We all tried, when we were children, to write
Thanks to the technological advancements, it is now possible to write texts without leaving visible signs, or, at least, signs that are visible to the human eye. In fact, you need two advanced tools: an invisible ink marker, and an infrared videocamera.
By using these two elements together, you can for example mark banknotes or papers, or write particularly sensitive correspondence, with the invisible marker. At a later stage all you have to do is point the digital infrared camera towards the object on which invisible ink has been used, and you will be able to see the text, otherwise invisible to the naked eye.
This system can be used, for example, by police forces to trace banknotes coming from a ransom, or by secret services to exchange classified documents. Furthermore, the infrared camera is also very useful to fight organized crime, for example when gangsters are exchanging messages written with invisible ink to circulate their orders.
The infrared camera can record between 7 and 20 hours of video footage (depending on the resolution level) on its internal 20Gb hard drive, and can also take JPG snapshots, perfect to photograph documents written with the special fluorescent ink supplied along with the digital video camera. Thanks to an enhancement on the camera, it can see a lower light spectrum, normally invisible to the human eye. Its invisible inks are visible within this lower range of the light frequencies.
Invisible ink can resist to direct sunlight for up to a week, but naturally, it is recommended that any documents written with infrared ink be kept away from direct light. By doing this, infrared reading through the modified video camera will be easier, and will be possible for a longer time.
To have more details, and for any questions concerning the operation of the infrared video camera, of the invisible ink marker, and for a wide range of devices and systems for surveillance and security, such as covert listening devices, you can visit Endoacustica, one of the most renowned operators in this field, with several years of experience at your full disposal.