Time-Domain Terahertz Spectrometer For Angular Reflection Measurements

We describe a terahertz time-domain spectrometer developed to perform measurements by reflection under a wide range of angles. The different parts of the device are described as well as the process of frequency-scale calibration and signal linearity evaluation. Also the main parameters that characterize the system and account their performance are measured. Finally an example of application to the measurement of the bandgap of a photonic crystal designed for the terahertz band is presented.