Phase retrieval algorithm is gradually applied to the terahertz in-line digital holography, as its effectiveness in the removal of the zero-order diffraction light and twin image. Based on the experiments, the reconstruction results of the double-exposed phase retrieval algorithm are obtained which demonstrate that the method can improve the quality of reconstructed images, compared to the angular spectrum method. Furthermore, the influence of the superimposed frame number of the holograms in double-exposed phase retrieval algorithm is discussed. The result shows that the recording time can be reduced by reasonably decreasing the frames of the holograms and it contributes to real-time imaging and the algorithm practicality is also further improved.
The technology of terahertz (THz) is a major research area in the 21st century. THz imaging is an important research direction. The single-frequency continuous-wave THz technology is combined with coaxial reflection-mode confocal scanning microscopic imaging in this article. Under the given system parameters, the transverse response character of 2.52THz (118.83μm) coaxial reflection-mode confocal scanning microscopic imaging is emulated and analyzed. The results of emulation show that coaxial reflection-mode confocal scanning microscopic imaging is feasible in THz region.
Terahertz (THz) digital holography is a combination of THz technology and digital holography which has drawn wide attention. Exact measurements of real recording distances in terahertz (THz) digital holography are important. Autofocusing experimental researches have been conducted based on the holograms in THz off-axis digital holography. Five criterion functions are utilized in this paper. Autofocusing performance of these criterion functions has been analyzed and compared by changing the numbers of the superposition frames of holograms. Experiment results show that five criterion functions all have preferable autofocusing performance with the 5-frame averaged holograms; standard deviation–based correlation criterion function has the worst autofocusing performance.
Because of the particularity of terahertz radiation, terahertz digital holographic imaging has attracted increasing attention.
Thereinto, the resolution is the key to this field. Within an inverse problem framework, the simulation on the single point
resolution of 2.52 THz on-axis digital hologram at different recording distances and object positions is made in this paper.
Simulation results show that the recording distance and the object position have a great influence on the single point
resolution. Simulation results have important directive significance to the practical terahertz digital holographic imaging.
Terahertz imaging can make up the defect of imaging opaque samples in visible light domain. Digital holography is a new technology for extracting full information of the original object. In the paper, the improved angular spectrum (AS) algorithm is coulping the original AS algorithm with direct current (DC) suppression method, apodization and piecewise-nonlinear transformation. The reconstruction characteristics of the algorithm have been studied by numerical analysis and experimental researches. The experimental results validate the application value of the algorithms in improving 2D reconstructed image quality in terahertz Gabor inline digital holography.