Goniospectrophotometry
Definition
A spectrophotometric technique that measures reflectance spectra at multiple illumination and viewing angle combinations simultaneously, enabling quantitative characterisation of OVI colour-shift profiles for comparison against authenticated note references.
- Measures
- Reflectance spectra at multiple angle combinations
- Application
- Optically variable ink colour-shift analysis
- Use case
- Counterfeit currency authentication
- Output
- Quantitative angle-dependent colour profile
Common questions
Why is angle-dependent measurement necessary for OVI analysis?+
Optically variable ink is designed to shift colour depending on viewing angle, so a single fixed-angle reflectance reading would miss this defining property; goniospectrophotometry captures the full colour-shift behaviour needed to compare against genuine note references.
How does this technique help distinguish genuine from counterfeit currency?+
Genuine OVI uses precisely engineered thin-film or pigment structures that produce a specific, repeatable colour-shift curve, while counterfeit inks or printed simulations of the effect typically deviate from the authentic reflectance profile at one or more angles.
Is goniospectrophotometry a portable field technique?+
It generally requires a laboratory-grade instrument for precise multi-angle measurement, though simplified portable devices exist for field screening, with full quantitative comparison reserved for laboratory confirmation.
Related terms
- BOPP (Biaxially Oriented Polypropylene)
- The polymer film substrate for polymer-substrate banknotes (Australia, New Zealand, UK, Canada). Distinguished from cotton-linen paper notes by FTIR-ATR (CH3 methyl peaks...
- Europol PEX (Project Ester)
- Europol's coordination framework for EUR counterfeit currency intelligence across EU member states, linked to the ECB's Counterfeit Monitoring System (CMS) and the...
- FICN (Fake Indian Currency Notes)
- Counterfeit Indian banknotes, especially high-denomination ₹500 and ₹2000 notes. High-quality FICN (sometimes called 'super FICN') is coordinated under NIA investigation and intelligence...
- Fluorescent Security Ink
- An ink visible only under UV illumination at a specific wavelength (typically 365 nm), used to print denomination numerals, flag motifs, and...
- Intaglio Printing
- A high-pressure printing process in which ink is forced into engraved recesses in a steel plate and transferred to paper, producing a...
- Optically Variable Ink (OVI)
- An ink containing thin-film interference flakes (metal + dielectric layers, manufactured by SICPA and others) that produce a visible colour shift with...
- Security Thread
- A strip of metallised biaxially-oriented PET film embedded in the paper substrate, alternating between visible (windowed) and embedded segments. May carry magnetic...
- SICPA OVI
- Optically variable ink technology commercialised by SICPA Security Inks and Coatings SA, Lausanne. Each flake is a vacuum-deposited Al / dielectric (MgF2...
- USSS Counterfeit Division
- The division of the United States Secret Service responsible for counterfeit currency investigation, including 'supernote' investigations attributed to DPRK and Iranian state-sponsored...