الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Pulsed air cooled Xenon filled flashlamp with certain specifications
has been used as optical pumping source. Driver circuit of this flashlamp
has been designed and constructed with certain values of inductance,
capacitance, and capacitor voltage to avoid the undesired cases of
underdamped and overdamped behavior. The designed driver circuit of
flashlamp by these values of Ko, E0, C, tp Vo, L, and Z0 is satisfied critical
damping factor of 0.80, which is important to insure the most efficient
transfer of energy from the capacitor to the flashlamp. The flashlamp
operates at around 10% of its explosion energy which insures long life time
of the lamp more than one million shot.
2. The elliptical cavity has been constructed from copper which has relatively
low thermal expansion and high thermal conductivity and then coated with
gold which increases the reflectivity. Since the reflectance of gold is high for
wavelengths between 700 nm and 900 nm. This range corresponds to the
maximum absorption of the Nd:glass rod. Thus, the optical pumping
efficiency increases. The transfer efficiency of the designed elliptical pump
cavity is about 0.65, which is relatively high. Since it increased with the
increase of the ratio of the rod and lamp radii rR/rL, which equals to 0.83, and
decreases the eccentricity which equals to 0.50.
3. A series of glass samples of composition 70GeO2-20PbO-10K2O-x Nd2O3
(where x ranges from 0.0 wt% to 6.0 wt%), have been synthesized by melt
quenching technique. X-ray diffraction confirmed the amorphous nature of
all prepared samples. The Element analytic by dispersive energy X-ray
confirmed the nominal composition, i.e. no impurities or rare earth ion loss.
4. The DTA curve shows that the glass transition temperature is (Tg = 439 oC)
and crystallization temperature is (Tx = 565 oC) of this sample. It also
indicates that their thermal stability ΔT equals 126 oC, which is better than
those of tellurite (118 oC) and fluoride (105 oC) glasses.
5. FTIR spectroscopy shows that the increase of the Nd3+ ions concentration
from (0.0 to 6.0 Wt %), doesn’t influence the position or relative intensities
of IR absorption bands. This in turn indicates that the Nd2O3 content has a
minor effect on the structure and that Nd+3 ions occupy interstitial positions
in the germanate glass network. And insure very good dispersion of the Nd3+
ions, with no evidence of the formation of Nd3+ ion clusters in these glasses.
Also, it is indicated that the maximum phonon energy in these glasses is
around 788 cm-1, which is smaller than those of borate (~1350 cm-1),
phosphate (~1100 cm-1), silicate (~1000 cm-1), some other germanate (~900
cm-1) and pure GeO2 glass (~865 cm-1) glasses. Consequently, this reduce the
nonradiative relaxation, which enhances the radiative transition and
increases the quantum efficiency of luminescence in these optical media.
6. The spectroscopic properties of these glasses are studied using optical
absorption and emission spectra. f-f transitions of the Nd+3 give rise to
absorption peaks in the visible and near IR regions of spectrum. Optical
absorption measurements show that the main absorption band around
808 nm. With the increase of Nd3+ concentration, the absorption intensity
around 585.5 nm increases linearly. This indicated that Nd3+ ions have good
solubility in this glass. The optical band gap energy Eopt vary from 3.55 to
3.48 eV with variation of Nd2O3 content from 0 to 6. % wt. A slight increase
of Nd2O3 content in the glass system causes a slight decrease of Eopt.
7. The emission spectra of Nd3+ doped potassium lead germanate glass show
two emission peaks corresponding to the transitions 4F3/2 ĺ4I9/2 and, 4F3/2 ĺ
4I11/2. The corresponding wavelengths of these peaks are nearly around 880
nm and 1059 nm, respectively. It is observed that the emission intensity of
transitions 4F3/2 ĺ 4I11/2 around 1059 nm is increasing at Nd3+ concentration at
a maximum of 4.0 wt%. Then, the emission is quenched at higher
concentration. Hence the obtained results suggest that 4.0 wt% of Nd2O3 ions
doped potassium-lead-germanate glasses is the optimum concentration.
8. After these characterizations of samples the rod has been manufactured
from optimum composition of 4.0 wt% of Nd3+ concentration, which gives
the highest emission intensity at the same conditions of the samples in
certain dimensions of 9 cm length and 5mm diameter.
9. The components have been assembled and aligned. The output laser energy
increases with the increase of the output coupler reflectivity.
10.The output laser beam is applied to tooth with caries to remove them. SEM
of the tooth confirmed ablation of these caries.
Homemade Nd:glass laser system has been constructed, with ë = 1059 nm,
tp = 360 µs, Eout around 500 mJ and one Hertz. The constructed system is used
in laser ablation and as a pumping source for other laser system and many other
applications. This system can be used as different solid state laser system or as
Q-Switching or mode locking for various applications.