In the thesis the dependance of the optical properties of wood on the wood moisture are studied in the microwave region. Structure and properties of wood with the emphasis on anisotropic optical properties are summarised in the first chapter. Next the methods for changing and measuring wood moisture are described. It turns out that the most accurate measurements of the changes of wood moisture are obtained by the so called gravimetric method. Furthermore, this method is simple and easy to perform, its only drawback is the lack of precisely determining the zero moisture state of wood. Detailed description of the procedures for changing wood moisture as well as for determining birefringence and both absorption coefficients of wood are the core content of the thesis. Finally, two important findings result from the study. Firstly, we show that standard school microwave set, including a transmitter and a receiver, enables one to measure birefringence as well as both absorption coefficients to a reasonable accuracy at all observable wood moistures. This result is particularly important for all physics teachers from the point of view of using wood and microwaves as means to show anisotropic properties of matter. In addition, our measurements confirm that both, birefringence and absorption of microwaves in wood increase with increasing wood moisture. We show that birefringence can be modelled as a linear function of wood moisture whereas the increase of absorption of microwaves with wood moisture is modelled significantly better with a parabolic function. Collaterally we noticed that wood moisture is difficult to measure accurately and that it is quite a complex and time consuming task to change wood moisture in a controlled way.
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