Spectral signature coding has been used to characterize spectral features where a binary code book is designed to encode
an individual spectral signature and the Hamming distance is then used to perform signature discrimination. The
effectiveness of such a binary signature coding largely relies on how well the Hamming distance can capture spectral
variations that characterize a signature. Unfortunately, in most cases, such coding does not provide sufficient
information for signature analysis, thus it has received little interest in the past. This paper reinvents the wheel by
introducing a new concept, referred to as spectral feature probabilistic coding (SFPC) into signature coding. Since the
Hamming distance does not take into account the band-to-band variation, it can be considered as a memoryless distance.
Therefore, one approach is to extend the Hamming distance to a distance with memory. One such coding technique is the
well-known arithmetic coding (AC) which encodes a signature in a probabilistic manner. The values resulting from the
AC is then used to measure the distance between two signatures. This paper investigates AC-based signature coding for
signature analysis and conducts a comparative analysis with spectral binary coding.
The test operation of Hefei synchrotron radiation source was started in Oct. 1991. We test the first scanning transmission x-ray microscope, which is installed in beamline U12A, designed primarily for soft x-ray microscopy in China. We also perform the studies of contact x-ray microscopy with synchrotron radiation to some biological and medical specimens. In this paper we describe the instrumentation of the scanning x-ray microscope and show some experimental results.
At the Hefei Synchrotron Radiation Laboratory (HESYRL), beamline 6A is dedicated to soft x-ray imaging studies. We are constructing a prototype scanning soft x-ray microscope. An effort in the fabrication of microzone plate has been started. We have designed and fabricated the first Fresnel zone plate as a microzone plate in China. Our microzone plates are fabricated by UV exposure. The finest width of the outmost zone is about 0.5 micrometers . In this paper, we describe the design and fabrication of our microzone plate and report first results.
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