Effect of Azimuthal Angle on Infrared Diffuse Reflection Spectra of Fabrics

• NCJ Number: 249669
• Journal: Spectroscopy Volume: 30 Issue: 12 Dated: December 2015 Pages: 23-25
• Author(s): Stephanie A. DeJong; Brianna M. Cassidy; Zhenyu Lu; Megan R. Pearl; Jessica N. McCutcheon; Wayne O'Brien; Nicholas D. Boltin; Ray G. Belliveau; Stephen L. Morgan; M. L. Myrick
• Date Published: December 2015
• Length: 3 pages
• Grant Number(s): 2011-IJ-CX-K055
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored)
• Award: Multimode Imaging in the Thermal Infrared: Validation for Blood, Extension to Latent Prints

Annotation

This study examined how the spectra of cotton fabric varied as a result of the azimuthal angle of the sample during infrared diffuse reflection spectroscopy, with a focus on how to minimize the influence of azimuthally angle variability on the spectra.

Abstract

Although the detection of biological fluids is generally the goal of infrared spectroscopy, understanding the spectral variability of the substrate, such as fabric, on which these fluids are found is critical for optimizing detection capabilities. There are two primary sources of variability in the collected data, i.e., fabric rotation and instrument drift. These changes mostly influence the magnitude of reflection, but they produce much less of an effect on the spectral shape. Because of this lesser effect on the spectral shape, regions of high fabric absorption show minimal change related to fabric orientation. In contrast, regions with lower absorption (higher reflectance) are more susceptible to variation. A figure is presented to show spectra collected upon translational movement at each rotation angle. A second figure shows the same data after a standard normal variate (SNV) transformation to reduce scattering effects on the spectra. The procedures and equipment used in this study are described. 2 figures and 4 references