Stained Glass of a cathedral investigated with UV light

Microscopy illumination for cathedral restoration

The Historical Monuments Research Laboratory (Laboratoire de Recherche des Monuments Historiques, LRMH) in France provides scientific and technical assistance for the conservation and restoration of historic monuments, whether they are buildings, large ornamental ensembles, or movable objects. Current projects involve SCHOTT’s lighting solution for stereo microscopy in the analysis of stained glass from cathedrals such as Notre-Dame de Paris.


LRMH is dedicated to the research of materials and their alterations. Organized in nine thematic departments, one is devoted to stained glass and assists architects and curators by providing scientific and technical support during restorations. So when Notre-Dame de Paris burned down in 2019, LRMH was immediately involved and, with its partners, set up a methodology for sorting, classifying, and inventorizing the rubble in order to study and, where possible, reuse it during the restoration phase. The Laboratory also advised the project’s management and the public institution on diagnosis of the vaults and the cleaning methods of the cathedral.

Notre-Dame de Verdun cathedral
Notre-Dame de Verdun cathedral, Picture: © LRMH


Stained glass windows pose serious conservation problems due to their fragility and direct exposure to the weather and atmospheric pollution. Analysis enables the identification of surface morphologies, alteration products, and microorganisms to determine pathologies so that advice can be given on the cleaning methods that need to be used or the choice of restoration products (gluing, consolidating, filling gaps). Prior to the restoration, previous restorations often need to be undone and organic and synthetic materials need to be removed. LRMH was looking for an appropriate lighting solution for stereo microscopy to make these remaining traces visible.


LRMH decided to go for the SCHOTT® VisiLED UV Ring Light. This ring light for stereo microscopes combines classic bright-field illumination with UV illumination, where white light and UV LEDs are alternately installed in eight segments. This LED arrangement allows objects to be examined from the same illumination angle, which significantly improves the ability to compare and reproduce the resulting images. While the homogenous white light displays samples in natural color, UV excitation reveals previously invisible parts of the sample through fluorescence. The SCHOTT MC 1100 Controller allows the ring light to switch easily between the two illumination modes.

SCHOTT UV Ring Light
The SCHOTT UV Ring Light for stereo microscopy combines classic bright-field illumination with UV illumination
Barbara Trichereau (engineer at the LRMH) and Gilles Vaillant (Product Manager at Microvision) with a UV ring light

Barbara Trichereau (Design Engineer at the LRMH) and Gilles Vaillant (Product Manager at Microvision Instruments)

Stained Glass of a cathedral investigated with UV light

Stained glass under UV Ring Light

Barbara Trichereau in front of stained glass pieces
Barbara Trichereau, Design Engineer, Scientific Department Stained Glass at the LRMH
Microscopy is the tool that makes the difference in every restoration project. Despite the important surface of glass that needs to be treated, it has to be done under a microscope in order to preserve the original materials and artwork. With the UV light, it is possible to go even further into the treatment as the synthetic materials from previous restorations can be revealed and the cleaning adjusted.

Used materials and similar products

The SCHOTT VisiLED UV Ring Light is part of SCHOTT’s VisiLED series, which offers a range of advanced modular LED illumination products specially designed for stereo microscopy. Active control of the LED temperature, the option to select different controllers, and a large number of accessories enable bespoke lighting systems for your application. As well as direct LED lighting, we also offer a range of fiber optic solutions with our KL Light Sources and Light Guides.

The right solution with the right teamwork

To provide the best possible service and answer customer needs, SCHOTT collaborates with a broad network of microscope resellers around the globe. For this project, LRMH chose Microvision Instruments. A French leader in microscopic measurement, designing and marketing turnkey systems for the characterization of objects at the microscopic and macroscopic scales, Microvision Instruments offers solutions from the preparation of samples to the editing of analysis reports, including image capture and processing equipment. SCHOTT has a long partnership with Microvision Instruments as they have been cooperating since 1999.

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