Flash lamp pumping

Figure 7.19 Principle of a flash-lamp pumped-dye laser. FL, flash lamp D, dye cell G, diffraction grating...

Experimental Setup. The instrumentation (both optics and electronics) for studying saturated laser induced fluorescence spectroscopy is much less conplicated than for CARS. The experimental setup shown in Figure 18, as used in our laboratory, is typical for these studies. In some experiments it is advantageous to use a monochromator rather than band pass filters to isolate the laser induced fluorescence signal. The lasers used are either flash lamp pumped systems or NdsYAG pumped dye lasers. 

Equation 31 is plotted in Figure 5 for typical combustion conditions and with the combined uncertainty in k. > ft and V as a parameter. The sample time is 1 Usee, typical of flash-lamp pumped dye laser pulses, and thus remarkably low detectability limits are achievable with single pulse sampling. 

From Figures 6, 18, and 20 we see that relative fluorescence measurements for OH, SH, S2, and SO along with the method for data reduction leads to reasonable agreement with the equilibrium expectations. In Figures 19 and 21 there is a somewhat wider spread of the data about the equilibrium expectation. This is probably caused by the use of non-optimal measuring conditions and data reduction for S02 which has a very complex spectrum at flame temperatures. We are expecting a Nd-Yag laser shortly which will operate deeper into the UV than our present flash lamp pumped dye laser and will permit a more extensive characterization of SO2 fluorescence in the flame environment. 

The excitation spectra of marine phytoplankton were found to be broad (6). Considering this feature, we emphasized continuous and rapid measurement at discrete excitation wavelengths. Flash-lamp pumped dye lasers were used because of their simplicity and their high efficiency. The excitation wavelengths were at 457, 499, 536, and 578 nm. 

Schlieren photographs of the spark kernel and the developing flame were obtained using a conventional arrangement. A flash-lamp-pumped dye laser was used to furnish a 1 ys light pulse (X 600 nm) to illuminate the interior of the combustion bomb. 

The most common LA-ICP/MS work to date is with flash-lamp pumped Nd YAG lasers that produce a light pulse of 3-10 nanoseconds in width and are relatively inexpensive. Shorter pulse width lasers (picosecond to femtosecond) are widely available but more expensive. A wavelength other than IR or UV is used only for resonant laser ionization or ablation. In this case, the goal is to excite or ionize a specific element preferentially, and the laser wavelength is chosen to correspond to a particular transition of an element, as discussed in Section 17.7.4. 

Kaufmann and co-workersexplored several complementary methods to prepare 2,5-disubstituted oxazoles and 2,4,5-trisubstituted oxazoles as flash-lamp pumped laser dyes (Scheme 1.122). Prolonged reflux of 440 with POCI3 effected cyclodehydration to 5-(4-methoxyphenyl)-2-(4-pyridyl)oxazole 441 in modest... 

The main advantage of Nd glass is that it can be fabricated in large sizes with excellent optical quality. By contrast, the size of crystals is usually much more limited. The sensitization of Nd + by Cr +, as has been accomplished into the GSGG host, results in a material that gives flash lamp-pumped efficiencies that are about twice as large as can be obtained for Nd YAG. 

There are two basic methods with which an inversion can be created in a solid-state laser flash lamp pumping and laser diode array pumping. The cheapest and most common method uses flash lamps (Fig. 16). A flash lamp essentially consists of a fused sihca tube of suitable diameter and length with an electrode at each end. Flash lamps for a laser like that in Fig. 23 are nominally four to five inches long, and around a centimeter in diameter. Those for large fusion lasers can be as long as a meter, and be several centimeters in diameter. Once triggered with a short... 

However, such up-conversion lasers in crystals are still limited to low temperatures for CW operation (Tong et al. 1989, Hebert et al. 1990, Macfariane et al. 1988, Scott et al. 1993, Stephens and Macfariane 1993), because the laser schemes are generally of the 3-level type. Room-temperature laser operation of KYF4 Er + and LiYF4 Er was recently obtained in the green in pulsed operation with a flash-lamp-pumped Ti.sapphire laser as an ESA pump (Brede et al. 1993). 

G. Marowsky A tunable flash lamp pumped dye ring laser of extremely narrow bandwidth. IEEE J. QE-9, 245 (1973)... 

The lasers we have considered so far have a solid material as the active medium. Generally, flash-lamp pumping is employed and short pulses are obtained at a repetition rate of typically 10 Hz. High peak powers are obtained in the Q-switched mode (MW-GW). Gaseous media can also be used for the generation of short laser pulses. We shall here consider the nitrogen laser, the excimer laser and the copper vapour laser. The relevant parts of... 

The ICG was intravenously administered to 15 patients with CM at a total dose of 4 mg/kg b.w. Immediately after ICG injection, diode laser pulses with different radiant exposure (20-110 J/cm ) were applied as one single treatment. Five patients with extensive CM additionally received IPL (555-950 nm) therapy. Safety and efficacy were assessed at 1 and 3 months after the single treatment by a blinded investigator and the patient. Furthermore, coloxu- of the CM was objectively measured by means of a colour metre. Treatment with tire flash lamp-pumped pulsed dye laser (FPDL) and the IPL alone (five patients) served as the reference treatment. 

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