scholarly journals Controlled-source interferometric redatuming by crosscorrelation and multidimensional deconvolution in elastic media

Geophysics ◽  
2011 ◽  
Vol 76 (4) ◽  
pp. SA63-SA76 ◽  
Author(s):  
Joost van der Neut ◽  
Jan Thorbecke ◽  
Kurang Mehta ◽  
Evert Slob ◽  
Kees Wapenaar
Keyword(s):  
Wave Propagation ◽  
Velocity Model ◽  
Seismic Sources ◽  
Elastic Media ◽  
Virtual Source ◽  
Controlled Source ◽  
Point Spread ◽  
Spread Function ◽  
Wavefield Decomposition

Various researchers have shown that accurate redatuming of controlled seismic sources to downhole receiver locations can be achieved without requiring a velocity model. By placing receivers in a horizontal or deviated well and turning them into virtual sources, accurate images can be obtained even below a complex near-subsurface. Examples include controlled-source interferometry and the virtual-source method, both based on crosscorrelated signals at two downhole receiver locations, stacked over source locations at the surface. Because the required redatuming operators are taken directly from the data, even multiple scattered waveforms can be focused at the virtual-source location, and accurate redatuming can be achieved. To reach such precision in a solid earth, representations for elastic wave propagation that require multicomponent sources and receivers must be implemented. Wavefield decomposition prior to crosscorrelation allows us to enforce virtual sources to radiate only downward or only upward. Virtual-source focusing and undesired multiples from the overburden can be diagnosed with the interferometric point-spread function (PSF), which can be obtained directly from the data if an array of subsurface receivers is deployed. The quality of retrieved responses can be improved by filtering with the inverse of the PSF, a methodology referred to as multidimensional deconvolution.

scholarly journals Deghosting, Demultiple, and Deblurring in Controlled-Source Seismic Interferometry

2011 ◽  
Vol 2011 ◽  
pp. 1-28 ◽  
Author(s):  
Joost van der Neut ◽  
Maria Tatanova ◽  
Jan Thorbecke ◽  
Evert Slob ◽  
Kees Wapenaar
Keyword(s):  
Point Spread Function ◽  
Cross Correlation ◽  
Velocity Model ◽  
Seismic Interferometry ◽  
Controlled Source ◽  
Point Spread ◽  
Spread Function ◽  
Different Types

With controlled-source seismic interferometry we aim to redatum sources to downhole receiver locations without requiring a velocity model. Interferometry is generally based on a source integral over cross-correlation (CC) pairs of full, perturbed (time-gated), or decomposed wavefields. We provide an overview of ghosts, multiples, and spatial blurring effects that can occur for different types of interferometry. We show that replacing cross-correlation by multidimensional deconvolution (MDD) can deghost, demultiple, and deblur retrieved data. We derive and analyze MDD for perturbed and decomposed wavefields. An interferometric point spread function (PSF) is introduced that can be obtained directly from downhole data. Ghosts, multiples, and blurring effects that may populate the retrieved gathers can be locally diagnosed with the PSF. MDD of perturbed fields can remove ghosts and deblur retrieved data, but it leaves particular multiples in place. To remove all overburden-related effects, MDD of decomposed fields should be applied.

Imaging through Scattering Media with a Learning Based Prior

2020 ◽  
Vol 2020 (14) ◽  
pp. 306-1-306-6
Author(s):  
Florian Schiffers ◽  
Lionel Fiske ◽  
Pablo Ruiz ◽  
Aggelos K. Katsaggelos ◽  
Oliver Cossairt
Keyword(s):  
Optimization Problem ◽  
Autonomous Driving ◽  
Scattering Media ◽  
Photon Scattering ◽  
Point Spread ◽  
Spread Function ◽  
Radiative Transport Equation ◽  
Spatio Temporal ◽  
Transient Imaging

Imaging through scattering media finds applications in diverse fields from biomedicine to autonomous driving. However, interpreting the resulting images is difficult due to blur caused by the scattering of photons within the medium. Transient information, captured with fast temporal sensors, can be used to significantly improve the quality of images acquired in scattering conditions. Photon scattering, within a highly scattering media, is well modeled by the diffusion approximation of the Radiative Transport Equation (RTE). Its solution is easily derived which can be interpreted as a Spatio-Temporal Point Spread Function (STPSF). In this paper, we first discuss the properties of the ST-PSF and subsequently use this knowledge to simulate transient imaging through highly scattering media. We then propose a framework to invert the forward model, which assumes Poisson noise, to recover a noise-free, unblurred image by solving an optimization problem.

scholarly journals Point spread function for diffuser cameras based on wave propagation and projection model

2019 ◽  
Vol 27 (9) ◽  
pp. 12748 ◽  
Author(s):  
Xin Jin ◽  
David Mao San Wei ◽  
Qionghai Dai
Keyword(s):  
Wave Propagation ◽  
Point Spread Function ◽  
Projection Model ◽  
Point Spread ◽  
Spread Function

An Approach to Measuring the Point Spread Function of the Confocal Raman Microscope

2020 ◽  
Vol 74 (10) ◽  
pp. 1230-1237
Author(s):  
Xiang Ding ◽  
Yanzhe Fu ◽  
Jiyan Zhang ◽  
Yao Hu ◽  
Shihang Fu
Keyword(s):  
Image Quality ◽  
Size Effect ◽  
Point Spread Function ◽  
Performance Indicator ◽  
Signal To Noise Ratio ◽  
Polystyrene Microspheres ◽  
Point Spread ◽  
Spread Function ◽  
Confocal Raman

The confocal Raman microscope (CRM) is a powerful tool in analytical science. Image quality is the most important performance indicator of CRM systems. The point spread function (PSF) is one of the most useful tools to evaluate the image quality of microscopic systems. A method based on a point-like object is proposed to measure the PSF of CRM, and the size effect of spherical objects is discussed. A series of phantoms are fabricated by embedding different sizes of polystyrene microspheres into polydimethylsiloxane matrix. The diameters of microspheres are from 0.2 µm to 5 µm. The phantoms are tested by measuring the PSF of a commercial CRM whose nominal lateral resolution is about 1 µm. Results of the PSF are obtained and the accuracy of resolution is used to evaluate the size effect of the microspheres. Experimental results are well consistent with theoretical analysis. The error of the PSF can be decreased by reducing the diameter of the microsphere but meanwhile the signal-to-noise ratio (S/N) will be lowered as well. The proper diameter of microspheres is proposed in consideration of the trade-off between the S/N and the measurement error of the PSF. Results indicate that the method provides a useful approach to measurement of the PSF and the resolution of the CRM.

Calibrating an area-detector diffractometer: integral response

1990 ◽  
Vol 428 (1874) ◽  
pp. 181-214 ◽  
Keyword(s):  
Differential Absorption ◽  
Fast System ◽  
Imaging Geometry ◽  
Area Detector ◽  
Point Spread ◽  
Spread Function ◽  
Satisfactory Method ◽  
Integral Response ◽  
Imaging Detectors

The quality of diffraction data measured with electronic area-detectors is improved by correcting for non-uniformities in the response of the detector. Many detectors are actually much more uniform than they appear because much of the perceived non-uniformity is an artefact of the distortions in their imaging geometry and of the methods of illumination during calibration. Indeed, every known correction reduces the perceived non-uniformity. Our inability to illuminate the detector uniformly with radiation of the same wavelength as is used during data-collection is a particular worry because of differential absorption. The tails of the point-spread function also perturb the apparent response, particularly near to the edges of the imaging area. These problems are difficult to compensate, so there is no completely satisfactory method of determining the true response of real detectors. However, this does not prevent us from making calibrations of usable accuracy. Although this paper applies to all types of area-detector, the discussion is centred mainly on the ENRAF-NONIUS fast system, which is a commercially available television diffractometer, calibrated using software written by the present author. Calibrating the response of imaging detectors is a general problem, and many of the techniques expounded here are of wide applicability.

scholarly journals TIME DEPENDENCE OF THE POINT SPREAD FUNCTION OF A FOUR-WAVE CONVERTER IN A WAVEGUIDE WITH THERMAL NONLINEARITY

2017 ◽  
Vol 20 (10) ◽  
pp. 130-139
Author(s):  
E.V. Vorobieva ◽  
V.V. Ivakhnik ◽  
M.V. Luneva
Keyword(s):  
Time Dependence ◽  
Point Spread Function ◽  
Wave Interaction ◽  
Single Mode ◽  
Initial State ◽  
Thermal Nonlinearity ◽  
Point Spread ◽  
Spread Function ◽  
Wave Converter

The time dependence of a quality of wave-front reversal has been analyzed at four-wave interaction in a waveguide with thermal nonlinearity. The influence of waveguide parameters and mode structure of pumping waves on time dependence character has been investigated. It has been shown, that increases of number of single-mode pumping waves lead to decreases of difference in point spread function width in steady state and initial state.

scholarly journals Wavefront Parameters Recovering by Using Point Spread Function

2020 ◽  
pp. short47-1-short47-7
Author(s):  
Olga Kalinkina ◽  
Tatyana Ivanova ◽  
Julia Kushtyseva
Keyword(s):  
Optical System ◽  
Point Spread Function ◽  
Optical Systems ◽  
Adjustment Process ◽  
Substantial Part ◽  
Zernike Polynomials ◽  
Reconstruction Algorithms ◽  
Point Spread ◽  
Spread Function

At various stages of the life cycle of optical systems, one of the most important tasks is quality of optical system elements assembly and alignment control. The different wavefront reconstruction algorithms have already proven themselves to be excellent assistants in this. Every year increasing technical capacities opens access to the new algorithms and the possibilities of their application. The paper considers an iterative algorithm for recovering the wavefront parameters. The parameters of the wavefront are the Zernike polynomials coefficients. The method involves using a previously known point spread function to recover Zernike polynomials coefficients. This work is devoted to the research of the defocusing influence on the convergence of the algorithm. The method is designed to control the manufacturing quality of optical systems by point image. A substantial part of the optical systems can use this method without additional equipment. It can help automate the controlled optical system adjustment process.

scholarly journals Engineering the point spread function of layered metamaterials

2013 ◽  
Vol 21 (4) ◽  
Author(s):  
A. Pastuszczak ◽  
M. Stolarek ◽  
R. Kotyński
Keyword(s):  
Frequency Domain ◽  
Numerical Optimization ◽  
Optical Signal ◽  
Criterion Function ◽  
Optimization Framework ◽  
Point Spread ◽  
Spread Function ◽  
Diffraction Imaging ◽  
Measure Of Similarity

AbstractLayered metal-dielectric metamaterials have filtering properties both in the frequency domain and in the spatial frequency domain. Engineering their spatial filtering response is a way of designing structures with specific diffraction properties for such applications as sub-diffraction imaging, supercollimation, or optical signal processing at the nanoscale. In this paper we review the recent progress in this field.We also present a numerical optimization framework for layered metamaterials, based on the use of evolutionary algorithms. A measure of similarity obtained using Hölder’s inequality is adapted to construct the overall criterion function. We analyse the influence of surface roughness on the quality of imaging.

scholarly journals Limits of the Efficiency of Imaging with Obstructing Apertures

2007 ◽  
Vol 12 (1) ◽  
pp. 67
Author(s):  
A.T. Mohammed
Keyword(s):  
Modulation Transfer Function ◽  
Numerical Solutions ◽  
Average Frequency ◽  
Maximum Intensity ◽  
Average Intensity ◽  
Modulation Transfer ◽  
Point Spread ◽  
Spread Function ◽  
Frequency Components

Two-dimensional numerical solutions are carried out to asses the quality of obstructing apertures in terms of the diffraction limited resolution. This include the quality of the point spread function (psf), the modulation transfer function (MTF), and an image of  double lines. These are average intensity of the psf (AI), maximum intensity of the psf,(MI), full width at half maximum of the psf (FW) average frequency components of MTF (AFC), and average side loops of an image of a double lines. The results indicate that the separation of the two lines becomes recognizable using central obstruction of radius equal to or greater than approximately 0.6 times the radius of the primary aperture.  

scholarly journals A Contribution to Sonograph Image Quality Estimation Using Point Spread Function

2004 ◽  
Vol 47 (4) ◽  
pp. 293-295
Author(s):  
Ladislav Doležal ◽  
Jan Hálek
Keyword(s):  
Image Quality ◽  
Point Spread Function ◽  
Signal To Noise Ratio ◽  
Region Of Interest ◽  
Measuring System ◽  
Point Spread ◽  
Scanning Area ◽  
Spread Function ◽  
Gain Compensation

In medical sonography, sonograph image quality is an essential aspect for the safety of both patient and doctor. Its evaluation therefore requires an accurate and objective method for measurement. In this regard, a number of methods are in current use. Most of these are based on tissue mimicking phantom imaging. In contrast, we have used another principle based on Point Spread Function (PSF) analysis which is a product of the measuring system we have developed. In this case, the measured sonograph scans a small metallic ball target that moves in a water bath on a specified trajectory. The Region Of Interest (ROI) of the sonogram containing the ball target picture is digitised and the amplitude of the pixels analysed. The result is the PSF from which we calculate the lateral resolution (LR). For this purpose, we use our own original software. Using this method, we have to date been able to plot LR characteristics over the scanning plane. The method allows us to differentiate separate scanning lines and even multiple focal areas for dynamic focussing systems. It can detect malfunctions in dynamic focussing, size of aperture, time gain compensation function and/or transducer element failure. The procedure itself is not as easy or as fast to use as tissue mimicking phantoms or 3D signal to noise ratio evaluation, but it provides accurate and objective numeric parameters corresponding to the quality of image at any specified point over the whole scanning area. It is also a very powerful tool when used in combination with the other methods mentioned above.

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