{"id":{"repo_id":"greece","oai_identifier":"oai:10442/1424"},"canonical_url":"https://search.dev.ndltd.org/etd/greece/oai:10442/1424","repository":{"repo_id":"greece","name":"Greek National Archive of PhD Theses","base_url":"https://phdtheses.ekt.gr/eadd_oai/request"},"display":{"title":"Ανάπτυξη συστημάτων παλμωτών lasers αερίων και χρήση τους στην μελέτη των οπτικών ιδιοτήτων του αδάμαντα","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Papadopoulos, Abraham","Παπαδόπουλος, Αβραάμ"],"institution":"National Technical University of Athens (NTUA)","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1990,"date_issued":"1990","date_published":"1990","updated_at":"2026-07-24T02:24:56Z","subjects":["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"],"languages":["gre"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["10.12681/eadd/1424"],"render_values":[{"text":"10.12681/eadd/1424","href":"https://doi.org/10.12681/eadd/1424","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10442/hedi/1424","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Papadopoulos, Abraham","Παπαδόπουλος, Αβραάμ"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1990"]},{"key":"dc:publisher","label":"Institution","values":["National Technical University of Athens (NTUA)","Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)"]},{"key":"dc:type","label":"Dc Type","values":["PhD Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["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"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["gre"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["10.12681/eadd/1424","http://hdl.handle.net/10442/hedi/1424"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["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.","Ο διπλός σκοπός της διατριβής αυτής είναι αφενός μεν η μελέτη και η βελτίωση των χαρακτηριστικών λειτουργίας των παλμωτών lasers αερίων, έτσι ώστε αυτά να μπορούν να χρησιμοποιηθούν σε μελέτες των οπτικών ιδιοτήτων των υλικών, αφετέρου δε η μελέτη αυτών των ίδιων των οπτικών ιδιοτήτων των υλικών και ειδικότερα του αδάμαντα. Έτσι μελετάται ένας νέος τρόπος προιονισμού του αερίου των παλμωτών lasers, με χρήση SiC σε μορφή κόκκων τοποθετημένων πάνω σε διηλεκτρικό υπόστρωμα. Αποδεικνύεται ότι η χρήση του υλικού αυτού είναι εξίσου αποδοτική με την χρήση ημιαγωγού ή διηλεκτρικού και ότι παρουσιάζει τα χαρακτηριστικά και των δύο. Μελετώνται ακόμη τα χαρακτηριστικά των ηλεκτρικών κυκλωμάτων \"διπλασιασμού τάσης\" και \"μεταφοράς φορτίου\" αντίστοιχα, τα οποία χρησιμοποιούνται για την διέγερση του ενεργού αερίου των παλμωτών lasers. Επιλύονται οι διαφορικές εξισώσεις που ικανοποιούνται από τα ρεύματα που ρέουν στους δύο βρόγχους των κυκλωμάτων και βρίσκονται οι αναλυτικές εξισώσεις που περιγράφουν την χρονική εξέλιξη των ρευμάτων αυτών. Επίσης υπολογίζονται οι μη μετρήσιμες παράμετροι των δύο ηλεκτρικών κυκλωμάτων και εντοπίζονται οι παράμετροι εκείνες που επηρεάζουν την απόδοση του laser. Τέλος, οι θεωρητικές προβλέψεις επαληθεύονται πειραματικά σε έναν laser αζώτου, ο οποίος χρησιμοποιείται σαν μοντέλο. Με βάση τα αποτελέσματα της παραπάνω μελέτης κατασκευάστηκε παλμωτός laser αζώτου, ο οποίος μαζί με lasers συνεχούς λειτουργίας χρησιμοποιήθηκε για την μελέτη των οπτικών και ελαστοοπτικών ιδιοτήτων του αδάμαντα στις περιοχές 0÷25 eV και 0÷5.5 eV αντίστοιχα. Ένα τροποποιημένο θεωρητικό μοντέλο παραβολικών ενεργειακών ζωνών χρησιμοποιείται για την διασπορά του πραγματικού και φανταστικού μέρους της διηλεκτρικής σταθεράς, καθώς επίσης και της ανακλαστικότητας, του δείκτη διάθλασης και του συντελεστή εξάλειψης. Το ίδιο μοντέλο χρησιμοποιείται και για την εξήγηση της διασποράς της εξάρτησης των ελαστοοπτικών σταθερών Ρ₁₁⁻ Ρ₁₂ και P₄₄ του αδάμαντα από την θερμοκρασία, η οποία μετρήθηκε στην περιοχή 80÷380 Κ. Η εξάρτηση αυτή αποδίδεται στην θερμοκρασιακή εξάρτηση του θεμελιώδους άμεσου ενεργειακού χάσματος του υλικού, η οποία και προσδιορίζεται από τα παρόντα πειραματικά δεδομένα."]},{"key":"dc:title","label":"Title","values":["Ανάπτυξη συστημάτων παλμωτών lasers αερίων και χρήση τους στην μελέτη των οπτικών ιδιοτήτων του αδάμαντα","Development of pulsed gas laser systems and their use in the study of the optical properties of diamond"]}]}],"canonical_facts":{"dc:creator":["Papadopoulos, Abraham","Παπαδόπουλος, Αβραάμ"],"dc:date":["1990"],"dc:description":["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.","Ο διπλός σκοπός της διατριβής αυτής είναι αφενός μεν η μελέτη και η βελτίωση των χαρακτηριστικών λειτουργίας των παλμωτών lasers αερίων, έτσι ώστε αυτά να μπορούν να χρησιμοποιηθούν σε μελέτες των οπτικών ιδιοτήτων των υλικών, αφετέρου δε η μελέτη αυτών των ίδιων των οπτικών ιδιοτήτων των υλικών και ειδικότερα του αδάμαντα. Έτσι μελετάται ένας νέος τρόπος προιονισμού του αερίου των παλμωτών lasers, με χρήση SiC σε μορφή κόκκων τοποθετημένων πάνω σε διηλεκτρικό υπόστρωμα. Αποδεικνύεται ότι η χρήση του υλικού αυτού είναι εξίσου αποδοτική με την χρήση ημιαγωγού ή διηλεκτρικού και ότι παρουσιάζει τα χαρακτηριστικά και των δύο. Μελετώνται ακόμη τα χαρακτηριστικά των ηλεκτρικών κυκλωμάτων \"διπλασιασμού τάσης\" και \"μεταφοράς φορτίου\" αντίστοιχα, τα οποία χρησιμοποιούνται για την διέγερση του ενεργού αερίου των παλμωτών lasers. Επιλύονται οι διαφορικές εξισώσεις που ικανοποιούνται από τα ρεύματα που ρέουν στους δύο βρόγχους των κυκλωμάτων και βρίσκονται οι αναλυτικές εξισώσεις που περιγράφουν την χρονική εξέλιξη των ρευμάτων αυτών. Επίσης υπολογίζονται οι μη μετρήσιμες παράμετροι των δύο ηλεκτρικών κυκλωμάτων και εντοπίζονται οι παράμετροι εκείνες που επηρεάζουν την απόδοση του laser. Τέλος, οι θεωρητικές προβλέψεις επαληθεύονται πειραματικά σε έναν laser αζώτου, ο οποίος χρησιμοποιείται σαν μοντέλο. Με βάση τα αποτελέσματα της παραπάνω μελέτης κατασκευάστηκε παλμωτός laser αζώτου, ο οποίος μαζί με lasers συνεχούς λειτουργίας χρησιμοποιήθηκε για την μελέτη των οπτικών και ελαστοοπτικών ιδιοτήτων του αδάμαντα στις περιοχές 0÷25 eV και 0÷5.5 eV αντίστοιχα. Ένα τροποποιημένο θεωρητικό μοντέλο παραβολικών ενεργειακών ζωνών χρησιμοποιείται για την διασπορά του πραγματικού και φανταστικού μέρους της διηλεκτρικής σταθεράς, καθώς επίσης και της ανακλαστικότητας, του δείκτη διάθλασης και του συντελεστή εξάλειψης. Το ίδιο μοντέλο χρησιμοποιείται και για την εξήγηση της διασποράς της εξάρτησης των ελαστοοπτικών σταθερών Ρ₁₁⁻ Ρ₁₂ και P₄₄ του αδάμαντα από την θερμοκρασία, η οποία μετρήθηκε στην περιοχή 80÷380 Κ. Η εξάρτηση αυτή αποδίδεται στην θερμοκρασιακή εξάρτηση του θεμελιώδους άμεσου ενεργειακού χάσματος του υλικού, η οποία και προσδιορίζεται από τα παρόντα πειραματικά δεδομένα."],"dc:identifier":["10.12681/eadd/1424","http://hdl.handle.net/10442/hedi/1424"],"dc:language":["gre"],"dc:publisher":["National Technical University of Athens (NTUA)","Εθνικό Μετσόβιο Πολυτεχνείο (ΕΜΠ)"],"dc:subject":["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"],"dc:title":["Ανάπτυξη συστημάτων παλμωτών lasers αερίων και χρήση τους στην μελέτη των οπτικών ιδιοτήτων του αδάμαντα","Development of pulsed gas laser systems and their use in the study of the optical properties of diamond"],"dc:type":["PhD Thesis"]},"updated_at":"2026-07-24T02:24:56Z"}