THz remote sensing with μm resolution

Abstract

In the paper a frequency modulated THz system is presented. The system is constructed with a solid state THz source and is modulated approx. ±10% of central frequency of 0.3THz. The detector is room temperature sensor array with a square low characteristic allowing a mixer operation between a portion of transmitted signal from the beam splitter and the received signal. Due to this heterodyne approach a very good signal to noise ratio has been achieved, allowing accurate and repeatable signal analysis. The phase of the received signal is very stable and can be used for fine position measurements with the resolution well below 1μm. In this paper the focus is on measurements of thin foil thickness. Various experiments set-ups and measured results are presented.