Disclosed are a device and method for detecting a subsurface defect of an optical component. According to the device and method, a spectral confocal technology, a laser scattering technology and a laser-induced ultrasonic technology are combined, excitation laser and detection laser are simultaneously focused to different depths of the optical component through a dispersion lens set, the excitation laser generates a transient thermal expansion effect on a subsurface of the optical component, the detection laser is used for observing and analyzing ultrasonic vibration of the subsurface defect under an action of the thermal expansion effect, and spatial distribution information and scattered spectral information of scattered light at a position of the subsurface defect are acquired by the spectral confocal technology. The device and method are suitable for nondestructive testing of a finished product of an ultra-precise optical component with a strict requirement on the subsurface defect.

A measuring device for non-mechanical-contact measurement of a layer, the measuring device including a light source operative to generate a pulse adapted to interact with the layer so as to generate a thermal wave in a gas medium present adjacent the layer. The thermal wave causes an acoustic signal to be generated. The measuring device further includes a detector adapted to detect a first signal responsive to the acoustic signal, the detector not being in mechanical contact with the layer. The first signal is representative of the measured layer.

A photoacoustic remote sensing system for imaging a subsurface structure in a sample, comprising exactly one laser source configured to generate a pulsed or intensity-modulated excitation beam configured to generate ultrasonic pressure signals in the sample at an excitation location, and an interrogation beam incident on the sample at the excitation location, a portion of the interrogation beam returning from the sample that is indicative of the generated ultrasonic pressure signals, an optical system configured to focus the excitation beam and the interrogation beam below a surface of the sample, a detector configured to detect the returning portion of the interrogation beam, and a processor configured to calculate an image of the sample based on a detected intensity modulation of the returning portion of the interrogation beam from below the surface of the sample.

In a defect detection device (10), an input receiver (161) receives an input, by a user, of information concerning the kind and size of a defect expected to be present in or on a test object. An exciter (11, 12) induces an elastic wave in the test object, with the frequency of the elastic wave being variable. A measurer (15) optically measures a vibration state of the surface of the test object caused by the elastic wave. A wavelength determiner (164) determines the wavelength of the elastic wave induced in the test object, based on the vibration state obtained by the measurer. A frequency selector (165) selects an appropriate frequency from a plurality of frequencies, based on the kind and size of the expected defect as well as the wavelength acquired for each of the plurality of frequencies by the wavelength determiner by varying the frequency of the elastic wave.

A photoacoustic remote sensing system for imaging a subsurface structure in a sample, comprising exactly one laser source configured to generate a pulsed or intensity-modulated excitation beam configured to generate ultrasonic pressure signals in the sample at an excitation location, and an interrogation beam incident on the sample at the excitation location, a portion of the interrogation beam returning from the sample that is indicative of the generated ultrasonic pressure signals, an optical system configured to focus the excitation beam and the interrogation beam below a surface of the sample, a detector configured to detect the returning portion of the interrogation beam, and a processor configured to calculate an image of the sample based on a detected intensity modulation of the returning portion of the interrogation beam from below the surface of the sample.

A method and a system for photoacoustic inspection of a part are provided herein. The method may include the following steps: photo-acoustically exciting a predetermined position in a predetermined region on a part by pulsed laser illumination, to yield ultrasonic excitation of the part; coherently illuminating a predetermined location in the predetermined region on the part; detecting an illumination scattered from the predetermined location; determining, based on the scattered illumination, a plurality of sequence of two or more temporally-sequential de-focused speckle pattern images, wherein each of the sequences corresponds to one of the predetermined illuminated locations; and determining a set of translations, each determined based on the sequences, wherein each translation in the set is determined based on two temporally-sequential speckle patterns images in the respective sequence.

A vibrometer may measure acoustic responses in portions of a structure along a scan path to acoustic excitation of the structure. A ranging device may measure distances to the portions of the structure along the scan path. A three-dimensional point cloud may be generated based on the acoustic responses in the portions of the structure and the distances to the portions of the structure. The three-dimensional point cloud may include points representing geometry of the portions of the structure. The points may be associated with the acoustic responses in corresponding portions of the structure. One or more properties of the structure may be determined based on an analysis of the three-dimensional point cloud.

Multifocal photoacoustic imaging systems and methods that implement an ergodic relay to encode photoacoustic signals detected from a plurality of illuminated optical foci regions.

A method and a system for illuminating a substrate, the system may include an acousto-optic device (AOD); and an etendue expanding optical module. The AOD may include a surface having an illuminated region; wherein the illuminated region is configured to receive a collimated input beam while being fed with a control signal that causes the illuminated region to output illuminated region output beams that are collimated and exhibit deflection angles that scan, during a scan period, a deflection angular range. The etendue expanding optical module is configured to convert the illuminated region output beams to collimated output beams that impinge on an output aperture; wherein a collimated output beam has a width that exceeds a width of an illuminated region output beam; and wherein the etendue expanding optical module comprises a Dammann grating that is configured to output diffraction patterns, each diffraction pattern comprises diffraction orders that cover a continuous angular range.

A photoacoustic apparatus includes a light source configured to generate a plurality of pulsed lights in different wavelengths, an irradiation optical system configured to irradiate an object with the pulsed light from the light source and configured to irradiate the object in different irradiation positions along a rotational trajectory during a rotational scanning period in a corresponding wavelength, and a probe configured to receive photoacoustic wave from the object in response to each pulsed light irradiation in the different irradiation positions and to convert the received photoacoustic wave into an electric signal. The irradiation optical system is moved to irradiate the object with a first wavelength in a plurality of times during a first rotational scanning period and irradiate the object with a second wavelength in a plurality of times during a second rotational scanning period after the first rotational scanning period.