Video Spectral Comparator (VSC)
Definition
A multispectral imaging instrument combining UV, visible, and near-infrared illumination with selectable emission filters and a calibrated digital camera; the primary bench instrument for spectral ink differentiation, alteration detection, and security feature examination in forensic document laboratories.
- Primary uses
- Spectral ink differentiation, alteration detection, security feature examination
- Light modes
- UV, visible, and near-infrared wavelengths in reflected, transmitted, and oblique illumination
- Destructive
- Non-destructive method, preserving evidence for further analysis
Common questions
What can a Video Spectral Comparator detect in documents?+
A VSC reveals alterations, erasures, overwriting, and ink differences that may not be visible to the naked eye. It images documents under multiple wavelengths from ultraviolet to near-infrared, allowing examiners to see how different inks respond to each light source.
Why is the VSC a first choice in document examination?+
It's non-destructive, so the evidence remains intact for further testing. It quickly differentiates inks and detects security features without any chemical extraction or physical damage to the document.
How does the VSC work?+
The instrument combines UV, visible, and near-infrared illumination with selectable filters and a calibrated digital camera. It can image documents in reflected, transmitted, and oblique modes, revealing details that single-wavelength imaging would miss.
Related terms
- IR Luminescence
- Emission of near-infrared radiation by ink dye molecules when excited by visible light; different ink formulations luminesce at different intensities, allowing differentiation...
- Acid-Free Packaging
- Paper folders or envelopes manufactured without acidic buffers, used for long-term storage of questioned documents to prevent acid-catalysed paper and ink degradation.
- ATR-FTIR (Attenuated Total Reflectance FTIR)
- An FTIR sampling mode in which infrared light undergoes total internal reflection in a crystal pressed against the sample surface, probing only...
- Auto-Forgery
- A genuine signature executed by the legitimate signer on a document they later deny, undetectable by handwriting comparison alone; requires document-dating and...
- Chain of Custody
- The documented chronological record of who collected, handled, transferred, and examined a piece of evidence. For digital evidence, chain of custody includes...
- D Band and G Band (Raman)
- The characteristic Raman bands of graphitic carbon materials at approximately 1350 cm-1 (D, disorder) and 1590 cm-1 (G, graphitic C-C stretch); diagnostic...
- ENFSI Document and Handwriting Working Group
- The European Network of Forensic Science Institutes working group responsible for harmonising best-practice guidelines for forensic document examination across European national laboratories.
- ENFSI FIDE-WG
- The European Network of Forensic Science Institutes Forensic Document Examination Working Group, which publishes best-practice manuals for document examination methods including ink...
- ESDA
- Electrostatic Detection Apparatus; detects latent indentations in paper by charging the surface and cascading toner particles, revealing tracing stylus pressure and writing...
- ESDA (Electrostatic Detection Apparatus)
- A non-destructive technique for detecting indented impressions on paper caused by writing pressure. A physical ink signature on paper produces detectable ESDA...
- ESI-MS (Electrospray Ionisation Mass Spectrometry)
- An ionisation technique for LC-MS coupling that gently ionises analytes from solution at atmospheric pressure; produces molecular ion clusters and charge-state distributions...
- Exemplar Set
- The collection of known genuine signatures used as the comparison baseline; SWGDOC and ENFSI guidelines specify a minimum of 20-30 exemplars spanning...
Explained in these topics
- Detection Methods: Oblique, Transmitted, UV, IR and the VSCAn integrated forensic document examination instrument combining reflected, transmitted, oblique, UV, and IR illumination modes under a calibrated imaging syst...
- Ink Analysis Methods: TLC, HPLC, Raman, FTIR and Mass SpectrometryA forensic optical instrument that illuminates documents under UV, visible, and near-infrared wavebands with matched detection filters; used as a non-destructi...
- Lab Equipment, Evidence Handling and Chain of Custody in QDEA multispectral imaging instrument combining UV, visible, and near-infrared illumination with selectable emission filters and a calibrated digital camera; the...
- Signature Examination: Genuine, Simulated, Traced and Auto-ForgeryAn instrument that images documents under UV-to-IR wavelengths in reflected, transmitted and oblique modes; used to differentiate inks, reveal erasures, and de...