Safety Technologies for the Inspection of Documents
To create banknotes and identification papers that are as counterfeit-proof as possible, they are equipped with different safety features: some are visible with the naked eye, some are haptic in nature, and others can only be detected with special scanners.
Counterfeit Money Scandal
The counterfeiting of banknotes leads, first and foremost, to monetary losses. However, the largest scam in history, which occurred at the beginning of the 20th century, almost bankrupted the Portuguese economy when Alves dos Reis forged banknotes at a value of approximately 1% of the country’s gross domestic product. The political repercussions were enormous: the public trust in the political ruling class at the time declined; this scandal paved the way for the military coup that took place in 1926 and the authoritarian dictatorship  which ultimately followed.
The pursuit of counterfeit-proof banknotes is understandable especially after hearing the story above. There are only thirty companies worldwide that manufacture the security paper used for banknotes and identification documents. Each currency has its own requirements such as, for example, reliefs, watermarks, viewing windows, holograms, and security threads that are worked directly into the paper.
See for Yourself: Second-Generation Euro Banknotes
Some features of the euro banknote are easy to test yourself; for example, you can feel the relief worked into the paper on the short side of the euro banknote. If you hold the money up to the light, you will see the dark security stripe with the numeric value, € symbol, and watermark (starting with the 10 EUR note).
There is a portrait window in the new 20 EUR and 50 EUR banknotes. If you hold the banknote up to the light, the hologram is transparent. If you tilt the banknote in front of a background, you will see its value – on the back side only in the window and on the front side along the entire silver stripe.
Scanners See Even More!
There are many more security elements in our money, which can only be detected with the help of special equipment. Microlettering can only be deciphered using a magnifying glass; for all other features, infrared or ultraviolet light is required.
IR. Infrared (IR) inks exist that can be seen with the naked eye but that remain invisible for an IR camera because they absorb infrared light. Other IR inks reflect IR light, making the areas illuminate. If you hold a euro banknote under IR light, you will only see parts of the print.
Fluorescence. Fluorescent printing inks and fibers illuminate differently in UVA and UVC light. In the photograph, you will recognize small colored lines. These fibers are woven into the paper and illuminate in UV light. Under UVC light, certain printed areas fluoresce orange and yellow.
Again with Portugal...
Back to Portugal: In 1974, the Carnation Revolution triggered the fall of the Portuguese dictator. According to research scientists, this Revolution paved the way for a wave of democratization that has led to a free Europe – one without customs or travel borders. In spite of the Schengen Agreement, it is still possible to carry out identity checks in exceptional cases: this was done, for example, in Germany during the World Cup in 2006. Identity checks are just as relevant for security reasons as the inspection of banknotes; thus, the inspection mechanisms are similar.
Equipment for Authentication
Machine authentication is used in many areas (e.g., in ATMs, banknote authentication, and ID inspection). Read the above to see how UV light is used in the authentication process.