Journals >Chinese Optics Letters
Contents
2006
Volume: 4 Issue 10
18 Article(s)
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Research Article
Slant path average intensity of finite optical beam propagating in turbulent atmosphere
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The average intensity of finite laser beam propagating through turbulent atmosphere is calculated from the extended Huygens Fresnel principle. Formulas are presented for the slant path average intensity from an arbitrarily truncated Gaussian beam. The new expressions are derived from the modified von Karman spectrum foThe average intensity of finite laser beam propagating through turbulent atmosphere is calculated from the extended Huygens Fresnel principle. Formulas are presented for the slant path average intensity from an arbitrarily truncated Gaussian beam. The new expressions are derived from the modified von Karman spectrum for refractive-index fluctuations, quadratic approximation of the structure function, and Gaussian approximation for the product of Gaussian function and Bessel function. It is shown that the form of average intensity is not a Gaussian function but a polynomial of the power of the binomial function, Gaussian function, and the incomplete gamma function. The results also show that the mean irradiance of a finite optical beam propagating in slant path turbulent atmosphere not only depends on the effective beam radius at the transmitting aperture plane, propagation distance, and long-term lateral coherence length of spherical wave, but also on the radius of emit aperture..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 559 (2006)
Asymmetric Fabry-Perot interferometric cavity for fiber optical sensors
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Good linearity and wide dynamic range are the advantages of asymmetric Fabry-Perot (F-P) interferometric cavity, whose realization has been long for. Based on optical thin film characteristic matrix theory, an asymmetric F-P interferometric cavity with good linearity and wide dynamic range is designed. And by choosing Good linearity and wide dynamic range are the advantages of asymmetric Fabry-Perot (F-P) interferometric cavity, whose realization has been long for. Based on optical thin film characteristic matrix theory, an asymmetric F-P interferometric cavity with good linearity and wide dynamic range is designed. And by choosing the material of two different thin metallic layers, the asymmetric F-P interferometric cavity is successfully fabricated. The design theory and method of this asymmetric F-P interferometric cavity have been described in detailed. In this paper an asymmetric F-P interferometric cavity used in fiber optical sensor is reported..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 563 (2006)
Study on the photonic bandgaps of hollow-core microstructured fibers
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A simple method is presented to measure the transmission spectrum of hollow-core microstructured fibers in the visible, near-infrared, and mid-infrared regions. The plane wave expansion method is applied to analyze the photonic bandgaps of hollow-core microstructured fibers. The experimental results indicate that thereA simple method is presented to measure the transmission spectrum of hollow-core microstructured fibers in the visible, near-infrared, and mid-infrared regions. The plane wave expansion method is applied to analyze the photonic bandgaps of hollow-core microstructured fibers. The experimental results indicate that there are several strong transmission bands in the near-infrared and mid-infrared region, but hardly any transmission phenomena in the visible region, which shows that there are some bandgaps in near-infrared wavelength. The experimental results are consistent with the numerically simulative results using a plane wave expansion method..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 566 (2006)
Joint tracking algorithm using particle filter and mean shift with target model updating
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Roughly, visual tracking algorithms can be divided into two main classes: deterministic tracking and stochastic tracking. Mean shift and particle filter are their typical representatives, respectively. Recently, a hybrid tracker, seamlessly integrating the respective advantages of mean shift and particle filter (MSPF) Roughly, visual tracking algorithms can be divided into two main classes: deterministic tracking and stochastic tracking. Mean shift and particle filter are their typical representatives, respectively. Recently, a hybrid tracker, seamlessly integrating the respective advantages of mean shift and particle filter (MSPF) has achieved impressive success in robust tracking. The pivot of MSPF is to sample fewer particles using particle filter and then those particles are shifted to their respective local maximum of target searching space by mean shift. MSPF not only can greatly reduce the number of particles that particle filter required, but can remedy the deficiency of mean shift. Unfortunately, due to its inherent principle, MSPF is restricted to those applications with little changes of the target model. To make MSPF more flexible and robust, an adaptive target model is extended to MSPF in this paper. Experimental results show that MSPF with target model updating can robustly track the target through the whole sequences regardless of the change of target model..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 569 (2006)
Blind noisy image separation based on a new robust independent component analysis network
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The separation of noisy image is a very exciting area of research, especially when no prior information is available about the noisy image. In this paper, we propose a robust independent component analysis (ICA) network for separation images contaminated with high-level additive noise or outliers. We reduce the power oThe separation of noisy image is a very exciting area of research, especially when no prior information is available about the noisy image. In this paper, we propose a robust independent component analysis (ICA) network for separation images contaminated with high-level additive noise or outliers. We reduce the power of additive noise by adding outlier rejection rule in ICA. Extensive computer simulations confirm robustness and the excellent performance of the resulting algorithms..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 573 (2006)
Investigation on the temperature compensating model for ring laser gyroscope
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Thermal effects impose the greatest limit on the precision of a ring laser gyro (RLG). Selections of temperature sensing points were comparatively discussed based on large numbers of experimental data to improve its precision, and the optimum combination was selected to establish a practical compensating model. The modThermal effects impose the greatest limit on the precision of a ring laser gyro (RLG). Selections of temperature sensing points were comparatively discussed based on large numbers of experimental data to improve its precision, and the optimum combination was selected to establish a practical compensating model. The model is applied to new experimental data under the given and varied temperatures. Results show that the bias trend changing with the temperature is basically eliminated and the bias stability is enhanced significantly..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 576 (2006)
Scanned-cantilever atomic force microscope with large scanning range
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A scanned-cantilever atomic force microscope (AFM) with large scanning range is proposed, which adopts a new design named laser spot tracking. The scanned-cantilever AFM uses the separate flexure x-y scanner and z scanner instead of the conventional piezoelectric tube scanner. The closed-loop control and integrated capA scanned-cantilever atomic force microscope (AFM) with large scanning range is proposed, which adopts a new design named laser spot tracking. The scanned-cantilever AFM uses the separate flexure x-y scanner and z scanner instead of the conventional piezoelectric tube scanner. The closed-loop control and integrated capacitive sensors of these scanners can insure that the images of samples have excellent linearity and stability. According to the experimental results, the scanned-cantilever AFM can realize maximal 100*100 (micron) scanning range, and 1-nm resolution in z direction, which can meet the requirements of large scale sample testing..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 580 (2006)
Beam quality improvement and focused peak intensity measurement of an intense femtosecond Ti:sapphire laser system
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Micro-lens arrays were adopted to homogenize the beam profile of 532-nm pumping laser for the main amplifier of an intense femtosecond, chirped pulse amplification (CPA) Ti:sapphire laser. Experimental measurements showed a great improvement of the near-field pattern of the CPA beam after the main amplifier and the sizMicro-lens arrays were adopted to homogenize the beam profile of 532-nm pumping laser for the main amplifier of an intense femtosecond, chirped pulse amplification (CPA) Ti:sapphire laser. Experimental measurements showed a great improvement of the near-field pattern of the CPA beam after the main amplifier and the size of the focal spot was improved from 2.7 times diffraction limitation (DL) to 1.6 DL. The spot size focused by an f/4 off-axis parabola (OAP) in the target chamber was measured to be 5.8 micron (full-width at half-maximum (FWHM)), and a peak intensity of 2.6*10^(20) W/cm2 was obtained at the output power of 120 TW. Peak intensity exceeding 10^(21) W/cm2 or even 10^(22) W/cm2 can be expected with smaller f-number focusing configuration and wavefront correction..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 583 (2006)
Definition and measurement of the beam propagation factor M2 for chromatic laser beams
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The concept of the beam propagation factor M2 is extended for chromatic laser beams. The definition of the beam propagation factor can be generalized with the weighted effective wavelength. Using the new definition of factor M2, the propagation of chromatic beams can be analyzed by the beam propagation factor M2 as samThe concept of the beam propagation factor M2 is extended for chromatic laser beams. The definition of the beam propagation factor can be generalized with the weighted effective wavelength. Using the new definition of factor M2, the propagation of chromatic beams can be analyzed by the beam propagation factor M2 as same as that of monochromatic beams. A simple method to measure the chromatic beam factor M2 is demonstrated. The chromatic factor M2 is found invariable while the laser beam propagates through the dispersion-free ABCD system..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 586 (2006)
Study on the laser treatment of electroless Ni-P-SiC composite coatings
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Effect of the laser treatment on electroless Ni-P-SiC composite coatings was investigated. The microscopic structure, surface morphology, ingredient, and performance of the Ni-P-SiC composite coatings were synthetically analyzed by the use of X-ray diffraction apparatus, scanning electron microscope, energy distributioEffect of the laser treatment on electroless Ni-P-SiC composite coatings was investigated. The microscopic structure, surface morphology, ingredient, and performance of the Ni-P-SiC composite coatings were synthetically analyzed by the use of X-ray diffraction apparatus, scanning electron microscope, energy distribution spectrometer, micro-hardness tester, wear tester and so on. It was found that the composite coatings did make crystalloblastic transformation after laser heating. Structural analysis confirmed that some new types of phase Ni2Si or Ni3Si compound would emerge in the Ni-P-SiC coatings after laser treatment. The micro-hardness measurement results showed that when the laser power was 450 W with scanning speed of 0.5 m/min, the hardness of the coating was superior to the coating obtained by the conventional furnace heating, and wear resistance of the composite coating after laser treating could also improve..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 589 (2006)
Novel Tm3+-doped transparent fluorozirconate glass-ceramic containing nanocrystalline
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A new transparent Tm3+-doped ZrF4-based nanocrystallized glass with the composition of 55ZrF4-20BaF2-18.8YF3-5AlF5-1.2TmF3 (mol%) (ZBYA) has been prepared by a conventional melting quenching technique and the subsequent heat treatment processes. The glass characteristic temperatures, the apparent activation energy, andA new transparent Tm3+-doped ZrF4-based nanocrystallized glass with the composition of 55ZrF4-20BaF2-18.8YF3-5AlF5-1.2TmF3 (mol%) (ZBYA) has been prepared by a conventional melting quenching technique and the subsequent heat treatment processes. The glass characteristic temperatures, the apparent activation energy, and the Avrami parameter for crystallization are estimated on the basis of different scanning calorimetry (DSC). The sizes of grown nanocrystals in the glass matrix appear to be 30-36.5 nm and it is studied as a function of the nucleation temperature, also the peak intensity of the nanocrystalline is studied as a function of the nucleation temperature from the X-ray diffraction (XRD) measurement. The microhardness measurement shows that the Vickers microhardness (Hv) values of the heat-treated glass samples are larger than that of the based glass about 17.26%-42.04%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 592 (2006)
Linear scheme for time-domain fluorescence molecular tomography
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Based on the generalized pulse spectrum technique that was previously developed for time-domain diffuse optical tomography, we propose a linear framework of time-domain fluorescence molecular tomography for simultaneous reconstruction of both the yield and lifetime of multi-fluorophores. The methodology is exemplified Based on the generalized pulse spectrum technique that was previously developed for time-domain diffuse optical tomography, we propose a linear framework of time-domain fluorescence molecular tomography for simultaneous reconstruction of both the yield and lifetime of multi-fluorophores. The methodology is exemplified for mono-component case and validated with simulated data..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 595 (2006)
Two-photon excited spectroscopies of ex vivo human skin endogenous species irradiated by femtosecond laser pulses
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Two-photon excited spectroscopies from ex vivo human skin are investigated by using a femtosecond laser and a confocal microscope (Zeiss LSM 510 META). In the dermis, collagen is responsible for second harmonic generation (SHG); elastin, nicotinamide adenine dinucleotide (NADH), melanin and porphyrin are the primary enTwo-photon excited spectroscopies from ex vivo human skin are investigated by using a femtosecond laser and a confocal microscope (Zeiss LSM 510 META). In the dermis, collagen is responsible for second harmonic generation (SHG); elastin, nicotinamide adenine dinucleotide (NADH), melanin and porphyrin are the primary endogenous sources of two-photon excited autofluorescence. In the epidermis, keratin, NADH, melanin and porphyrins contribute to autofluorescence signals. The results also show that the SHG spectra have the ability to shift with the excitation wavelength and the autofluorescence spectra display a red shift of the spectral peaks when increasing the excitation wavelength. These results may have practical implications for diagnosis of skin diseases..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 598 (2006)
Multi-channel and sharp angular spatial filters based on one-dimensional photonic crystals
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A photonic heterostructure with multi-channel and sharp angular defect modes by combining two different one-dimensional defective photonic crystals is proposed. The filters designed on the basis of this heterostructure possess both functions of multi-channel narrow band filtering and sharp angular filtering. The channeA photonic heterostructure with multi-channel and sharp angular defect modes by combining two different one-dimensional defective photonic crystals is proposed. The filters designed on the basis of this heterostructure possess both functions of multi-channel narrow band filtering and sharp angular filtering. The channels, channel interval, and number of channels can be tuned by adjusting the geometric and physical parameters of the heterostuctures. This kind of filters will benefit the development of multi-channel interstellar or atmosphere optical communication..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 605 (2006)
Mid-infrared absorption spectra of dimethyl methylphosphonate as molecular simulant of nerve agents
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The fine mid-infrared absorption features of dimethyl methylphosphonate vapor have been characterized by using Fourier transforms infrared spectroscopy, and the nitrous oxide was used for calibration purpose. The results show that the main P-O-C and P=O bonds related absorption bands of dimethyl methylphosphonate vaporThe fine mid-infrared absorption features of dimethyl methylphosphonate vapor have been characterized by using Fourier transforms infrared spectroscopy, and the nitrous oxide was used for calibration purpose. The results show that the main P-O-C and P=O bonds related absorption bands of dimethyl methylphosphonate vapor are peaked at 1050.01 and 1275.76 cm^(-1) respectively, those two bands show continuous characteristics at resolution of 0.125 cm^(-1)..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 608 (2006)
B4C/Mo/Si high reflectivity multilayer mirror at 30.4 nm
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The B4C/Mo/Si high reflectivity multilayer mirror was designed for He-II radiation (30.4 nm) using the layer-by-layer method. The theoretical peak reflectivity was up to 38.2% at the incident angle of 5 degrees. The B4C/Mo/Si multilayer was fabricated by direct current magnetron sputtering and measured at the National The B4C/Mo/Si high reflectivity multilayer mirror was designed for He-II radiation (30.4 nm) using the layer-by-layer method. The theoretical peak reflectivity was up to 38.2% at the incident angle of 5 degrees. The B4C/Mo/Si multilayer was fabricated by direct current magnetron sputtering and measured at the National Synchrotron Radiation Laboratory (NSRL) of China. The experimental reflectivity of the B4C/Mo/Si multilayer at 30.4 nm was about 32.5%. The promising performances of the B4C/Mo/Si multilayer mirror could be used for the construction of solar physics instrumentation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 611 (2006)
Generation of near transform-limited ultrashort laser pulses in kilohertz chirped-pulse amplification system by compensating high order phase distortions
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The effects of gain narrowing and high order dispersions on the pulse duration in our kilohertz chirped-pulse amplification system have been compensated experimentally. Using an acousto-optic programmable dispersive filter (AOPDF), the spectral full-width at half-maximum (FWHM) is expanded from 30 to 50 nm. Stable laseThe effects of gain narrowing and high order dispersions on the pulse duration in our kilohertz chirped-pulse amplification system have been compensated experimentally. Using an acousto-optic programmable dispersive filter (AOPDF), the spectral full-width at half-maximum (FWHM) is expanded from 30 to 50 nm. Stable laser pulses with the duration of 30 fs (FWHM), which is 1.07 times Fourier-transform-limitation, have been acquired by pre-compensating the high order phase distortions using the phase measured by spectral phase interferometry for direct electric-field reconstruction (SPIDER)..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 614 (2006)
Plasma-induced spatiotemporal modulation of propagating femtosecond pulses
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The dynamics of the femtosecond pulse propagation in a plasma channel is investigated by the pump-probe longitudinal diffractometry and second harmonic generation frequency-resolved optical gating (SHG-FROG) technique. The spatial characteristics, corresponding to the electronic density and the size of the channel, canThe dynamics of the femtosecond pulse propagation in a plasma channel is investigated by the pump-probe longitudinal diffractometry and second harmonic generation frequency-resolved optical gating (SHG-FROG) technique. The spatial characteristics, corresponding to the electronic density and the size of the channel, can be observed by the recorded ring pattern, and the spectral and temporal characteristics are recorded by the SHG-FROG traces. The spatiotemporal characteristics will help us to better understand the dynamics of the plasma induced by the femtosecond pulse and the femtosecond pulse propagating in the plasma channel..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 10, 617 (2006)
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