Oscilloscope Traces Research Articles

Characterization of soliton compounds in a passively mode-locked high power fiber laser

We characterize soliton complexes in a high power double-clad erbium-doped fiber laser passively mode-locked through nonlinear polarization evolution. Such complexes involve some hundreds of solitons and form self-organized or disorganized patterns analogous to the states of the matter. Experimentally these soliton compounds are characterized through the autocorrelation trace, the optical spectrum and the oscilloscope trace which is limited due to its finite bandwidth. We perform here a reconstruction of the experimental results thus allowing us to identify the temporal distribution of the solitons inside the cavity. The reconstruction allows us to clarify and either to confirm or to correct the former intuitive interpretation. Especially, a soliton ‘spray’ is identified.

The First Half‐Century of Laser Development

AbstractThe laser was born on May 16, 1960 at Hughes Research Laboratories in Malibu, California. Instead of enjoying the view of the Pacific from his new office window, Theodore Maiman closeted himself in a windowless lab, where he slipped a spring‐shaped photographic flashlamp over a stubby ruby rod, then put the assembly inside a reflective cylinder. Firing pulses with higher and higher voltage through the lamp, he carefully studied oscilloscope traces of the rise and fall of the ruby's red fluorescence. Once the voltage exceeded 950 volts, the lamp flashed bright enough to excite the ruby above laser threshold. The red light suddenly flashed so bright that Maiman's colorblind assistant Irnee D'Haenens saw red light for the first time [1]! The instruments recorded what Maiman had predicted would happen above laser threshold – the pulse rose and fell faster, and the range of red wavelengths narrowed. This article provides an overview of the first 50 years of laser development as well as a brief outlook what's coming next.

Hardware implementation of CNN architecture‐based test bed for studying synchronization phenomenon in oscillatory and chaotic networks

AbstractA 3D modular cellular nonlinear network (CNN) architecture‐based test bed, with four‐neighbor connectivity, used to study synchronization phenomena in oscillatory and chaotic networks is designed. The architecture is implemented as hardware panels including a standalone robust Chua's circuit kit. The details of electronic implementation along with several test cases of connecting Chua's circuits in different topologies are provided. Test cases are adequately supported by oscilloscope traces. Copyright © 2008 John Wiley & Sons, Ltd.

VECTOR FIELD DESIGN OF SCREW-TYPE CHAOS

The design of a screw-type chaotic system in [Formula: see text] is presented whereby the dynamical equations are constructed using geometric methods that produce a vector field with the desired properties. We utilize piecewise linear and constant dynamics for simplicity; the piecemeal dynamics are combined using switching functions. An analysis of the system shows invariance and the absence of equilibria — implying the existence of limit cycles and strange attractors; a bifurcation diagram confirms the existence of these behavioral modes and that the system undergoes a period-doubling cascade to chaos. We finally present a hardware realization of this system, and oscilloscope traces showing a chaotic system trajectory.

Multichannel direct sequence spectrum signaling using code phase shift keying

In this paper, we have designed and realized multichannel direct sequence spread spectrum (DSSS) system using code phase shift keying (CPSK). In the transmitter, taking each bit from each channel, data word is made as a symbol for selecting PN sequence, which is modulated with frequency of 100 MHz as DSSS signals. At the receiver, the correlator, integrator and decoder are used for separation of the signal of respective channel after demodulation. Oscilloscope traces show that the transmitted signals are matched with the simulated signals at the receiver. The bit error rate (BER) variation with jamming signal is estimated by our proposed simulation model, matching well with experimental values of BER measured by BER meter.

Psychophysiological aspects of voluntary skilled movement after stroke: a follow-up study.

The aim of the study was to follow the psychophysiological evolution of a self-paced voluntary skilled movement in hemiparetic subjects after ischemic stroke by means of a skilled performance task (SPT). The task consisted in starting a sweep of an oscilloscope trace by pushing one button with the left index finger (trigger point), and in stopping it within a central area on the oscilloscope screen, between 40 and 60 ms (correct performance) after the start of the sweep, by pushing the other button with the right index finger. A SPT yields a considerable amount of information on the electrophysiological components, which reflect pre-programming activity (Bereitschaftspotential--BP), control strategies (Skilled Performance Positivity--SPP) and behavioural response (Correct Performances). The study was also aimed at detecting any longitudinal changes in the psychophysiological pattern, as evaluated by the clinical examination and specific motility scales, that parallel motor recovery. Movement related potentials (MRPs) were recorded in 12 control subjects and 9 patients in the acute phase, before the start of neurorehabilitation (time 0), when the patients were able to execute an index finger press with the affected hand. The patients (mean age = 62.33 years, SD = 8.17) presented a mild to moderate central arm paresis caused by a first-ever unilateral supratentorial and subcortical ischemic lesion. The subsequent recordings were carried out respectively 3, 9 and 12 months later. At the first recording, hemiparetic patients achieved a significantly lower percentage of correct performances and had a lower BP amplitude than controls (p < 0.001); SPP was absent. The number of correct performances did not improve significantly during the subsequent recordings. BP amplitude showed a mild increase in the second, third and fourth recordings (p < 0.05), while SPP amplitude revealed a slight improvement at the second and a marked improvement at the third and fourth recordings, when there was no longer a statistically significant difference from controls. Our findings point to an early recovery of pre-programming activity and a delayed improvement in control activity. The delayed development of control activity in the absence of procedural learning, i.e. skill learning through practice, forces patients to exploit attentional strategies to compensate for their procedural learning impairment. SPT shows that the efficacy of physical therapy aimed at motor ability recovery in hemiparetic patients does not keep up with the slow recovery process of an automatic motor level.

Dead time correction in coincidence counting of photon pairs

We describe two methods for evaluating the dead time of a time-to-amplitude converter (TAC). The dead time is obtained by measuring either the corresponding time interval in an oscilloscope trace or the relation between the single count rate and the coincidence count rate. Values for the TAC dead time are obtained in the range from 3.4 µs to 14.3 µs for the two methods with respective standard uncertainties of 2.9 × 10−8 s and 3.3 × 10−9 s. The TAC dead time is applied to the calibration of coincidence-counting measurements of optical transmission and photon-heralding efficiency.

Source of far and vacuum ultraviolet radiation based on a transverse high-frequency discharge

We present the results of an investigation of a short-wavelength radiation source (Δλ = 130–350 nm) with excitation by a transverse high-frequency (f = 1.76 MHz) discharge based on a mixture of argon and chlorine (p = 100–500 Pa). We have studied the spectral characteristics of the plasma, the oscilloscope traces of the voltage, the current and emission of the discharge, the dependence of the power of the emission on the electrical power of the discharge, and also the pressure and partial composition of the Ar/Cl2 mixture. The UV-VUV source emits in a system of broadened and overlapping ArCl(B/X), Cl2(D′/A′), and Cl**2 molecular bands.

Dynamics of multichannel and quasi-homogeneous sliding discharge formation in rare gases

Results of experiments with Ne, Ar and Xe as well as computer simulations are presented, aimed at testing an earlier proposed model of temporal dynamics of multichannel structure development in a pulsed high-current sliding gas discharge. The obtained and discussed experimental data include the values of an averaged channel radius, the pulsed near-surface breakdown voltage, the saturated spark resistance, the spatial structure of spark channels registered photographically under different discharge voltages and the oscilloscope traces of the discharge gap voltage. The experiments were performed at two values of gas pressure (30 and 100 kPa) with a setup in two modifications which differed from each other by an impedance (27 times) and a stored electric energy (250 times) of a pulsed power supply source. A comparison of the experimental channel structure and the discharge voltage time dependence with those calculated using the discussed model showed good agreement, and this approves an application of the model to quantitative estimations of the sliding discharge parameters. The relation revealed between the channel radii and the square root of mobility of electrons is explained by a drift of electrons in a transverse electric field. Attention is also paid to the problem of stability of a multichannel mode of the sliding discharge. Both experimental data and computer modelling demonstrate that the most stable mode of the discharge is a quasi-homogeneous one, in which the spark channels fill the interelectrode gap entirely. But a certain instability of plasma brightness seems to be an intrinsic feature of the multispark sliding discharge even in its quasi-homogeneous mode, which results from non-simultaneous initiation of the spark channels.

Observation of Q-switching and mode-locking in two-section InAs/InP (100) quantum dot lasers around 1.55 μm

First observation of passive mode-locking in two-section quantum-dot lasers operating at wavelengths around 1.55 mum is reported. Pulse generation at 4.6 GHz from a 9 mm long device is verified by background-free autocorrelation, RF-spectra and real-time oscilloscope traces. The output pulses are stretched in time and heavily up-chirped with a value of 20 ps/nm, contrary to what is normally observed in passively mode-locked semiconductor lasers. The complete output spectrum is shown to be coherent over 10 nm. From a 7 mm long device Q-switching is observed over a large operating regime. The lasers have been realized using a fabrication technology that is compatible with further photonic integration. This makes the laser a promising candidate for e.g. a mode-comb generator in a complex photonic chip.

Nanosecond discharge in air at atmospheric pressure as an x-ray source with high pulse repetition rates

The properties of x-ray radiation and runaway electrons produced using a nanosecond volume discharge are examined. X-ray radiation at a pulse repetition rate of 3kHz was obtained time in a gas diode filled with air at atmospheric pressure. The current pulse width (FWHM) for runaway electrons generated in the gas diode was ∼100ps. A prepulse was observed on an oscilloscope trace of the main runaway electron beam current.

The Emission Characteristics of Laser Plume from the PbGa2S4 Crystal Surface

Averaged spectra and oscilloscope traces of emission of laser plasma in vacuum produced by the impact of neodymium laser radiation (τ = 20 ns, λ = 1.06 µm, f = 12 Hz, W =108–109 W/cm2) on Pb, Ga, and polycrystalline PbGa2S4 targets were studied. From spectroscopic diagnostic data, the electron temperature, the recombination time of singly charged ions, and the number density of electrons in the laser plume of lead gallium sulfide were determined. An analysis of the results is given.

The effects of pulse frequency and substrate bias to the mechanical properties of CrN coatings deposited by pulsed DC magnetron sputtering

The chromium nitride coatings have been prepared by the bipolar symmetric pulsed DC magnetron reactive sputtering process at 2 kHz and 20 kHz pulse frequencies, respectively. Different substrate bias was applied with a pulsed DC bias unit with 50 kHz pulse frequency. Oscilloscope traces of the I– V waveforms indicate high power and high current density outputs during the symmetric bipolar pulsed mode. It is concluded that the (200) orientation of CrN films is observed. The grain size decreases with increasing pulse frequency and substrate bias. The substrate bias has a strong influence on the mechanical properties of CrN films. The scratch tests of the CrN coatings show that almost only tiny chipping failure is occurred. Sufficient adhesion strength quality of the coating is also observed. The substrate bias for the deposition of CrN films with sufficient hardness and adhesion properties combination is − 290 V at 20 kHz and − 408 V at 2 kHz pulse frequency, respectively.

An ultrasonic nondestructive technique for evaluating layer thickness in human teeth

An ultrasonic nondestructive evaluation technique of the layer thickness in human teeth using a leaky Lamb wave device with two arch-shaped interdigital transducers (IDTs) is proposed. Each of the two IDTs on a piezoelectric ceramic plate operates as an input or an output transducer at a plate/water interface, in the configuration of an acoustic delay line of reflected ultrasound beams from the tooth section at the spot under investigation. The use of a higher-order mode, second symmetric (S 2) mode, leaky Lamb wave with a phase velocity higher than the longitudinal wave velocity in the human tooth is essential to enable the oblique incidence of the focused ultrasound beam. The echoes from dentin–pulp and enamel–dentin junctions are similar in the oscilloscope traces. The layer thickness of dentin or enamel for a number of teeth, estimated from the measured time interval between two reflected echoes, from the tooth surface and from the interface in the tooth, is in good agreement with the optically measured data.

A simple laser-heated thermocouple anemometer

A device based on the principle of hot wire anemometry but which employs a fine, laser-heated thermocouple as its sensor, is described. Its steady-state thermal equilibrium as a function of gas stream velocity is analysed theoretically and calibrated experimentally. Transient behaviour is then studied from heating/cooling curves, derived from photographic records of oscilloscope traces, obtained by switching the laser on/off at various flow velocities. This allows calculation of thermal inertia and elucidates its trade off against robustness of the sensor.

The effect of electrical dental equipment on a vagus nerve stimulator’s function

Dental patients who have epilepsy with pharmacologically refractory seizures may be treated with an implanted pulse generator that electrically stimulates the left vagus nerve. The pulse generator functions like a cardiac pacemaker. Some electrical dental devices have been shown to cause electromagnetic interference with the function of cardiac pacemakers. The potential effect of similar dental equipment on vagus nerve stimulators is unknown. Common electrical dental devices were operated at maximum power settings in close proximity to a representative vagus nerve stimulator. The author assessed any interference of the dental devices with the nerve stimulator function by observing oscilloscope tracings. Under the conditions of this evaluation, none of the dental devices tested altered the function of the vagus nerve stimulator. Some commonly used electrical dental devices may be used in close proximity to patients who have implanted vagus nerve stimulators without adverse effects on the nerve stimulator function. Dentists and dental hygienists may encounter patients with implanted vagus nerve stimulators, and they need to be cognizant of developments in the treatment of epilepsy. Under the conditions of this study, use of common dental electrical devices did not alter the function of a vagus nerve stimulator. The findings of this study, however, should not be generalized to all types of electrical dental or medical devices, as a recent report indicates that treatment with diathermy devices is contraindicated for patients with implanted nerve stimulators.

Turbulent plumes of heat, moist heat, and carbon dioxide elicit upwind anemotaxis in tsetse fliesGlossina morsitans morsitansWestwood (Diptera: Glossinidae)

The roles and interactions of turbulent plumes of heat, moist heat, and carbon dioxide in mediating upwind flight of adult tsetse flies (Glossina morsitans morsitans Westwood) were investigated using a wind tunnel in a constant-environment chamber. Heat fluctuations in the plume that were detected by a thermocouple and displayed as oscilloscope traces allowed direct visualization of the structures of the plumes. Significantly more flies flew upwind when exposed to plumes of (i) carbon dioxide (0.0051% above background) and air (58% relative humidity) compared with air alone; (ii) carbon dioxide and heated air (35% relative humidity and temperature fluctuating up to 0.09°C above background) compared with carbon dioxide and air; and (iii) carbon dioxide and moist (82% relative humidity) heated air (temperature fluctuating up to 0.05°C above background) compared with carbon dioxide and heated air. However, there were no significant differences in upwind flight of flies exposed to plumes of (i) air compared with humidified air (65% relative humidity); (ii) carbon dioxide and heated air compared with heated air alone; and (iii) carbon dioxide and moist heated air compared with moist heated air alone. Recorded temperature fluctuations in heat plumes transported downwind from a tethered steer in a pasture showed patterns similar to those produced in the wind-tunnel plumes. These results suggest that host emissions of carbon dioxide alone and combined heat and moisture carried downwind by low-velocity winds elicit upwind anemotaxis in tsetse flies, which distinguish these emissions from a background of lower atmospheric levels.

Optodynamic measurement of a non-stationary temperature field in air bymultiple laser-beam deflection

A new method for non-stationary temperature-field measurement ispresented. Optoacoustic generation is used to emit short acoustic transientswithin the observed field. The transient deflects a probe laser beam, whichis folded by two parallel mirrors in such a way that it passes through theobserved field several times before it reaches a position-sensitivephoto-detector. The timing of the acoustic wavefront transits at severaldistances from the source is obtained from a single oscilloscope trace of thephoto-detector output. By measuring the acoustic wavefront transit times andthe distances between the probe-beam segments, the velocity of sound isdetermined and from this we were able to calculate the local temperature.

Discharge characteristics in a nonchain HF(DF) laser

It is found that for SF6—hydrocarbon (deuterocarbon) mixtures having a composition typical for nonchain HF(DF) lasers, the electric field strength reduced to the partial pressure of SF6 (pSF6) in the quasistationary phase of a volume self-sustained discharge (E/pSF6)st=92 V m-1 Pa-1 is close to the known critical value (E/p)cr=89 V m-1 Pa-1, which is specified by the condition that the electron-impact ionisation rate of SF6 is equal to the rate of electron attachment to SF6 molecules. This testifies to the decisive role of these two processes and allows the use of the known approximations of the effective ionisation coefficient and the electron drift velocity for pure SF6 when calculating the discharge characteristics. The oscilloscope traces of voltage and current calculated in this approximation for lasers with apertures ranging from 4 to 27 cm deviated from the experimental data by no more than 10%.

Application of instrumented impact test for studying dynamic fracture property of 9Cr-1Mo-V-Nb-N steel

Dynamic fracture toughness property of 9Cr-1Mo-V-Nb-N heat-resistant steel was studied over a broad range of temperatures from −196 to 650°C. Results show that reasonable dynamic fracture toughness values of 9Cr-1Mo-V-Nb-N steel can be obtained from instrumented impact test of pre-cracked Charpy specimens, according to the assumption that crack initiation occurs at a load equal to P m +P y /2 . Fractographic observation shows, close correspondence exists between P– D oscilloscope traces and fracture morphology, thus P– D traces can be used to analyse the fracture process of 9Cr-1Mo-V-Nb-N steel.