9,079 research outputs found
Nonlinear imaging through a golden spiral multicore fiber
We report two-photon lensless imaging through a novel golden spiral multicore
fiber. This unique layout optimizes the sidelobe levels, field of view,
cross-talk, group delay and mode density to achieve a sidelobe contrast of
atleast 10.9 dB. We demonstrate experimentally the ability to generate and scan
a focal point with a femtosecond pulse and perform two-photon imaging.Comment: Submitted to Optics Letter
Phased-Array antenna beam squinting related to frequency dependency of delay circuits
Abstract-Practical time delay circuits do not have a perfectly linear phase-frequency characteristic. When these delay circuits are applied in a phased-array system, this frequency dependency shows up as a frequency dependent beam direction (“beam squinting”). This paper quantifies beam squinting for a linear one-dimensional phased array with equally spaced antenna elements. The analysis is based on a (frequency-dependent) linear approximation of the phase transfer function of the delay circuit. The resulting relation turns out to be invariant for cascaded cells. Also a method is presented to design time-delay circuits to meet a maximum phased-array beam squinting requirement
- …