Advanced Scientific Devices
The instruments employed by Art-Test are the result of a thorough and complex study carried out by experts with wide experience in this field, with the objective of optimizing both performance and portability.
This means that they can travel and be where you want them to be!
Some of the appliances Art-Test employs have been designed and realized in-house, thanks to the know-how and expertise acquired by its professionals and by our partner companies, specialized in scientific instruments, as well as to the cooperation with research institutes.
Upon request we develop and commercialize dedicated instruments, ask us for a quotation!
It is also possible to rent out some of our devices!
This is a partial list of the unique range of scientific instruments we use for our investigations:
Art-Test IntraVedo scanner at work on the wonderful Pala Nerli by Filippino Lippi, in Lisa Venerosi restoration lab in Florence
IntraVedo IR Scanner
Possibly the best device on the market for infrared reflectography, is our custom developed, unique and high performance InGaAs scanner.
Our device consists of a motorized planar scanner equipped with an InGaAs sensor. It can acquire high (16 pt mm2) and very high (64pt mm2) resolution digital reflectographies with high tonal dynamics (12 bit/pixel). It features a light modular structure, with respect to the wide surface that can be acquired with one single scan (up to 6.5 m2.).
The performances of this system are much higher compared to Vidicon or CCDs camera and enable a better readability of the acquired images. The resulting images do not require any post-processing since they do not suffer from any geometric distortion, uneven illumination effects, vignetting, etc.
Technical data of the Single Point Scanner for Digital IR Reflectography
– IR sensor: InGaAs Photodiode, spectral sensitivity 0.8 – 1.7 micron
– Lighting: 2 halogen lamps 10 W
– Spatial Resolution of Scanned Area 101,6 dpi
– Reflectogram gray levels: 12 bit/pixel resolution
– Overall amplitude XYZ Area Analysis in a single acquisition: 1.8 x 3.8 m
– Acquisition speed: about 1h30’/m2
– Modular and transportable device, easy to assemble
– Light structure, easy to transport
– External stabilized power supply 24 V
– Computer controlled
– Proprietary software
Multispectral/Hyperspectral camera system
Multispectral and hyperspectral imaging of painted surfaces is a well established method, stemming from years of research in e.g. remote sensing, to detect, map and identify different physical behaviors. The performance depends on the kind of spectral range, on the camera and on the filters used.
Art-Test has a long history of research and application in this domain, being one of the first company to master such a method (check also our scientific publication and the data processing page), and has developed several techniques, tailored to give answer to different queries.
Multispectral images in the near infrared range provide an unique method to investigate a painted surface and the layers beneath. It can be used e.g. to investigate the layering structure and search for an underdrawing that is elusive to other detection methods, e.g. when traced with a red pencil or other materials different from carbon based ones.
Multispectral images in the visible range can be used for accurate colorimetry and color image reproduction because the color-matching functions of the human visual system are described more precisely by combining the sensitivity functions of a multispectral system then by using RGB camera sensitivity.
The multispectral data achieved can be also used to estimate surface spectral reflectance, which is a inherent physical property of the artwork surface. In this way we infer information about the nature and the chemical composition of the materials on them, and with this system this information can be acquired at the same time on the whole surface of the object.
Although not as accurate as other scientific methods (please be very careful accepting pigment identification using this method, as proposed by some other pseudo scientific labs), it can provide a useful guidance to map similar pigment composition areas, and restoration areas.
Multispectral imaging can also be very useful for UV fluorescence imaging. The possibility of recording calibrated emission color can be very important in order to identify the kind of material emitting such signal.
Non calibrated UV fluorescence images are often hard to read, as they have a strong blue component and are not very defined, due to the low intensity of the fluorescence signal recorded.
The calibrated multispectral methods offers the possibility of accurate colorimetry and color image reproduction of such low signal images as well, and to fully remove any visible stray light, both from the UV light and from the environment.
Best results are obtained using the best devices
The devices we used are cooled CCD scientific cameras, equipped with a set of interferential filters and special lamps.
The CCD cameras we have chosen are mainly characterized by high sensitivity. The are built around scientific CCD sensors with high quantum efficiency. Proprietary technology is then able to use the sensor to the maximum of this intrinsic performances. Some of the key features:
- Scientific Cooled CCD camera
- Sensor: UV enhanced, high quantum efficiency till 1100 nm, front side illuminated transparent gate true two phase technology sensor 3072×2048 pixels, 9x9micron.
- Full Well Capacity: 100 ke
- Dark Current: 0.5 e-/pixelsec
- Quantum Efficency a 450,550,650 nm: 40, 55, 64
- Fill Factor: 100%
- 16-bit electronics at very low noise (std<1)
- CCD soft hyperdrive, advanced technique of sensor management which can exploit at the maximum its intrinsic characteristics
- High sensor temperature stabilization (±0.1 °C) to provide a high reproducibility of sensor’s performance
A very new technique. We were the first to present the new concept of XRF scanning at Salone del Restauro in 2012. Since then a few universities have also proposed similar devices.
Our instruments offers very high performance, reaching the resolution of 0,25 mm both horizontally and vertically. Being fully software controlled the integration time can be customized.
This new technique can be used to produce maps of the the various chemical elements and therefore help identify the pigments used both for the superficial and the hidden layers (when present)
Broadband Vidicon System
Digitized B/W acquisition performed with a Vidicon tube, with sensitivity till 2200 nm.
We one of the few companies equipped with such device.
It is a camera mounting a lead sulfide detector (PbS): the first instrument traditionally used for digital reflectography to replace the photograph film. It has a spectral sensitivity up to approximately 2.2 µm. Widely used in the past, today, due to the reduced spatial resolution (720×480 pixels), the limited tonal resolution and some geometric distortion (due to the optical aberrations introduced by the lenses), this device is mainly used for preliminary investigations, when the paint layer is particularly thick or non-transparent to shorter wavelengths, or when the environmental situation does not consent the use of any other device, like eg. when exploring ceilings.
Xrays Imaging System
X-Radiography is an imaging technique applicable for the examination of any art object on a movable support that allows X-Ray, to run through. Thanks to the high penetration power of the X-ray, which are high-energy electromagnetic waves able to traverse the artwork in all its thickness, X-radiography is a fundamental method for the visual perception of the integral (surface and inner) structure of objects and it is well established as art diagnostic methods since the discovery of Xrays in 1896.
We can choose between employing traditional Xrays plates with a very high resolution or the more modern Digital Direct Xrays system.
X-Ray Fluorescence (XRF) is a technique of elemental analysis based on the emission of characteristic X-rays, following the irradiation of the sample with a primary beam of high-energy X-rays or gamma rays. The term fluorescence refers to phenomena in which the absorption of higher-energy radiation results in the re-emission of lower-energy radiation. Thanks to this technique a number of pigments can be identified in a non-destructive manner.
Art-Test employs different X-Ray Fluorescence Devices depending on the characteristics of the artwork to be analysed, in order to assure the best performance
– 8- 14 micron spectral range.
– Detector type: Focal Plane Array microbolometer 320×240 pixels, cooled.
– Thermal sensibility range: -20 e 300°C.
– Accuracy: 2° below 100°C and 2% above.
– Resolution: 0,08°C.
– Equipped with 22 mm objective. E.g. it allows 5.37 x 4,03 acquisition area at 10 m distance.
IR Digital Camera
Digital Photocamera Sony F828 Infrared option
Digital IR B/W acquisition performed with a commercial CCD camera, with nominal sensitivity till 1100 nm.
– 2/3″ type (8.8 x 6.6 mm) RGBE color filter array (for improved colour response)
– 2.7 µm pixel pitch
– Effective pixels 8.0 M
– Carl Zeiss T 28 28 – 200 mm equiv. (7x zoom)
– F2.0 – F2.8.
Portable videoCCD microscope
- Adjustable focus and magnification
- Magnification up to 250x
- Software switchable built-in LED
- Illumination in visible range and UV 400nm
- Software measurement capability
Optical and Electronic Microscopy
Optical Microscopy (CS)
The morphology of a great variety of painting materials can be investigated, characterized and documented using an ordinary white light microscope or a polarized light microscope. The color of pigment grains, their luster, density and morphology can be observed in both reflected and transmitted ordinary white light. Under polarized light their identification is made possible through their isotropic and anisotropic characteristics, due to their crystallographic structure. Optical microscopy, in both transmission and reflection mode, represents the most widely used investigation tool for thin and paint cross—section analyses. In these cases, observation under ultra violet (UV) light source allows a better localization and documentation of the specific organic materials showing fluorescence effects when excited by UV lights (binders, varnishes, organic coatings, etc). During the last decades, the study of paintings has associated light microscopy to other complementary spectroscopic molecular techniques, in order to chemically characterize and spatially locate painting grounds, pigments and binding media in paint cross-sections.
Ultraviolet fluorescence microscopy allows a better differentiation among original and repainted layers, as well as determining the presence and spatial localization of external varnishes/finishers. Auto- fluorescence phenomena are also shown by some pigments such as madder lake, which has an intense fluorescence and is detectable in cross-section observed under UV light illumination.
Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDS)
Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDS) is used for imaging and analyzing (micro) samples from works of art. SEM/EDS can be used to study al kinds of materials, both organic and inorganic. The SEM is a type of electron microscope that images the sample surface by scanning it with a high-energy beam of electrons. The electrons interact with the atoms that make up the sample producing signals that contain information about the sample’s surface topography and chemical composition.
|Optical Microscope||Olympus BX-41, fibers Optika Microscopes, lampada UV Olympus U-RFL-T, filter cube Olympus U-MWU (330-385 nm).|
|SEM-EDS||XVP-SEM ZEISS EVO 50 with LaB6 filament|