title: Dichroism measurements in forensic fibre examination. Part 4-dyed acrylic and acetate fibres.
abstract: A number of dyed acrylic and acetate fibre samples were examined with plane polarized light on their dichroic behavior by optical light microscopy (OLM) and microspectrophotometry with plane polarized light (MSP-PPL). It was found that most of these low birefringent fibres possess weak dichroic effects that are very hard to observe with microscopy. However, using MSP-PPL, the linear dichroism could be measured. A comparison between the dichroic effects found for the same disperse dyes on triacetate (TrAc), diacetate (Ac), polyester (PES) and polyamide (PA) shows that the linear dichroism follows the order: PA>PES >>TrAc, Ac.
authors.affiliation: National Institute for Criminalistics and Criminology, Brussels, Belgium. kris.dewael@just.fgov.be
authors.forename: K
authors.initials: K
authors.lastname: De Wael