We all have to do our taxes, right? And, sometimes we put it off till almost the last minute, right? Have you ever been sorting through your financial documents and come upon a cash receipt that is so badly faded that you can barely read any of the information? No idea who was the vendor or what was the amount? Maybe it is even a blank paper, but just the right size and paper type to be some sort of receipt.... You need to account for all that cash you spent, and this receipt could be important. Well, you are not alone. It probably happens to everyone. It happened here this week.
This totally "blank" slip of paper was in the pile of receipts being recorded. In other circumstances, it would probably have been thrown away as a useless scrap of paper. But, at tax time, and in the tax receipt folder, this must have had some meaning.
Ink that fades to invisibility can leave behind traces that can be seen only when reactions to Ultraviolet (UV) and Infrared (IR) radiation are considered. The "blank" receipt was placed in the VSC-4 (Video Spectral Comparator).
Green light (wavelength 480-620 nm, or nanometers) was directed at the document. An IR filter (645 nm) was inserted in front of the video camera of the unit. The result, shown here, was that the invisible, but remaining, traces of ink luminesced (glowed). This luminescence could not be seen with the naked eye because it was at a wavelength outside that of visible light.
The VSC camera is sensitive to IR radiation. The IR filter blocked out all visible light so that only radiation longer than 645 nanometers could be seen by the camera. The monitor of the VSC shows the examiner what the camera sees - glowing letters instead of a blank slip of paper. A print was made on the attached printer to satisfy the IRS, and a frame grabber was used to capture the image for display here.
So who says tax time isn't fun? Any time a blank slip of paper suddenly glows with information is a good time if you are a document examiner. Keep this in mind if you ever need to restore faded writing, uncover an obliteration, recapture erased information, see differences in ink on a document, or look at a document in a new way.
If you would like to see more lab equipment at work, take a tour of the newly-expanded, QDEWill forensic document examination laboratory.
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