The present invention relates to a method of observing a changing surface by means of laser interferometry, in particular by means of laser speckle interferometry, wherein the changing surface is preferably a surface of a tube and the method is used to determine the pressure in the tube. A further aspect of the invention relates to a corresponding apparatus.

[PROBLEM] To provide a defect detection device capable of detecting not only a defect within a visible range but also a defect outside the visible range among the objects to be inspected. [SOLUTION] A defect detection device 10 includes: an excitation source 11 capable of being placed at any position on a surface of an inspection target object S, the excitation source 11 being configured to excite an elastic wave within the inspection target object S, the elastic wave being predominant in one vibration mode and propagating in a predetermined direction; an illumination unit (pulsed laser light source 13, illumination light lens 14) configured to perform stroboscopic illumination on an illumination area of the surface of the inspection target object by using a laser light source; a displacement measurement unit (speckle shearing interferometer 15) configured to collectively measure a displacement of each point in a front-back direction within the illumination area in at least three different phases of the elastic wave, by speckle interferometry or speckle shearing interferometry; and a reflected wave/scattered wave detector 16 configured to detect either one or both of a reflected wave and a scattered wave of the elastic wave, based on the displacement measured by the displacement measurement unit.

A shearography a system and method for regularizing phase resolved shearograms with an arctan regularization function to produce regularized phase resolved shearogram outputs is provided. The system and method of the present disclosure optimizes the processing of phase resolved shearography allowing interference fringe analysis techniques to be applied to the regularized phase resolved shearogram output results of the processing.

Surface changes are estimated using multiple speckle interferograms acquired using beams incident at different angles. Beam irradiation conditions can be changed to increase signal to noise ratio with averaging, such as weighted averaging. Irradiation conditions can be varied with a tilt plate, a wedge, or by changing beam wavelengths.

A defect detection device 10 includes: an excitation source 11 capable of being placed at any position on a surface of an inspection target object S, the excitation source 11 being configured to excite an elastic wave within the inspection target object S, the elastic wave being predominant in one vibration mode and propagating in a predetermined direction; an illumination unit (pulsed laser light source 13, illumination light lens 14) configured to perform stroboscopic illumination on an illumination area of the surface of the inspection target object by using a laser light source; a displacement measurement unit (speckle shearing interferometer 15) configured to collectively measure a displacement of each point in a front-back direction within the illumination area in at least three different phases of the elastic wave, by speckle interferometry or speckle shearing interferometry; and a reflected wave/scattered wave detector 16 configured to detect either one or both of a reflected wave and a scattered wave of the elastic wave, based on the displacement measured by the displacement measurement unit.

A vibration measurement device 10 includes an excitation unit (signal generator 11 and vibrator 12) for exciting an elastic wave to an inspection target S, an illumination unit (wavelength stabilized laser beam source 13 and illumination light lens 14) for performing stroboscopic illumination to a measurement region of a surface of the inspection target S using a wavelength stabilized laser beam source 13, a displacement measurement unit (speckle-sharing interferometer 15) for collectively measuring a displacement of each point of the measurement region in the back-and-forth direction by speckle interferometry or speckle-sharing interferometer. By using the wavelength stabilized laser beam source 13, an interference image can be obtained even when the inspection target S has large surface irregularities.

A system for use in inspection of a sample is described, the system comprises: an illumination unit configured to provide coherent illumination comprising a plurality of at least two wavelengths and direct said coherent illumination onto an inspection region of a sample; and a collection unit comprising at least one detector array and configured for collecting light returning from said inspection region and generate data indicative of speckle patterns in said plurality of at least two wavelengths at a predetermined sampling rate, wherein said illumination unit is configured for directing light components of said at least two wavelengths toward corresponding two or more segments of said inspection region, and wherein said data indicative of speckle patterns corresponding with said two or more segments.

A laser transmission apparatus utilizing multiple laser beams and beam paths with a diverger lens to provide an illumination pattern that can compensate for lateral movement of the platform during shearography is provided. Further, this optical setup requires no moving parts and does not reduce power of the laser beams as they move through the individual components thereof. From the perspective of the surface being scanned or inspected, the present disclosure may provide two laser images of a single surface that appear to be identical despite the fact that they were taken from two different spatial positions of the moving platform.

A laser shearography testing system for non-destructively testing a component includes a component heating sub-system coupled to the component. The component heating sub-system excites the component into a loaded state by passing an electric current through the component. A resistivity of the component causes the component to internally and uniformly heat as the electric current passes through the component.

A laser shearography testing system for non-destructively testing a component includes a component heating sub-system coupled to the component. The component heating sub-system excites the component into a loaded state by passing an electric current through the component. A resistivity of the component causes the component to internally and uniformly heat as the electric current passes through the component.