The Video Spectral Comparator (VSC) is a comprehensive imaging device. It enables forensic document examiners to analyse, compare and distinguish between different inks and papers, reveal alterations on a document, identify obliterated entries, identify instances of page substitution, and visualise hidden security printing features.
Basic components of this apparatus include: built-in colour video camera with a monochrome video camera and image comparison modes; monitor, and camera longpass and bandpass filters; a range of light-sources with variable filters, and automatic filter selection sequences its extensive selection of filters. There is an extensive editing menu of special features and video effects to facilitate advanced forensic document examination procedures.
The VSC enables us to perform technical document examination operations including:
- Imaging in the near infra red and visible spectrum, showing both absorption and reflectance differences of inks at particular wavelengths;
- Imaging the fluorescence properties of inks, excited by examination with U.V. light. This may prove different inks and fraudulent additions of alterations;
- Spectrometer facility which measures the spectrum of the area being examined, to record absorption, reflectance and transmission spectra. This may distinguish differences between inks;
- Produce graphs and tables which show the recorded measurements and comparisons of the colour spectrum analysis of inks, in relation to their absorption and reflectance qualities at different wave-lengths;
- Examination with low-angle lighting, to view evidential writing indentations, to show indications of traced forgery, erasure and retouching sites, machine generated indentations, or embossing effects;
- Transmitted light examination to reveal paper features such as water-marks or sites of physical erasures / alterations; and
- Examine documents for hidden security printing features. Evidence of any interference in relation to hidden security features may be indicative of an alteration involved in producing a bogus document.