Terahertz Tomography with the Conjugate Gradient Least Squares Algorithm

In this work we report on the application of the conjugate gradient least squares (CGLS) algorithm in terahertz tomography. The algorithm outperforms most established reconstruction techniques, especially the widely used filtered back projection (FBP). The performance of the algorithms is tested with simulated projection data as well as measured data from a frequency-modulated continuous-wave transmission tomography setup operating from 230 to 320 GHz. A 2D image of a test scene is reconstructed. This algorithm promises great improvement for the application of terahertz tomography in the field of non-destructive testing.