Continuous-wave terahertz high-resolution imaging via synthetic hologram extrapolation method using pyroelectric detector

A feasible and novel method for achieving high resolution and improving the quality of reconstruction of continuous-wave terahertz digital holography is demonstrated. To our knowledge, the synthetic pyroelectric-recording hologram extrapolation method is proposed in the terahertz field for the first time, which mainly consists of signal pre-processing, image synthesis and self-extrapolation. The improvements of the imaging quality have been achieved through the signal averaging and the constraint mask, which are applied to suppress the disturbance of the background thermal noise that results from the pyroelectric effect. The enhancements of the resolution are obtained from a synthetic aperture extrapolation method, which is initially implemented to expand the detection area from an original array size (similar to 124 pixels) to a synthetic size (similar to 320 pixels). Furthermore, the terahertz synthetic holograms are extrapolated through the iterative process to enrich the holographic fringes in the expanded area with a larger size (similar to 500 pixels). Compared with the conventional approaches, the proposed method has been proven to improve the reconstructed image quality and resolving power, which is almost independent of the performance of the terahertz equipments. Those positive experimental verifications show that the proposed technique can be employed in numerous domains.