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- 13(1)1.PDF
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Review of drop analysis technology
for liquid property study
Q.
Song, G.X. Zhang, and Z.R. Qiu
Drop analysis takes a multidisciplinary and integrated
approach to monitor the drop growth in the process of liquid forming into
the drop, so as to measure the physical and chemical parameters of the
tested liquids and to discriminate different liquids qualitatively and
quantitatively. In this paper, fiber drop analysis (FDA), capacitive drop
analysis (CDA), image drop analysis (IDA,) and spectral drop analysis (SDA)
are summarized in review. Main features and application fields of each
method are introduced. The combination of various drop analysis technologies
and its significance are presented.
Keywords: drop analysis, liquid drop fingerprint, fiber, capacitive, image, spectral.
9- 13(1)9.PDF
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Raman system for on-line monitoring
and optimisation of hybrid polymer gelation
M.
Gnyba, M. Keranen, A. Maaninen, J. Suhonen, M. Jedrzejewska-Szczerska,
B.B. Kosmowski, and P. Wierzba
Authors
designed and built a Raman spectroscopic system for non-invasive, remote,
on-line monitoring of gelation, which is the first step of a sol-gel process
used for synthesis of hybrid polymers for photonics. The system was connected
with typical glass reaction vessel. Suitable design of an optical system
reduced excitation of interfering Raman signal in the wall of the reactor.
Application of two excitation wavelengths reduced influence of fluorescence
on measurements and provided high efficiency of the Raman system in wide
range extending from 200 to 3500 cm–1. Synthesised materials were based on silane precursors having epoxy and
amino functionality. Raman spectroscopy enabled strict control over molecular
structure of the materials during the polymerization process. Time and
efficiency of monomers hydrolysis were measured. Products of this reaction
were evaluated. The obtained data enabled us optimisation of the process
parameters which ensured high efficiency of hydrolysis and subsequent control
of solution viscosity. Moreover, behaviour of amine groups and epoxy rings
was investigated and influence of water and solvents was found.
Keywords: Raman spectroscopy, process monitoring, hybrid polymers, sol-gel technology.
19- 13(1)19.PDF
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Contrast sensitive fiber optic
Michelson interferometer as elongation sensor
M.
Szustakowski and N. Palka
Theoretical
description of a contrast phenomenon in an unbalanced fiber optic Michelson’s
interferometer with a multimode laser is shown. Required characteristic
features of the contrast function for an elongation sensor are determined.
Optimal spectrum for the dislocation sensor is calculated theoretically.
A laser which parameters fulfilled the requirements was found. The elongation
sensor based on contrast oscillations in an unbalanced fiber optic Michelson
interferometer with a 3x3 coupler is described. Direct contrast-sensitive
elongation measurement range limited to 200-µm long slope is expanded
up to 5 mm by means of contrast oscillations linearization scheme. Elongation
modulator in a reference arm of the interferometer is used. Experimental
setup, signal processing scheme and software were worked out. For 1-m long
sensor, the 5-mm measuring range with 28-µm uncertainty was obtained.
Keywords: fiber optic, Michelson interferometer, contrast function, elongation sensor.
27- 13(1)27.PDF
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Output characteristics of weak-coupling
fiber grating external cavity semiconductor laser
H.
Zhou, G. Xia, Y. Fan, T. Deng, and Z. Wu
After
taking into account the contribution of fiber grating to the phase condition,
the mode distribution of fiber grating external cavity semiconductor laser
(FGESL) has been determined, and the output characteristics of weak-coupling
fiber grating external cavity semiconductor laser (WCFGESL) have been investigated
theoretically through solving the multi-mode rate equations numerically.
The results show that with increase in the injected current, the lasing
wavelength of WCFGESL appears fluctuation, whose amplitude is influenced
by the external cavity length to a certain degree, the side mode suppression
ratio (SMSR) increases accompanied by an oscillation, and the P-I curve
distorts slightly. All these theoretical estimations accord with the reported
experimental observations.
Keywords: weak-coupling fiber grating external cavity semiconductor laser, lasing wavelength, side mode suppression ratio.
31- 13(1)31.PDF
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Effect of heat treatment at
enhanced pressure on electrical and structural properties of silicon surface
layer co-implanted with hydrogen and helium ions
W.
Jung, A. Misiuk, J. Ratajczak, and A. Barcz
Electrical
and structural properties of silicon surface layer created by high pressure
annealing of hydrogen and helium co-implanted silicon were investigated
by current and capacitance measurements of Schottky barrier junction Hg-Si
(mercury probe), cross-sectional transmission electron microscopy and SIMS
analysis. The most striking result is finding that hydrogen and helium
co-implantation leads to shallow donors generation and changes in the type
of conductivity even for low concentration of oxygen in silicon. High pressure
thermal anneals result in additional donor formation in the implanted silicon
surface layer.
Keywords: silicon, hydrogen and helium implantation, SOI, smart-cut process.
35- 13(1)35.PDF
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Novel gas sensor based on porous
silicon measured by photovoltage, photoluminescence,
and admittance spectroscopy
A.
Bratkowski, A. Korcala, Z. Lukasiak, P. Borowski, and W. Bala
Porous
silicon (PSi) layer as gas sensor, based on the change in photoconductivity,
photoluminescence and admittance has been presented. PSi layer was prepared
by electrochemical dissolution of p-type silicon wafer in HF. Photovoltage
curves, photoluminescence spectra (PL) and admittance spectra have been
measured in different gas concentrations. Photoconductivity (PC) spectra
in vacuum and different gas atmosphere have been compared. Changes of photovoltage
intensity curves and change of PC spectra versus concentration of vapour
have been observed.
Keywords: porous silicon, gas sensor, photocurrent.
39- 13(1)39.PDF
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A diffractive optical element
based machine vision system for local optical inspection of compressed
paper
A.
Oksman, R. Silvennoinen, K.E. Peiponen, M. Avikainen, and H. Komulainen
Surface
quality of fine and supercalendered (SC) paper samples was investigated
by using a pressure gauge together with a machine vision system. It is
shown in this study that a machine vision system that exploits diffractive
optical element (DOE) along with a focused laser beam detects local specular
reflectance variation of the compressed paper. It is suggested that this
machine vision system can be utilized for inspection of optical quality
variations of compressed paper.
Keywords: diffractive optical element, local specular reflectance, paper compressing.
43- 13(1)43.PDF
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Numerical analysis of a passively
Q-switched Nd:YAG laser with a Cr4+:YAG exhibiting ESA
J.
Swiderski, M. Skorczakowski, A. Zajac, and P. Konieczny
Mathematical
description of a passively Q-switched Nd:YAG laser has been presented.
The numerical analysis of saturable absorber influence on the laser efficiency
was made. The aspect taken into account here is the Cr4+:YAG – saturable
absorber exhibiting excited state absorption (ESA). The optimization procedure
points to the optimal circumstances of the laser system considered. The
numerical model developed is a very useful tool in designing solid state
lasers Q-switched by means of different nonlinear absorbers.
Keywords: Q-switched solid state laser, saturable absorber, numerical simulation.
51-
13(1)51.PDF
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Diagonal relations between elegant
Hermite-Gaussian and Laguerre-Gaussian beam fields
Y.
Pagani and W. Nasalski
Standard
Hermite-Gaussian and standard Laguerre-Gaussian diagonal beams can be expressed
by similar summation of non-diagonal standard Hermite-Gaussian beams with
expansion coefficients that are equal in magnitude in both cases. We show
theoretically and numerically that the same relations hold also for elegant
Hermite-Gaussian beams and elegant Laguerre-Gaussian beams. On the other
hand, our theoretical estimations and numerical simulations show substantial
differences between standard and elegant beams in their phase transverse
distribution and evolution of this distribution during beam propagation.
Keywords: optical beams, singular optics, phase singularities.
61-
13(1)61.PDF
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A randomized algorithm for detecting
multiple ellipses based on least square approach
L.
Li, Z. Feng, and K. He
In
this paper, a randomized method for detecting multiple ellipses based on
the least square approach is presented. The main concept used is that we
first randomly select three edge pixels in the image, which are the centre
of three windows with the same size. In order to determine a possible ellipse,
we use the least square method to fit all the edge points in these three
window, and to solve the ellipse parameters through Lagrange multiplier
method. Then we randomly select the fourth edge pixel in the image and
define a distance criterion to determine whether there is a possible ellipse
in the image. After finding a possible ellipse, we apply a further verification
process to determine whether the possible ellipse is a true ellipse or
not. Some artificial images with different levels of noises and some natural
grey images containing circular objects with some occluded ellipses and
missing edges have been taken to test the performance. Experimental results
demonstrate that the proposed algorithm is faster and more accurate than
other methods.
Keywords: circular feature, ellipse, detection, randomized, least square.
69- 13(1)69.PDF
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Thermo-optic effects in solid
state lasers end-pumped by fiber coupled diodes
J.K.
Jabczynski, J. Jagus, W. Zendzian, and J. Kwiatkowski
Review
of thermo-optic effects in gain media of diode pumped lasers is presented.
Methods of modelling and compensation of such effects are discussed. Results
of characterization of end-pumped lasers by means of energetic and caustics
measurement techniques are presented and discussed. Also application of
Wigner distribution method for characterization of aberrated laser beams
is discussed. Thermally induced astigmatism was observed for the anisotropic
rods at high heat load.
Keywords: diode pumped solid state lasers, thermo-optics, laser beam characterization.