The microtag concept is an anticounterfeiting and security measure. Microtags are computer-generated holograms (CGH’s) consisting of 150-nm lines arranged to form 300-nm-period gratings. The microtags that we describe were designed for readout at 442nm . The smallest microtag measures 56µm×80 µm when viewed at normal incidence. The CGH design process uses a modified iterative Fourier-transform algorithm to create either phase-only or phase-and-amplitude microtags. We also report on a simple and compact readout system for recording the diffraction pattern formed by a microtag. The measured diffraction patterns agree very well with predictions.
© 1998 Optical Society of America
(050.1950) Diffraction and gratings : Diffraction gratings
(070.2590) Fourier optics and signal processing : ABCD transforms
(090.1760) Holography : Computer holography
(110.5220) Imaging systems : Photolithography
M. R. Descour, D. I. Simon, W. C. Sweatt, M. E. Warren, S. H. Kravitz, K. D. Krenz, A. K. Ray-Chaudhuri, and R. H. Stulen, "Microtags with 150-nm line gratings fabricated by use of extreme-ultraviolet lithography," Opt. Lett. 23, 13-15 (1998)