UV Fluorescence Examination
Definition
Examination under 365 nm or 254 nm ultraviolet light to reveal optical brightener fluorescence in paper, ink luminescence, and areas of altered fluorescence caused by chemical erasure or added text.
- Common wavelengths
- 365 nm and 254 nm
- Field
- Questioned document examination
- Reveals
- Optical brightener fluorescence, ink luminescence, altered areas
- Detects
- Chemical erasure, added or overwritten text
Common questions
How does UV fluorescence expose chemical erasure that is invisible in normal light?+
Erasing fluids and abrasion disturb the paper's optical brightener coating or fibre surface, so the treated area fluoresces differently from the surrounding untouched paper under UV, even when the visible page looks uniformly clean.
Can UV fluorescence date a document?+
Not precisely by itself. Optical brightener use became common from the mid-20th century onward, so its presence or absence can support a rough dating boundary, but examiners combine it with ink and paper analysis for a defensible age estimate.
Related terms
- 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.
- 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...
- 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...
- 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...
- IR Reflectance
- Imaging under near-infrared illumination (715-1000 nm) to differentiate inks by their IR absorption: carbon-based inks remain dark, many synthetic dye inks become...
- Mylar (Polyester) Sleeve
- A chemically inert, optically clear polyester film sleeve used to protect questioned documents during examination and archival storage without introducing chemical contaminants...
- Oblique Illumination
- Lighting applied at a very low angle to the document surface (below 10 degrees from horizontal) to reveal topographic features: writing indentations,...
- Transmitted Illumination
- Lighting passed through the document from the back face to reveal paper-body features invisible from the surface: watermarks, security threads, and paper-thickness...
- Video Spectral Comparator (VSC)
- A multispectral imaging instrument combining UV, visible, and near-infrared illumination with selectable emission filters and a calibrated digital camera; the primary bench...