Fourier imaging and distance approximation using time of flight method for terahertz wave imaging

Abstract

An active terahertz wave imaging method is investigated for improved system simplicity, inexpensive implementation, and distance approximation. The proposed technique is composed of a single-pixel setup that allows acquiring the two-dimensional (2-D) Fourier transform intensity map of the imaged object and additional depth data using time of flight method. A raster scan is performed to achieve the object’s 2-D Fourier transform intensity and depth information. Iterative phase retrieval methods are employed to accomplish good image reconstruction using only the measured object’s Fourier transform magnitude. The proposed method uses a glow discharge detector (GDD) as its single millimeter wave pixel and offers a simple noncalibrating scheme for 2-D imaging and distance approximation. This work shows experimental results of using the GDD as a distance approximation detector and specifies the advantages, disadvantages, and constraints when using such a sensor. Basic aperture imaging (transmission imaging) experimental results are also shown, and complex aperture imaging simulations and their corresponding reconstructions are presented. Finally, both 2-D imaging and acquired depth data are fused into a single three-dimensional reconstructed image to reveal the potential of the proposed method.