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There’s More to Reflectance Spectroscopy Than Lux

Beeby, Andrew; Garner, Louise; Howell, David; Nicholson, Catherine E.

There’s More to Reflectance Spectroscopy Than Lux Thumbnail


Louise Garner

David Howell

Catherine E. Nicholson


Fibre-optic reflectance spectroscopy is widely used as a tool for the analysis of coloured materials such as pigments and paints. We describe a new design for a FORS probe which is held some 5cm away from the sample surface and interrogates a spot of 2mm diameter, offering a significant advantage over existing methods. The spectrometer employs an illuminance of 1250lux, equivalent to 0.5mWcm−2 averaged across the visible spectrum. The spectral measurements take less than a second ensuring that the risk of sample photodegradation is minimal. Under these conditions there is no detectable temperature rise of the illuminated area. Increasing the illuminance above 25mWcm−2, a light level significantly higher than that required for our measurements, gave rise to significant localised temperature rises in model manuscripts. This demonstrates the need for caution when using this technique for the analysis of precious heritage items.

Journal Article Type Article
Acceptance Date Apr 9, 2018
Online Publication Date May 8, 2018
Publication Date May 8, 2018
Deposit Date Apr 11, 2018
Publicly Available Date Apr 11, 2018
Journal Journal of the Institute of Conservation
Print ISSN 1945-5224
Electronic ISSN 1945-5232
Publisher Taylor and Francis Group
Peer Reviewed Peer Reviewed
Volume 41
Issue 2
Pages 142-153
Public URL


Accepted Journal Article (848 Kb)

Copyright Statement
© 2018 The Authors. Published by Informa UK Limited, trading as Taylor & Francis Group This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which
permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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