Phase-Only Fourier Hologram As An Optical Matched Spatial Filter

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

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Optimum spatial filter for optical defocus sensing

Electrical Engineering in Japan ◽

10.1002/ecja.4400640915 ◽

1981 ◽

Vol 64 (9) ◽

pp. 113-120

Author(s):

Kohji Takemura ◽

Suteo Tsutsumi

Keyword(s):

Spatial Filter ◽

Optical Defocus

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Investigation of surface texture filtering error using spline spatial filter

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2018-3-27-32 ◽

2018 ◽

pp. 27-32

Author(s):

V. V. Poroshin ◽

D. G. Bogomolov ◽

V. G. Lysenko

Keyword(s):

Surface Texture ◽

Spatial Filter ◽

Texture Filtering

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Power Experimental Optimization of Horizontal Axis Wind Turbine

Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) ◽

10.2174/2352096511666180906150812 ◽

2020 ◽

Vol 13 (3) ◽

pp. 438-443

Author(s):

Sadek Ameziane ◽

Abdesselem Chikhi ◽

Mohammed Salah Aggouner

Keyword(s):

Wind Turbine ◽

Vertical Axis ◽

Energy System ◽

Spatial Filter ◽

Complex Model ◽

Vertical Axis Wind Turbine ◽

Horizontal Axis Wind Turbine ◽

Detailed Model ◽

Continuous Current ◽

Mechanical Sensors

Background: The presented article is a contribution to the realization of a wind emulator based on a continuous-current machine. The development of this topic focuses on the modeling of a vertical axis wind turbine, a DC motor with independent excitation and its control via a chopper. Methods: To carry out this work, we have studied and designed the electronic and mechanical sensors as well as a command implemented on the dSPACE DS1103 system. Results: The main purpose of this work is related, on one hand, to the control of the motor turbine by imposing the wind profile and on the other hand generate the command of the implanted MPPT. The experimental results obtained showed the great performances which characterize this improved wind energy system. Conclusion: Finally, a wind turbine with variable speed is a system having a complex model; however, a detailed model of the interaction between the wind and the aero-turbine is useful to understand certain phenomena such as rotational sampling or the spatial filter.

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Spatial filtering of signals with spectrum overlapping

Issues of radio electronics ◽

10.21778/2218-5453-2019-12-27-33 ◽

2019 ◽

pp. 27-33

Author(s):

M. E. Shevchenko ◽

A. V. Gorovoy ◽

S. N. Solovyov

Keyword(s):

Antenna Arrays ◽

A Priori ◽

Spatial Filtering ◽

Spatial Filter ◽

Radio Sources ◽

Probability Of Error ◽

Shift Keying ◽

A Priori Uncertainty

The paper considers the spatial filtering methods of signals with spectrum overlapping under conditions of a priori uncertainty of the directions of arrival from radio sources. The estimates of the directions of signals arrival obtained by ESPRIT or MUSIC are used in order to build a spatial filter. It is shown that when using ESPRIT, unlike MUSIC, an additional calculations of filter coefficients based on estimates of the directions of signals arrival are not required, and the quadrature components of the signals are formed simultaneously with estimates of the direction of their arrival. The probability of error performances of minimum shift keying signals which were divided by spatial filtering on the basis of ESPRIT and MUSIC using seven-element circular and angular antenna arrays are given.

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Two-Photon Excitation Imaging of Glucose Metabolism in Living Tissue

Microscopy and Microanalysis ◽

10.1017/s1431927600008412 ◽

1997 ◽

Vol 3 (S2) ◽

pp. 305-306

Author(s):

David W. Piston

Keyword(s):

Confocal Microscopy ◽

Collection Efficiency ◽

Three Dimensional ◽

Spatial Filter ◽

Input Power ◽

Photon Absorption ◽

Focal Volume ◽

Two Photon ◽

Photon Excitation ◽

Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. It provides three-dimensional resolution and eliminates background equivalent to an ideal confocal microscope without requiring a confocal spatial filter, whose absence enhances fluorescence collection efficiency. This results in inherent submicron optical sectioning by excitation alone. In practice, TPEM is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 limits the average input power to less than 10 mW, only slightly greater than the power normally used in confocal microscopy. Because of the intensity-squared dependence of the two-photon absorption, the excitation is limited to the focal volume.

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