Fiber optics reflectance spectroscopy: A unique tool for the investigationof Japanese paintings

Ultraviolet-visible reflectance spectroscopy is a rapid and accurate techni que for the investigation of painted surfaces. The use of a high efficiency beveled-tip fiber optic probe and a pulsed xenon source gives improved det ection efficiency and minimizes the interference from ambient light, elimin ating the need to shield the analyzed area and allowing non-contact, non-in vasive analysis. Thin washed of orgnaic colorants, often impossible to samp le, are ideally suited to this kind of analysis. This study describes the i n situ identification of indigo, Prussian blue and a red insect dye (cochin eal carmine or lac dye) in two paintings by Katsushika Hokusai.