Open AccessEdge detection by spiral phase contrast imaging at terahertz frequencies
Author(s) -
Liu Hui,
Wu Shiyou,
Zhao Meng,
Zheng Shen,
Li Chao,
Fang Guangyou
Publication year - 2021
Publication title -
electronics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.375
H-Index - 146
eISSN - 1350-911X
pISSN - 0013-5194
DOI - 10.1049/ell2.12167
Subject(s) - terahertz radiation , optics , spiral (railway) , phase contrast imaging , physics , edge detection , phase (matter) , enhanced data rates for gsm evolution , contrast (vision) , image plane , image processing , phase contrast microscopy , image (mathematics) , computer science , mathematics , artificial intelligence , mathematical analysis , quantum mechanics
Abstract This paper proposes the spiral phase contrast (SPC) imaging at terahertz (THz) frequencies to achieve the target edge detection. The THz SPC imaging is built based on a classical 4 f imaging system, and a spiral phase plate is placed in the Fourier plane to generate the spiral phase. Owing to the unique nature of the spiral phase, edge detection can be achieved. The THz SPC imaging mechanism is analysed by the scalar diffraction theory, and its corresponding analytic expression is derived. A circle target is simulated and the resultant image shows a remarkable edge detection. A proof‐of‐principle experiment is carried out using our designed THz SPC imaging system and the effectiveness of target edge extraction on the THz images is validated. A circle same as the simulation is imaged firstly, which is consistent with the simulated result. And the letter “Z” with more edges is imaged later. All edges in experiments are extracted perfectly, which are extremely consistent with the THz SPC imaging theory.