By introducing noncanonical vortex pairs to partially coherent beams, spatial correlation singularity (SCS) and orbital angular momenta (OAM) of the resulting beams are studied using the Fraunhofer diffraction integra...By introducing noncanonical vortex pairs to partially coherent beams, spatial correlation singularity (SCS) and orbital angular momenta (OAM) of the resulting beams are studied using the Fraunhofer diffraction integral. The effect of noncanonical strength, off-axis distance and vortex sign on spatial correlation singularities in far field is stressed. Furthermore, far-field OAM spectra and densities are also investigated, and the OAM detection and crosstalk probabilities are discussed. The results show that the number of dislocations of SCS always equals the sum of absolute values of topological charges for canonical or noncanonical vortex pairs. Although the sum of the product of each OAM mode and its power weight equals the algebraic sum of topological charges for canonical vortex pairs, the relationship no longer holds in the noncanonical case except for opposite-charge vortex pairs. The changes of off-axis distance, noncanonical strength or coherence length can lead to a more dominant power in adjacent mode than that in center detection mode, which also indicates that crosstalk probabilities of adjacent modes exceed the center detection probability. This work may provide potential applications in OAM-based optical communication, imaging, sensing and computing.展开更多
The basic principles of the partial and multiple coherence ananlysis and their utilization on vibration source identification are discussed in detail in this paper. The partial coherence analysis is the effective meth...The basic principles of the partial and multiple coherence ananlysis and their utilization on vibration source identification are discussed in detail in this paper. The partial coherence analysis is the effective method of vibration source identification in multiple input single output systems.Formerly, there was not any this kind of function in the signal processor, and there was not any special software too. The software which we developed and used in the 7T 17S signal processor has this function. This software can be used not only for the partial and multiple coherence analysis of signal, but also for the correlation analysis, power spectrum analysis, transfer function analysis et al.We used this software to make the identifcation of the vibration source of the car floor board of electrical measuring vehicle, and to find the main factors which effect the vibration of the car board.The excellent result was obtained. This method can also be used for making the identifications of noise source and other sources.展开更多
文摘By introducing noncanonical vortex pairs to partially coherent beams, spatial correlation singularity (SCS) and orbital angular momenta (OAM) of the resulting beams are studied using the Fraunhofer diffraction integral. The effect of noncanonical strength, off-axis distance and vortex sign on spatial correlation singularities in far field is stressed. Furthermore, far-field OAM spectra and densities are also investigated, and the OAM detection and crosstalk probabilities are discussed. The results show that the number of dislocations of SCS always equals the sum of absolute values of topological charges for canonical or noncanonical vortex pairs. Although the sum of the product of each OAM mode and its power weight equals the algebraic sum of topological charges for canonical vortex pairs, the relationship no longer holds in the noncanonical case except for opposite-charge vortex pairs. The changes of off-axis distance, noncanonical strength or coherence length can lead to a more dominant power in adjacent mode than that in center detection mode, which also indicates that crosstalk probabilities of adjacent modes exceed the center detection probability. This work may provide potential applications in OAM-based optical communication, imaging, sensing and computing.
文摘The basic principles of the partial and multiple coherence ananlysis and their utilization on vibration source identification are discussed in detail in this paper. The partial coherence analysis is the effective method of vibration source identification in multiple input single output systems.Formerly, there was not any this kind of function in the signal processor, and there was not any special software too. The software which we developed and used in the 7T 17S signal processor has this function. This software can be used not only for the partial and multiple coherence analysis of signal, but also for the correlation analysis, power spectrum analysis, transfer function analysis et al.We used this software to make the identifcation of the vibration source of the car floor board of electrical measuring vehicle, and to find the main factors which effect the vibration of the car board.The excellent result was obtained. This method can also be used for making the identifications of noise source and other sources.
