共查询到20条相似文献,搜索用时 15 毫秒
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在传统刀口仪的基础上,提出一种数字化刀口仪,利用该刀口仪可实现球面光学元件表面面形的定量检验。介绍数字刀口仪的组成、工作原理及测试过程等,并利用该刀口仪对一个半径为1000mm,口径为160mm的球面光学元件的面形进行了实际测量,给出了光学元件均方根值和峰谷值测量结果,最后对测量结果进行了讨论。 相似文献
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A single shot algorithm using a Fizeau interferometer was used to measure the form profile of a spherical smooth surface by means of fringe thinning process, which plays an important role in fringe patterns analysis. In this paper, an automatic processing technique based on the fringe thinning process is presented. The circular interference fringe pattern of the spherical smooth surface captured by the Fizeau interferometer was corrected by using the flat fielding method and then processed. Based on the fringe thinning and the assignment of the fringe orders, the information on the fringe feature was recovered automatically and the interference wavefront was reconstructed by the Zernike polynomial fitting method. The results were compared with the results measured by Bünnagel method, and the results were in good agreement. This means that the single shot algorithm is reliable, fast, and less sensitive to vibration and turbulence in surface form measurements. Simulation fringes with the ray tracing technique were obtained to match the practical fringes. 相似文献
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基于双面质点振速测量的声场分离技术 总被引:2,自引:0,他引:2
现有的声场分离技术或是基于双面声压测量或是基于单面声压和质点振速测量。本文以二维空间傅里叶变换法作为声场分离算法,提出一种基于双面质点振速测量的声场分离技术。论文首先推导出了该方法的理论模型,随后通过仿真研究验证了该方法的有效性,并通过与基于双面声压测量的声场分离方法的比较说明了其优越性。结果表明:采用基于双面质点振速测量的声场分离方法可以有效实现声场分离;基于双面质点振速测量的声场分离方法可以获得更高的质点振速分离精度,而基于双面声压测量的声场分离方法可以获得更高的声压分离精度。 相似文献
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The microrheology of viscoelastic fluids is obtained from rotational diffusion of optically anisotropic spherical colloidal probes, measured by depolarized dynamic light scattering. The storage and loss moduli obtained from the rotational mean squared displacement is in excellent agreement with those obtained from translational diffusion and by mechanical measurements. We also show that this method is applicable to samples with strong light scattering components. This extends the capabilities of the microrheological methods based on the diffusional motion of colloidal probes. 相似文献
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We report a simple method for fabricating a concave refractive microlens array (MLA) in solgel glass by using a proximity-effect-assisted reflow technique. The solgel concave refractive MLA that we fabricated had excellent surface smoothness; good dimensional conformity, with an 8.23% nonuniformity of the microlens elements; and structural perfection, with a biggest deviation of 1% from a perfect concave spherical crown. The relative error between the measured and the designed values of the concave MLA's focal length was only 1.83%. Compared with the conventional fabrication techniques for concave MLAs, the proposed method has significant advantages including simplicity, low cost, good element conformity, and smooth device surface. 相似文献
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Two dominant systematic errors in the absolute interferometric test of high numerical-aperture sphericals are discussed and measured experimentally in pursuit of an accuracy of λ=100. Gravitational sag deformation of a 4-inch spherical concave surface was measured in a vertical phase-shifting Fizeau interferometer. The surface shapes of two identical transmission spherical concaves were measured via the two-surface comparison method using three positional measurements. One of the surfaces was then rotated around the optical axis and the interference phases were averaged to extract a rotationally symmetric component of the aberration. The gravitational sag was then determined by the aberration component independent of the rotation. The geometrical error in the phase shift is also estimated theoretically and corrected in the experiment. Experimental results show that the both errors amount to 6 to 7 nm peak-to-valley lengths, the magnitudes of which are comparable to that of the total aberration of the spherical surface. 相似文献
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The two-sphere method with multiple confocal measurements and a “cat's-eye” measurement is used widely in high accuracy interferometry, which can obtain the absolute surface data of the tested spherical surface. We provide a comparative experimental study on absolute testing procedures for spherical surface with two-sphere method, which include the classical Jensen method with three position measurements, the Zygo method with five position measurements and a variant of the Jensen method. The variant of the Jensen method can combine the multiple “three-position” measurements based on the fiducial method and averaging method. The repeatability of the involved absolute measurement methods is also studied by the five set experiments, and the corresponding Zernike fitting coefficients are compared in detail. The experimental results are meaningful for implementation of two-sphere method with higher repeatability in practice. 相似文献
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Focusing the power emitted from a source with spherical wave front by a specially profiled reflecting surface has been attempted using the simple ray tracing method. The reflector (mirror) surface profile that achieves such power redistribution is obtained from solving an ordinary first order differential equation using common numerical techniques. Furthermore, the proposed methodology can be useful to design complex reflectors for the electomagnatic and the acoustic systems, which finds broad engineering, industrial and biomedical applications. 相似文献
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Shape identification using phase shifting interferometry and liquid-crystal phase modulator 总被引:6,自引:0,他引:6
A phase shifting technique using a Michelson interferometry system is presented and applied to surface contour measurement. Hyperbolic fringes are produced by the interference of two spherical wavefronts expanded from a beam expander. The fringe pattern is projected on an object surface and the deformed grating image is captured by a CCD camera for subsequent analysis by a PC. Phase variation is achieved by a liquid-crystal device incorporated in the Michelson interferometry system. Results obtained using the proposed method for objects of various shapes and sizes compared well with those from a conventional profilometer. 相似文献
14.
LI Li CHEN Ying-Tian HU Sen 《理论物理通讯》2009,51(2):315-320
By using the derivative method, we obtained the same result with that of the previous work of Chen et al. in 2006. Different from the integral form, the derivative form of the surface expression published in this paper is derived from differential equation and based on the theory of non-imaging focusing heliostat proposed by Chen et al. in 2001. The comparison of the derivative form of fixed aberration correction surface has been made with that of integral form surface as well as that of spherical surface in concentrating the solar ray. 相似文献
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A method of determining the field of a radiator from pressure measurements in its near zone is proposed. The method is based
on parametrization of the field by a set of complex spherical sources. The field of the radiator is calculated using the spherical
harmonic amplitudes, which are determined by solving the inverse problem. Results of numerical simulation are presented. 相似文献
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We present a new method for calculating the surface tension of an electrolyte-air interface using Monte Carlo (MC) simulations with an implicit solvent in a spherical drop geometry. The boundary conditions for the electric field at the interface are accounted for using image and counter-image charges. The density profiles obtained from the simulations are used to calculate the excess surface tension of the electrolyte-air interface using the Gibbs adsorption isotherm equation. The results are found to be in good agreement with experiments and the earlier theoretical calculations. 相似文献
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Geometric aberrations in interferometric testing system can significantly influence the measurement results in the case of high-numerical-aperture test spherical surface, in which obvious high-order aberrations introduced by wavefront defocus could be observed and they cannot be removed with the traditional calibration method. A technique based on the rigorous model for the analysis of geometric aberrations introduced by wavefront tilt and defocus, is presented for the calibration of the corresponding geometrical systematic error. The calibration method can be carried out either with or without a prior knowledge of the spherical surface under test. The feasibility of the proposed method has been demonstrated by computer simulation, and the residual error less than 0.001λ is obtained. Experimental validation is carried out by testing a high-numerical-aperture spherical surface with the ZYGO interferometer, and an accuracy RMS about 0.003λ with the proposed calibration technique is achieved. The effect of geometric aberrations on the measurement is discussed in detail. The proposed calibration method provides a feasible way to lower the requirement on the adjusting precision of mechanical device, and is of great practicality for the high-precision measurement of high-numerical-aperture spherical surface. 相似文献
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In previous work, we proposed a computational methodology that addresses the elimination of the self-interaction error from the Kohn–Sham formulation of the density functional theory. We demonstrated how the exchange potential can be obtained, and presented results of calculations for atomic systems up to Kr carried out within a Cartesian coordinate system. In this paper, we provide complete details of this self-interaction free method formulated in spherical coordinates based on the explicit equidensity basis ansatz. We prove analytically that derivatives obtained using this method satisfy the Virial theorem for spherical orbitals, where the problem can be reduced to one dimension. We present the results of calculations of ground-state energies of atomic systems throughout the periodic table carried out within the exchange-only mode. 相似文献
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Dae Seung Cho 《Applied Acoustics》2008,69(11):1120-1128
A highway traffic noise prediction model has been developed for environmental assessment in South Korea. The model is based on an outdoor sound propagation method and is fully compliant with ISO 9613 and the sound power level (PWL) estimation for a road segment, as suggested in the ASJ Model-1998 that is based on PWLs. Due to that model’s selection of two pavement types, such as asphalt or concrete pavement, an unacceptable traffic noise prediction is made in cases where the road surface is different from that on which the model is based. In order to address this problem, several road surface types are categorized, and the PWL of each surface type is determined and modeled by measuring the noise levels obtained from newly developed methods. An evaluation of the traffic noise prediction model using field measurements finds good agreement between predicted and measured noise levels. 相似文献