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Showing papers on "Pulse duration published in 1985"


Journal ArticleDOI
TL;DR: It is shown that, for example, a train of unchirped pulses randomly distributed in frequency can have the same interferometric autocorrelation than a single chirped pulse, proof that pulse-to-pulse fluctuations are negligible.
Abstract: The performances of a tunable femtosecond dye laser are analyzed using accurate correlation techniques. The source is a passively mode-locked dye laser, of which both the frequency and frequency modulation are controlled by one or two intracavity prisms. Interferometric second-order autocorrelations, with a peak-to-background ratio of 8 to 1, are used simultaneously with the conventional intensity autocorrelation and the pulse spectrum to determine the pulse shape. The main advantages of the interferometric autocorrelations are that they provide phase information otherwise not available, and they are more sensitive to the pulse shape than the intensity autocorrelation. The phase sensitivity is demonstrated in an analysis of the Gaussian pulses with a linear frequency modulation. Analytical expressions for the envelopes of the interferometric autocorrelations of typical pulse shapes are provided for quick pulse shape identification. A numerical method is used to analyze the more complex pulse shapes and chirps that can be produced by the laser. A series of examples demonstrates the control of this laser over various pulse shapes and frequency modulations. Pulse broadening or compression by propagation through glass is calculated for the pulse shapes determined from the fittings. Comparisons of autocorrelations and cross correlations calculated for the dispersed pulses, with the actual measurements, demonstrate the accuracy of the fitting procedure. The method of pulse shape determination demonstrated here requires a train of identical pulses. Indeed, it is shown that, for example, a train of unchirped pulses randomly distributed in frequency can have the same interferometric autocorrelation than a single chirped pulse. In the case of the present source, a comparison of the pulse spectrum, with that of the second harmonic, gives an additional proof that pulse-to-pulse fluctuations are negligible.

480 citations


Journal ArticleDOI
TL;DR: The results indicate that the sensations of threshold and loudness are determined by a complex function of the stimulating current waveform, and could lead to perceptual tests of peripheral nerve viability.

143 citations


Journal ArticleDOI
TL;DR: In this article, the propagation of suitably shaped millimetre wave pulses through a linear resonant molecular absorber is studied in order to give an experimental support to the concept of negative group velocity.

137 citations


Journal ArticleDOI
TL;DR: Pathologic injury associated with laser-induced tissue ablation may be substantially reduced by use of pulsed energy delivery at low repetition rates, which could lead to a more benign healing process, a less thrombogenic surface, and improved preservation of structural tissue integrity.
Abstract: Continuous-wave (CW) laser irradiation of cardiovascular tissues is characterized by 2 distinctive histologic findings: a superficial zone of coagulation necrosis and a subjacent zone of polymorphous lacunae. The present investigation was designed to determine whether such injury could be eliminated by altering the temporal profile of laser energy delivery. One hundred forty-five myocardial slices were irradiated with an air-tissue interface using CW laser irradiation at wavelengths of 488 to 515 nm (argon), 1,064 nm (Nd-YAG) and 10,600 nm (CO2). Pulsed laser irradiation included 248 nm (excimer); 355, 532 and 1,064 nm (Nd-YAG); and 515 nm (mode-locked argon). Energy profiles in the pulsed mode included a range of repetition rates (1 Hz to 256 MHz), pulse duration (0.2 to 358 ns) and pulse energies (2 nJ to 370 mJ). Resultant average powers were 0.1 to 38 W. Grossly visible charring of myocardial tissue was observed at all laser wavelengths when the laser energy profile was CW or pulsed at high repetition rates (more than 2 KHz) and low pulse energies (less than 3 mJ) independent of the wavelengths used. In contrast, when laser energy was pulsed at low repetition rates (less than 200 Hz) and large pulse energies (more than 10 mJ), neither gross nor histologic signs of thermal injury were observed. Pathologic injury associated with laser-induced tissue ablation may thus be substantially reduced by use of pulsed energy delivery at low repetition rates. Potential advantages of pulsed laser energy include a more benign healing process, a less thrombogenic surface, and improved preservation of structural tissue integrity.

125 citations


Journal ArticleDOI
TL;DR: Subjects overwhelmingly preferred the 300 μs pulse duration regardless of waveform or source regulation, strongly preferred the symmetrical biphasic waveform, and had inconsistent preference for either regulated voltage or regulated current sources.
Abstract: Twenty-three females between the ages of 19 and 35 were studied in order to compare the effects of variations in pulse duration, waveform symmetry, and source regulation on comfort during quadriceps surface stimulation at amplitudes necessary to produce 27 Nm torque. Stimulation parameters compared were: 1) 50 and 300 μs pulse durations, 2) asymmetrical and symmetrical biphasic waveforms, and 3) current and voltage source regulation. Subjects overwhelmingly preferred the 300 μs pulse duration regardless of waveform or source regulation, strongly preferred the symmetrical biphasic waveform, and had inconsistent preference for either regulated voltage or regulated current sources.

118 citations


Journal ArticleDOI
TL;DR: It will be the objective of this communication to show how the essential constants can be obtained.
Abstract: The strength-duration curve is a plot of the lowest (threshold) current (I) required for stimulation versus pulse duration (d); it forms the basis for describing the excitability of a given tissue. It is extremely useful in all manner of studies in which excitable tissues are stimulated because it describes the manner in which the current required is changed when the pulse duration is changed. Moreover, it can be used to determine the charge and energy-duration relationships. It will be the objective of this communication to show how the essential constants can be obtained.

114 citations


27 Jun 1985
TL;DR: In this paper, the chemical reaction rate law in the ignition and growth model of shock initiation and detonation of solid explosives is modified so that the model can accurately simulate short pulse duration shock initiation, and three terms to model the ignition of hot spots by shock compression, the slow growth of reaction from these isolated hot spots, and the rapid completion of reaction as the hot spots coalesce.
Abstract: The chemical reaction rate law in the ignition and growth model of shock initiation and detonation of solid explosives is modified so that the model can accurately simulate short pulse duration shock initiation The reaction rate law contains three terms to model the ignition of hot spots by shock compression, the slow growth of reaction from these isolated hot spots, and the rapid completion of reaction as the hot spots coalesce Comparisons for PBX 9404 between calculated and experimental records are presented for the electric gun mylar flyer plate system, the minimum priming charge test, embedded manganin pressure and particle velocity gauges, and VISAR particle velocity measurements for a wide variety of input pressures, rise times and pulse durations The ignition and growth model is now a fully developed phenomenological tool that can be applied with confidence to almost any hazard, vulnerability or explosive performance problem 27 refs, 16 figs, 2 tabs

106 citations


Journal ArticleDOI
TL;DR: In this paper, the characteristics of the amplified pulses have been investigated as a function of wavelength, pulse duration, and the pressure in the gain medium, using a high-power pulse compression technique.
Abstract: Picosecond pulses, generated by semiconductor switching (2-40 ps), have been regeneratively amplified to an energy density of ∼1.5 J/cm2in a multiatmosphere CO 2 laser. The characteristics of the amplified pulses have been investigated as a function of wavelength, pulse duration, and the pressure in the gain medium. Using a high-power pulse compression technique, 10 μm pulses as short as 600 fs have been obtained.

93 citations


Journal ArticleDOI
S. L. Palfrey1, Tony F. Heinz1
TL;DR: In this article, the authors show that in order to describe completely the coherent coupling between the pump and probe pulses in a pump-probe measurement of transient absorption, the influence of induced phase gratings must be included.
Abstract: We show that in order to describe completely the coherent coupling between the pump and probe pulses in a pump– probe measurement of transient absorption, the influence of induced phase gratings must be included. The importance of phase gratings is demonstrated experimentally for the case of a bleachable dye and analyzed in terms of transient four-wave mixing. These results are relevant to the interpretation of pump–probe measurements on all time scales performed with pulses from a single laser, particularly when the pulse duration is comparable with the material response time.

90 citations


Journal ArticleDOI
TL;DR: In this paper, a simple theory for evaluating the several measures used to characterize the intermittency of fine-scale turbulence, and corroborates the theoretical results from comparison with experimental data, some of which are new.
Abstract: This paper presents a simple theory for evaluating the several measures used to characterize the intermittency of fine-scale turbulence, and corroborates the theoretical results from comparison with experimental data, some of which are new. The basic analytical tool is the envelope of the narrow-bandpass-filtered turbulent signal, defined via its Hilbert transform and the analytic signal. The contribution of this paper is twofold. First, it correctly identifies the roles played by the filter characteristics (such as the bandwidth) in determining the intermittency factor, the width of the active regions (pulses) in narrow-bandpass-filtered turbulent signals, and the pulse frequency; it also reveals that all dynamical characteristics of the signal enter indirectly through the peak pulse frequency and the threshold setting. Secondly, the theory suggests that, in the far-dissipation range, the most important feature of signals exhibiting internal intermittency is the stronger-than-algebraic roll-off of the spectral density in that region; it is argued that this feature of turbulence essentially determines the peak pulse frequency in that region. The theory is incomplete in that it does not show how the threshold setting depends on the signal dynamics, but here the discussion is supplemented by experimental data.

89 citations


Journal ArticleDOI
L. F. Mollenauer1
TL;DR: This paper describes both fundamental and higher-order solitons in optical fibres, their remarkable properties, and the first experimental observation of them, and proposes a mode-locked (short-pulse) laser whose pulse characteristics are determ ined by a length of single-mode fibre in its feedback loop.
Abstract: In this paper, I describe both fundamental and higher-order solitons in optical fibres, their remarkable properties, and the first experimental observation of them. It will be shown that such solitons are easily created and, once formed, are quite stable in the one-dimensional world of single-mode fibres. Consequently, a number of exciting uses have already been found, or have been proposed for them. One of those uses is in the soliton laser, a mode-locked (short-pulse) laser, whose pulse characteristics are determ ined by a length of single-mode fibre in its feedback loop. Pulse width scales with the square root of the fibre’s length, in accord with N = 2 soliton behaviour. The first version of this device, based on a colour-centre laser broadly tunable in the 1.5 pm wavelength region, has already produced pulses as short as 0.13 ps. Compression in a second, external fibre has reduced those pulse widths to less than 50 fs, and reduction by at least another factor of two is considered likely in the near future.


Journal ArticleDOI
TL;DR: In this article, the theory of mode locking with such a saturable absorber is investigated, and it is found that the fast component contributes substantially to the formation of short pulses, while the presence of the fast absorbing component removes the requirement for gain depletion for the stabilization of the pulse against growth of noise following the pulse for pulses shorter than 1.5 psec.
Abstract: The multiple-quantum-well structure exhibits both a fast and a slow saturation. The theory of mode locking with such a saturable absorber is investigated, and it is found that the fast component contributes substantially to the formation of short pulses. The presence of the fast-absorber component removes the requirement for gain depletion for the stabilization of the pulse against growth of noise following the pulse for pulses shorter than 1.5 psec. However, the buildup of short pulses from longer ones still calls for gain depletion. We also investigate the conditions for self-starting and stability against relaxation oscillations to arrive at criteria for the construction of short resonator structures.

Patent
07 Aug 1985
TL;DR: In this article, a high voltage supply circuit for an x-ray tube is described, which includes sub-circuits for controlling the pulse repetition frequency, which is selected as equal to a parallel resonant frequency of a high-voltage generator connected to the secondary side of the transformer.
Abstract: A high voltage supply circuit for an x-ray tube includes a high voltage transformer having a primary side driven by voltage pulses generated by a drive circuit. The drive circuit includes sub-circuits for controlling the pulse repetition frequency, which is selected as equal to a parallel resonant frequency of a high voltage generator connected to the secondary side of the transformer, for the purpose of saving energy. The drive circuit also includes a sub-circuit for controlling the pulse duration, with the filament voltage in the x-ray tube being regulated by this pulse duration.

Journal ArticleDOI
TL;DR: In this article, the problem of the propagation of an intense ultrashort pulse in a cubic (χ 3 ) nonlinear medium is generalized to include coupling between the primary and second harmonics signals.

Journal ArticleDOI
TL;DR: The relationship between stomatal responses and pulse duration approximately fitted an exponential function, with a t 9s. as mentioned in this paper showed that the response peaked 15 min after the pulse and was completed within 50-60 min.
Abstract: — Intact leaves of Commelina communis irradiated with high fluence rates of red light, showed discrete increases in stomatal conductance in response to pulses (1-100 s) of blue light (250 μmol m−2 s−1). Red light pulses were ineffective, indicating that the conductance increases were not mediated by photosynthesis and that they constitute a specific stomatal response to blue light. The response peaked 15 min after the pulse and was completed within50–60 min. Conductance increases were proportional to pulse duration up to about 30 s and saturated at longer exposures. The relationship between stomatal responses and pulse duration approximately fitted an exponential function, with a t 9s. Pulse responses at two different fluences indicated that reciprocity held. Responses to two consecutive pulses varied with time between pulses. A saturating pulse applied immediately after a preceding one induced no additional response; two saturating pulses 50 min apart caused two identical, consecutive responses. Total increases in conductance induced by two pulses separated by intermediate time intervals increased with time between pulses with a = 9 min. These results point to a blue light-dependent photoconversion of a molecular form, with the activity of the photoconversion product decaying in a thermal reaction. Under continuous blue light, prevailing fluence rates and rates of the light and thermal reactions are postulated to determine steady-state activities of the photoconversion product and proportional increases in conductance levels. These findings have implications for the environmental and metabolic roles of the stomatal response to blue light.

Patent
22 Jul 1985
TL;DR: In this paper, a thermoelectric cooler control circuit for a laser diode that has its terature regulated by a temperature sensor and its temperature sensed by a LIDAR temperature sensor is presented.
Abstract: A thermoelectric cooler control circuit for a laser diode that has its terature regulated by a thermoelectric cooler and its temperature sensed by a laser diode temperature sensor. The purpose of the control circuit is to regulate the thermoelectric cooler to maintain the laser diode at a constant temperature. The output of the laser diode temperature sensor is amplified and compared to a reference voltage in an integrator. The output of the integrator controls a pulse width modulator that controls a switching transistor that varies the pulse duration of power applied to a filter network. The power output of the filter network is applied to a mode controller that is controlled by the output of the integrator so that the mode controller switches the direction that power is applied to the thermoelectric cooler to maintain the temperature of the laser diode at a constant level.

Journal ArticleDOI
TL;DR: In this article, the authors reported current densities of over 200 A in an ultrahigh vacuum chamber from a 1 cm2 Cs3Sb photocathode irradiated by a frequency-doubled, Q-switched pulse from a Nd: glass laser.
Abstract: High-current-density, bunched electron beams with low emittance are required for efficient operation of rf-linac-driven free-electron lasers (FELs). Laser-irradiated, photoemissive electron sources are suitable for this application. Currents of over 200 A have been generated in an ultrahigh vacuum chamber from a 1-cm2 Cs3Sb photocathode irradiated by a frequency-doubled, Q-switched pulse from a Nd: glass laser. These currents are over two times larger than previously reported from any photocathode. The duration of the electron pulse was 50 ns (FWHM), corresponding to the width of the 532-nm laser pulse.

Proceedings ArticleDOI
Gary Yu1
TL;DR: In this article, controlled-amplitude processing is designed to obtain the true amplitude inforð mation which is geologie in origin, which may be successfully used to predict the fluid type in reservoir sands.
Abstract: The partition of plane seismie waves at plane inter­ faces introduces changes in seismie amplitude which vary with angle of incidence. These amplitude variations are a function of the e1astic parameters of rocks on either side of the interface. Controlled-amplitude pro­ cessing is designed to obtain the true amplitude infor­ mation which is geologie in origin. The offset-amplitude information may be successfully used to predict the fluid type in reservoir sands. Various tests were carried out on a seismie profile from the Gulf Coast. The processing comparison em­ phasized the effects and pitfalls of trace equalization, coherent noise, offset, and surface-related problems. Two wells drilled at amplitude anomaly locations con­ firmed the prediction of hydrocarbons from offset­ amplitude analysis. Furthermore, controlled-amplitude processing provided clues in evaluating reservoir quali­ ty, which was not evident on the conventional relative amplitude data.

Patent
18 Jan 1985
TL;DR: In this paper, a PWM inverter system for converting DC power to AC power comprises an output voltage setting circuit for generating a pattern of output voltage value corresponding to a speed command value, an oscillator for producing a pulse train having a frequency proportional to the speed command values, a frequency division circuit for dividing the frequency of the pulse train produced by the oscillator to produce interrupt pulses, a pulse interval measuring circuit, an arithmetic unit responding to the input of the interrupt pulses from the frequency-division circuit to produce a timing signal corresponding to the timing at which said interrupt pulse is
Abstract: A PWM inverter system for converting DC power to AC power comprises an output voltage setting circuit for generating a pattern of output voltage value corresponding to a speed command value, an oscillator for generating a pulse train having a frequency proportional to the speed command value, a frequency division circuit for dividing the frequency of the pulse train produced by the oscillator to produce interrupt pulses, a pulse interval measuring circuit for measuring a pulse interval between predetermined ones of the interrupt pulses supplied from the frequency division circuit, an arithmetic unit responding to the input of the interrupt pulses from the frequency division circuit to produce a timing signal corresponding to the timing at which said interrupt pulse is inputted and update data associated with current operating phase relative to a fundamental wave, to thereby produce pulse width data corresponding to the result of multiplication of a value associated with the output voltage value supplied from the output voltage setting circuit, a value associated with the pulse interval supplied from the pulse interval measuring circuit and a value associated with the operating phase relative to said fundamental wave, a pulse width conversion circuit supplied with the pulse width data from the arithmetic unit for producing a width pulse train conforming to the pulse width data at every timing signal supplied from the arithmetic unit, and a waveform processing circuit supplied with the width pulse train from the pulse width conversion circuit and the timing signal from the arithmetic unit to produce sequentially phase output pulse trains.

Patent
08 Apr 1985
TL;DR: In this paper, a fused silica glass optical fiber is machined by a pulsed infrared laser beam 20 from a carbon dioxide laser 22 focussed by a germanium lens 24.
Abstract: A fused silica glass optical fiber 10 is machined by a pulsed infrared laser beam 20 from a carbon dioxide laser 22 focussed by a germanium lens 24. The beam has a power density of about 70,000 watts per square centimeter at the focussed machining region b and is pulsed at about one pulse per second with a one-half second pulse duration. The fiber workpiece edge is gradually brought into the beam from the side to result in progressive flash evaporation.

Journal ArticleDOI
TL;DR: XeCl laser pulse durations of 1.5 μs (full width at half maximum) have been obtained using a recently developed UV-preionized magnetically induced pulser laser excitation scheme as mentioned in this paper.
Abstract: XeCl laser pulse durations of 1.5 μs (full width at half‐maximum) have been obtained using a recently developed UV‐preionized magnetically induced pulser laser excitation scheme.

Journal ArticleDOI
TL;DR: In this article, a flash x-ray source was used to preionize high-pressure CO2 laser mixtures so as to obtain uniform glow discharges, and the resulting discharges were shown to tolerate oxygen (up to 2.6%) better.
Abstract: X rays with a mean energy of ∼50 keV produced by a flash x‐ray source have been used to preionize high‐pressure CO2 laser mixtures so as to obtain uniform glow discharges. The x‐ray exposure measured in the active volume was 1–2 mR/pulse with a pulse duration of 100 nsec (FWHM) which permitted specific energy inputs of up to 300 J/l atm. Glow discharges were obtained for a variety of pressures and gas mixtures including some which were helium‐free or in which helium was replaced by argon. Further, a realistic comparison of UV and x‐ray schemes was made under sealed‐off conditions. X‐ray preionization appears to be advantageous and the resulting discharges are shown to tolerate oxygen (up to 2.6%) better. Additives such as xenon or organic compounds were not necessary for obtaining uniform glow discharges.

Journal ArticleDOI
TL;DR: Tory studies that examine the relationship of interelectrode distance, current level, and pulse duration to the achievement of successful capture agree with clinical findings and recommend increased pulse duration reduces current requirements and close bipolar spacing combines efficacy with safety.
Abstract: The pill electrode, which was developed for esophageal electrocardiography, has found application in transesophageal atrial pacing during procedures such as conversion of tachycardia, electrophysiologic measurement, and acceleration of heart rate to produce stress during cardiac imaging studies. This paper presents theoretical studies that examine the relationship of interelectrode distance, current level, and pulse duration to the achievement of successful capture. Theoretical results agree with our clinical findings, i.e., current levels of 25 mA are effective to sustain capture; increased pulse duration reduces current requirements; and close bipolar spacing combines efficacy with safety. Results of animal studies performed to assess the extent of esophageal burn injury reveal that current levels in excess of 75 mA are required to produce lesions in short-term (under 30 minutes) pacing, and greater than 60 mA in long-term (4 hours) pacing. These results are based on experiments using a pulse duration of 2 ms, and the current levels that produce injury will be considerably lower if longer pulse durations are used. Typical current levels and pulse durations for successful capture are presented for 46 subjects in several new clinical applications. Termination of tachycardia, basic electrophysiologic measurements, and controlled acceleration of heart rate can be performed noninvasively with this technique.

Proceedings Article
01 Jan 1985

Patent
06 May 1985
TL;DR: In this article, a missing pulse detector in which the absence of a pulse in a variable frequency periodic pulse train (30) is detected and distinguished from a reduction in the pulse repetition rate is detected.
Abstract: A missing pulse detector in which the absence of a pulse in a variable frequency periodic pulse train (30) is detected and distinguished from a reduction in the pulse repetition rate. Between successive pulse train pulses a first counter (46 or 70) counts clock pulses at a first rate (3f1) and develops a maximum count related to the time duration between successive pulse train pulses. This maximum count is effectively maintained by a latch circuit (47 or 71) during the next time duration between successive pulse train pulses and is effectively compared with the count of a second pulse counter (49 or 71) which counts clock pulses during successive pulse train pulses at a second rate (2f1) normally less than the first incrementing rate (3f1). When the count of the second counter (49 or 71) exceeds by a predetermined amount the effectively latched count of the first counter (46 or 70), this indicates the occurence of longer time duration and a count comparator (48 or 71) and logic circuit (55) provides an arming output signal (64). In response to the arming output signal, the incrementing rate of the second pulse counter (49 or 71) is increased to a third rate (4f1) which exceeds the first incrementing rate (3f1). If after the arming output signal (64) the maximum count of the second counter (49 or 71) between successive pulse train pulses is less than the maximum count achieved by the first counter (46) between preceding succesive pulse train pulses, then a missing pulse detection signal (66) is produced.

Patent
Horace Furumoto1
24 Oct 1985
TL;DR: A tunable dye laser has been found particularly suited to selective photothermolysis as mentioned in this paper, which makes the system suitable for a wider range of applications by modifying the laser to generate a spatially non-coherent beam.
Abstract: A tunable dye laser has been found particularly suited to selective photothermolysis. A longer pulse duration which makes the system suitable for a wider range of applications is obtained by modifying the laser to generate a spatially noncoherent beam. The optical system at each end of the laser cell (12), which may include a lens (28, 30) or spherical mirror (32, 34), refocuses the aperture (18, 20) of the dye cell near to itself so that substantially all light emanating from the dye cell is returned to the dye cell until the light passes through one of the optic systems as a noncoherent laser beam. A tunable intracavity element (31) tunes the laser across the gain curve of the dye solution. The pulse duration of the laser beam can be selected from a range of durations up to about one millisecond.

Patent
15 Oct 1985
TL;DR: In this article, an optical sorter for beans and grains, including a detector providing a signal pulse for each of the sampled objects, and a signal processor for receiving and amplifying the pulse, is presented.
Abstract: An optical sorter for beans and grains, including a detector providing a signal pulse for each of the sampled objects, and a signal processor for receiving and amplifying the pulse. The signal processor measures the amplitude of the amplifier pulse and compares the amplitude value to a predetermined standard value. The pulses are counted up to a predetermined count, and the number of pulses having an amplitude value above the predetermined standard value out of the total number of counted pulses, is counted. The counted number of pulses having an amplitude above the standard value is compared to a preselected number, and the gain of the signal processor is adjusted with a negative feedback signal to adjust toward the preselected number, the counted number of pulses in the next count having an amplitude value at the predetermined standard value. The sorter uses the peak amplitude value of the pulse which is determined by taking a derivative of the signal and determining the zero crossing time of the derivative signal.

Journal ArticleDOI
TL;DR: In this article, the construction and performance of an X-ray preionised XeCl discharge laser is described, which gives an output energy of up to 4.65 J with a pulse duration of 140 ns and a beam cross-section of 4.2 x 3.0 cm2.

Patent
04 Sep 1985
TL;DR: In this article, the authors proposed a pulse width discrimination system, where the oscillator outputs frequency pulses to a comparison counter which counts the frequency pulses and compares them to a predetermined value, representing a minimum pulse width in which the user is interested.
Abstract: The pulse-width discrimination system receives an input pulse whose leading edge enables an oscillator. The oscillator outputs frequency pulses to a comparison counter which counts the frequency pulses and compares them to a predetermined value, representing a minimum pulse width in which the user is interested. If the predetermined value is reached, the comparison counter triggers a tolerance window network which outputs a pulse, whose width represents the tolerance window, to one input of a coincidence output network. The input pulse is also received by a trailing-edge detector, which outputs a pulse to another input of the coincidence output network upon detection of the input pulse's trailing edge. If the input pulse's trailing edge coincides with the tolerance window, the coincidence output network will output an indication signal. Regardless of coincidence, the trailing edge of the input pulse disenables the oscillator, and the comparison counter is reset by the trailing-edge detector's output pulse. The oscillator is enabled for the length of the input pulse, and the comparison counter, which counts the oscillator frequency pulses, resets to an initial value every time it reaches a predetermined value. As the predetermined value represents the minimum pulse width, the comparison counter triggers the tolerance window network every minimum pulse-width duration, and harmonics thereof. Accordingly, the pulse-width discrimination system of the present invention will discriminate all pulses whose width is within the tolerance window of the fundamental pulse duration, or harmonics thereof. The pulse-width discrimination system can also be configured to detect only pulses whose width is within the fundamental pulse duration, disregarding harmonics thereof.