Pico Quant's LSM Upgrade Kits greatly enhance the capabilities of these microscopes by extension to time-resolved techniques, and thereby providing not only Fluorescence Lifetime Imaging (FLIM) but also Fluorescence Correlation Spectroscopy (FCS) and a wealth of other time resolved techniques.
Therefore, it would be possible to identify the ink mixture and attribute it to the company producing that ink type.
In this example, FLIM images of a paper showing a guilloché pattern written in invisible ink were acquired.
In order to acquire a fluorescence lifetime image, the photons have to be attributed to the different pixels, which is done by storing the absolute arrival times of the photons additionally to the relative arrival time in respect to the laser pulse.
Line and frame marker signals from the scanner of the confocal microscope are additionally recorded in order to sort the time stream of photons into the different pixels.
The information represented in lifetime-resolved images may be the actual (or apparent) lifetimes, or another spectroscopic parameter that is able to be determined only by virtue of the fluorescence signal being lifetime-resolved.