Innovative non-invasive analysis techniques for cultural heritage using terahertz technology
TL;DR: Terahertz spectroscopy and THz imaging techniques are expected to have great potential for carrying out the non-invasive analysis of artworks as discussed by the authors, and they can perform three-dimensional material mapping non-destructively by spectroscopic imaging.
About: This article is published in Comptes Rendus Physique.The article was published on 2010-08-01. It has received 84 citations till now.
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TL;DR: In this paper, the principles of tomography for terahertz Computed tomography (CT), tomosynthesis (TS), synthetic aperture radar (SAR), and time-of-flight (TOF) tomography are established.
Abstract: Terahertz and millimeter waves penetrate various dielectric materials, including plastics, ceramics, crystals, and concrete, allowing terahertz transmission and reflection images to be considered as a new imaging tool complementary to X-Ray or Infrared. Terahertz imaging is a well-established technique in various laboratory and industrial applications. However, these images are often two-dimensional. Three-dimensional, transmission-mode imaging is limited to thin samples, due to the absorption of the sample accumulated in the propagation direction. A tomographic imaging procedure can be used to acquire and to render three-dimensional images in the terahertz frequency range, as in the optical, infrared or X-ray regions of the electromagnetic spectrum. In this paper, after a brief introduction to two dimensional millimeter waves and terahertz imaging we establish the principles of tomography for Terahertz Computed tomography (CT), tomosynthesis (TS), synthetic aperture radar (SAR) and time-of-flight (TOF) terahertz tomography. For each technique, we present advantages, drawbacks and limitations for imaging the internal structure of an object.
215 citations
Additional excerpts
...A similar study was presented by Fukunaga and coworkers [127] to quantify the transmittance of several pigments....
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TL;DR: A review of the advances that have been made to establish terahertz applications in the cultural heritage conservation sector over the last several years is presented in this paper, which includes material spectroscopy, 2D and 3D imaging and tomographic studies.
Abstract: The authors present a review of the advances that have been made to establish terahertz applications in the cultural heritage conservation sector over the last several years. This includes material spectroscopy, 2D and 3D imaging and tomographic studies, using a broad range of terahertz sources demonstrating the breadth and application of this burgeoning community.
200 citations
Cites background from "Innovative non-invasive analysis te..."
...Based on their spectra, it was determined that there are two principle cobalt components, aureolin K Co NO H O) and cobalt blue CoAl O , which have distinct spectral signatures in the terahertz region [see Fig....
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TL;DR: In this article, the authors used terahertz time-gated spectral imaging to extract occluded text from paper pages with subwavelength spacing, which may be used to non-destructively detect and study defects and structures within materials.
Abstract: Terahertz radiation may be used to nondestructively detect and study defects and structures within materials. Here the authors use terahertz time-gated spectral imaging to extract occluded text from paper pages with subwavelength spacing.
144 citations
TL;DR: This review focuses on mobile non-destructive subsurface imaging and depth profiling techniques, which allow for the in-situ investigation of easel paintings, i.e. paintings on a portable support.
98 citations
Journal Article•
TL;DR: The sub-picosecond time resolution along with spectral resolution provided by terahertz time-domain spectroscopy is exploited to computationally extract occluding content from layers whose thicknesses are wavelength comparable.
Abstract: Spatial resolution, spectral contrast and occlusion are three major bottlenecks for non-invasive inspection of complex samples with current imaging technologies. We exploit the sub-picosecond time resolution along with spectral resolution provided by terahertz time-domain spectroscopy to computationally extract occluding content from layers whose thicknesses are wavelength comparable. The method uses the statistics of the reflected terahertz electric field at subwavelength gaps to lock into each layer position and then uses a time-gated spectral kurtosis to tune to highest spectral contrast of the content on that specific layer. To demonstrate, occluding textual content was successfully extracted from a packed stack of paper pages down to nine pages without human supervision. The method provides over an order of magnitude enhancement in the signal contrast and can impact inspection of structural defects in wooden objects, plastic components, composites, drugs and especially cultural artefacts with subwavelength or wavelength comparable layers.
87 citations
References
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Book•
12 Jul 1985
TL;DR: In this paper, E.D. Palik and R.R. Potter, Basic Parameters for Measuring Optical Properties, and W.W.Hunter, Measurement of Optical Constants in the Vacuum Ultraviolet Spectral Region.
Abstract: VOLUME ONE: Determination of Optical Constants: E.D. Palik, Introductory Remarks. R.F. Potter, Basic Parameters for Measuring Optical Properties. D.Y. Smith, Dispersion Theory, Sum Rules, and Their Application to the Analysis of Optical Data. W.R. Hunter, Measurement of Optical Constants in the Vacuum Ultraviolet Spectral Region. D.E. Aspnes, The Accurate Determination of Optical Properties by Ellipsometry. J. Shamir, Interferometric Methods for the Determination of Thin-Film Parameters. P.A. Temple, Thin-Film Absorplance Measurements Using Laser Colorimetry. G.J. Simonis, Complex Index of Refraction Measurements of Near-Millimeter Wavelengths. B. Jensen, The Quantum Extension of the Drude--Zener Theory in Polar Semiconductors. D.W. Lynch, Interband Absorption--Mechanisms and Interpretation. S.S. Mitra, Optical Properties of Nonmetallic Solids for Photon Energies below the Fundamental Band Gap. Critiques--Metals: D.W. Lynch and W.R. Hunter, Comments of the Optical Constants of Metals and an Introduction to the Data for Several Metals. D.Y. Smith, E. Shiles, and M. Inokuti, The Optical Properties of Metallic Aluminum. Critiques--Semiconductors: E.D. Palik, Cadium Telluride (CdTe). E.D. Palik, Gallium Arsenide (GaAs). A. Borghesi and G. Guizzetti, Gallium Phosphide (GaP). R.F. Potter, Germanium (Ge). E.D. Palik and R.T. Holm, Indium Arsenide (InAs). R.T. Holm, Indium Antimonide (InSb). O.J. Glembocki and H. Piller, Indium Phosphide (InP). G. Bauer and H. Krenn, Lead Selenide (PbSe). G. Guizzetti and A. Borghesi, Lead Sulfide (PbS). G. Bauer and H. Krenn, Lead Telluride (PbTe). D.F. Edwards, Silicon (Si). H. Piller, Silicon (Amorphous) (-Si). W.J. Choyke and E.D. Palik, Silicon Carbide (SiC). E.D. Palik and A. Addamiano, Zinc Sulfide (ZnS). Critiques--Insulators: D.J. Treacy, Arsenic Selenide (As 2 gt Se 3 gt ). D.J. Treacy, Arsenic Sulfide (As 2 gt S 3 gt ). D.F. Edwards and H.R. Philipp, Cubic Carbon (Diamond). E.D. Palik and W.R. Hunter, Litium Fluoride (LiF). E.D. Palik, Lithium Niobote (LiNbO 3 gt ). E.D. Palik, Potassium Chloride (KCl). H.R. Philipp, Silicon Dioxide (SiO 2 gt ), Type ( (Crystalline). H.R. Philipp, Silicon Dioxide (SiO 2 gt ) (Glass). gt H.R. Philipp, Silicon Monoxide (SiO) (Noncrystalline). H.R. Philipp, Silicon Nitride (Si 3 gt N 4 gt ) (Noncrystalline). J.E. Eldridge and E.D. Palik, Sodium Chloride (NaCl). M.W. Ribarsky, Titanium Dioxide (TiO 2 gt ) (Rutile).
17,491 citations
TL;DR: An overview of the status of the terahertz technology, its uses and its future prospects are presented in this article, with a focus on the use of the waveband in a wide range of applications.
Abstract: Research into terahertz technology is now receiving increasing attention around the world, and devices exploiting this waveband are set to become increasingly important in a very diverse range of applications. Here, an overview of the status of the technology, its uses and its future prospects are presented.
5,512 citations
01 Jan 2003
TL;DR: In this paper, the authors describe the use of photomixers for continuous-wave terahertz radiation and apply them to time domain ranging and scattering in bio-medical applications.
Abstract: Spectroscopy in the Terahertz Spectral Region.- Terahertz Imaging.- Free-Space Electro-Optic Techniques.- Photomixers for Continuous-Wave Terahertz Radiation.- Applications of Optically Generated Terahertz Pulses to Time Domain Ranging and Scattering.- Bio-medical Applications of THz Imaging.- Electronic Sources and Detectors for Wideband Sensing in the Terahertz Regime.
850 citations
Book•
16 Mar 2000
TL;DR: The history of infrared spectroscopy can be found in this paper, where the authors present an overview of the history of the infrared spectra and its application in art and art conservation.
Abstract: Part 1 History of infrared spectroscopy: additional reading. Part 2 Infrared absorption theory: electromagnetic radiation absorption theory infrared spectra infrared regions summary additional reading. Part 3 Sample collection and preparation: sampling methodology sampling implementation sample collection and preparation procedures summary additional reading. Part 4 Infrared analysis methods: infrared transmission measurements infrared reflection measurements infrared microspectroscopy summary additional reading. Part 5 Spectral interpretation: infrared spectra qualitative analysis identification of materials used in art and art conservation quantitative analysis mathematical manipulations of spectra summary additional reading. Part 6 Case studies: identification and characterization of materials deterioration studies the case studies case study 1 - ultramarine pigments case study 2 - creosote lac resin case study 3 - Chumash Indian paints case study 4 - varnish on a desk case study 5 - reflection versus transmission case study 6 -painting cross sections case study 7 - vikane case study 8 -parylene case study 9 - cellulose nitrate sculptures 10 - Dead Sea scrolls summary appendices.
512 citations
TL;DR: In this paper, the phase and amplitude of a terahertz time-domain spectroscopy (THz-TDS) pulse at each frequency can be determined by using a digital holography method.
Abstract: Terahertz time-domain spectroscopy (THz-TDS) is a coherent measurement technology. Using THz-TDS, the phase and amplitude of the THz pulse at each frequency can be determined. Like radar, THz-TDS also provides time information that allows us to develop various three-dimensional THz tomographic imaging modalities. The three-dimensional THz tomographic imagings we investigated are: terahertz diffraction tomography (THz DT), terahertz computed tomography (THz CT), THz binary lens tomography and THz digital holography. THz DT uses the THz wave as a probe beam to interact with a target, and then reconstructs the three-dimensional image of the target using the THz waves scattered by the target. THz CT is based on geometrical optics and inspired by x-ray CT. THz binary lens tomography uses the frequency dependent focal length property of binary lenses to obtain tomographic images of an object. THz three-dimensional holography combines radar and conventional holography technology. By separating the multiple scattered THz waves of different scattering orders, we used a digital holography method to reconstruct the sparsely distributed scattering centres. Three-dimensional THz imaging has potential in such applications as non-destructive inspection. The interaction between a coherent THz pulse and an object provides rich information about the object under study; therefore, three-dimensional THz imaging is a very useful tool to inspect or characterize dielectric and semiconductor objects. For example, three-dimensional THz imaging can be used to detect and identify the defects inside a space shuttle insulation tile.
257 citations