Pulse Duration Dependence

Hare DE, Rhea ST, Dlott DD, D Amato RJ, Lewis TE. 1998. Pulse duration dependence of lithographic printing plate imaging by near-infrared lasers. J Imag Soc Technol 42 90 97. 

The relative decrease Atq of the pulse duration depends approximately linearly on when 2 < 0 (Fig.31). For 2 > 0, at high powers (e.g. ppeak > 2 in Fig.31), the relative increase of the pulse duration is also almost linear. In this case, such propagation is possible when the pulse duration virtually does not depend on the power of the initial beam. This might result from a balance between the self-focusing effect which decreases the pulse duration (dashed line in Fig.31) and the normal GVD effect which broadens the pulse. 

Of particular interest is the pulse duration dependence of the threshold energy density thr for the appearance of mass spectra (Fig. 2) in the case of the multiple-photon UV ionization of the Trp Gly Ala molecule. It is clearly seen that the threshold energy density is reduced by a factor of 10 in the case of irradiation with femtosecond pulses. The same effect is observed with a pure tryptophan powder. The threshold energy density for the appearance of the 300-fs pulse mass spectrum, E%r = 10-3 J/cm2 (3 x 109 W/cm2), is an order of magnitude lower than that of the 15-ns mass spectrum, [ r = 10 2 J/cm2 (6 x 105 W/cm2). 

Fig. 12.7. The pulse duration dependence of the mean ion energy measured at a fixed laser energy of 49 mJ and a laser contrast of 5 x 10 6 with positive and negative chirps...

Fig. 12.8. a The pulse duration dependence of the Heai line shape for a fixed laser energy of 49 mJ. Open circles, triangles, and squares represent experimental data for pulse durations of 30, 500, and 1000 fs, respectively. The solid, dotted, and dashed lines represent Doppler profiles obtained by fitting the central part of the line to the experimental data, b The pulse duration dependence of the kinetic energies of He-like argon ions calculated from the Doppler shift... 

CCF dependences on the -factor of loaded probe vibrators are shown in Fig.4. For s(l) pulses growth of 2 factor increase CCF maximum amplitude and selectivity. In this case the higher the Q, the longer the pulse duration and the more its periods contribute to the processing. F or q(t) pulses rising of g-factor decrease CCF maximum amplitudes and reduce the selectivity. As q(l) pulse consists of a few first periods only its maximum amplitude depends on Q. the higher the Q, the lower the final pulse amplitude, and therefore, CCF amplitude and selectivity. 

To illustrate the effect of radial release interactions on the structure/ property relationships in shock-loaded materials, experiments were conducted on copper shock loaded using several shock-recovery designs that yielded differences in es but all having been subjected to a 10 GPa, 1 fis pulse duration, shock process [13]. Compression specimens were sectioned from these soft recovery samples to measure the reload yield behavior, and examined in the transmission electron microscope (TEM) to study the substructure evolution. The substructure and yield strength of the bulk shock-loaded copper samples were found to depend on the amount of e, in the shock-recovered sample at a constant peak pressure and pulse duration. In Fig. 6.8 the quasi-static reload yield strength of the 10 GPa shock-loaded copper is observed to increase with increasing residual sample strain. 

So far powerful lasers with picosecond to nanosecond pulse duration have usually been used for the ablation of material from a solid sample. The very first results from application of the lasers with femtosecond pulse duration were published only quite recently. The ablation thresholds vary within a pretty wide interval of laser fluences of 0.1-10 J cm , depending on the type of a sample, the wavelength of the laser, and the pulse duration. Different advanced laser systems have been tested for LA ... 

The potential of LA-based techniques for depth profiling of coated and multilayer samples have been exemplified in recent publications. The depth profiling of the zinc-coated steels by LIBS has been demonstrated [4.242]. An XeCl excimer laser with 28 ns pulse duration and variable pulse energy was used for ablation. The emission of the laser plume was monitored by use of a Czerny-Turner grating spectrometer with a CCD two-dimensional detector. The dependence of the intensities of the Zn and Fe lines on the number of laser shots applied to the same spot was measured and the depth profile of Zn coating was constructed by using the estimated ablation rate per laser shot. To obtain the true Zn-Fe profile the measured intensities of both analytes were normalized to the sum of the line intensities. The LIBS profile thus obtained correlated very well with the GD-OES profile of the same sample. Both profiles are shown in Fig. 4.40. The ablation rate of approximately 8 nm shot ... 

Figure 5 shows the dependence of the total emission intensity on the excitation intensity and its spectral width obtained from DCM-encapsulated dendrimers. A nitrogen laser (wavelength of 337 run, pulse duration of 4 ns, and repetition rate of 10 Hz) was used as the excitation source. A cylindrical lens focused the excitation beam onto a stripe 200 pm wide on a quartz cuvette... 

Fig. 1.8. Ground state vibrations resulting from Lochfrass and bond-softening showing different phases of the motion. The pulse duration is 25 fs. The intensity is 2.5 1014Wcm-2 for Lochfrass and 3.4 1013Wcm 2 for bondsoftening. These were chosen to make the amplitude of the motion the same for the two processes. The vibrational phase does not depend on intensity. The wavelength for the bond-softening calculation is 400 nm...

Davis et al. reported the successful etching of PTFE using single-photon energies in the quartz UV (308 nm and a pulse duration of 25 ns) by sensitizing the fluoropolymer with polyimide. 72 The number of pulses varied depending on fluence and material composition in order to achieve ablated features whose depths were reproducible as measured by a stylus-type profilometer. The pulse repetition rate was on the order of about 200 Hz. In that study, dopant levels... 

Non-stationary self-effects of the light beam depend on the pulse duration with respect to the time Tr of nonlinear response of the medium. When the response is instantaneous, the refractive index at the time t is defined by the value of electrical field at the same moment. If the time of a nonlinear response is finite, the nonlinear part of the refractive index satisfies the... 

Behind the junction, power of the field propagating within the core increases due to the self-focusing effect, while the pulse duration at the waveguide axis decreases. In the quasi-static approximation, this effect does not depend on the initial pulse duration. Total losses vary with power at the pulse peak similar to the case of stationary wave propagation in the structure A, i.e. they increase with the power (Fig.21, compare with Fig.l 1). 

Another result of Sec. 3.3.1 is that the transmittance of the structure A is power dependent, moreover the transmittance evaluated via intensity integration within the core (Ti) and within the computational window depends on the initial beam power differently (Fig.13,14). The pulse duration also depends on the domain —X, ) over which the moments Mi (2.15) of... 

Figure 22. Normalized pulse duration calculated by intensity integration within the spatial domain (—X , Xn) waveguide cross-section, depending on the dimensions of the...

Figure 23. Pulse duration calculated at the waveguide axis depending on peak power of the initial pulse, z = 8 mm, a=3.0 pm.

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