Depicting the multimode laser beam by modal decomposition can potentially assess light field variations in the fiber, during propagation. The practical engineering conditions in the lab however could not realize ideal levels, hence further research on factors influencing this method, such as defocus, is especially necessitated. The grid spacing in observation plane by Fast Fourier Transform is fixed and unchangeable within diffraction imaging, hence possibly yielding erroneous data during obtaining light field intensities. Our research resolves these issues via a Two-step ABCD algorithm, applied in the modal decomposition to characterize various guided modes at the output of multimode fibers. A direct benefit is that the image plane size can be altered, further refining laser facula clarity. Furthermore, the quantitative expressions that analyze defocus factors impacting modal decomposition are acquired. The conclusions thereby prove the modal decomposition algorithm can keep effectiveness in the range of −0.25% to 0.25% of relative defocus for low order eigenmodes, having no suitable limited band for high order eigenmodes, with reference value in engineering applications.
The multi-interface transport card is designed for equipments with different interfaces, which could realize the functions such as twisted pair transmission with LVDS level, optical-fiber transmission with LVPECL level and twisted pair transmission with RS422 level. This design can test the equipment which has the appropriate interface with the appropriate transmission mode. In the twisted pair transmission with LVDS level and optical-fiber transmission with LVPECL level, the design use pre-emphasis driver and receiver equalization to improve the long-distance transmission capacity of LVDS data. In twisted pair transmission with RS422 level, the design takes the 4-channel interface chip in both transmitter port and receiver port, so as to increase the number of transmission port.
A passive acoustic localization method is proposed to estimate the position and bearing of a moving target whose acoustic energy emissions are received by a ground-based array field. The basic array of this array field is a particular type of planar array consisting of two orthogonally orientated linear subarrays with a common sensor at the center. This technology overcomes the ambiguity of linear array localization. We also discuss error factors related to the localization. In contrast to other array configuration, the configuration we proposed is simple and fast in computation and has high accuracy in estimating target range and bearing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.