Continuous-wave Terahertz Computed Tomography Based on Bessel Beam

We report a continuous-wave terahertz computed tomography using Bessel beam generated by the axicon. Two-dimensional cross-sectional images of the internal structure of plastic pipes at different distances are reconstructed by using the filtered back projection algorithm. Compared with conventional Gaussian beam, Bessel beam can extend the depth of field and improve the fidelity of the reconstruction.