scholarly journals A New Method to Retrieve the Three-Dimensional Refractive Index and Specimen Size Using the Transport Intensity Equation, Taking Diffraction into Account

2018 ◽  
Vol 8 (9) ◽  
pp. 1649 ◽  
Author(s):  
Marcel Agnero ◽  
Kouakou Konan ◽  
Alvarez Kossonou ◽  
Olivier Bagui ◽  
Jérémie Zoueu
Keyword(s):  
Refractive Index ◽  
Three Dimensional ◽  
Specimen Size ◽  
Three Dimensions ◽  
Point Spread ◽  
Spread Function ◽  
3D Point Spread Function ◽  
Paraxial Ray ◽  
Diffraction Effects

Refractive index retrieval is possible using the transport intensity equation (TIE), which presents advantages over interferometric techniques. The TIE method is valid only for paraxial ray assumptions. However, diffraction can nullify these TIE model assumptions. Therefore, the refractive index is problematic for reconstruction in three-dimensions (3D) using a set of defocused images, as diffraction effects become prominent. We propose a method to recover the 3D refractive index by combining TIE and deconvolution. A brightfield (BF) microscope was then constructed to apply the proposed technique. A microsphere was used as a sample with well-known properties. The deconvolution of the BF-images of the sample using the microscope’s 3D point spread function led to significantly reduced diffraction effects. TIE was then applied for each set of three images. Applying TIE without taking into account diffraction failed to reconstruct the 3D refractive index. Taking diffraction into account, the refractive index of the sample was clearly recovered, and the sectioning effect of the microsphere was highlighted, leading to a determination of its size. This work is of great significance in improving the 3D reconstruction of the refractive index using the TIE method.

scholarly journals Microscope 3D Point Spread Function Evaluation Method on a Confirmed Object Plane Perpendicular to the Optical Axis

2020 ◽  
Vol 10 (7) ◽  
pp. 2430
Author(s):  
Shuai Mao ◽  
Zhenzhou Wang ◽  
Jinfeng Pan
Keyword(s):  
Point Spread Function ◽  
Evaluation Method ◽  
Optical Axis ◽  
Incident Beam ◽  
Function Evaluation ◽  
Object Plane ◽  
Point Spread ◽  
Spread Function ◽  
3D Point Spread Function

A point spread function evaluation method for a microscope on the object plane that is perpendicular to the optical axis is proposed. The measurement of the incident beam direction from the dual position-sensitive-detector (PSD)-based units, the determination of the object plane perpendicularity and the paraxial region, and evaluation methods for the point spread function (PSF) are presented and integrated into the proposed method. The experimental verification demonstrates that the proposed method can achieve a 3D PSF on the perpendicular object plane, as well as magnification, paraxial region evaluation, and confirmation for any microscopic system.

scholarly journals Scanning FCS, a novel method for three-dimensional particle tracking

2003 ◽  
Vol 31 (5) ◽  
pp. 997-1000 ◽  
Author(s):  
V. Levi ◽  
Q. Ruan ◽  
K. Kis-Petikova ◽  
E. Gratton
Keyword(s):  
Laser Beam ◽  
Fluorescence Intensity ◽  
Point Spread Function ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Circular Path ◽  
Fluorescent Particle ◽  
Point Spread ◽  
Spread Function ◽  
Novel Method

We describe a novel method to track fluorescent particles in three dimensions with nanometre precision and millisecond time resolution. In this method, we use our two-photon excitation microscope. The galvomotor-driven x–y scanning mirrors allow the laser beam to move repetitively in a circular path with a radius of half the width of the point spread function of the laser. When the fluorescent particle is located within the scanning radius of the laser, the precise position of the particle in the x–x plane can be determined by its fluorescence intensity distribution along the circular scanning path. A z-nanopositioner on the objective was used to change the laser focus at two planes (half width of the point spread function apart). The difference of the fluorescence intensity in the two planes is used to calculate the z-position of the fluorescent particle. The laser beam is allowed to scan multiple circular orbits before it is moved to the other plane, thus improving the signal to noise ratio. With a fast feedback mechanism, the position of the laser beam is directed to the centre of the fluorescent particle, thus allowing us to track a particle in three dimensions. In this contribution we describe some calibration experiments performed to test the three-dimensional tracking capability of our system over a large range.

The three-dimensional point spread function and statistical image surface of the image-intensifier electron-optical system

1988 ◽  
Vol 66 (10) ◽  
pp. 883-887
Author(s):  
J. M. Woźnicki
Keyword(s):  
Point Spread Function ◽  
Three Dimensional ◽  
Image Intensifier ◽  
Optical Systems ◽  
Focal Surface ◽  
Point Spread ◽  
Spread Function ◽  
Sample Application ◽  
Optical Ray Tracing

An improvement in the methods of numerical calculations of the field distribution and electron-optical ray tracing makes numerical evaluation of image-intensifier systems very practical for real devices. The essential means of assessing the system's properties are the classical two-dimensional point spread function (PSF) and the electron focal surface. However, the positions of separate image points depend on the initial photoelectron parameters, resulting in a statistical longitudinal spread of the image surface positions. This paper contains a three-dimensional PSF generalization based on a statistical-image-surface (SIS) concept, which is proposed for electron-optical systems. The aim of this work is to present a computer method for the numerical determination of the SIS concept and to show a sample application to the image-intensifier system with monochromatic illumination.

Determination of the Point Spread Function of a Computer-Generated Lens Formed by a Phase Light Modulator

2020 ◽  
Vol 128 (7) ◽  
pp. 1036-1040 ◽  
Author(s):  
N. G. Stsepuro ◽  
G. K. Krasin ◽  
M. S. Kovalev ◽  
V. N. Pestereva
Keyword(s):  
Point Spread Function ◽  
Light Modulator ◽  
Point Spread ◽  
Spread Function

scholarly journals Deconvolution of vibroacoustic images using a simulation model based on a three dimensional point spread function

Ultrasonics ◽  
2013 ◽  
Vol 53 (1) ◽  
pp. 36-44 ◽  
Author(s):  
Talita Perciano ◽  
Matthew W. Urban ◽  
Nelson D.A. Mascarenhas ◽  
Mostafa Fatemi ◽  
Alejandro C. Frery ◽  
...  
Keyword(s):  
Simulation Model ◽  
Point Spread Function ◽  
Three Dimensional ◽  
Model Based ◽  
Point Spread ◽  
Spread Function

Diffraction

2002 ◽  
Author(s):  
David Blow
Keyword(s):  
Red Light ◽  
Three Dimensional ◽  
Three Dimensions ◽  
X Rays ◽  
X Ray ◽  
Original Direction ◽  
Computational Procedures ◽  
Scattering Material ◽  
Opaque Object ◽  
Diffraction Effects

Diffraction refers to the effects observed when light is scattered into directions other than the original direction of the light, without change of wavelength. An X-ray photon may interact with an electron and set the electron oscillating with the X-ray frequency. The oscillating electron may radiate an X-ray photon of the same wavelength, in a random direction, when it returns to its unexcited state. Other processes may also occur, akin to fluorescence, which emit X-rays of longer wavelengths, but these processes do not give diffraction effects. Just as we see a red card because red light is scattered off the card into our eyes, objects are observed with X-rays because an illuminating X-ray beam is scattered into the X-ray detector. Our eye can analyse details of the card because its lens forms an image on the retina. Since no X-ray lens is available, the scattered X-ray beam cannot be converted directly into an image. Indirect computational procedures have to be used instead. X-rays are penetrating radiation, and can be scattered from electrons throughout the whole scattering object, while light only shows the external shape of an opaque object like a red card. This allows X-rays to provide a truly three-dimensional image. When X-rays pass near an atom, only a tiny fraction of them is scattered: most of the X-rays pass further into the object, and usually most of them come straight out the other side of the whole object. In forming an image, these ‘straight through’ X-rays tell us nothing about the structure, and they are usually captured by a beam stop and ignored. This chapter begins by explaining that the diffraction of light or X-rays can provide a precise physical realization of Fourier’s method of analysing a regularly repeating function. This method may be used to study regularly repeating distributions of scattering material. Beginning in one dimension, examples will be used to bring out some fundamental features of diffraction analysis. Graphic examples of two-dimensional diffraction provide further demonstrations. Although the analysis in three dimensions depends on exactly the same principles, diffraction by a three-dimensional crystal raises additional complications.

A Moving Pseudo-Boundary MFS for Three-Dimensional Void Detection

2013 ◽  
Vol 5 (04) ◽  
pp. 510-527 ◽  
Author(s):  
Andreas Karageorghis ◽  
Daniel Lesnic ◽  
Liviu Marin
Keyword(s):  
Three Dimensional ◽  
Nonlinear Least Squares ◽  
Fundamental Solutions ◽  
Cauchy Data ◽  
Three Dimensions ◽  
Method Of Fundamental Solutions ◽  
Void Detection ◽  
Spherical Parametrization ◽  
Least Squares Minimization

AbstractWe propose a new moving pseudo-boundary method of fundamental solutions (MFS) for the determination of the boundary of a three-dimensional void (rigid inclusion or cavity) within a conducting homogeneous host medium from overdetermined Cauchy data on the accessible exterior boundary. The algorithm for imaging the interior of the medium also makes use of radial spherical parametrization of the unknown star-shaped void and its centre in three dimensions. We also include the contraction and dilation factors in selecting the fictitious surfaces where the MFS sources are to be positioned in the set of unknowns in the resulting regularized nonlinear least-squares minimization. The feasibility of this new method is illustrated in several numerical examples.

Local bond order parameters for accurate determination of crystal structures in two and three dimensions

2018 ◽  
Vol 20 (42) ◽  
pp. 27059-27068 ◽  
Author(s):  
Hossein Eslami ◽  
Parvin Sedaghat ◽  
Florian Müller-Plathe
Keyword(s):  
Crystal Structures ◽  
Bond Order ◽  
Accurate Determination ◽  
Three Dimensional ◽  
Order Parameters ◽  
Three Dimensions ◽  
Local Order ◽  
Crystalline Structures

Local order parameters for the characterization of liquid and different two- and three-dimensional crystalline structures are presented.

Sign in / Sign up

Export Citation Format

Share Document