Gorgias – Reflectance Spectroscopy system

Gorgias – Reflectance Spectroscopy system

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Application: woodcut prints

Learn more about this application.

We have developed Gorgias, the Reflectance Spectroscopy System for art professionals. It uses a simple software and has plenty of features specifically designed for art examination.

In the analysis of polychrome artworks, among the techniques available in a portable version, Reflectance Spectroscopy (RS) has been established as a powerful one for the identification of pigments. The peculiar advantage of this method with respect to the other spectroscopies most commonly used, such as XRF and Raman, is that the RS equipment can be assembled with relatively low-cost components.Reflectance Spectroscopy shows, for each wavelength, the ratio between the intensity of the reflected light and the incident light, measured with respect to a standard white reference (reflectance). The reflectance spectra provide information useful for the identification of pigments.

In brief

Reflectance Spectroscopy shows, for each wavelength, the ratio between the intensity of the reflected light and the incident light, measured with respect to a standard white reference (reflectance). The reflectance spectra provide information useful for the identification of pigments.

Gorgias, our Reflectance Spectroscopy System designed for the examination of Art and Archaeology.

Gorgias Reflectance Spectroscopy System has 3 components. A professional Reflectance spectrometer, a convenient Reflectance fiber probe, and a compact Light Source.  The Reflectance Spectrometer covers the spectral range 300-1000 nm with 2 nm resolution. It has a new 16 bits electronics for better signal and less noise. You can plug it directly to your laptop with a simple USB cable and start to analyze artworks. Bring it with you for your field projects, it weighs just 430 grams and fits in your palm. At its heart is a linear array featuring 3648 pixels, for high-quality professional reflectance spectra. The system allows measuring practical in any positions thanks to its convenient reflectance fiber probe.

Gorgias, who was him?

We name our tools after famous scientists, artists, and writers that enriched Sicily’s long history.  Gorgias (c. 485 – c. 380 BC) was a Greek sophist and pre-Socratic philosopher and rhetorician who was a native of Leontini in Sicily. Along with Protagoras, he forms the first generation of Sophists. His chief claim to recognition is that he transplanted rhetoric from his native Sicily to Attica. He is considered to be one of the founders of sophism, a movement traditionally associated with philosophy, that emphasizes the practical application of rhetoric toward civic and political life.

What makes Gorgias unique for Art examination?

Mount for Photographic tripods

Only Gorgias has a mount for photographic tripods, just as a camera. How convenient! We work on scaffoldings and on-site, not just in laboratories, so we need to secure our spectrometer while taking the measurements.

Simple software

Acquire and interpret reflectance spectra with our simple custom software for art professionals. It has just a few key buttons to make the workflow fast and easy. Just what we need. The complete software suite with much more functions is also provided with Gorgias. You can switch to one or the other at any time.

Standards for calibration

 Gorgias brings on his top a calibration card and a set of selected historical pigments to double check the system is working correctly.

Free Spectral library of historical and modern pigments 

The software contains the reflectance spectra library of the historical pigments selected in Pigments Checker. You can compare immediately your acquired spectrum with our growing database. It is free and comes with the Gorgias software.

Adapter for Imaging filters 

Gorgias comes with our special adaptor to measure transmittance curves of Imaging filters (technical photography filters and multispectral imaging bandpass filters). The art professionals using Imaging methods for the examination of art and archaeology need this adapter to measure or verify the transmittance of their filters.

CHSOS protective sheet

Use this special sheet to protect the art you are analyzing and still get perfect reflectance spectra.

Technical specifications

Spectrometer
Weight: 430 grams
Dimensions: 102 mm x 84 mm x 59 mm
Detector: Toshiba TCD1304DG linear array (no interference pattern)
Detector spectral range: 300 – 1000 nm (100 microns slit)
Pixels: 3648
Pixel size: 8 um x 200 um
Pixel well depth: 100,000 electrons
Signal-to-noise ratio: 400:1 (10000:1 with averaging)
A/D resolution: 16 bit
Fiber optic connector: SMA 905 to 0.22 numerical aperture single-strand optical fiber.
Diffraction order sorting filter: included
Exposure time: 10 us – 60 s
CCD reading time: 14 ms
Power consumption: 100mA @ 5V from USB interface
Onboard memory capacity: 64 spectra
Data transfer speed: 200 ms / 100 ms (2 points binding)
Computer interface: USB 2.0, HID 2.0
Operational system: Windows 10 /Windows 8 / Windows 7 / Vista / XP ; 32/64b
Software: application software, driver,
Hardware: USB cable

Reflection fiber probe
Stainless steel tubing for extra strength. 7 x 600 microns core fibers (6 excitation fibers, 1 collection fiber). It is 1 meter long and it has a 45 degr. adapter for reflectance measures.

Light Source
Dimension (LxWxH): 90 mm x 80 mm x 31 mm
Weight: 70 g
Light source: 10W halogen lamp
Cooling: active, fan, 12 VDC, 25×10 mm
Power: AC-DC transformer, 100 – 240 VAC, Voltage output: 12 VDC
Spectral range: 300 – 1000 nm (halogen lamp)

FAQ

Q: I am worried about the light level and temperature rise at the surface of the object that you are getting using the 10W halogen source in the Gorgias. I think this can be of some concern, particularly with in-situ analysis of pigments on works on paper. Do you have measurements for light and temperature at the object surface that you could share?
R: The system uses a 10W halogen lamp and, as you observed, this lamp generates heat. Though, the system uses fiber optics for probing and so the hot lamp can be kept conveniently almost 1 meter from the subject. Furthermore, fiber optics do not transfer heat, just the radiation between the near UV and the near IR. This radiation is low because the fiber optics probe just collect a tiny fraction of the radiation emitted by the lamp and deliver it to the sample. We measure it and it is about 200 lux. To understand the magnitude of this value we can consider that standard Office illumination is around 300-500 lux.

References

Setup and calibration

Applications

How to identify pigments on woodcut prints using Gorgias.

Application notes