Topic
Pulse duration
About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.
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Patent•
06 Dec 1982
TL;DR: In this article, a servomechanism regeneratively controls motion by a brushless coreless axial-field motor, exerting torque via its permanent magnet disk rotor, resulting from synchronized polyphase sinusoidal stator currents, controlled by a switching controller responsive to input commands and to Hall-effect transducer signals that vary sinusoidally with rotor angle and respectively correspond to stator phases.
Abstract: A servomechanism regeneratively controls motion by a brushless coreless axial-field motor, exerting torque thru its permanent-magnet disk rotor, resulting from synchronized polyphase sinusoidal stator currents, controlled by a switching controller responsive to input commands and to Hall-effect transducer signals that vary sinusoidally with rotor angle and respectively correspond to stator phases. The controller operates with a dc power source and sink. Its signal processors derive from the transducer signals instantaneous magnitudes and polarities thereof and continuous lagless speed feedback. The instantaneous magnitudes are multiplied by a torque amplitude signal to provide respective synchronized amplitude control signals. Current transformers having primary windings in series with power switching transistors provide current feedback pulses with amplitude proportional to instaneous current in associated stator windings. Pulse control means initiate bi-phase pulses having restricted duty-cycle, and dictate pulse duration by comparing each current feedback pulse with the associated synchronized amplitude control signal. Switching logic responsive to the bi-phase pulses, to forward and reverse drive and brake commands, and to said polarities, accordingly controls selection and duty-cycle of said power switching transistors which, cooperative with free-wheeling diodes and inductors, effect controlled alternating stator currents. Various signal interface means process the input commands with feedback derived from the transducer signals, such as speed, direction of rotation, and interpolated digital position, to provide said torque amplitude signal, and variously, said drive and brake commands; so the motor and controller constitute a complete servomechanism, that provides precise speed and position control with regenerative reversing and braking, ultra-high efficiency, and fast dynamic response.
65 citations
TL;DR: In this paper, a high energy, tunable nanosecond laser system in the region of 6 μm is introduced, which is ideally suited to record IR spectra in the regions of C O stretching and NH bending vibrations.
65 citations
TL;DR: In this article, the emission spectra of laser-ablated Cu atoms in water were examined, focusing on the irradiation-pulse duration effects, and the spectral line profile was observed for the pulse duration of 19, 90, and 150 ns at various delay times.
65 citations
TL;DR: In this paper, the profile of single mode fibers over a flame generates tapered fibers with waist diameters of approximately 1-3 micrometers and waist lengths of up to 90 mm.
Abstract: Drawing single mode fibers over a flame generates tapered fibers with waist diameters of approximately 1–3 micrometers and waist lengths of up to 90 mm. We demonstrate how the profile of such tapered fibers can be determined. We then characterize the white light that is generated in a variety of such fibers, showing its dependence on waist length and waist diameter and demonstrating its dependence on pulse parameters such as pulse duration, spectral position, and pulse power. A comparison with theoretical calculations using a nonlinear Schrodinger equation model including Kerr nonlinearities is given. Furthermore, we show XFROG spectrograms of the pulses propagating through tapered fibers, confirming the model of soliton splitting in the anomalous dispersion regime.
65 citations
TL;DR: In this paper, the authors studied the effect of the laser-pulse duration on the thickness of polycrystalline diamond surface and showed that the diamond graphitisation during multipulse laser ablation is a thermally stimulated process, and the dependence of the diamond-ablation rates on the radiation energy density under the action of laser pulses of various durations.
Abstract: Processes of graphitisation of laser-irradiated polycrystalline diamond surface exposed to multipulse irradiation are studied experimentally. The thickness of the laser-modified layer as a function of the laser-pulse duration ranging from 100 fs to 1.5 μs and the effect of the radiation wavelength on this thickness are studied. It is shown that the diamond graphitisation during multipulse laser ablation is a thermally stimulated process. The dependences of the diamond-ablation rates on the radiation energy density under the action of laser pulses of various durations are presented.
65 citations