A versatile optical profilometer based on conoscopic holography sensors for acquisition of specular and diffusive surfaces in artworks

Gaburro, Nicola; Marchioro, Giacomo; Daffara, Claudia

doi:10.1117/12.2270307

Cited by 9 publications

(16 citation statements)

References 8 publications

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“…As shown by Gaburro et al [ 26 ], by exploiting the raw total signal recorded by the detector, the different colored regions can be discriminated, point-wise in the scan step sampling grid. This way, the texture information can be accurately selected and the features of interest enhanced.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Surface microprofilometry is performed with a custom device based on conoscopic holography and scanning techniques. The prototype was specifically designed to tailor the needs of cultural heritage applications [ 26 ], where target objects (from 2D paintings to 3D artifacts) have irregular shapes, deformations, and microtextures, with heterogeneous and polychrome materials, and the measurements (absolutely noninvasive) are performed in situ.…”

Section: Materials and Methodsmentioning

confidence: 99%

“…In this work, we will perform 3D optical profilometry using a prototype, detailed later, that exploits conoscopic holography sensors to enable a versatile surface measurement with micrometric accuracy and micrometric resolution (depth and lateral) [ 26 , 27 , 28 ]. Laser scanning microprofilometry was demonstrated as effective for surface analysis in artworks (see the pioneering works [ 9 , 10 ]), including treatment monitoring [ 5 ].…”

Section: Introduction and Backgroundmentioning

confidence: 99%

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Experiencing the Untouchable: A Method for Scientific Exploration and Haptic Fruition of Artworks Microsurface Based on Optical Scanning Profilometry

Mazzocato

Daffara

2021

Sensors

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The experience of an object derives not only from the sight but also from the touch: a tactile exploration can reveal the smallest information trapped within the surface up to our tactile detective threshold. Starting from the importance of this observation in the case of works of art, this research demonstrates the use of conoscopic holography sensors for high-quality acquisition of the surface of artworks (up to the micro-scale) suitable also to 3D printing. The purpose is twofold, allowing for the tactile use of the artwork, which is otherwise impossible, for visually impaired people and for new use in regard to scientific information purposes. In detail, the workflow to obtain a 3D printed replica of multiscale and polychrome artworks suitable for the haptic fruition is validated, but the potential of the tool as an innovative resource for scientific visualization of the microsurface of the artwork for conservation issues is also demonstrated. The validation was performed on notable Italian masterpieces, such as Donatello’s “Death Cristh” bronze relief in Padua and the Tintoretto painting “St. Martial in Glory with the Saints Peter and Paul” in Venice.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Materials and Methodsmentioning

confidence: 99%

Section: Introduction and Backgroundmentioning

confidence: 99%

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Experiencing the Untouchable: A Method for Scientific Exploration and Haptic Fruition of Artworks Microsurface Based on Optical Scanning Profilometry

Mazzocato

Daffara

2021

Sensors

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“…The optical scanner microprofilometer is a prototype based on conoscopic holography depth sensors combined with a scanning system of orthogonally mounted linear stages. 7 This system allows for high resolution and accuracy in both depth (sub-micrometer order) and lateral direction (micrometer order), as well as the ability to scan regions on the order of tens of centimeters. A detailed description of the prototype can be found in the literature.…”

Section: The Optical Scanner Microprofilometermentioning

confidence: 99%

Can we unlock more information from interferometric sensors? Feasibility and performance analysis

Mazzocato,

Daffara

2023

Optics for Arts, Architecture, and Archaeology (O3A) IX

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The surface is the most representative part of an artwork and it is also the part most exposed to alterations due to interaction with the surrounding environment. Non-destructive surface monitoring is of crucial importance in preserving and conserving cultural heritage and optical interferometric techniques allow to acquire the surface structure down to the submicrometric scale. In this work, we start from laser microprofilometry based on conoscopic holography sensors to unlock a new way of measuring the surface. In the last years, this technique has proven effective for surface diagnostic in heritage science providing high-quality surface dataset on diffusive, highly reflective, and polychrome artworks. However, an open problem in profilometry is the spatial referencing of surface topography at the micrometer scale, due to the lack of references in the height data with respect to the visually readable surface. We have recently developed a solution that exploits the raw intensity signal collected by the single-point sensor (i.e. the backscattered signal of the laser diode) and the interferometric height dataset, which are intrinsically registered. This method provides additional information about material texture, color variations or artist's marks that enable spatial registration and data fusion tasks, otherwise difficult in traditional laser profilometry. In this paper we analyzed the feasibility and the performance of the whole process chain from the acquisition to the exploitation of the dual height-intensity datasets, focusing the attention on the raw intensity signal interpreted as a "raw reflectance signal". We demonstrate the effectiveness of the proposed approach by presenting results on exemplary case studies.

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“…For acquiring the surface at micrometric level we have used a custom optical micro-profilometer that has been implemented in the framework of the Scan4Reco European project [15]. The system is based on a laser conoscopic holography probe mounted on two linear micrometric stages (30 × 30 cm 2 scan size).…”

Section: Surface Measurementsmentioning

confidence: 99%

Surface micro-profilometry for the assessment of the effects of traditional and innovative cleaning treatments of silver

Daffara¹,

Gaburro²,

Marchioro³

et al. 2017

Proceedings of the International Conference LACONA XI

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In the complex procedure for the conservation of a work of art, the effective monitoring of the surface treatment is an important step in order to establish a conservation protocol. The evaluation of the effects of the cleaning requires the inspection of the outermost layer with complementary diagnostic techniques to obtain information on both materials and surface morphology. In this interdisciplinary work, a custom optical micro-profilometry device based on laser conoscopic holography was used for testing the performance of different mechanical procedures for the cleaning of silver alloy objects. Tarnishing is the main alteration phenomenon for silver alloy artworks. Even if such modification does not affect the long-term preservation of the objects, it heavily influences aesthetical features, making the removal of tarnishing one of the most important conservation treatments of the case. The mechanical cleaning procedure based on abrasive powders suspended in a liquid matrix is of widespread use. Recently, a novel dry cleaning procedure based on the use of erasers was proposed as alternative method and tested for both the efficacy of tarnishing removal and effects on the surface appearance using optical microscopy and scanning electron microscopy. However, the employed laboratory techniques cannot provide an objective measure of the roughness at micrometric scale over the sample. In this work, the effects on the surface structure of traditional and innovative silver treatments was investigated with multiscale profilometry, using scanning conoscopic holography and atomic-force microscopy. 3D surface metrology was carried out using standard areal amplitude parameters and a multiscale approach. Preliminary results are presented, addressing two aspects: 1) the validation of laser optical micro-profilometry for the diagnostics of silver objects, which are challenging due to the highly specular surface; 2) the validation of the dry-cleaning treatment based on rubbers, by adding to the previous study the complimentary analysis of the micro-surface. The results obtained on silver mockups confirm that the proposed dry cleaning methods produce surface variations less or similar to traditional methods. The optical micro-profilometry results are of particular significance since this technique is portable with wide field capability, thus allowing an in-situ use and a real monitoring of actual artwork surfaces.

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A versatile optical profilometer based on conoscopic holography sensors for acquisition of specular and diffusive surfaces in artworks

Cited by 9 publications

References 8 publications

Experiencing the Untouchable: A Method for Scientific Exploration and Haptic Fruition of Artworks Microsurface Based on Optical Scanning Profilometry

Experiencing the Untouchable: A Method for Scientific Exploration and Haptic Fruition of Artworks Microsurface Based on Optical Scanning Profilometry

Can we unlock more information from interferometric sensors? Feasibility and performance analysis

Surface micro-profilometry for the assessment of the effects of traditional and innovative cleaning treatments of silver

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