Advances in Terahertz Imaging
Arijit Saha
Abstract Since the discovery of photography in the mid-1820s, imaging technology
has moved far beyond the visible wavelength range. On one hand x-ray radiography
is such an imaging technique which uses subatomic wavelengths, whereas on the
other hand radars employ waves with wavelengths of several metres. However, it is
seen that in last several years the field of terahertz imaging technology has become
an area of interest, due to its various advantages. Actually discovery of new technologies in generation and detection of terahertz radiation have revolutionized this
field. Promising applications for terahertz imaging, spectroscopy and sensing have
generated much of this interest. By terahertz, generally the electromagnetic spectrum
within frequency range of 0.1-10 THz is meant, which corresponds to 3000-30 μm.
Terahertz waves are non-ionizing and non-invasive and hence have no risk for living
organisms. Also they can provide images which are comparable to x-ray images.
Though some of the techniques of THz imaging have been borrowed from wellestablished techniques like x-ray computed tomography, synthetic aperture radar
etc., but several techniques have been exclusively developed for terahertz imaging.
Compared to microwaves the THz radiation has much smaller wavelengths and thus
provides higher image resolution. However, due to long wavelengths of THz radiation compared to visible wavelengths, far-field imaging using THz radiations has low
resolution compared to optical systems. It is found that THz imaging has tremendous
potential in applications like security screening, inspection of foods, inspection of
semiconductors, pharmaceutical inspection, 2D and 3D imaging, including medical
diagnosis to name a few.
Keywords THz-TDS · Reflection spectroscopy · Transmission spectroscopy ·
THz pulsed imaging
A. Saha (B)
Department of Electronics and Communication Engineering, B. P. Poddar Institute of
Management and Technology, Kolkata, India
e-mail: arijit_sh@yahoo.com
© Springer Nature Singapore Pte Ltd. 2020
A. Biswas et al. (eds.), Emerging Trends in Terahertz Solid-State Physics and Devices,
https://doi.org/10.1007/978-981-15-3235-1_10
143
Arijit Saha
Abstract Since the discovery of photography in the mid-1820s, imaging technology
has moved far beyond the visible wavelength range. On one hand x-ray radiography
is such an imaging technique which uses subatomic wavelengths, whereas on the
other hand radars employ waves with wavelengths of several metres. However, it is
seen that in last several years the field of terahertz imaging technology has become
an area of interest, due to its various advantages. Actually discovery of new technologies in generation and detection of terahertz radiation have revolutionized this
field. Promising applications for terahertz imaging, spectroscopy and sensing have
generated much of this interest. By terahertz, generally the electromagnetic spectrum
within frequency range of 0.1-10 THz is meant, which corresponds to 3000-30 μm.
Terahertz waves are non-ionizing and non-invasive and hence have no risk for living
organisms. Also they can provide images which are comparable to x-ray images.
Though some of the techniques of THz imaging have been borrowed from wellestablished techniques like x-ray computed tomography, synthetic aperture radar
etc., but several techniques have been exclusively developed for terahertz imaging.
Compared to microwaves the THz radiation has much smaller wavelengths and thus
provides higher image resolution. However, due to long wavelengths of THz radiation compared to visible wavelengths, far-field imaging using THz radiations has low
resolution compared to optical systems. It is found that THz imaging has tremendous
potential in applications like security screening, inspection of foods, inspection of
semiconductors, pharmaceutical inspection, 2D and 3D imaging, including medical
diagnosis to name a few.
Keywords THz-TDS · Reflection spectroscopy · Transmission spectroscopy ·
THz pulsed imaging
A. Saha (B)
Department of Electronics and Communication Engineering, B. P. Poddar Institute of
Management and Technology, Kolkata, India
e-mail: arijit_sh@yahoo.com
© Springer Nature Singapore Pte Ltd. 2020
A. Biswas et al. (eds.), Emerging Trends in Terahertz Solid-State Physics and Devices,
https://doi.org/10.1007/978-981-15-3235-1_10
143