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Infrared ink nm nanometer

Our IR Inks and Pens are a new class of very high security inks.  These inks are completely invisible to the human eye yet can be seen by using a device which can see in the infrared range - such as our modified cameras and camcorders.  These inks do not fluoresce in the visible range, cannot be seen with ultraviolet lights and cannot be seen by the human eye alone.

The human eye can see from about 400nm (violet) to about 700nm (red).  The human eye cannot see below 400nm or above 700nm.  Below 400nm is the ultraviolet range and above 700nm is the infrared range.  Please see our Vision FAQ for more information.

The nm stands for nanometer and is a measure of length.  One nanometer is a billionth of a meter. The measurement is for one full light wave length.

Our IR1 ink fluoresces at 840nm using and has a peak stimulation (absorption) frequency of 793nm. That means that if you want to see the writing of this pen, you can do so in two ways

1: Look at where the ink absorbs light

The easiest way is to look at where the ink absorbs light.  Since the ink absorbs light a 793nm and emits light at 840nm, you want to filter out the 840nm light and look at the 793nm portion.  By using one of our XNite 715nm filters on an IR sensitive camera or camcorder, you will be able to see the writing as dark marks.

We use a fairly concentrated form for the IR ink which can result in a very light green mark just barely visible to the human eye when the mark is on white paper.  Using our 630nm filter, the human eye can see the IR ink fairly well unaided.  Some customers have used these filters to make custom glasses to aid in viewing the ink.

Our IR Reader can see our IR ink.  You can learn more about the IR Reader here.

2: Look at where the ink fluoresces

 Another way to see this ink is by looking at the fluorescence of the ink.  The ink will fluoresce in the same way as our UV inks fluoresce, but the IR1 ink fluoresces out of the human visible range.

You can stimulate the IR ink to fluoresce using visible or invisible light.  The fluorescence of the ink will always be in the infrared rage.

Visible light stimulation / IR fluorescence:  Using a common red laser pointer, illuminate the spot with the IR ink.  Using an IR camera with a 780nm filter, you will see the IR ink as a bright white dot. The camera will not be able to see the laser pointer.

IR stimulation / IR fluorescence: This method has the advantage that both the stimulation source and emission are invisible to the human eye.  However, the equipment is more difficult to setup.  You can illuminate using an infrared laser or narrow band IR source in the 715nm to 800nm range while viewing with an IR camera with a 830nm filter.  It is important that the IR illumination be limited to under 800nm else the IR camera will see the illumination source.

The simplest method to see the ink is by using a 715nm filter such as our XNite715 with an infrared sensitive camera or camcorder.

GS marked cards factory have comprehensive way to detect any infrared ink marked cards.

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