High-resolution terahertz digital holography based on frequency-domain diagonal extension imaging

By leveraging frequency-domain diagonal extension (FDDE) imaging in terahertz (THz) in-line digital holography, the resolution of THz digital holography would be dramatically improved. The holography system in this work which utilizes a CO2-pumped 2.52 THz (118.83 mu m) continuous-wave laser as the source and a pyroelectric-array camera with a pixel pitch of 100 mu m as the detector could attain a resolution of 150 mu m (similar to 1.26 lambda) near to the resolution limit of the system. FDDE imaging is a simple and effective method for resolution enhancement, where no new detector or other equipment is employed. Samples are imaged twice from different angles and then the high-frequency components of images are stitched to improve the resolution. Different from the traditional FDDE, weight-FDDE (w-FDDE) which can reduce the visibility distinction between different orientations of the synthetic picture by adding weight factors to produce a superior synthetic image is proposed in this work.