Compressed sensing with near-field THz radiation

We demonstrate a form of near-field terahertz (THz) imaging that is compatible with compressed sensing algorithms. By spatially photomodulating THz pulses using a set of shaped binary optical patterns and employing a 6-mu m-thick silicon wafer, we are able to reconstruct THz images of an object placed on the exit interface of the wafer. A single-element detector is used to measure the electric field amplitude of transmitted THz radiation for each projected pattern, with the ultra-thin wafer allowing us to access the THz evanescent near fields to achieve a spatial resolution of similar to 9 mu m (lambda/45 at 0.75 THz). We conclude by experimentally improving the image rate by a factor of similar to 3 by undersampling the object with adaptive and compressed sensing algorithms.