Ανάπτυξη συστημάτων παλμωτών lasers αερίων και χρήση τους στην μελέτη των οπτικών ιδιοτήτων του αδάμαντα

The double purpose of this thesis is the study and the improvement of the working characteristics of pulsed gas lasers, so that they can be used in the studies of the optical properties of materials and the study of the optical properties of materials themselves and especially those of diamond. Thus a new type of preionization of the active gas of pulsed gas lasers is investigated, that is, the use of SiC in the form of grains on the surface of a dielectric. It is proved that the use of this material as a preionizer, is equally effective as that of a semiconductor or a dielectric and that it presents the characteristics of both of them. Also, the characteristics of the "doubling" and the "charge transfer" electrical circuits which are used for the excitation of pulsed gas lasers, are studied. The differential equations that are obeyed by the currents that flow through the two loops of the circuits are solved and the analytical equations that describe the time evolution of these currents are found. Also the immeasurable parameters of the circuits are calculated and the parameters that influence the laser output are found. The theoretical predictions are experimentally confirmed on a nitrogen laser which is used as a model. According to the results of the above study, a pulsed nitrogen laser was constructed, which, together with cw lasers, was used for the study of the optical and elastooptical properties of diamond in the ranges 0÷25 eV and 0÷5.5 eV respectively. A modified theoretical parabolic energy band model is used to explain existing experimental data on the dispersion of the real and imaginary part of the dielectric function, as well as that of the reflectivity, the index of refraction and the extinction coefficient. The same model is also used to explain the dispersion of the temperature dependence of the elastooptical constants Ρ₁₁⁻ Ρ₁₂ and P₄₄ of diamond, which has been measured in the range 80÷380 K. This dependence is attributed to the temperature dependence of the direct energy gap of the material, which is also determined from the present experimental data.

Grantor dc:publisher

National Technical University of Athens (NTUA)

Year dc:date

1990

Authors dc:creator

• Papadopoulos, Abraham
• Παπαδόπουλος, Αβραάμ

• Αδάμας
• Ελαστοοπτικές σταθερές
• Οπτικές ιδιότητες
• Παλμωτοί lasers αερίων
• Προιονισμός αερίων
• Φωτοελαστικότητα
• Diamond
• Elastooptical constants
• Optical properties
• Photoelasticity
• Preionization
• Pulsed gas lasers
• Φυσικές Επιστήμες
• Φυσική
• Natural Sciences
• Physical Sciences

Language dc:language

gre

Identifier

10.12681/eadd/1424

OAI identifier oai:identifier

oai:10442/1424