A study of the design and development of transversely
excited atmospheric pressure carbon dioxide lasers has been
carried out. Three lasers were constructed with output
energies ranging from a few millijoules to several joules.
Damage in transmitting output mirrors is one of the limiting
factors in the development of high energy density carbon
dioxide lasers. One form of damage in uncoated germanium
components is characterised by regular patterns.
A detailed examination of these damage patterns on several
mirrors has been carried out using both optical and electron
A semi-quantitative physical model describing the damage
structure formation is proposed, and good agreement with
experimental observation is found.
The thesis goes on to examine in depth particular aspects
of the model with the object of making the analysis fully
The thesis concludes by preparing the necessary data base
for quantitative computer modelling. A full description is
prepared of the behaviour of all the relevant physical
parameters characterising germanium from room temperature to
melting point temperature (300K - 1210K).
The technique adopted is to use a theoretical (or sometimes
empirical) framew6rk within which to extrapolate from available
published data into parameter ranges not hitherto available.
For germanium, numerical values have been assigned to all
relevant physical parameters (thermal, electrical and optical)
over the full temperature range.
The way is now open for computer simulation of. the interaction
between laser radiation and germanium under a wide variety of
A significant refinement of the model describing damage
structure has already occurred.
When the magnitudes and temperature variation of Є' and Є"
for germanium were established, the particular model behaviour
of germanium suggested a generalised view of the behaviour
of other materials. At the time of writing, the model is
being adapted to account for the observations of other
workers on a wide variety of other materials.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.