Three-dimensional detection of sequence of strokes using confocal microscope

Abstract

Background: In the present study, three-dimensional application of confocal microscope is explored. The aim is to determine the sequence of intersecting lines written on a questioned document as a non-destructive technique. The authors have tested the Nikon confocal A1 microscope on two major criteria. The criterion 1 focuses on the analysis of homogenous intersecting lines, whereas the criterion 2 focuses on the effect of pen pressure on the sequence of the strokes. Fifty-four and 42 samples from criterion 1 and criterion 2 respectively were examined. All the intersecting strokes were homogeneous and in either black-or blue-coloured ink. They were made from glycolbased (ballpoint pen) and liquid-based (fountain pen and gel pen) inks. Result: The authors were able to determine the correct sequence of homogeneous intersecting lines in 81 and 83% of the average data of samples for criterion 1 (the analysis of homogenous intersecting lines) and criterion 2 (the effect of pen pressure on the sequence of the strokes) respectively. Conclusion: The confocal microscope proved to be a reliable and precise technique for analysing the homogeneous intersected lines made by any pen pressure beyond all the errors during interpretation.

Deposition order and physicochemical process visualization of ink intersections using X‐ray photoelectron spectroscopy imaging for forensic analysis

“…The use of this topographic ridge feature for determining the deposition order between homogeneous intersections has been previously studied with 3D laser profilometry and 3D confocal microscopy with high but inconsistent success 26,27 . Our results agree with Spagnolo's report 26 .…”

“…The use of this topographic ridge feature for determining the deposition order between homogeneous intersections has been previously studied with 3D laser profilometry and 3D confocal microscopy with high but inconsistent success. 26,27 Our results agree with Spagnolo's report. 26 Their success with laser profilometry was reportedly dependent on the type of pen used, with ballpoint pen having the highest success, and felt-tip the least.…”

Interpol review of questioned documents 2016–2019

“…The determination of the sequence of crossing ink lines remains a challenging task for FDEs despite the several studies published, demonstrated by the review of Brito L. and al [ 78 ]. The difficulties of this task is also highlighted by the several methods that were tested: microscopy [ [79] , [80] , [81] , [82] ], AFM [ [83] , [84] , [85] ], the hyperspectral imaging [ 86 , 87 ], MSP [ 88 ], Raman spectroscopy [ 89 ], FIB-SEM/EDX [ 90 ], TOF-SIMS [ [91] , [92] , [93] ], TLC [ 94 ], GC/MS [ 94 ], HPLC [ 94 ], MALDI-MS [ 94 ], DART-MS [ 94 ], LC-MS [ 94 ] and PS-MS [ 95 ].…”

“…3D application of confocal microscope was explored by Mann M. and al [ 80 ]. to determine the sequence of homogeneous line intersections produced using black or blue ballpoint, fountain or gel pens.…”

Application of Absorption Spectra to Study Order of Sequence in Intersecting Printed and Pen Strokes

“…Application of reflection spectra generated by Video Spectral Comparator-2000HR is found very effective to determine sequence of order in heterogeneous crossing strokes by ballpoint pens [2]. Also, M. Mann et al discussed about the application of confocal microscope [3] and Docubox Dragon [4] to find order of sequence in crossing lines. G. S. Spagnolo described about potentiality of 3D laser profilometry for determining sequence of homogeneous crossing lines [5].…”