting data from a detector array, operating an algorithm to calculate the size of interference modulation between the light waves, operating an algorithm based on multiple calculation of the modulation at different vibration phases between the excitation of the object on one hand, and the reference phase modulation on the other, and operating an algorithm based on use of the result from the calculation of the second modulation, calculating amplitude values and phase values for the vibration of the surface of the object.

Abstract: Method for measuring vibrations in small and microscopic objects, The method comprises use of a calculation algorithm with the collection of more data sets or data images from a detector array, such that these data sets or data images are used to calculate the size of the interference modulation between the interfering light waves, while the object at the same time is vibrated at a frequency, and while a reference light or object light at the same time is phase modulated at the same frequency. Furthermore, use of a calculation algorithm based on that the said calculation of the modulation is done several times at a different vibration phase between the excitation of the object on one hand and reference modulation or the phase modulation of the object light on the other hand. Finally, the method comprises use of a calculation algorithm based on use of the results from the said calculation of the modulation to calculate amplitude values and phase values for the vibration of the surface of the object.

Abstract: Continuously cast metal billets are continuously passed by a symmetric light source comprising a plurality of single light sources arranged in a circle or in another way such that the light falls substantially symmetrically on the part of the surface of the metal billet which is to be detected in such a way that the surface of the metal billet which faces the light source is illuminated except for pinholes. Reflected light from the surface of the billet is detected by a linescan camera arranged centrally in relation to the light source, which camera has a scanning direction normal to the direction of movement of the metal billet, whereby pinholes are detected by registration of reflected light intensity below a preset threshold value.