Non-contact measurement & inspection F


lir thermal imaging technology is helping researchers in Italy unlock hidden text from the Herculaneum papyri, a unique collection of ancient manuscripts carbonised during the eruption of Mount Vesuvius in 79 AD. Using pulsed thermography that leverages the 2.775 MHz fast


analog lock-in input port offered by advanced Flir thermal imaging cameras, scientists are recovering writing previously invisible to the naked eye while also gaining new insight into the fragile internal structure of the documents. The vital project is being led by researchers at the Institute of Heritage Science, part of the National Research Council of Italy (CNR), who are exploring non-destructive ways to study and preserve what remains the only surviving library from the ancient Greco-Roman world. Discovered during excavations in the 18th century at the Villa dei Papiri in Herculaneum, the scrolls survived the volcanic eruption through carbonisation caused by intense heat and burial beneath volcanic material.


While this extraordinary process preserved the manuscripts, it also created major challenges for historians and conservators attempting to read and protect them.


Many of the papyri were mechanically unrolled centuries ago and mounted to supporting boards. However, the resulting fragments are extremely fragile, often heavily layered, and in many cases almost unreadable.


CONVENTIONAL IMAGING FALLS SHORT One of the principal challenges facing researchers is that both the carbonised papyrus substrate and the ink are black, making differentiation extremely difficult using conventional imaging methods as the contrast in the visible range is lost. Other more sophisticated techniques like X-ray can work, particularly in combination with artificial intelligence, but are more complex and expensive, requiring transportation of the papyri to special labs where these techniques are available. To address these challenges, conservators turned to pulsed thermography, a technique that combines controlled light excitation with high-speed thermal imaging. The method works by illuminating the papyrus with a short pulse of light and recording the resulting thermal response over time.


Surface inscriptions become visible almost immediately in the first few infrared frames after excitation because the ink absorbs light differently to the surrounding papyrus material. As heat propagates through the sample over the following seconds, deeper structural details and underlying features begin to emerge. This time-based thermal behavior provides researchers with a way to distinguish writing from substrate material.


48


FLIR THERMAL IMAGING HELPS REVEAL HIDDEN TEXT IN ANCIENT HERCULANEUM PAPYRI


Flir thermal imaging technology is helping researchers in Italy unlock hidden text from the Herculaneum papyri, a unique collection of ancient manuscripts carbonised during the eruption of Mount Vesuvius in 79 AD.


researchers to detect faint signals or minute temperature differences in materials. The researchers used dual flash lamps to generate controlled excitation while limiting temperature increases within the papyri to 2-3°C, well below any level considered harmful to the ancient material. Special filtering systems also prevented ultraviolet exposure and minimised unwanted infrared reflections. According to the project team, the high sensitivity, spatial resolution and advanced recording capabilities of the Flir X-Series proved particularly important when identifying fine thermal contrasts and preserving image clarity throughout the acquisition process. The ability to stream and record thermal data continuously without dropped frames also supported detailed post-processing and analysis using Flir Research Studio software.


Notably, the method remains entirely non-contact and non-destructive, a critical requirement when working with fragile cultural heritage artefacts that cannot be physically manipulated or removed from their historical supports.


BEYOND TEXT RECOVERY


ADVANCED THERMAL IMAGING Central to the project is the use of Flir X-Series thermal imaging cameras. Combining high-speed, high-sensitivity infrared imaging with advanced thermal management capabilities, the cameras are ideal for scientific and research environments where precision and data integrity are vital. Operating in the mid-wave infrared spectrum, Flir X-Series cameras enabled researchers to capture rapid thermal events with exceptional sensitivity, allowing subtle temperature differences between inked and non-inked areas of the papyri to become visible during pulsed thermography analysis. The X-Series features a fast analog lock-in input port designed to receive external reference signals, enabling high-speed thermal analysis at a sampling rate of 2.775 MHz. This capability allows


While the primary objective of the project involves revealing hidden text, pulsed thermography also provides valuable structural information for conservation specialists.


As heat diffuses through the papyrus over longer timescales, the thermal data begins to reveal features such as fiber patterns, overlapping layers, and adhesion points between the papyrus and its supporting board. These details help conservators better understand the physical condition of the manuscripts and identify areas where deterioration or detachment may be occurring. The ability to investigate both writing and substrate morphology from the same thermal dataset provides significant advantages for restoration planning and long-term preservation strategies. The technique is particularly useful


June 2026 Instrumentation Monthly


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72