NCJ Number
130215
Journal
Journal of Forensic Sciences Volume: 36 Issue: 3 Dated: (May 1991) Pages: 838-843
Date Published
1991
Length
6 pages
Annotation
The effectiveness of an argon-ion (AR) laser induced infrared luminescence (LIRL) was examined in differentiating between different samples of inks of the same color.
Abstract
Fifty-six writing instruments of four different colors (blue, black, red, and green) were used in the study. The inks were initially examined for ultraviolet fluorescence (UVF) and then scanned on the video spectral comparator (VSC-1) for infrared reflectance (IRR) and infrared luminescence (IRL). Each ink was then examined for laser luminescence (LL) with the AR laser and scanned on an IRDE 1200 document examiner's kit. The examinations for LIRL involved moving the IRDE 1200 to the AR laser and substituting the laser for the Olympus light source. None of the inks produced detectable UVF. Twenty-eight inks produced IRL under the VSC-1 as well as LIRL. In addition, 7 of the remaining 28 inks which did not produce IRL under the VSC-1 produced LIRL. The results show that AR laser will sometimes stimulate IRL in inks which did not produce IRL under the VSC-1. This IRL was always at a higher range usually 830-900 nanometers than that found under the VSC-1. Results indicate that LIRL may serve as a useful tool for examiners in differentiating between two writing inks of the same color in addition to the IRR, IRL, LL. 1 table, 2 figures, and 5 references (Author abstract modified)