Image restoration algorithm for terahertz FMCW radar imaging

The terahertz frequency modulation continuous-wave (THz FMCW) imaging technology has been widely used in non-destructive testing applications. However, THz FMCW real-aperture radar usually has a small depth of field and poor lateral resolution, thus restricting the high-precision imaging application...

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Bibliographic Details
Published in:Applied optics (2004) 2023-07, Vol.62 (20), p.5399
Main Authors: Hu, Weidong, Xu, Zhihao, Jiang, Huanyu, Liu, Qingguo, Yao, Zhiyu, Tan, Zhen, Ligthart, Leo P.
Format: Article
Language:English
Subjects:
Algorithms
Continuous radiation
Convolution
Depth of field
Frequency modulation
Gaussian beams (optics)
Image enhancement
Image restoration
Nondestructive testing
Point spread functions
Radar imaging
Semiconductor devices
Terahertz frequencies
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Summary:The terahertz frequency modulation continuous-wave (THz FMCW) imaging technology has been widely used in non-destructive testing applications. However, THz FMCW real-aperture radar usually has a small depth of field and poor lateral resolution, thus restricting the high-precision imaging application. This paper proposes a 150–220 GHz FMCW Bessel beam imaging system, effectively doubling the depth of field and unifying the lateral resolution compared to the Gaussian beam quasi-optical system. Moreover, a THz image restoration algorithm based on local gradients and convolution kernel priors is proposed to eliminate further the convolution effect introduced by the Bessel beam, thereby enhancing the lateral resolution to 2 mm. It effectively improves the image under-restoration or over-restoration caused by the mismatch between the ideal and actual point spread function. The imaging results of the resolution test target and semiconductor device verify the advantages of the proposed system and algorithm.
ISSN:1559-128X
2155-3165
DOI:10.1364/AO.493964