Contents
2001
Volume: 21 Issue 4
29 Article(s)
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Diffraction and Gratings
Effect of Time-Varied Wave Field on the Diffraction Tomography
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The basic formula of the diffraction tomography with time-varied incident wave was established. The angle distribution and plane distribution of the diffraction tomography with ultrashort pulse incident wave was simulated. The effect of time-varied wave field on the diffraction tomography was analyzed.The basic formula of the diffraction tomography with time-varied incident wave was established. The angle distribution and plane distribution of the diffraction tomography with ultrashort pulse incident wave was simulated. The effect of time-varied wave field on the diffraction tomography was analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 433 (2001)
Fiber Optics and Optical Communications
Mode Calculation of Arbitrarily Shaped Waveguide
[in Chinese], and [in Chinese]
A method for the mode calculation of arbitrarily shaped waveguide with near-ideal section is proposed. Two formulae for the electromagnetic field and the propagation constant calculation are derived from the perturbation theory. By using these two formulae, the dispersion characteristics of a ladder-shaped waveguide isA method for the mode calculation of arbitrarily shaped waveguide with near-ideal section is proposed. Two formulae for the electromagnetic field and the propagation constant calculation are derived from the perturbation theory. By using these two formulae, the dispersion characteristics of a ladder-shaped waveguide is conveniently given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 422 (2001)
Fourier Optics and Signal Processing
Color Distinction and Its Application in Color-Coded Grating Profilometry
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A transformation from RGB model to HIS model is prosented based on the luminosity of the object and its reverse transformation. I is used to represent the brightness of the color defined as the average value of RGB, and S is used to represent the whiteness of the color defined as the minimum value of RGB divided by briA transformation from RGB model to HIS model is prosented based on the luminosity of the object and its reverse transformation. I is used to represent the brightness of the color defined as the average value of RGB, and S is used to represent the whiteness of the color defined as the minimum value of RGB divided by brightness. H is used to represent the hue of the color. Two larger values of RGB are subtracted by the minimum value of RGB. The H is defined as the ratio of the differences. In HIS model, the brightness is separated from color. Thus, the brightness has no influence on the distinction of colors. By setting certain thresholds, it is easy to distinguish red, green, cyan, magenta and yellow strips in HIS model..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 454 (2001)
Instrumentation, Measurement and Metrology
Fourier Transform Spectrometer for Ultraviolet and Vacuum Ultraviolet Regions
[in Chinese], [in Chinese], and [in Chinese]
A novel ultraviolet and vacuum ultraviolet Fourier transform spectrometer consisting of beamsplitter/recombiner, cat’s-eye retroreflectors, a sampling system with frequency stabilized laser and photoelectric detectors has been developed. The measuring range is in the wavelength region from 170 nm to 600 nm. The spectraA novel ultraviolet and vacuum ultraviolet Fourier transform spectrometer consisting of beamsplitter/recombiner, cat’s-eye retroreflectors, a sampling system with frequency stabilized laser and photoelectric detectors has been developed. The measuring range is in the wavelength region from 170 nm to 600 nm. The spectral resolution of transformed spectrum at 300 nm is better than 1.5×105. The emission and absorption spectrum of materials in the ultraviolet and vacuum ultraviolet regions can be measured with high resolution. It is especially suitable for spectral experiments in combination with synchrotron radiation source..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 459 (2001)
The Optimum Wavelength Combination in Multi-Light-Source White-Light Interferometer
[in Chinese], [in Chinese], and [in Chinese]
The interference signal of white-light interferometer with several broadband light sources is the superposition of those only with one broadband light source. Then the signal intensity is redistributed. An optimum wavelength combination that makes the intensity difference between zero-order and first-order fringe increThe interference signal of white-light interferometer with several broadband light sources is the superposition of those only with one broadband light source. Then the signal intensity is redistributed. An optimum wavelength combination that makes the intensity difference between zero-order and first-order fringe increase is found by theoretical analysis and computer simulations. The use of the optimum wavelength combination results in the more accurate determination of zero-order fringe, the enhancement of the system resolution, and the decrease of the needed signal-noise-ratio for identifying zero-order fringe. The method to select the optimum wavelength combination is also presented..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 463 (2001)
Self-Calibrating for Phase-Shifting Adapter Consisting of Three PZT
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A self-calibrating method was proposed to calibrate the nonlinear of phase shifting adapter (PSA) consisting of three piezoelectric ceramics. Fast Fourier transform and linear polynomial fitting algorithms were used to rectify the nonlinearity of PSA, and fringe processing method was used to decline the rotation to 1&#A self-calibrating method was proposed to calibrate the nonlinear of phase shifting adapter (PSA) consisting of three piezoelectric ceramics. Fast Fourier transform and linear polynomial fitting algorithms were used to rectify the nonlinearity of PSA, and fringe processing method was used to decline the rotation to 1° and the change of fringe distance to 2%. Experiments give testing results and show the priority of the calibrating method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 468 (2001)
Lasers and Laser Optics
CW Laser by Intracavity Frequency Doubling with LBO in a LD Pumped Nd:YVO4 Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A maximum of 5.3 W CW output green laser has been obtained by intracavity frequency doubling with LBO in a Nd:YVO4 laser doubly pumped by two laser diodes. With Ⅰ-type noncritical-phase-match (NCPM), temperature tuning of LBO crystal, a maximum of 5.3 W of cw TEM00 mode output at 532 nm has been obtained with 20 W pumpA maximum of 5.3 W CW output green laser has been obtained by intracavity frequency doubling with LBO in a Nd:YVO4 laser doubly pumped by two laser diodes. With Ⅰ-type noncritical-phase-match (NCPM), temperature tuning of LBO crystal, a maximum of 5.3 W of cw TEM00 mode output at 532 nm has been obtained with 20 W pump power, the optical-optical conversion efficiency is 26.5%. The mode of the green light and the relation between the output power of green laser and the temperature of LBO crystal have been measured, they all agree well with the theoretical results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 437 (2001)
Wide Range Temperature Tunable MgO:LiNbO3 Optical Parametric Oscillator
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A temperature tuned MgO:LiNbO3 optical parametric oscillator (OPO) pumped by a Nd:YAG-SHG pulse laser with the wide tunable range of 800 nm～1750 nm is demonstrated. At the singly resonant forms, the oscillation threshold is 21.5 mJ, and the highest output energy is 6.45 mJ when pumped by the highest energy of 58 mJ. TA temperature tuned MgO:LiNbO3 optical parametric oscillator (OPO) pumped by a Nd:YAG-SHG pulse laser with the wide tunable range of 800 nm～1750 nm is demonstrated. At the singly resonant forms, the oscillation threshold is 21.5 mJ, and the highest output energy is 6.45 mJ when pumped by the highest energy of 58 mJ. The OPO conversion efficiency of energy was 11%. Linewidth of the OPO signal light is near 1 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 440 (2001)
Study of KTP Singly Resonant Optical Parametric Oscillator Pumped by Pulsed Tunable Ti:Sapphire Lasers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A singly resonant KTP-optical parametric oscillator (OPO) pumped by a pulse tunable Ti:sapphire laser is experimentally demonstrated and analyzed. Using one KTP crystal (θ=62.5°, φ=0°), the continuous output wavelength from 1261 nm to 2532 nm of type Ⅱ(A) OPO is obtained by tuning the pump laser from 700 nm tA singly resonant KTP-optical parametric oscillator (OPO) pumped by a pulse tunable Ti:sapphire laser is experimentally demonstrated and analyzed. Using one KTP crystal (θ=62.5°, φ=0°), the continuous output wavelength from 1261 nm to 2532 nm of type Ⅱ(A) OPO is obtained by tuning the pump laser from 700 nm to 980 nm, with the maximum output energy of 27.2 mJ and the maximum conversion efficiency of 35.7%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 444 (2001)
Study of Electrooptically Q-Switched RF Excited CO2 Waveguide Laser with Two Channels
[in Chinese], [in Chinese], and [in Chinese]
An electrooptically Q-switched RF excited waveguide CO2 laser with two channels is demonstrated. The Q-switched pulse laser has been obtained from one of the channels with a grating. The peak power is 150 W and the pulse width is 180 ns. CW laser output has been obtained from the other channel, which can been tuned by An electrooptically Q-switched RF excited waveguide CO2 laser with two channels is demonstrated. The Q-switched pulse laser has been obtained from one of the channels with a grating. The peak power is 150 W and the pulse width is 180 ns. CW laser output has been obtained from the other channel, which can been tuned by a PZT. In addition, the tuning range of the laser heterodyne frequency is analyzed in theory and the largest tuning range is 150 MHz in experiment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 447 (2001)
XeF(C-A) Laser Pumped Optically by Radiation from a Segmented Surface Discharge
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A detailed description of the design and experimental techniques of the XeF(C-A) laser pumped by segmented surface discharge radiation is given. An optical pumping source is developed on the basis of a segmented surface discharge with a brightness temperature Tb≈1.5×104 K emitting at 140 nm～170 nm. The characterisA detailed description of the design and experimental techniques of the XeF(C-A) laser pumped by segmented surface discharge radiation is given. An optical pumping source is developed on the basis of a segmented surface discharge with a brightness temperature Tb≈1.5×104 K emitting at 140 nm～170 nm. The characteristics of an XeF(C-A) laser pumped by this source are studied. The pulses width (FWHM)of this laser is 340 ns and the width of the emission spectrum (470 nm～495 nm) is about 15 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 450 (2001)
Materials
Photoinduced Hexagonal Symmetry Microstructure in Azobenzene Polymer Films
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A method for laser induced hexagonal symmetry microstructures in an azobenzene containing polymer film is presented based on forward degenerate four-wave mixing. Multiple forward phase conjugate waves are observed. Three p-polarized input laser beams induce only one-dimensional gratings, but using a proper combination A method for laser induced hexagonal symmetry microstructures in an azobenzene containing polymer film is presented based on forward degenerate four-wave mixing. Multiple forward phase conjugate waves are observed. Three p-polarized input laser beams induce only one-dimensional gratings, but using a proper combination of s-polarized and p-polarized laser beams, hexagonal symmetry microstructures can be induced in the azobenzene polymer film. The experimental results indicate that both the periodic variations of light field intensity and the alternation of the resultant electric field polarization in the film are essential to the formation of the microstructures in the crystal..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 491 (2001)
Fluorescence Spectral Properties of Azo Dye-Doped Polymer Film
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new azo dyedoped poly (methymethacrylate) (PMMA) film has been prepared by means of spincoating method. Absorption, steadystate fluorescence and timeresolved fluorescence spectra of the film have been measured. The kinetics of the decay process of fluorescence has been studied. The excited singlet (S1) state lifetimeA new azo dyedoped poly (methymethacrylate) (PMMA) film has been prepared by means of spincoating method. Absorption, steadystate fluorescence and timeresolved fluorescence spectra of the film have been measured. The kinetics of the decay process of fluorescence has been studied. The excited singlet (S1) state lifetimes for trans and cis isomers of the film at room temperature have been obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 495 (2001)
Spontaneous Crystallization of Amorphous Se Thin Film
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Thin a-Se films were prepared by thermal evaporation method. Optical transmission spectra and Raman scattering spectra were measured for stable a-Se film, unstable a-Se film and its initially spontaneous crystallization film. The transmission spectra were simulated and, refractive indexes varying with wavelength and thThin a-Se films were prepared by thermal evaporation method. Optical transmission spectra and Raman scattering spectra were measured for stable a-Se film, unstable a-Se film and its initially spontaneous crystallization film. The transmission spectra were simulated and, refractive indexes varying with wavelength and thickness of films were calculated. The refractive index was increased during the spontaneous crystallization and, decreased with the increasing wavelength. The transmission intensity of the spontaneous crystallization of Se thin film was lower than that of the amorphous Se thin film and the absorption edge was shifted to longer wavelength. The distorted chain and incomplete Se8 ring structures were also enhanced during the spontaneous crystallization process measured by the Raman scattering measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 499 (2001)
Nonlinear Optics
High-Intensity Pulse Compression with Plasma Nonlinearity
[in Chinese], [in Chinese], and [in Chinese]
Ultrashort-pulses with a duration of several optical cycles are very important in intense field physics research. 0.1 TW/5 fs laser pulses have been generated successfully. However, the high intensity ionization of medium limits the pulse energy of the self-phase modulation in single-mode fiber and hollow fiber filled Ultrashort-pulses with a duration of several optical cycles are very important in intense field physics research. 0.1 TW/5 fs laser pulses have been generated successfully. However, the high intensity ionization of medium limits the pulse energy of the self-phase modulation in single-mode fiber and hollow fiber filled with noble gases. G. Tempea and T. Brebec suggested that plasma nonlinearity can be used to compress the pulse. The possibility of compressing a 50 fs pulse of about 10 mJ is investigated and the pulse compression involved in the ionization on the inner face of a hollow fiber is discussed in this paper. Based on numerical simulation, it is found that the pulse can be compressed to 5 fs in a lower density gas. So it is possible by decreasing the gas density to reduce the electron density because too much electrons will destroy pulse shape..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 385 (2001)
Breakup and Suppression of Self-Focusing Rings Originated From high Intensity Super-Gaussian Beams
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In this work, the self-focusing ring originated from a rotation symmetric super-Gaussian beam (RSSGB) incident on the Nd:glass medium is described in detail, with the aid of the numerical solution to the nonlinear paraxial wave equation. For a RSSGB with initial undulations, the self-focusing ring may split after traveIn this work, the self-focusing ring originated from a rotation symmetric super-Gaussian beam (RSSGB) incident on the Nd:glass medium is described in detail, with the aid of the numerical solution to the nonlinear paraxial wave equation. For a RSSGB with initial undulations, the self-focusing ring may split after traveling certain distance inside the nonlinear medium, resulting in some high intensity filaments near the verge of the beam. For a RSSGB with a certain peak power, one can select the width and rank of the beam to suppress the formation of the self-focusing ring, so that the filaments due to the breakup of self-focusing rings may be eliminated finally..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 390 (2001)
Method for Third Harmonic Generation of Double Wavelength and Double Pulse Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The method for third harmonic generation of double wavelength and double pulse laser is proposed. Two pulsed laser beams with different wavelengths are reflected to make them near close and passing through two BBO crystals. Two wavelength second harmonics (SH) of laser pulses are generated after two times passing throuThe method for third harmonic generation of double wavelength and double pulse laser is proposed. Two pulsed laser beams with different wavelengths are reflected to make them near close and passing through two BBO crystals. Two wavelength second harmonics (SH) of laser pulses are generated after two times passing through the BBO of SHG. SHs and laser fundamental waves pass through the BBO of third harmonic generation (THG) to obtain two wavelength THGs, and couple out by 45° output mirror. The four phase matching conditions are analyzed to be satisfied in SHG and THG. This method can be used to intracavity THG of double wavelength and double pulse laser. The corresponding experimental results are given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 394 (2001)
χ(2):χ(2) Cascaded Nonlinearity Measurements by Spectrally Resolved Two-Beam Coupling
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Aimed for the applications of χ(2):χ(2) cascaded second-order nonlinear phase shifts, it is theoretically proved that this nonlinear phase shifts can be measured by spectrally resolved two-beam coupling. The dependence of the cascaded nonlinear phase shifts on the phase mismatching in femtosecond time scald is investigAimed for the applications of χ(2):χ(2) cascaded second-order nonlinear phase shifts, it is theoretically proved that this nonlinear phase shifts can be measured by spectrally resolved two-beam coupling. The dependence of the cascaded nonlinear phase shifts on the phase mismatching in femtosecond time scald is investigated experimently. The proposed novel approach has advantages of high sensitivity and easy to be applied. The cascaded nonlinearities of weak χ(2) crystals can be measured easily by use of low energy femotosecond laser oscillators..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 397 (2001)
Experimental Research on Stimulated Raman Scattering Using Raman Cell without Solid Window
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The window and its coating of the Raman cell are easily damaged by the laser beam with very high power laser. A novel Raman cell without solid windows is designed. Two gas switches are used at two ends of the Raman cell, a gas mixture with a density very close to the air is used as Raman medium. This gas mixture will nThe window and its coating of the Raman cell are easily damaged by the laser beam with very high power laser. A novel Raman cell without solid windows is designed. Two gas switches are used at two ends of the Raman cell, a gas mixture with a density very close to the air is used as Raman medium. This gas mixture will not diffuse very fast after the gas switch is open. So the Raman conversion can be obtained without solid windows. The effects of gas flow during the gas window operation on the Stimulated Raman scattering are investigated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 400 (2001)
Time Distribution of the Continuum Radiation in the Plasma Induced by Laser Ablating Al
[in Chinese], and [in Chinese]
With time- and space- resolved technique, the time-resolved spectra of the plasma induced by Nd:YAG laser ablating metal aluminum in Ar were recorded, in which, laser pulse energy was set up to 115 mJ and the buffer pressure 10 kPa. The continuum radiation of aluminum plasma was studied. The mechanism of the continuum With time- and space- resolved technique, the time-resolved spectra of the plasma induced by Nd:YAG laser ablating metal aluminum in Ar were recorded, in which, laser pulse energy was set up to 115 mJ and the buffer pressure 10 kPa. The continuum radiation of aluminum plasma was studied. The mechanism of the continuum radiation of the plasma induced by laser ablating aluminum is discussed. Resonantly absorbing continuum radiation was suggested. Bremsstrahlung and compound radiation of electron were considered as main mechanism of continuum radiation. Short after the laser beam getting to the surface of the target, Bremsstrahlung is the primary mechanism of the continuum, during early stage of the plasma involution the continuum radiation derives from Bremsstrahlung and compound radiation of electron; but during late stage the continuum emission only comes from compound radiation of electron. Atom Al selectively absorbs continuum radiation, it leads to the change of the smooth distribution of continuum emission with wavelength under normal condition..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 404 (2001)
Optical Devices
Dispersion Compensation Fiber Gratings Suitable for CATV Systems
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The influence of fiber grating dispersion ripple on CATV signals is analyzed and the power of intermodulation terms fallen into the range of 50 MHz～550 MHz is estimated about 10%～50% of the total power of all the intermodulation terms. In order to restrain the amplitude of dispersion ripple, the refraction index changeThe influence of fiber grating dispersion ripple on CATV signals is analyzed and the power of intermodulation terms fallen into the range of 50 MHz～550 MHz is estimated about 10%～50% of the total power of all the intermodulation terms. In order to restrain the amplitude of dispersion ripple, the refraction index change of fiber gratings should be made to rise from zero to its maximum value gradually. 10 cm-length fiber gratings with apodized refraction index profiles of raised-cosine or tanh(4z) shape can be used in CATV systems in theory. The longer the fiber gratings are, the smaller period of dispersion ripples they have, and subsequently the much less the influence on CATV signals. It is found that the fiber gratings with raised-cosine tapered profile have smaller dispersion ripple amplitude than those with tanh(4z) profile..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 472 (2001)
Transmission Characteristics of Sagnac Loop with Fiber Bragg Gratings Inserted
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The transmission characteristics of the filter composed of a Sagnac loop and fiber Bragg gratings are studied in detail. The analytical results are given for the uniformed fiber grating. It was found that the transmission spectrum of the filter is the cosine function modulated reflection spectrum of the fiber grating. The transmission characteristics of the filter composed of a Sagnac loop and fiber Bragg gratings are studied in detail. The analytical results are given for the uniformed fiber grating. It was found that the transmission spectrum of the filter is the cosine function modulated reflection spectrum of the fiber grating. When the fiber grating is “strong” coupling, a multi-passband filter can be constructed. When the fiber grating is “weak” coupling, a single-passband filter can be constructed. These filters can be used in modern optical fiber communications..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 476 (2001)
Design of Fully Continuous Phase Plates for Beam Smoothing in ICFConcave Refractive Microlens Arrays Fabricated by Ion Beam Etching
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A method of designing fully continuous phase plates (FCPP) for beam smoothing in inertial confinement fusion (ICF) has been studied. By using a local constraint function in Gerchberg-Saxton (G-S) algorithm’s iterative procedure, fully continuous phase plates free of 2π-line were obtained.The concave microlens arrays ofA method of designing fully continuous phase plates (FCPP) for beam smoothing in inertial confinement fusion (ICF) has been studied. By using a local constraint function in Gerchberg-Saxton (G-S) algorithm’s iterative procedure, fully continuous phase plates free of 2π-line were obtained.The concave microlens arrays of 128×128 element are fabricated using a multiple-process including photolithography heat treatment, and ion beam etching. The typical structures of concave microlenses in quartz and silicon fabricated are concave sphere crown shape, concave cylinder, and square-top concave shape. The main characteristics, such as the matching behaviors of films coated on substrates in fabrication of concave cylinder photoresist microlens arrays, the structural parameter design of photoetching mask which is relevant to the fabrication of the microlens, and control basis of photoresist mask technological parameters, are analyzed respectively. The fabrication of plane refractive microlens arrays, for instance using the coating technique on the concave microlens plate, is discussed. The dimension and the surface micromorphology of the concave microlens array in quartz substrate are determined with scanning electron microscope and surface contourgraph. The far-field optical characteristics of concave microlens array in quartz substrate are given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 480 (2001)
Quantum Optics
Influence of Atomic Coherence on Rydberg-Atom Stabilization
[in Chinese], and [in Chinese]
The atomic coherent population trapping is studied in a multilevel laser-induced continuum structure system including cascade two-photon processes. The condition leading to the atomic coherent population and the dark state are given explicity. The effects of atomic initial state and the laser intensity on the amount ofThe atomic coherent population trapping is studied in a multilevel laser-induced continuum structure system including cascade two-photon processes. The condition leading to the atomic coherent population and the dark state are given explicity. The effects of atomic initial state and the laser intensity on the amount of population trapped in the dark state and the populations distributed in the atomic bound states are discussed. Influence of atomic coherence on Rydberg-atom stabilization is revealed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 410 (2001)
A New Method for Measuring Density and Temperature of Cold Atoms in Magneto-Optical Trap
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The experimental observation of the absorption spectrum of cold atoms in magneto-optical trap (MOT) was reported. Because the Doppler broadening of cold atoms in MOT is far less than the hyperfine structure splitting, three abosrption peaks (Cs,6S1/2,F=4→6P3/2,F=3,4,5) with a ratio of absorption coefficient of 3:7:12 wThe experimental observation of the absorption spectrum of cold atoms in magneto-optical trap (MOT) was reported. Because the Doppler broadening of cold atoms in MOT is far less than the hyperfine structure splitting, three abosrption peaks (Cs,6S1/2,F=4→6P3/2,F=3,4,5) with a ratio of absorption coefficient of 3:7:12 were observed. The density of cold atoms was also measured by using absorption signal and the result agreed with fluorescence detecting method within 10% tolerance. The temperature of cold atoms measured using absorption method agreed well with that by fluorescence TOF method and release and recapture method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 414 (2001)
Rapid Communications
Road Extraction by Combined Using Statistical and Structural Information
[in Chinese], and [in Chinese]
An algorithm for road extraction from a remote sensing image is presented. It contains three steps: the road elements and the road segments are firstly extracted by using multiple local statistic characteristics of the image, and the road boundaries are extracted by using energy function. Structural information is descAn algorithm for road extraction from a remote sensing image is presented. It contains three steps: the road elements and the road segments are firstly extracted by using multiple local statistic characteristics of the image, and the road boundaries are extracted by using energy function. Structural information is described by using statistical analysis in detecting the road elements instead of using lines extracted, to enhance the algorithm’s robustness; the parameters of energy function are determined from the result of above calculation in detecting the road boundaries to make the algorithm’s self-adaptive ability..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 504 (2001)
Study on Sonoluminescence Imaging of Living Body
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Imaging biological tissues using sonoluminescence (SL) is a new research field developing in the latest two years. Sonoluminescence image of living body (nude mouse) was obtained by the high quantum efficiency imaging system. Fluoresceinyl Cypridina Luminescent Analog (FCLA), a chemiluminescent analytic agent, is used Imaging biological tissues using sonoluminescence (SL) is a new research field developing in the latest two years. Sonoluminescence image of living body (nude mouse) was obtained by the high quantum efficiency imaging system. Fluoresceinyl Cypridina Luminescent Analog (FCLA), a chemiluminescent analytic agent, is used in vivo for the first time to enhance biological SL. An image of FCLA enhanced SL in vivo was observed too. This technique has potential application in clinics for imaging diagnosis..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 509 (2001)
Spectroscopy
A Novel Differential Concentration Modulation Spectroscopy
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel differential concentration modulation spectroscopic technique was demonstrated with the spectrum of N+2 in the near infrared region. Its properties have been studied. Combining the concentration modulation spectroscopy with velocity modulation spectroscopy, the dependence of the signal to noise ratio on the modA novel differential concentration modulation spectroscopic technique was demonstrated with the spectrum of N+2 in the near infrared region. Its properties have been studied. Combining the concentration modulation spectroscopy with velocity modulation spectroscopy, the dependence of the signal to noise ratio on the modulation depth and various other factors are obtained. The high signal to noise ratio concentration modulation spectrum of Ar suggests that this spectroscopic technique will be a very sensitive and convenient method for detecting neutral free radicals and molecular ions..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 417 (2001)
Vision, Color, and Visual Optics
Study of the Parametric Effects in Colour-Difference Evaluation Using CRT Display
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Parametric effects in colour-difference evaluation were investigated using a CRT display controlled by a computer. A large number of visual data were obtained by a set of observers assessing colour-differences of sample pairs presented under 16 groups of parameters with grey-scale method. The results of preliminary proParametric effects in colour-difference evaluation were investigated using a CRT display controlled by a computer. A large number of visual data were obtained by a set of observers assessing colour-differences of sample pairs presented under 16 groups of parameters with grey-scale method. The results of preliminary processing and analyses indicated that the effects of sample frame and background colour on colour-difference perception were more obvious than other parameters considered in the experiments. The performance of BFD colour-difference formula for predicting colour-difference perception was the best and CIELAB the worst among four colour-difference formulae in comparison. Finally, two observing conditions were obtained for achieving the closest colour-difference perception of fluorescent colour on CRT and of surface colour on textile samples..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 21, Issue 4, 426 (2001)
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