High resolution Fourier domain optical coherence tomography in the 2 μm wavelength range using a broadband supercontinuum source

Cheung, Chi Shing; Daniel, J. M. O.; Tokurakawa, Masaki; Clarkson, W.A.; Liang, Haida

doi:10.1364/oe.23.001992

Cited by 63 publications

(44 citation statements)

References 17 publications

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“…The OCT image only shows layers above this, as it has limited depth of penetration. To improve the penetration for highly opaque material (opaque due to scattering or absorption), long wavelength OCTs in the 2 µm wavelength regime have been developed within the framework of the same project [35,36]. For the layers above, the UHR OCT not only allows the thinnest layers to be resolved, but also makes it easier to discern the features of the thicker layers and to make more detailed interpretations with greater confidence.…”

Section: In Situ Uhr Oct Imaging Of An Old Master Paintingmentioning

confidence: 99%

Ultra-high resolution Fourier domain optical coherence tomography for old master paintings

Cheung¹,

Spring²,

Liang³

2015

Opt. Express

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Abstract:In the last 10 years, Optical Coherence Tomography (OCT) has been successfully applied to art conservation, history and archaeology. OCT has the potential to become a routine non-invasive tool in museums allowing cross-section imaging anywhere on an intact object where there are no other methods of obtaining subsurface information. While current commercial OCTs have shown potential in this field, they are still limited in depth resolution (> 4 μm in paint and varnish) compared to conventional microscopic examination of sampled paint cross-sections (~1 μm). An ultrahigh resolution fiber-based Fourier domain optical coherence tomography system with a constant axial resolution of 1.2 μm in varnish or paint throughout a depth range of 1.5 mm has been developed. While Fourier domain OCT of similar resolution has been demonstrated recently, the sensitivity roll-off of some of these systems are still significant. In contrast, this current system achieved a sensitivity roll-off that is less than 2 dB over a 1.2 mm depth range with an incident power of ~1 mW on the sample. The high resolution and sensitivity of the system makes it convenient to image thin varnish and glaze layers with unprecedented contrast. The non-invasive 'virtual' cross-section images obtained with the system show the thin varnish layers with similar resolution in the depth direction but superior clarity in the layer interfaces when compared with conventional optical microscope images of actual paint sample cross-sections obtained microdestructively.

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Section: In Situ Uhr Oct Imaging Of An Old Master Paintingmentioning

confidence: 99%

Ultra-high resolution Fourier domain optical coherence tomography for old master paintings

Cheung¹,

Spring²,

Liang³

2015

Opt. Express

Self Cite

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“…Techniques involved-multispectral reflectography [1][2][3][4][5][6][7][8][9][10][11][12][13][14], colorimetry [15][16][17][18][19][20], laser scanning microprofilometry [21][22][23][24][25][26][27][28][29][30], and optical coherence tomography (OCT) [31][32][33][34][35][36][37][38][39][40][41][42][43][44]-allowed for a non-invasive quantitative analysis of significant alterations resulting from the cleaning process, while enabling the restorer/conservator to objectively assess the overall outcome.…”

Section: Introductionmentioning

confidence: 99%

Application of non-invasive optical monitoring methodologies to follow and record painting cleaning processes

et al. 2015

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The cleaning of painted artworks, i.e. the critical operation whereby materials are selectively removed from a painted surface by partial thinning or complete elimination of varnish, is one of the most debated conservation operations, being an irreversible process, which may result in chromatic and morphological variations in the painted surface. Due to ageing, the upper layer is subject to darkening and yellowing because of blanching and fading from ultraviolet exposure, dust deposition, and overpainted layers due, for instance, to restoration interventions. This degradation can either alter the original appearance of painting polychromy or cause mechanical failure of the finishes. To address these adverse conditions, a process of examination and analysis is critical to the definition and interpretation of the varnish layer. When investigating the ageing process of old paintings, it is of great importance to obtain insight into the painting technique as practiced in the past, and the first step in gaining this knowledge is, to a large extent, based on the study of the varnish film. An effective control of the process and objective evaluation of its outcome requires therefore instrumental/analytical support. The present study illustrates the successful application of non-invasive optical techniques-such as colorimetry, multispectral reflectography, laser scanning micro-profilometry, and optical coherence tomography-to the monitoring of an Italian fourteenth-century painting cleaning process. Results presented here confirm that optical techniques play a pivotal role in artwork diagnostics, especially with regard to conservation operations, while also indicating their validity when applied to the monitoring of the cleaning process.

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“…A recent AHRC/EPSRC research project developed OCT instrumentation optimised towards cultural heritage applications [10,11] . This included an ultra-high-resolution OCT (UHR OCT) with an axial resolution of 1.2 microns (in glass) for the highest resolution to distinguish thin layers [10] and a longwavelength OCT with a central wavelength of 1960 nm for deeper penetration into highly scattering material [11] . In this work, UHR OCT was used to examine the gel layers and internal structures of the enamel.…”

Section: Optical Coherence Tomographymentioning

confidence: 99%

Using non-invasive non-destructive techniques to monitor cultural heritage objects

Thickett¹,

Cheung²,

Liang³

et al. 2017

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High resolution Fourier domain optical coherence tomography in the 2 μm wavelength range using a broadband supercontinuum source

Cited by 63 publications

References 17 publications

Ultra-high resolution Fourier domain optical coherence tomography for old master paintings

Ultra-high resolution Fourier domain optical coherence tomography for old master paintings

Application of non-invasive optical monitoring methodologies to follow and record painting cleaning processes

Using non-invasive non-destructive techniques to monitor cultural heritage objects

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