Abstract: The disclosure includes a system for photoacoustic inspection of an object. The system includes a broadband emission source configured to generate an emission beam, a direction apparatus including at least one spectrum splitter configured to split the emission beam into at least a first and a second component, the direction apparatus being configured to sequentially direct the respective components to N respective locations on the object at N times to generate N respective acoustic waves within the object. The N respective locations and N times are such that the respective N acoustic waves at least semi-constructively interfere to generate a respective propagating acoustic wave within the object. The system also includes a vibration sensing system configured to detect said respective propagating acoustic waves at a respective detection location on the object.

Abstract: A crystal is of a non-centrosymmetric structure and belongs to the ?43 m point group of the cubic crystal system. M denotes an alkaline earth metal, which can be Ba, Ca, or Sr, and RE denotes a rare earth element, which can be Y, La, Gd, or Yb. The growth method of the M3RE(PO4)3 crystal comprises steps as follows: (1) polycrystalline material synthesis: MCO3, RE2O3, and phosphorous compound are used as raw materials and blended according to the stoichiometric proportions; then, the phosphorous compound is further added to be excessive; the raw materials are sintered twice to obtain the M3RE(PO4)3 polycrystalline material; (2) polycrystalline material melting; (3) Czochralski crystal growth. The M3RE(PO4)3 crystal prepared by the invention is a high-quality single crystal.

Abstract: Example embodiments relate to phase difference detection systems and method for detecting phase difference. One embodiment includes a phase difference detection system for a single target location. The system includes a laser source to generate a laser beam. The system also includes a phase difference detector coupled to the laser source and having a multi-layer structure. The phase difference detector includes a planar waveguide for guiding the laser beam. The phase difference detector also includes a grating coupler to split the laser beam into a reference beam and a measurement beam. Additionally, the phase detector includes a planar imager array forming a second layer of the multi-layer structure. Further, the phase difference detector includes an optical system configured to focus the measurement beam output from the phase difference detector on the single target location and to focus signals reflected at the target location to the phase difference detector.

Abstract: Example embodiments relate to photonic integrated circuits (PICs) and three-dimensional (3D) laser Doppler vibrometers (LDVs) including the same. One embodiment includes a PIC for a 3D LDV. The PIC includes a splitter to split a laser beam into a measurement signal and a reference signal. The PIC also includes a phase-amplitude modulator array coupled to a transmitting array to generate, from the measurement signal, n output signals to be directed to a single target location and output from substantially a single location. Each output signal has a different direction and carrier frequency. The PIC further includes a receiving array having m receiving antennas. Each receiving antenna is configured to receive a reflection signal from a different receiving direction. Each reflection signal is indicative of the output signals reflected at the single target location. M and N are natural numbers greater than or equal to three.

Abstract: Described herein is a method and system for mitigating the effects of speckle in a laser Doppler system, and, in particular in a laser Doppler vibrometry/velocimetry system. A scan unit is provided in at least one of: a transmit path for scanning at least one beam from a transmitting antenna over a moving target surface and a receive path for scanning at least one reflected beam received from the moving target surface onto a receiving antenna. An averaging unit is provided prior to post-processing or demodulation to average electrical signals corresponding to the reflected beams. By averaging before demodulation, speckle in the output signal is mitigated.

Abstract: Described herein is a method and system for mitigating the effects of speckle in a laser Doppler system, and, in particular in a laser Doppler vibrometry/velocimetry system. A scan unit is provided in at least one of: a transmit path for scanning at least one beam from a transmitting antenna over a moving target surface and a receive path for scanning at least one reflected beam received from the moving target surface onto a receiving antenna. An averaging unit is provided prior to post-processing or demodulation to average electrical signals corresponding to the reflected beams. By averaging before demodulation, speckle in the output signal is mitigated.

Abstract: A photonic integrated device comprises a waveguide embedded in a photonic substrate. The waveguide has a waveguide radiation exit surface and the waveguide is optically connected to a two dimensional grating. The photonic integrated device also comprises a two dimensional grating having a plurality of curved elongate scattering elements. The two dimensional grating is adapted for diffracting radiation received from the waveguide toward a direction out of the photonic substrate and the curved elongate scattering elements are oriented with respect to the waveguide such that, for points of the scattering elements which can be irradiated by radiations stemming from the waveguide, normal lines to at least the curved elongate scattering element closest to the waveguide radiation exit surface do not substantially intersect with the waveguide radiation exit surface of the waveguide.

Abstract: A photonic integrated device comprises a waveguide embedded in a photonic substrate. The waveguide has a waveguide radiation exit surface and the waveguide is optically connected to a two dimensional grating. The photonic integrated device also comprises a two dimensional grating having a plurality of curved elongate scattering elements. The two dimensional grating is adapted for diffracting radiation received from the waveguide toward a direction out of the photonic substrate and the curved elongate scattering elements are oriented with respect to the waveguide such that, for points of the scattering elements which can be irradiated by radiations stemming from the waveguide, normal lines to at least the curved elongate scattering element closest to the waveguide radiation exit surface do not substantially intersect with the waveguide radiation exit surface of the waveguide.