ISSN: 0022-1198
CODEN: JFSCA
Published Online: 1 October 1986
Page Count: 11

Color Comparison in Questioned Document Examination Using Microspectrophotometry
Olson, LA
document analyst, Internal Revenue Service, Criminal Investigation Division, Forensic Laboratory, IL

(Received 21 December 1985; accepted 7 February 1986)

Abstract

The work of the document examiner is often aided through the use of specialized analytical instruments. One such instrument, in use at the Immigration & Naturalization Service Forensic Document Laboratory (INSFDL), is the Nanometrics 10S Microspectrophotometer, manufactured by Nanometrics, Inc., of Sunnyvale, CA. This pseudo-dual-beam spectrophotometer performs nondestructive color analysis of objects down to 2 μm in size. First, an object to be examined (such as an ink line) is viewed through a microscope and the light reflected from it is measured over the visible spectrum. The reflected energy is then compared with a standard stored in the system's microprocessor, and a spectral curve is provided which is characteristic of the color of the object examined. At INSFDL, the Nanospec 10S™ has been successfully used to differentiate similarly colored printing inks, stamp pad inks, and fibers found on various travel and identity documents. Examples from recent cases will be demonstrated.

Keywords:
questioned documents, spectroscopic analysis, colors (materials)

Paper ID: JFS11910J
DOI: 10.1520/JFS11910J
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