KEYWORDS: Telecommunications, Free space optics, Computer security, Sensors, System identification, Information security, Network security, Modulation, Radio optics, Transmitters
A free space optics based identification and interrogation system has been designed. The applications of the proposed
system lie primarily in areas which require a secure means of mutual identification and information exchange between
optical readers and tags. Conventional RFIDs raise issues regarding security threats, electromagnetic interference and
health safety. The security of RF-ID chips is low due to the wide spatial spread of radio waves. Malicious nodes can read
data being transmitted on the network, if they are in the receiving range. The proposed system provides an alternative
which utilizes the narrow paraxial beams of lasers and an RSA-based authentication scheme. These provide enhanced
security to communication between a tag and the base station or reader. The optical reader can also perform remote
identification and the tag can be read from a far off distance, given line of sight. The free space optical identification and
interrogation system can be used for inventory management, security systems at airports, port security, communication
with high security systems, etc. to name a few. The proposed system was implemented with low-cost, off-the-shelf
components and its performance in terms of throughput and bit error rate has been measured and analyzed. The range of
operation with a bit-error-rate lower than 10-9 was measured to be about 4.5 m. The security of the system is based on the
strengths of the RSA encryption scheme implemented using more than 1024 bits.
Digital image fusion is a useful technique that can be applied to achieve extended depth-of-field microscope
imaging. The central idea is to incorporate from all input images
the regions that contain most in-focus signals into a single composite image. The amount of signal content of a particular region is estimated by an activity measure in general. To our best
knowledge, all existing approaches in the literatures rely on estimates based on the strength of high frequency signal
components as the activity measure. However, such measure does not
distinguish true image signals from noise. We propose to use a multiscale point-wise product as the activity measure, which does not amplify the effect of noise. The resulting scheme shows a significant improvement on imaging of cytological specimens in
terms of both subjective and objective quality even under a noise-free environment. More importantly, the scheme has a significant advantage over existing methods in the presence of
noise.
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