Contents
2005
Volume: 25 Issue 4
28 Article(s)
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Research Article
Properties of Tetrahedral Amorphous Carbon Films Characterized By X-Ray Reflectivity Technique
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Density changing with substrate negative bias of tetrahedral amorphous carbon (ta-C) films deposited by filter cathode vacuum arc (FCVA) system was studied by X-ray reflectivity technique. According to the dependence of film density on substrate bias, it is found that the film density reaches a maximal value of 3.26 g/Density changing with substrate negative bias of tetrahedral amorphous carbon (ta-C) films deposited by filter cathode vacuum arc (FCVA) system was studied by X-ray reflectivity technique. According to the dependence of film density on substrate bias, it is found that the film density reaches a maximal value of 3.26 g/cm3 at -80 V bias. As the substrate bias moves up or down, the density tends to decrease gradually. When the substrate bias was set to a high value as -2000 V, the density of ta-C film falls to be 2.63 g/cm3, which does not change much comparing with the maximum. Furthermore, sp3 content of ta-C films was obtained from their corresponding density and the maximal value of sp3 content can be extrapolated to more than 80%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 572 (2005)
Atmospheric Optics and Oceanic Optics
Study on the Optical Scintillation for Gaussian Beam Propagation in the Slant Path through the Atmospheric Turbulence
[in Chinese], [in Chinese], and [in Chinese]
Based on the theory of optical wave propagation in the slant path and the ITU-R turbulence structure constant model which is dependent on altitude, the modified Rytov method, which is applicable to the optical wave propagation in the horizontal path, is extended to the propagation in the slant path. The formula of scinBased on the theory of optical wave propagation in the slant path and the ITU-R turbulence structure constant model which is dependent on altitude, the modified Rytov method, which is applicable to the optical wave propagation in the horizontal path, is extended to the propagation in the slant path. The formula of scintillation index as a function of the Rytov variance is derived and obtained from weak to strong fluctuation regions with Gaussian beam incidence, and the effect of the turbulence spectrum model with zero and non-zero inner scale in addition to a finite outer scale is included. The influence of different altitudes, different sizes of the inner and outer scale of the turbulence on the scintillation index with Gaussian beam propagation in the slant path is discussed in detail. Finally, the numerical results are compared and verified with the experimental data..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 433 (2005)
Diffraction and Gratings
Phase Compensative Technology for the Beam Beyond the Diffraction Limits with High Power
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The ratio of the power and the ratio of the power density are firstly defined to evaluate the quality of the beam beyond the diffraction limits. By use of the inverse transfer algorithm to calculate the phase distribution of an appropriate compensative phase, it is found that the reduction of the divergence of the laseThe ratio of the power and the ratio of the power density are firstly defined to evaluate the quality of the beam beyond the diffraction limits. By use of the inverse transfer algorithm to calculate the phase distribution of an appropriate compensative phase, it is found that the reduction of the divergence of the laser beam beyond the diffraction limits and its power density of the diffraction central spot in the far field after reduction doesn't clearly decrease. This conclusion has more significances for practical applications of Gaussian beam beyond the diffraction limits in laser emitting optics. For the given intensity distribution in the far field with certain reduction ratio and limited energy loss, the reverse structure of phase plate could be calculated according to the inverse algorithms and the phase with continuous spatial distribution is quantified into step-shaped distribution so as to simplify the fabrication of a phase plate. This conclusion not only solves the contradiction of the reduction and the power loss, but also provides the theoretic basis for the experimental study and the practical application of the beam..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 439 (2005)
Fiber Optics and Optical Communications
Study Polarization Mode Dispersion Compensation with Degree of Polarization as Feedback Signal
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The degradation of signal degree of polarization with second order polarization mode dispersion in 40 Gb/s RZ and NRZ optical communication is analyzed by numerical simulation. The results show that the degradation of signal degree of polarization is vibrated by second order polarization mode dispersion. The effect of The degradation of signal degree of polarization with second order polarization mode dispersion in 40 Gb/s RZ and NRZ optical communication is analyzed by numerical simulation. The results show that the degradation of signal degree of polarization is vibrated by second order polarization mode dispersion. The effect of higher-order polarization mode dispersion on degree of polarization of NRZ and RZ code are also numerically analyzed, the results show that the effect of second polarization mode dispersion on degree of polarization of RZ code are more evident than that on NRZ code. A experiment system is set up to compensate the first and high order polarization mode dispersion effectively by degree of polarization as feedback signal and PSO as compensation arithmetic for RZ and NRZ code system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 443 (2005)
A Study for Phase-Shift Characteristics of Polarization Controller Based on Simulated Annealing Algorithm
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A four-wave-plate electrooptic polarization controller (PC) is constructed with their fast axes oriented alternately at 0°, 45°, 0°, 45° with respect to horizontal. The simulated annealing feedback controlling algorithm is applied to the controlling process to get the desired output polarization staA four-wave-plate electrooptic polarization controller (PC) is constructed with their fast axes oriented alternately at 0°, 45°, 0°, 45° with respect to horizontal. The simulated annealing feedback controlling algorithm is applied to the controlling process to get the desired output polarization state. Simulating results show that this polarization controller is endless and the plate phase range can be limited within 0 to 2π. Using this controlling algorithm the controller can converge rapidly and the fluctuation of light intensity is less than 2%. To ensure the endless property of the controller a coercing reset method is introduced and here the reset process is stable. In searching the optimal value, the phase shift step of plates is variable but less than the maximum step of 3.36° while the step is fixed in 18° for the coercing reset..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 449 (2005)
Fourier Optics and Signal Processing
Apply Wavelet Transform to Phase Analysis of Spatial Carrier-Fringe Patterns
[in Chinese], and [in Chinese]
In order to overcome the disadvantages of Fourier transform analyzing nonstationary signals, the invariable resolution of Fourier transform, and the uncertainty scale of dilating Fourier transform, the Gabor wavelet transform is applied to analyze the spatial carrier-fringes. By introducing the Gabor wavelet to analyziIn order to overcome the disadvantages of Fourier transform analyzing nonstationary signals, the invariable resolution of Fourier transform, and the uncertainty scale of dilating Fourier transform, the Gabor wavelet transform is applied to analyze the spatial carrier-fringes. By introducing the Gabor wavelet to analyzing the spatial carrier-fringe patterns, the modulated phase distribution relative to the fundamental frequency is obtained finally. The theory, accuracy check using a simulation and an example of 3-D shape measurement are shown..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 454 (2005)
Image Processing
Quality-Guided Phase Unwrapping Method Based on Placement of Branch Cuts
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Two-dimensional phase unwrapping method is an active and interesting subject, and plays important roles in a great number of measurement applications. Although mask cut algorithm is successful in some applications, the algorithm has its own drawbacks. In order to overcome the drawbacks of the mask cut algorithm that exTwo-dimensional phase unwrapping method is an active and interesting subject, and plays important roles in a great number of measurement applications. Although mask cut algorithm is successful in some applications, the algorithm has its own drawbacks. In order to overcome the drawbacks of the mask cut algorithm that exists in some successful applications, a new two-dimensional quality-guided phase unwrapping algorithm, based on the placement of the branch cuts, is proposed. The new algorithm combines the advantages of the residue-compensation algorithms and those of the quality-guided ones. In the algorithm, an initial quality map of the wrapped phase image is firstly used to guide the placement of the phase unwrapping. Then the minimum quality value is assigned to pixels that belong to the branch cuts to generate a new quality map. Finally, the new quality map is used to guide the phase unwrapping process. The algorithm has been tested by use of several wrapped images. Computer simulation and experimental results make it clear that the proposed algorithm works more effectively than the mask cut algorithm even when complicated discontinuities and high levels of noise exist in the wrapped phase images..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 460 (2005)
Imaging Systems
Numerical Analysis of Interaction and Perturbation between Evanescent Field and Probe in Optical Field Detection by SNOM
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The interaction and the perturbation between a metal-coated fiber probe and an aperture evanescent field is analyzed numerically using finite-difference time-domain (FDTD) method. The simulation model consists of a sub-wavelength aperture and a metal-coated fiber probe scanning in constant height mode. Influences of thThe interaction and the perturbation between a metal-coated fiber probe and an aperture evanescent field is analyzed numerically using finite-difference time-domain (FDTD) method. The simulation model consists of a sub-wavelength aperture and a metal-coated fiber probe scanning in constant height mode. Influences of the scanning height and the aperture size of the fiber probe on optical field detection are discussed. Relationship between the measured optical field and the initial optical field without perturbation is compared and analyzed. The research results reveal that when the aperture size of the probe is comparable with the measured nano-structure and the scanning height is close to half of the aperture size, the measured field distribution shows better similarity with the initial one, that is to say, it can describe the initial one accurately..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 465 (2005)
The Numerical Simulation of Photon Scanning Tunnel Microscope's Image with Metallic Particle Probe
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The image of photon scanning tunnel microscope (PSTM), which uses fiber probe with metallic nanoparticle tip, is analyzed with the finite-difference time-domain (FDTD) formulation of dispersive materials. With considering the interaction between the field of the fiber probe and the sample, the influences of different aThe image of photon scanning tunnel microscope (PSTM), which uses fiber probe with metallic nanoparticle tip, is analyzed with the finite-difference time-domain (FDTD) formulation of dispersive materials. With considering the interaction between the field of the fiber probe and the sample, the influences of different angle of incidence, different distance between probe and sample, different kinds of metal and different size of the metallic nanoparticle on the resolution and the sensitivity of PSTM are investigated with the equivalent incident wave method. The simulated results show that the image of PSTM with metallic nanoparticle tip has higher resolution and sensitivity. The influences of different kinds of metallic nanoparticle on the resolution are not obvious, while the image of PSTM which uses fiber probe with silvery nanoparticle tip has the best sensitivity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 470 (2005)
Study on Three-Dimensional Superresolving Performances of Complex Amplitude Pupil Filters
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
At present, in the superresolution technique most of pure amplitude or pure phase filters only can realize transverse or axial superresolution, but cannot aehieve the three-dimensional superresolution which play an important role in the three-dimensional imaging systems. So in order to improve the three-dimensional resAt present, in the superresolution technique most of pure amplitude or pure phase filters only can realize transverse or axial superresolution, but cannot aehieve the three-dimensional superresolution which play an important role in the three-dimensional imaging systems. So in order to improve the three-dimensional resolving power of optical imaging system, a new set of complex amplitude pupil filter is designed, and its three-dimensional superresolving performances are studied. The effects of the radius and the transmittance of the first zone on the Strehl ratio, the transverse and axial gains, and the side lobes are analyzed in detail. With a series of simulation examples of such filter, it can be concluded that three-dimensional superresolution can be realized with the compleamplitude pupil filter. Advantage of such filter is easy to realize three-dimensional superresolution with high Strehl ratio. And disadvantage is that the influence of the side lobes is greater for some systems. But it can be suppressed by applying confocal scanning imaging systems..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 475 (2005)
Three-Dimensional Tomography of Incomplete Data with Fusion of Virtual and Real Experiments
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The optical computerized tomography (OCT) of incomplete data for three-dimensional detection of complex flow field is urgent to be but still not be resolved. A new three-dimensional tomography with the fusion of virtual and real experiments is proposed, which combines the technology computational fluid dynamics (CFD), The optical computerized tomography (OCT) of incomplete data for three-dimensional detection of complex flow field is urgent to be but still not be resolved. A new three-dimensional tomography with the fusion of virtual and real experiments is proposed, which combines the technology computational fluid dynamics (CFD), computational flow imaging (CFI), and OCT. The experimental results of double-peak temperature field indicate that, compared with the reconstructed results of full data, the error of unsymmetrical the double-peak reconstructed by the three-dimensional tomography with fusion of virtual and real experiments is less than 5%. So this new three-dimensional tomography can reconstruct the flow field of incomplete data satisfactorily, improve the reconstruction resolution greatly, and thus provides a brand-new way for the incomplete data reconstruction with limited viewing angle..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 479 (2005)
A Novel Method for Dynamic Calibrating Non-Uniform of Multiple CCD Imaging
[in Chinese], and [in Chinese]
The conventional methods for calibrating non-uniform of multiple charge coupled deivce (CCD) imaging are difficult and complex because of so many factors leading to imaging non-uniform in a multiple CCD imaging system. Based on analyzing imaging mechanism of multiple CCD, a novel calibration method for multiple CCD imaThe conventional methods for calibrating non-uniform of multiple charge coupled deivce (CCD) imaging are difficult and complex because of so many factors leading to imaging non-uniform in a multiple CCD imaging system. Based on analyzing imaging mechanism of multiple CCD, a novel calibration method for multiple CCD imaging using wavelet analysis was proposed. The calibration coefficient was constructed using wavelet transform for calibrating the images captured by different CCD after analyzing the pixel characteristic discrimination of different images. The dynamic calibration efficiency of different wavelets was also discussed in the real-time imaging calibration processing. The result indicated that the correlation value of the images of the same object captured by different CCD was 0.9975 after the calibration. Symlet3 wavelet was more effective than other wavelets both in the two CCD imaging and multiple CCD imaging calibrating. And also it indicated that Symlet serial wavelets were more effective in calibrating the non-uniform of multiple CCD imaging than other types of wavelet. This method provided an effective way for on-line calibrating the multiple CCD imaging system in practical application..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 485 (2005)
Instrumentation, Measurement and Metrology
High-Accuracy Measurement of Rotation Angle Based on Image
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A measurement method based on image is present to measure rotation angle at high precision of 5″ which uses a line as the character sign. A digital camera is used to capture the image of the line. The rotation angle is calculated by detecting the line slope angle with high accuracy in the image. The factors that affectA measurement method based on image is present to measure rotation angle at high precision of 5″ which uses a line as the character sign. A digital camera is used to capture the image of the line. The rotation angle is calculated by detecting the line slope angle with high accuracy in the image. The factors that affect the precision are analyzed. Then the guidelines to measure a rotation angle with high precision of seconds are proposed, which include the method to detect a line and the parameters of a line such as the length,the width and the direction. Experiments show that when the line is wide of 5～9 pixel and the angle between the line and the sampling direction is far away from 0° and 45° the rotation angle measurement gets the highest accuracy, and if the length is not less than 1000 pixel the precision is not less than 5″..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 491 (2005)
Research on Subdividing Method for Random Phase Difference Fringe Signals
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In order to eliminate the subdividing error caused by fring signals which is not in phase quadrature, a new method that can directly subdivide fringe signals for random phase relationship is presented. One signal period can be divided into eight sections according to the fringe signals polarity and amplitude. The fringIn order to eliminate the subdividing error caused by fring signals which is not in phase quadrature, a new method that can directly subdivide fringe signals for random phase relationship is presented. One signal period can be divided into eight sections according to the fringe signals polarity and amplitude. The fringe signals are sampled at high speed so that the section in which the sampled point locates can be calculated in real time. The fringe signals absolute amplitude joints can be dynamically traced by judging whether two successive sampling points are in different sections. After the amplitudes of fringe signals star point and stop point are sampled, the section in which they locate can be calculated, the fraction fringe can be worked out by combination of joints of start point and stop point. Experimental results show that the new method can subdivide fringe signals correctly even when they are in random phase relationship. This new method breaks through the limitation that the signals must be in phase quadrature for conventional subdividing methods and has better anti-jamming ability..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 497 (2005)
Influence of Stress Gradient on Measurement Accuracy of Brillouin Optical-Time-Domain-Reflectometry
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The spatial resolution of BOTDR (the Brillouin optical time domain reflectometer) based on pulse pump in fiber could reach meter order. The analytic relationship between Brillouin backscattering spectrum and stress gradient is set up to investigate the influence of the stress gradient within the resolution on the measuThe spatial resolution of BOTDR (the Brillouin optical time domain reflectometer) based on pulse pump in fiber could reach meter order. The analytic relationship between Brillouin backscattering spectrum and stress gradient is set up to investigate the influence of the stress gradient within the resolution on the measurement accuracy of Brillouin frequency shift. The numerical results show that the increasing stress gradient results in the linear increasing of the Brillouin frequency shift, the nonlinear decreasing of the peak and the flattening of Brillouin spectrum. With the spatial resolution of 10 m and the stress gradient of 100 με/m, the measurement error of Brillouin frequency shift is 2.04 times larger than that without the stress gradient. Based on pulse modulation of lightwave with linewidth less than 1 MHz and BOTDR with balanced coherent detection, the Brillouin spectra and stress along the test fiber are experimentally measured at different stress gradients with the sensing fiber fixed on a cantilever beam. The Brillouin spectra of the different stress gradients are obtained from the experimental data by the least squares fitting. Experimental results are in agreement with the theoretical prediction..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 501 (2005)
Materials
Organic-Inorganic Hybrid ZrO2-SiO2 Planar Waveguides
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
ZrO2-SiO2 organic-inorganic hybrid optical waveguide materials were synthesised by the sol-gel process. Refractive index of the hybrid films was adjusted with different amounts of ZrO2 for the use as guiding layers (refractive index ng≈1.497), buffer laters and clading layers (nb=nc≈1.479). The hybrid films were deposiZrO2-SiO2 organic-inorganic hybrid optical waveguide materials were synthesised by the sol-gel process. Refractive index of the hybrid films was adjusted with different amounts of ZrO2 for the use as guiding layers (refractive index ng≈1.497), buffer laters and clading layers (nb=nc≈1.479). The hybrid films were deposited on single-crystal silicon wafers (?肌?10 cm) by sol-gel spin-coating. The guiding layers were UV-photosensitive and so UV-patternable. Optical propagation loss in the slab waveguides was measured to be about 0.8 dB/cm at 632.8 nm, by the cut-back method, using prism-coupling. The buried channel waveguides were also prepared by patternning the guiding layers of the slab waveguides with UV-curing and rinsing with isopropanol. Propagation loss in the buried channel waveguides was also measured by the cut-back method, using butt-coupling. The loss was lower than the measurement error, or less then 0.1 dB/cm at 632.8 nm. The near-field patterns were observed, and absorption spectrum of the hybrid material for the guiding layers was measured..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 506 (2005)
Optical Properties of Cr, Nd Co-Doped Solid-State Laser Crystal (Cr4+,Nd3+)∶Gd3Ga5O12
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The high-average-power solid-state-laser (HAP SSL) crystal (Cr4+,Nd3+)∶Gd3Ga5O12 [(Cr4+,Nd3+)∶GGG] has been grown by the Czochralski method. The optical spectra of (Cr4+,Nd3+)∶Gd3Ga5O12 single crystals with 2at.% Nd and different Cr4+ concentrations were measured. The effect of Cr concentrations on, fluorescence lifetiThe high-average-power solid-state-laser (HAP SSL) crystal (Cr4+,Nd3+)∶Gd3Ga5O12 [(Cr4+,Nd3+)∶GGG] has been grown by the Czochralski method. The optical spectra of (Cr4+,Nd3+)∶Gd3Ga5O12 single crystals with 2at.% Nd and different Cr4+ concentrations were measured. The effect of Cr concentrations on, fluorescence lifetime and fluorescence peak wavelength of (Cr,Nd)∶GGG crystals were analyzed. The absorption spectra of Cr4+∶GGG, Nd3+∶GGG and (Cr4+,Nd3+)∶GGG crystal are compared. The fluorescent lifetime of (Cr4+,Nd3+)∶GGG and Nd3+∶GGG are 33 μs and 240 μs, respectively. This crystal may be potential materials for compact, efficient, high stability laser-diode-pumped passive Q-switched solid-state laser..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 511 (2005)
Nonlinear Optics
Spatial Effects in the Pump-Probe Process with Higher Order Nonlinearity
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In femtosecond pump-probe spectroscopy, spatial resolved probe signal reflects the nonlinear effects of the sample in different spatial positions. However, as the pump intensity increases, high order, especially fifth-order nonlinear effects will appear in the probe signal. The split-step method is used to directly solIn femtosecond pump-probe spectroscopy, spatial resolved probe signal reflects the nonlinear effects of the sample in different spatial positions. However, as the pump intensity increases, high order, especially fifth-order nonlinear effects will appear in the probe signal. The split-step method is used to directly solve the nonlinear propagation equation with one transverse dimension. In the numerical simulation, the effects of fifth-order nonlinearity in pump probe process are studied for different pump intensities and spatial positions. For sufficient intense pump field, the probe signal show distinct interference between the third- and fifth-order nonlinear polarization. Clearly oscillation has been observed in the signal. At the spatial position far away from the center of the pump field, the fifth-order contribution of the probe decays much faster than the third-order contribution. The physical mechanism and intention are discussed qualitatively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 515 (2005)
Induced Foucusing of Gaussian Elliptic Beam in Self-Defocusing Media
[in Chinese], and [in Chinese]
The effect of elliptic Gauss beam on the focusing of the signal beam under the other different parameters is discussed. There are six parameters, i.e. the wavelength ratio of the pump beam to the signal, the initial amplitudes of a pump beam and a signal beam, the initial separation between the beams' centers, and The effect of elliptic Gauss beam on the focusing of the signal beam under the other different parameters is discussed. There are six parameters, i.e. the wavelength ratio of the pump beam to the signal, the initial amplitudes of a pump beam and a signal beam, the initial separation between the beams' centers, and the ratio of the initial beam width of the X and Y of the pump to that of the signal, which influence the induced focusing of the signal optical beam. The numerical simulations are in good agreement with the experimental results obtained by Hickmann in 1992..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 520 (2005)
Optical Design and Fabrication
The Mathematical Analysis for the Active Lap Deformationon Proceeding Condition
[in Chinese]
Using active lap to polish an aspherical mirror is a dynamic proceeding, so the translation and spin of spindle, the spin, tilt, deformation, and rise and fall of the lap; and the spin of the primary mirror all together must be kept in step, under the computer control. According to author's ??910 mm, F/2, parabolicUsing active lap to polish an aspherical mirror is a dynamic proceeding, so the translation and spin of spindle, the spin, tilt, deformation, and rise and fall of the lap; and the spin of the primary mirror all together must be kept in step, under the computer control. According to author's ??910 mm, F/2, parabolic primary mirror and our active lap parameters, the author analyzes the deformation character of active lap base, that is, its deforming quantity, deforming velocity and deforming acceleration, and the difference between precision deformation and approximative analysis; the distance of rising and falling on 3-hoist points of the stressed lap back, that is, its moving velocity and acceleration; the relationship between reality deforming quantity of stressed lap and the measuring quantity using LVDT on measuring shelf. Also the relationship and features about deformation and hoisting movement with V1 (lap moving velocity along the crossbeam) and V2 (lap spinning speed around its spindle) are analyzed. Based those analyses, the author can guide to design mechanics and electronics of active lap, and guarantee all these movement keep in step..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 525 (2005)
Research of Mask Division for Improving the Edge Sharpness of Photolithography
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new technique of mask division for improving the sharpness of mask edge is put forward, which can be used to solve the lowpass filtering problem of the reduction lens in the system of mask fabrication with electrically addressed spatial light modulators. A mask image with high frequency is sampled with fixed or variaA new technique of mask division for improving the sharpness of mask edge is put forward, which can be used to solve the lowpass filtering problem of the reduction lens in the system of mask fabrication with electrically addressed spatial light modulators. A mask image with high frequency is sampled with fixed or variable low frequency. In each period of the low frequency mask, only one part of the initial mask is included. Using real-time mask technique, multiple division masks are exposed sequentially and the high frequency mask is restored. For fabrication of binary grating, the relative lost efficiency caused by aperture limit of the lens can be decreased from 35.23% to 6.09%. And part of the low frequency energy is moved to the middle and high frequency. The sharpness of the mask edge is ameliorated evidently. Using division mask, complex shape mask or multi-level mask can be changed into binary mask, which is easy to be designed and realized. Moreover, the transition of multi-level gray to binary, that is, black and white, can eliminate the disturbing effect of the refresh rate of screen..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 533 (2005)
Optical Devices
Finite Element Analysis for Wavefront Error of Lenses Induced by Gravity
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
When collimator with big diameter and long focal length is used to simulate laser far-field character, the deformation of its lens under gravity cannot be ignored. To analyze the effect, finite element analysis software ANSYS is adopted to simulate a ??400 mm plano-convex lens from a collimator, and a method is presentWhen collimator with big diameter and long focal length is used to simulate laser far-field character, the deformation of its lens under gravity cannot be ignored. To analyze the effect, finite element analysis software ANSYS is adopted to simulate a ??400 mm plano-convex lens from a collimator, and a method is presented to analyse wavefront error caused by axial deformation of lens, P-V and RMS values of axial deformations under gravity are computed in different cases, the contours of lens surface are plotted when RMS values of axial deformations is the smallest, the P-V and RMS wavefront error in ??350 mm are also calculated, finally the wavefront error of lenses is estimated in optimal case, and the rationality of collimator design is validated..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 538 (2005)
Physical Optics
Spectral Changes in Polychromatic Gauss-Schell-Model Beams Passing Through a Spherically Aberrated Lens
[in Chinese], and [in Chinese]
Based on the propagation equation of partially coherent light,the spectral changes in polychromatic Gauss-Schell-model (GSM) beams propagating through a lens with spherical aberration are studied .It is shown that the on-axis spectrum of polychromatic GSM beams passing through the spherically aberrated lens depends on Based on the propagation equation of partially coherent light,the spectral changes in polychromatic Gauss-Schell-model (GSM) beams propagating through a lens with spherical aberration are studied .It is shown that the on-axis spectrum of polychromatic GSM beams passing through the spherically aberrated lens depends on the spatial correlation parameter β, spherical aberration C4, band-width σ0 of the source and position parameter z in general. The attention is focused on the effect of spherical aberration on the on-axis spectrum and the results are compared with those for the aberration-free case. It is shown that the on-axis spectrum is blue-shifted or red-shifted in the presence of the spherical aberration, whereas there is only the blue shift for the aberration-free case. Additionally, the spectral splitting can take place. The spectrum is split into two curves with equal height, and a rapid transition appears at critical positions. Moreover, the effect of spherical aberration becomes noticeable with increasing spatial correlation. The spectral splitting vanishes if the spatial correlation parameter is less than a certain value..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 542 (2005)
Spectroscopy
Uncertainty Analysis of the Colour Temperature and the Correlated Colour Temperature
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The colour temperature and the correlated colour temperature are important parameters of the sources. Because of the complex calculation process between the colour temperature, the correlated colour temperature and the chromatic coordinate (u,v), it is difficult to analyze the expression of uncertainty according to theThe colour temperature and the correlated colour temperature are important parameters of the sources. Because of the complex calculation process between the colour temperature, the correlated colour temperature and the chromatic coordinate (u,v), it is difficult to analyze the expression of uncertainty according to the international organization for standardization (ISO) guide. Based on the ISO guide to the expression of uncertainty, correlated colour temperature uncertainty is derived from the analytical equation between the chromatic coordinate (u,v) and the colour temperature. Accurate analytical method, approximate calculation, geometrical projection method and traditional method are discussed and compared, which are used to evaluate the uncertainty of the new national secondary standard of colour temperature at National Institute of Metrology (NIM). Traditional uncertainty analysis is mostly based on experimental statistic and experience estimation, and no mathematical relation is found between the colour temperature uncertainty and the spectral irradiance values. The analytical methods described in this paper are more accurate and reasonable..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 547 (2005)
Experimental Study of High-Resolution Ion Spectra of NO Molecule and Oxygen Atom
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Resonance enhanced multiphoton ionization (REMPI) and time of flight (TOF) mass spectrometer technique is a high-resolution and high-sensitivity spectrum-research method. In this article the vibrotation state resolution ion spectrum of the NO (X2Π,ν″,J″) from NO (A2Σ+,ν′=0,1,J′← X2Π,ν″=0,1,J″) transition γ(0,0) γ(0,1) Resonance enhanced multiphoton ionization (REMPI) and time of flight (TOF) mass spectrometer technique is a high-resolution and high-sensitivity spectrum-research method. In this article the vibrotation state resolution ion spectrum of the NO (X2Π,ν″,J″) from NO (A2Σ+,ν′=0,1,J′← X2Π,ν″=0,1,J″) transition γ(0,0) γ(0,1) γ(1,1) and the spin-orbit fine structure resolved ion spectrum of the atomic oxygen from the two-photo transition of O(2P3PJ″→3P3PJ′) are obtained by the laser dissociation NO2 using above method. The O(2P3PJ″=2→3P3PJ′,2P3PJ″=1→3P3PJ′,2P3PJ″=0→3P3PJ′) ion signals correspond ultravidet (UV) ionization detection laser wavelength at 225.65 nm, 226.04 nm, 226.23 nm respectively. The experimental result shows, the resolution and sensitivity of REMPI and TOF mass spectrometer technique is higher that of laser induced fluorescence method (LIF). The obtained ion spectra of NO molecule and atom oxygen are very useful experimental information for research of the NO2 photodissociation and NO molecule atom oxygen ionization dynamics..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 553 (2005)
Study of Plasma Particles Recycling and Transport with Spectroscopic Method
[in Chinese], [in Chinese], and [in Chinese]
The fitting technique with three Gaussian functions is introduced, The remote wing of Hα line shape is fitted with single Gaussian function at first, the ion temperature of plasma is derived from the Doppler broadening, then the residuals of Hα line shape is fitted with double Gaussian functions. The incident velocity The fitting technique with three Gaussian functions is introduced, The remote wing of Hα line shape is fitted with single Gaussian function at first, the ion temperature of plasma is derived from the Doppler broadening, then the residuals of Hα line shape is fitted with double Gaussian functions. The incident velocity of reflected particles and desorbed particles are 3.0×104 m/s and 1×104 m/s respectively, which are derived from the Doppler shift of Hα line shape, the recycling particles consist of 60% reflected particle and 40% desorbed particles, which are derived from the intensity of Hα line. The profile of hydrogen atom density, the coefficient of emission and particle confinement time are also obtained from the simplified model of particles transport, agreeing with experimental results. The influence of incident velocity on particle confinement time is analyzed. The result shows that particle confinement time is 4～8 ms with normal discharge in HT-6M Tokamak, the velocity of reflected particles directly dominate the magnitude and the radial profile of particle confinement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 557 (2005)
Thin Films
Analysis of Deposition Rate of Inhomogeneous Coatings Prepared by Co-Evaporation
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Graded index coatings are also called inhomogeneous coatings. Based on Drude theory, the relationship of dielectric constants between inhomogeneous coatings and coating materials was analyzed. The mechanism of preparing inhomogeneous coatings by multi-source co-evaporation was introduced. Subsequently, we discussed howGraded index coatings are also called inhomogeneous coatings. Based on Drude theory, the relationship of dielectric constants between inhomogeneous coatings and coating materials was analyzed. The mechanism of preparing inhomogeneous coatings by multi-source co-evaporation was introduced. Subsequently, we discussed how to get the distribution of deposition rate v(x) of coating materials from the refractive index distribution n(x) of inhomogeneous coatings on the assumptions that the volumes of different materials were equal or not and the total deposition rate was constant or not, and some deposition rate expressions of different refractive index distribution such as linearity, sine, exponent, and hyperbola were given too. In the end, a simple example was given, in which the total deposition rate was constant and the change law of refractive index was linearity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 561 (2005)
Study of Silicon Oxynitride Film Deposited by RF Magnetron Sputtering
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The conditions of depositing graded refractive index silicon oxy-nitride films were studied when the optical properties of the films changed with the composition. SiOxNy thin films of different N/O ratios were deposited by rf magnetron reactive sputtering. Samples' refractive index, extinction coefficient, compositThe conditions of depositing graded refractive index silicon oxy-nitride films were studied when the optical properties of the films changed with the composition. SiOxNy thin films of different N/O ratios were deposited by rf magnetron reactive sputtering. Samples' refractive index, extinction coefficient, composition and deposition rate were studied. The transmission curve was measured by using UV-VIS spectrophotometer. A simple and accurate method is presented for determination of the optical constants and physical thickness of thin films. Which consists in fitting the experimental transmission curve with the help of the physical model. The composition of SiOxNy films was analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spoctroscopy (FTIR) characterization methods. The experiments indicated the film characteristics were related closely to the N2/O2 gas flow ratio. As a result, the samples' refractive index can be controlled from 1.92 to 1.46 by adjusting the gas flow and controlling the total pressure, and the optical gap calculated using Wemple-DiDomenico single-oscillator model lies between 5～6.5 eV..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 4, 567 (2005)
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