IR Inks & Phosphors
We have three classes of IR invisible marking products:
- IR Down-Conversion: Visible to IR, and IR to IR
- IR Up-Conversion: IR to Visible (anti-stokes shift)
- Black Visible - Black IR and Black Visible - Clear IR inks and pens
Our IR Fluorescent Items
- IR Ink writing pens: Our IR ink writing pens writes in a nearly invisible ink which will fluoresce in the infrared spectrum. Using a 630nm red filter, you can see the IR1 ink. We have two types of infrared inks: IR1 peak excitation is at 793nm and peak emission at 840nm while our IR2 ink has a peak excitation at 824nm and peak emission at 885nm.
- IRDC2: Visible to infrared fluorescing powder. When stimulated with a blue or red light, the powder will fluoresce in the infrared range.
- IRUCG, IRUCR, IRUCB: Infrared to visible fluorescing powder. When stimulated with infrared light, the powder will fluoresce in the visible range.
Up / Down Conversion refers to the fluorescence shift up or down the spectrum from the excitation source. All fluorescence occurs when a material is stimulated with energy (usually light) at one frequency (say a black light) and the material remits some of the energy at a lower frequency (your typical fluorescent paints the glow in the human visible range).
Fluorescence can occur at any point of the electromagnetic spectrum. Different materials exhibit different fluorescent properties. A material might absorb ultraviolet light and emit visible light, or absorb visible and emit infrared, or absorb near infrared and emit far infrared.
Fluorescence almost always occurs as a shift down in photon energy levels or down-conversion. An ultraviolet light photon has higher energy than a visible light photon which has higher energy than an infrared photon.
In the ultraviolet to infrared spectrum, energy levels go from
- UVC - ultraviolet short wave - 250nm (highest energy level)
- UVB - ultraviolet medium wave - 300nm
- UVA - ultraviolet long wave - 370nm
- Visible light - blue (400nm) to red (700nm)
- Infrared - 700nm to 8000nm (lowest energy level)
Within this spectrum, UVC has the highest energy or shortest wavelength. Infrared has the lowest energy or longest wavelength.
Up-Conversion is a very unusual phenomenon. A counter-intuitive anti-stokes process occurs where the material absorbs lower energy photons and emits higher energy photons as fluorescence. The trick is that up-conversion materials absorb two or more low energy photons and then emit one high energy photon. By definition, up-conversion phosphors must be much less efficient than down-conversion phosphors. Typically, up-conversion phosphors are illuminated with high intensity light sources such as lasers in a controlled (subdued) lighting environment.
We also have a large library of fluorescent materials not listed on our site. Contact us if you have a particular need.