Proceedings of Topical Meeting on Optoinformatics (pdf-format, 1.21 ...

12 OPTOINFORMATICS’05
OPTICAL CORRELATION SYSTEMS FOR SECURITY
VERIFICATION
Muravsky L.I.
Karpenko Physico-Mechanical Institute <strong>of</strong> NAS Ukraine, Lviv, Ukraine
“Optical Security Systems”
The overview <strong>of</strong> recent advances in optical image processing technologies for
security verification <strong>of</strong> documents and products is represented. The most
typical optical correlation systems for fingerprint and random phase mask
identification are considered.
The recent advances in development <strong>of</strong> optical image processing technologies for
security verification <strong>of</strong> documents and products are analyzed in this lecture. As a rule,
biometric images and phase masks are used as optical security elements (optical marks) in
these technologies. The optical marks are attached to an object that should be protected
from a counterfeiting. Because such marks are the transparent patterns, the optical
correlation methods can be simply adopted for their identification. A Vander Lugt
correlator and a joint transform correlator architectures are widely used for these
purposes. [1-4] But the hybrid optical-digital realizations <strong>of</strong> mentioned above architectures
are the most hopeful for creation <strong>of</strong> high-speed and reliable security verification systems.
Two main directions in the development <strong>of</strong> optoelectronic correlation systems for
security verification are considered in this report. First direction is represented by
correlation methods and systems for identification <strong>of</strong> biometric images, in particular,
fingerprints and faces. Second direction includes the information technologies for
identification <strong>of</strong> random, pseudorandom or deterministic phase masks and composed
patterns containing both phase mask and a fingerprint. First direction was developed after
invention <strong>of</strong> holographic matched filters. However absence <strong>of</strong> high-performance portable
devices for input-output <strong>of</strong> optical information those years has not allowed creating <strong>of</strong>
high-reliability automatic identification systems. Recently, the occurrence <strong>of</strong> high-speed
spatial light modulators and video cameras based on CCD- and CMOS-sensors has
stimulated creation <strong>of</strong> hybrid optical-digital correlation systems for fingerprint
identification. The “True Recognition System” (Mytec Technologies Inc.) [1] and the
compact correlation system for fingerprint recognition (Hamamatsu Photonics K.K.) [2] are
the typical examples <strong>of</strong> good results in this direction. Development <strong>of</strong> second direction was
initiated by Horner and Javidi. [3,4] The high-performance experimental setups <strong>of</strong> optical
and hybrid systems for identification <strong>of</strong> random phase masks were created in last years.
So-called transformed phase mask [5,6] can be considered as the improved modification <strong>of</strong> a
random phase mask. If a random phase mask is identified, only one sharp and narrow
correlation peak is formed at the optical correlator output. But if we use a transformed
phase mask for identification, several sharp peaks are produced. The relative positioning <strong>of</strong>
these peaks generates the spatial protective code that can be represented as a feature vector.
The identification <strong>of</strong> a presenting transformed phase mask is realized by comparison <strong>of</strong> its
feature vector with a reference feature vector. Such property <strong>of</strong> a transformed PM allows
raising the security level <strong>of</strong> a protected object.
The hybrid optical-digital system created in Karpenko Physiko-Mechanical Institute
<strong>of</strong> NAS Ukraine is intended for security verification <strong>of</strong> credit cards and other similar
products. [7-10] This system is built up on the basis <strong>of</strong> a joint transform correlator
architecture. It consists <strong>of</strong> an optical Fourier processor, a CCD-camera, and a PC with