26 May 2016 Developing terahertz imaging equation and enhancement of the resolution of terahertz images using deconvolution
Author Affiliations +
Abstract
This paper introduces a novel reconstruction approach for enhancing the resolution of the terahertz (THz) images. For this purpose the THz imaging equation is derived. According to our best knowledge we are reporting the first THz imaging equation by this paper. This imaging equation is universal for THz far-field imaging systems and can be used for analyzing, describing and modeling of these systems. The geometry and behavior of Gaussian beams in far-field region imply that the FWHM of the THz beams diverge as the frequencies of the beams decrease. Thus, the resolution of the measurement decreases in lower frequencies. On the other hand, the depth of penetration of THz beams decreases as frequency increases. Roughly speaking beams in sub 1.5 THz, are transmitted into integrated circuit (IC) packages and the similar packaged objects. Thus, it is not possible to use the THz pulse with higher frequencies in order to achieve higher resolution inspection of packaged items. In this paper, after developing the 3-D THz point spread function (PSF) of the scanning THz beam and then the THz imaging equation, THz images are enhanced through deconvolution of the THz PSF and THz images. As a result, the resolution has been improved several times beyond the physical limitations of the THz measurement setup in the far-field region and sub-Nyquist images have been achieved. Particularly, MSE and SSIM´ have been increased by 27% and 50% respectively. Details as small as 0.2 mm were made visible in the THz images which originally reveals no details smaller than 2.2 mm. In other words the resolution of the images has been increased by 10 times. The accuracy of the reconstructed images was proved by high resolution X-ray images.
© (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kiarash Ahi, Mehdi Anwar, "Developing terahertz imaging equation and enhancement of the resolution of terahertz images using deconvolution", Proc. SPIE 9856, Terahertz Physics, Devices, and Systems X: Advanced Applications in Industry and Defense, 98560N (26 May 2016); doi: 10.1117/12.2228680; http://dx.doi.org/10.1117/12.2228680
PROCEEDINGS
18 PAGES


SHARE
KEYWORDS
Terahertz radiation

Point spread functions

Imaging systems

Image resolution

X-rays

X-ray imaging

Absorption

RELATED CONTENT

NISAR ISRO science data processing and products
Proceedings of SPIE (May 02 2016)
Results of the development of modular microcryogenic systems
Proceedings of SPIE (October 10 2001)
C-band tomography system for imaging of cylindrical objects
Proceedings of SPIE (October 15 1999)
A Call For Standards The Demise Of Specsmanship
Proceedings of SPIE (January 17 1990)
RadSensor x ray detection by direct modulation of an...
Proceedings of SPIE (January 28 2004)

Back to Top