Co-linear common-path shearography with a zero-approaching shear amount and separate control of the spatial carrier for single-shot phase measurement.

A co-linear common-path shearography is proposed with spatial phase shift for single-shot phase measurement. The co-linear common-path configuration brings an enhanced robustness and stability of the measuring system, because the two laterally sheared interfering object waves propagate essentially along the same path, which cancels out the disturbance and noise in surroundings. Two functional features, which break through the limitations in conventional co-linear common-path shearography, are proposed and implemented, namely the zero-approaching shear amount and the separate control of the spatial carrier. Seldom shearography configured by co-linear common-path structure possesses with these two features, because the linearly aligned optics restricts the control parameters in regards to the shear amount and the spatial carrier. In the proposed scheme, an intermediate real image plane is created in the linearly aligned light path to address the issue of zero-approaching shear amount. A 4-f imaging system is embedded with an aperture in between to implement a separate control of the spatial carrier. The zero-approaching shear amount provides the sufficiently small shear to make sure the strain or slope field of complex deformation is resolvable. Meanwhile, the separate control of the spatial carrier further guarantees a well-distributed spatial frequency spectrum when the required zero-approaching shear amount is configured.

Crystal facets engineering and rGO hybridizing for synergistic enhancement of photocatalytic activity of nickel disulfide.

Crystal facets engineering and graphene hybridizing have been proved to be effective means to improve the photocatalytic activities of semiconductor photocatalysts in recent years. However, most of these efforts are concentrated in metal oxides. In the present study, crystal facets effect on the photocatalytic activity of metal sulfide NiS2 was studied for the first time. It was found that the {111}-faceted NiS2 nanocrystals showed improved photocatalytic activity in the degradation of various typical pollutants in water compared with {100}-faceted NiS2 nanocrystals. Moreover, through hybridizing with rGO nanosheets, the photocatalytic activity of the {111}-faceted NiS2 nanocrystals can be further improved, resulting in the complete degradation of heavy metal hexavalent chromium and organic dyes. The photocatalytic mechanism was studied in detail through theory calculation and experimental characterization. It was found that both the surface energies of Ni-terminated and S-terminated {111} facets were much higher than that of {100} facets, indicating that {111} facets were more active. Besides, rGO hybridizing can realize the effective separation of photogenerated electrons and holes. The results provide important guidance for the further development of efficient metal sulfide photocatalysts.