restoration introduction conclusions references setup

0 downloads 0 Views 868KB Size Report
nondestructive evaluation of painting and multilayer parts. Xue Maa,b, Kejia Wangb, Frédéric Fauqueta, Marie Rouxc, Corinna Ludovica Koch Dandoloa,.
Terahertz frequency modulated continuous wave imaging for nondestructive evaluation of painting and multilayer parts Xue Maa,b, Kejia Wangb, Frédéric Fauqueta, Marie Rouxc, Corinna Ludovica Koch Dandoloa, Patrick Mounaixa, Jean-Paul Guilleta a

University of Bordeaux, IMS Laboratory, UMR CNRS 5218 351 cours de la Libération 33405 TALENCE b Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China c L’Atelier des Renaissances, 1 allée de Gieu, 33650 SAUCATS, France

INTRODUCTION

RESTORATION

Most of the art painting measurement using

FMCW was used before restoration to detect

terahertz were done using time domain system,

some defects in the painting. Then another

but

measurement was done after restoration

Frequency

(FMCW)

modulated

system

have

continuous some

wave

advantages

(Synview ®)

Fig1. Basic principle of FMCW representing frequency of the signal as a function of time. Red curve corresponds to emited signal and blue to

Fig. 3 : Photography of the painting 78cm by 62cm

Fig. 6 : FMCW images helping art restorer to detect defects in the painting

received signal. Time of flight of electromagnetic wave

can

be

calculated

from

frequency

difference of these signals.

SETUP Fig. 7 : FMCW images after parameter extraction with fit and filtering [2] • Large scan area : 600 x 800 mm Four heads

:

two

both

receiving

and

two

emitting only

and

receiving

signals • Two frequency ranges, from 75 to 110

Fig. 4: On the left: 300GHz reflection image of the painting before restoration. The surrounded areas are air voids between pictorial layer and canvas On the right: 300GHz reflection image of the painting after first step of restoration. The surrounded areas have been restored

GHz and from 220 to 330 GHz

CONCLUSIONS We have demonstrated that Frequency Modulated Continuous Waves terahertz (300 GHz) can be proficiently used for

• The spatial resolution 3 mm at 100 GHz

detecting conservation problems such as

and 2 mm at 300 GHz

paint layer losses and subsurface cracks

• 50 to 60 dB dynamic range depending

in easel paintings.

topology and frequency

REFERENCES

Fig. 2: Photography of the painting in the FMCW system

Fig. 5 : Photography of the before, during and after restoration

L’atelier des renaissances

1. Guillet, J.-P., Roux, M., Wang, K., Ma, X., Fauquet, F., Balacey, H., Recur, B., Darracq, F. and Mounaix, P., “Art Painting Diagnostic Before Restoration with Terahertz and Millimeter Waves,” J. Infrared, Millimeter, Terahertz Waves 38(4) (2017). 2. Koch Dandolo C, Guillet JP, Ma X, Fauquet F,Roux M., Mounaix P, "Terahertz frequency modulated continuous wave imaging advanced data processing for art painting analysis", Optics Express, Accepted, to be published