Abstract: A luminescent infrared transparent sticker is disclosed herein. An example apparatus includes a substrate that is transparent with respect to light at a first wavelength and light at a second wavelength and an adhesive on a first side of the substrate, wherein the adhesive contains taggant that has luminescent properties such that when the taggant is illuminated with light at the first wavelength, it emits light at the second wavelength.

Abstract: Methods and apparatus for variable data printing for security purposes using ceramic sub-micron infrared-luminescent particles in inkjet ink. An example apparatus includes an inkjet printer containing marked ink, the marked ink containing particles consisting of rare earth doped ceramics, wherein the particles are less than one micron in size, the particles are suspended in the marked ink, and the particles have luminescent properties such that when the particles are illuminated by first electromagnetic radiation having a first wavelength, the particles emit infrared light having a peak wavelength at a second wavelength.

Abstract: Apparatus and methods for measuring dye concentration in liquids are described herein.

Abstract: Methods and apparatus for a product authenticator and barcode scanner interlock. An example apparatus includes a barcode scanner to scan a barcode on an item and a tester to determine whether the item is authentic, wherein the tester prevents the barcode from scanning the item if the item is not authentic.