Terahertz frequency-wavelet domain deconvolution for stratigraphic and subsurface investigation of art painting

Abstract

Terahertz frequency-wavelet deconvolution is utilized specifically for the stratigraphic and subsurface investigation of art paintings with terahertz reflective imaging. In order to resolve the optically thin paint layers, a deconvolution technique is enhanced by the combination of frequency-domain filtering and stationary wavelet shrinkage, and applied to investigate a mid-20th century Italian oil painting on paperboard, After Fishing, by Ausonio Tanda. Based on the deconvolved terahertz data, the stratigraphy of the painting including the paint layers is reconstructed and subsurface features are clearly revealed, demonstrating that terahertz frequency-wavelet deconvolution can be an effective tool to characterize stratified systems with optically thin layers.

Time‐domain imaging system in the terahertz range for immovable cultural heritage materials

“…A visualisation of the stratigraphy can be achieved by accumulating a series of A‐scans along a line (so‐called a B‐scan). Thus, a B‐scan gives indications of stratified boundaries in the material and features inside the sample, such as cracks, air gaps, or layers, with a depth resolution of better than 100 μm . An illustration of such a result is given in Figures and .…”

Visualization of subsurface damage in woven carbon fiber-reinforced composites using polarization-sensitive terahertz imaging

“…Our previous work has demonstrated the power of THz deconvolution to resolve overlapping echoes associated with closely-spaced features in depth [18][19][20]. In short, THz deconvolution aims to reconstruct the impulse-response function, that is intrinsic to the sample and independent of the THz pulse employed, which should ideally consist of a sequence of ideal impulses corresponding to reflections from the interfaces of a stratified system [21].…”

A Non-Linear Correction Method for Terahertz LFMCW Radar

“…Terahertz (THz) testing is a novel and promising measurement technique which offers new solutions for artworks conservation [1][2][3], products quality control [4][5][6][7][8][9], and standoff personnel screening [10][11][12][13], etc. This technique allows for the contactless and high-resolution inspection of both the object's surface and inner structure at any production stage and even in field use [2,3,6,7,10,14,15].…”

“…Terahertz (THz) testing is a novel and promising measurement technique which offers new solutions for artworks conservation [1][2][3], products quality control [4][5][6][7][8][9], and standoff personnel screening [10][11][12][13], etc. This technique allows for the contactless and high-resolution inspection of both the object's surface and inner structure at any production stage and even in field use [2,3,6,7,10,14,15]. With the demanding requirement of achieving highresolution range profiles, the linear frequency modulated continuous wave (LFMCW) chirp is extensively exploited to transmit large bandwidth signal [6,7,[10][11][12]16], and the deramping technique is adopted for range processing to dramatically reduce the sampling frequency [6,[10][11][12]16].…”