Accurate Terahertz Imaging Simulation With Ray Tracing Incorporating Beam Shape and Refraction

In this paper, we present an approach to realistically simulate terahertz (THz) transmission mode imaging. We model the THz beam shape and account for the refraction of the THz beam at the different media interfaces using ray optics. Our approach does not require prior knowledge on the interfaces, instead it utilizes the refractive index scalar field. We study the beam shape and refraction effects separately by comparing resulting sinograms with the ones simulated by a Gaussian beam model, as well as with a real acquisition of a plastic object. The proposed forward projection can be utilized in iterative reconstruction algorithms to improve the quality of THz CT images.