Ramsey Robinson (skillvise93)

Application of this approach toward fuel-rich methane-nitrogen-oxygen flames is also demonstrated.Two novel waveguide gratings for optical phased array transmitters are investigated. By offsetting the grating structures along the waveguide on the upper and lower surfaces of the silicon nitride (Si3N4) waveguide, the dual-level chain and dual-level fishbone structures can achieve 95% of unidirectional radiation with a single Si3N4 layer by design. With apodized perturbation along the gratings, both structures can achieve uniform radiation without compromising the unidirectional radiation performance. In experiment, both demonstrate ∼ 80-90% unidirectionality. With further analysis, it is found that the dual-level fishbone structure is more feasible and robust to process variations in uniform radiation.In this paper, we present a polarization spatial phase-shifting method for fringe projection profilometry. It enables us to measure the three-dimensional shape of a metal object in a fast way requiring only a single-shot implementation. With this method, a couple of projectors are equipped, in front of their lens, with linear polarization filters having orthogonal polarization directions, so that they can simultaneously cast two sinusoidal fringe patterns having different phase shifts onto the measured metal surfaces without mixture. To register the two projected patterns, we suggest a fringe alignment method based on the epipolar geometry between the projectors. By taking advantage of the property of metal surfaces in maintaining polarization state of incident light, the deformed fringe patterns on the measured surfaces are captured by using two coaxially-arranged polarization cameras. As a result, the fringe phases are calculated by using a two-step phase-shifting algorithm and further the 3D shapes of the measured surfaces are reconstructed. Experimental results demonstrate the proposed method to be valid and efficient in measuring metal objects.Compression, shaping and characterization of broadband mid-infrared (MIR) pulses based on an acousto-optic modulator (AOM) pulse shaper is presented. Characterization of the spectral phase is achieved by an AOM-shaper based implementation of a dispersion scan (d-scan). The abilities of the setup are demonstrated by imprinting several test phases with increasing complexity on broadband MIR pulses centered at 3.2 µm and retrieval of the imprinted phases with the presented d-scan method. Phase characterization with d-scan in combination with an evolutionary algorithm allows us to compress the MIR pulses below 50 fs FWHM autocorrelation after the shaper.Attitude jitter causes image motion and degrades geometric accuracy of high-resolution satellite images. This work studies the mechanism of the attitude jitter effect on the imaging geometry of three-line-array push-broom sensors onboard satellites, which is a typical configuration used for topographic mapping. Based on a rigorous physical imaging model, we derived quantitative models of the geometric effect of attitude jitter in the roll, pitch, and yaw angles on the image distortions of the forward, nadir, and backward view sensors, and the accuracy of the derived models is validated through comprehensive experiments and analyses. The experimental results reveal the following. First, the attitude jitter in the roll angle dominates the cross-track image deviation; it does not affect the along-track geometry of the nadir-view sensor but marginally affects the off-nadir-view sensors, and the image distortions share a linear relationship with the image column coordinates. Second, the attitude jitter in the pitch angle dominates the along-track image deviation, and the image distortions in the off-nadir-view images are relatively larger than those in the nadir-view images. The attitude jitter in the pitch angle does not affect the cross-track geometry of the nadir-view sensor but marginally affects the off-nadir-view sensors, and the image di