Edge detection by spiral phase contrast imaging at terahertz frequencies

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 4f imaging system, and a spiral phase plate is placed in the Fourier plane to generate the spiral phase. Owing to the uni...

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Bibliographic Details
Published in:Electronics letters 2021-06, Vol.57 (12), p.466-468
Main Authors: Liu, Hui, Wu, Shiyou, Zhao, Meng, Zheng, Shen, Li, Chao, Fang, Guangyou
Format: Article
Language:English
Subjects:
Computer vision and image processing techniques
Diffraction theory
Edge detection
Fourier transforms
Image recognition
Imaging
Microwave measurement techniques
Phase contrast
Phase plates
Sensors
Simulation
Target detection
Terahertz frequencies
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Summary: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 4f 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.
ISSN:0013-5194
1350-911X
DOI:10.1049/ell2.12167