Video Spectral Comparator

1. Presented
By :
Utkarsh Gupta
B.Sc 3rd Year
Batch: 2020-
2023
Video
Spectral
Comparato
r

2.  A digital imaging instrument manufactured by Foster + Freeman that
employs combination of light sources and filters to examine document
evidence under various wavelengths of radiation ranging from ultraviolet
to the infrared regions of the electromagnetic spectrum.
 VSC is an integrated composite system comprising of cameras, various
lights sources which include IR, Laser, UV, etc. and filters which assist in
comparison of questioned documents.
 VSC 6000 is the new version of VSC which is available for use for the
forensic and general purposes.
 EUROFINS FORENSIC SERVICES use a VSC 2000HR (Video Spectral
Comparator) for the specialized lighting examination of documents.
 This instrument is capable of viewing and recording the response of
documents/inks when exposed to light of various wavelengths.

3. • Video Spectral Comparator works in the basic principle of
light.
• Light is a form of electromagnetic radiation and consist of
different wavelengths.
• When light directed towards an object any of the one of
five things usually occurs depending on the emitted
wavelengths and the composition of the object –
1. Reflection – Object appears white or lighter.
2. Absorption – All or most of light can be absorbed by object.
3. Luminescence – It strikes the object, be absorbed and then
reemitted at a longer wavelength.
4. Transmission

4. • VSC is a non-destruction technique.
• IR and UV radiations are not visible to humans.
• Visible range in electromagnetic spectrum to humans 400nm –
700nm.
• The object that absorbed light in visible spectrum and appeared
black can now transmit radiant energy in IR spectrum.
** The VSC2000 is the FBI Laboratory’s latest tool in the analysis of
questioned documents. The VSC2000 is an imaging device that
allows an examined to analyze inks, visualize hidden security
features, and reveal alterations on a document.

5. • The main unit is a square box with 3 flaps.
• The main unit has :
1. A high resolution CCD firewire colour camera with sensitivity from
360 nm to 1100 nm.
2. Different light sources (incandescent filament lamps, LED, vapour
discharge tube, flash tube etc).
• The panel is situated in the centre of the document platen.
• Underneath the panel are light sources which can illuminate the
document from below. The document platen in itself is 650 mm * 650
mm while the translight panel is 235mm * 175mm.
• In the VSC there is also a high resolution grating spectrometer.
This can analyse light from a small region in document.
• As part of the VSC machinery is a 30** screen and a PC system
which is Windows based.

6. 1. Incandescent filament
lamps
These have a range from
400 nm to 1000 nm and
encompass visible and IR
light.
2. LED lamps
Wavelength from 400 nm
to 1000 nm and
encompass visible and IR
light.
3. Vapour discharge
tubes
The VSC offers three ranges
of UV light. This is with 365
nm (UV-A), 312 (UV-B), 254
(UV-C) peak wavelength.
4. Flash tube
This lamp has a range
of 850 nm to 1100 nm
and it is used for the
Anti-stocks flash
function.

7. • For close to 40-years, the Foster+Freeman Video Spectral Comparator
(VSC) has been an essential tool in the field of Questioned Document
Examination.
• Used by QDE professional in some of the busiest and most highly
regarded forensic science facilities worldwide, each new generation of
VSC workstation has further increased our ability to authenticate
genuine items and to identify counterfeits and falsified documents of an
increasingly high quality.

8. • Objects such as currency, stamps, legal documents, artwork and identification cards,
etc. can be examined.
• Used to observe security features of bank notes like ink, images, paper gradient and
security thread.
• To examine suspected fake cheques, fake certificates, notarized documents, license
agreements, degree certificates, birth certificates, etc.
• To examine passport and visa documents at airports.
• Examination of documents under high magnification can quickly reveal evidence of
tempering.
• Reveal latent images and watermarks.
• Anti Strokes Illuminator.
• Examining UV activated security features.

9. • This method is a convenient and comprehensive method for the non-destructive analysis of inks and
papers.
• It can help detect differences between inks in terms of chemical formulation and it reveals writing
that has been added using a different ink.
• The method also revels writing that has been altered or removed using the variations in the way
different inks respond to different wavelengths of light.
• It visualizes the security features printed into papers and allow quick examination of the
questioned document.
• Foster and Freeman noted that non-destructive VSC examination makes it possible to establish the
authenticity of an items, detect changes that have been made and to see beneath the surface of
an artefact revealing its history.

10. • The results obtained by using the VSC are only indicative and not
definite because the machine only compares one set of data to another.
Furthermore, when using the VSC for examination, comparison can only
be done only when the specimen comparison is available.
• This technique has been used only for differentiating purposes and not
for identification purposes.
• The instrument is very costly.
• It is not possible to carry the machine at the crime scene.

11. Thank
You