Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637304
Title: Studies of metal vapour lasers
Author: Hopkin, I. D.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1988
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Abstract:
This thesis is concerned with the design, construction and investigations of hollow cathode helium-cadmium lasers, which are capable of oscillating simultaneously on five lines, two red, two green and one blue, i.e. three primary colours, which results in the production of a 'white light' laser. For the first time simultaneous oscillation on seven cadmium lines is reported in the present study, which includes the afore-mentioned 5 lines together with two near infrared lines. The physical processes responsible for the creation of the population inversions between the twelve energy levels of the Cd+ ion are discussed in detail. The applications of white light lasers are in areas such as colour holography and colour printing, and a description of the basics of colour science and its application to these multicolour lasers is presented. Following a critical review of related investigations by other workers, which includes details of the hollow cathode designs used to produce the hollow cathode discharges, a discussion on the glow discharge and the hollow cathode effect is presented. The designs of lasers constructed in the present work, including details of the discharge tubes and optical resonators, are described in detail. The theoretical basis for designing hollow cathode discharge tubes for laser production is also presented. A description of the ancillary apparatus and the method used to align the white light laser is given. Measurements on gain and cavity optimization were made for each colour during multi-line operation of the laser, and these results are presented and discussed. Following a discussion on the general observations of the operating characteristics of the laser, a detailed parametric study is described, in which the effects of changing helium pressure and discharge current are investigated. On the basis of these measurements the fundamental processes involved in the creation of the population inversions are discussed. Of particular interest are the results obtained for the green transitions, which suggest that at pressures below ~ 15 mbar the population inversion is created by radiative cascades through the red laser lines (which are populated by charge transfer reactions with the He^+ ion), while, in contrast, at higher pressures the population inversion is produced via charge transfer reactions in collisions between ground state cadmium atoms and He_2^+ molecular ions. Spectroscopic studies of the discharge and the laser ouput were made and these results are presented and discussed. Finally in the light of the experience gained during the present work, suggestions for further work are given.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.637304  DOI: Not available
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