Scattering in the THz region, measurement prediction and extrapolation

Abstract

An instrument has been designed which is capable of measuring scattering from 0.075-0.5 THz. This will enable a more accurate determination of the optical properties of materials by correcting for scatter and also the characterisation of the mechanical properties of the surface. Models have been investigated to help in experimental design and in reducing the number of required measurements by extrapolation. The Generalized Harvey Shack (GHS) method has been evaluated for this purpose. Predictions for 40 grit gold coated sandpaper at 37 degrees incidence angle and 0.8 THz are made showing the surface to be almost completely diffuse. The GHS method was compared to the Integral Equation Model (IEM).

Experimental validation of the Generalized Harvey-Shack surface scatter theory

“…These locations were at the center of the surface and the four "corners" 10 mm laterally and vertically on the sample as depicted in Figure 4. 30. The inversion of the coordinate system is due to the method of changing the measurement location.…”