Use of Raman Microscopy and Band-Target Entropy Minimization Analysis To Identify Dyes in a Commercial Stamp. Implications for Authentication and Counterfeit Detection

Abstract

Raman microscopy was used in mapping mode to collect more than 1000 spectra in a 100 microm x 100 microm area from a commercial stamp. Band-target entropy minimization (BTEM) was then employed to unmix the mixture spectra in order to extract the pure component spectra of the samples. Three pure component spectral patterns with good signal-to-noise ratios were recovered, and their spatial distributions were determined. The three pure component spectral patterns were then identified as copper phthalocyanine blue, calcite-like material, and yellow organic dye material by comparison to known spectral libraries. The present investigation, consisting of (1) advanced curve resolution (blind-source separation) followed by (2) spectral data base matching, readily suggests extensions to authenticity and counterfeit studies of other types of commercial objects. The presence or absence of specific observable components form the basis for assessment. The present spectral analysis (BTEM) is applicable to highly overlapping spectral information. Since a priori information such as the number of components present and spectral libraries are not needed in BTEM, and since minor signals arising from trace components can be reconstructed, this analysis offers a robust approach to a wide variety of material problems involving authenticity and counterfeit issues.

Pure component Raman spectral reconstruction from glazed and unglazed Yuan, Ming, and Qing shards: a combined Raman microscopy and BTEM study

“…the combined use of Raman microscopy and BTEM analysis for the purpose of authentication, appears elsewhere. [32] For an in-depth mathematical discussion of the BTEM algorithm, the reader is referred to references. [24][25][26] …”

“…[31] Most recently, BTEM has begun to be used in the area of authentication. [32] In the present contribution, some glazed and unglazed Yuan, Ming, and Qing shards are analyzed. Raman microscopy and BTEM analysis are combined in order to reconstruct pure component spectra from the glazed as well as the unglazed parts of the shards.…”

Infrared spectroscopic imaging of latent fingerprints and associated forensic evidence

“…A combination of multivariate techniques, such as pricipal component analysis (PCA) and band-target entropy minimization (BTEM), was used to obtain spectral features of interest differentiated from background signals and spectral noise. 10–14 …”

Raman Spectroscopy

“…Scientists at AstraZeneca found that with a transmission Raman approach as few as three calibration samples were required to obtain prediction errors nearly equivalent to their full model [42] . It is hoped that this approach in combination with advanced data analysis techniques, such as band target entropy minimization (BTEM) [51] , might help improve Raman ' s quantitative sensitivity further. It is hoped that this approach in combination with advanced data analysis techniques, such as band target entropy minimization (BTEM) [51] , might help improve Raman ' s quantitative sensitivity further.…”