Numerical Ray Tracing in Media Involving Continuous and Discrete Refractive Boundaries

1980 ◽  
Vol 2 (4) ◽  
pp. 291-301 ◽  
Author(s):  
A.M. Smith ◽  
M. Goldberg ◽  
E.S.K. Liu
Keyword(s):  
Refractive Index ◽  
Medical Imaging ◽  
Boundary Conditions ◽  
Ray Tracing ◽  
Imaging Techniques ◽  
Biological Tissues ◽  
Inhomogeneous Media ◽  
Simulation Program ◽  
Digital Methods

Attempts to improve the performance of ultrasonic medical imaging techniques have led to an interest in digital methods for tracing rays through inhomogeneous media. Biological tissues involve both continuously varying and discrete refractive index boundaries. A ray tracing technique applicable for both cases is described. The performance of a simulation program is illustrated and discussed for a variety of boundary conditions.

scholarly journals Multiscale label-free volumetric holographic histopathology of thick-tissue slides with subcellular resolution

2020 ◽  
Author(s):  
Herve Hugonnet ◽  
Yeon Wook Kim ◽  
Moosung Lee ◽  
Seungwoo Shin ◽  
Ralph H. Hruban ◽  
...  
Keyword(s):  
Refractive Index ◽  
Present Method ◽  
Imaging Techniques ◽  
Numerical Algorithms ◽  
Biological Tissues ◽  
Phase Imaging ◽  
Label Free ◽  
Volumetric Imaging ◽  
Optical Modes ◽  
Volumetric Reconstruction

ABSTRACTHistopathology relies upon the staining and sectioning of biological tissues, which can be laborious and may cause artefacts and distort tissues. Here, we demonstrate label-free volumetric imaging of thick-tissue slides, exploiting refractive index distributions as intrinsic imaging contrast. The present method systematically exploits label-free quantitative phase imaging techniques, volumetric reconstruction of intrinsic refractive index distributions in tissues, and numerical algorithms for the seamless stitching of multiple 3D tomograms and for reducing scattering-induced image distortion. We demonstrate demonstrated label-free volumetric imaging of thick tissues with the field of view of 2 mm × 1.75 mm × 0.2 mm with a spatial resolution of 170 nm × 170 nm × 1200 nm. The number of optical modes, calculated as the reconstructed volume divided by the size of the point spread function, was approximately 20 Giga voxels. We have also demonstrated that different tumour types, and a variety of precursor lesions and pathologies can be visualized with the present method.Abstract Figure

scholarly journals Toward Better Medical Diagnosis: Tissue Optical Clearing

2020 ◽  
Vol 2 (1) ◽  
pp. 13-21
Author(s):  
Omnia Hamdy ◽  
Rania M. Abdelazeem
Keyword(s):  
Refractive Index ◽  
Medical Diagnosis ◽  
Imaging Techniques ◽  
High Refractive Index ◽  
Biological Tissues ◽  
Optical Clearing ◽  
Research Areas ◽  
Body Tissues ◽  
Deep Imaging ◽  
Tissue Optical Clearing

Reaching efficient, safe and painless medical diagnosis procedure is a very valued goal for many research areas. Despite the great advantages of using optical imaging techniques in medical diagnosis including high safety and relative simplicity, it still suffers from relatively low resolution and penetration depth in the multiple scattering mediums such as biological tissues. Therefore, researchers began to devise ways to reduce the scattering properties of the tissue, hence increasing the imaging contrast. Optical clearing concept is introduced to do this job. This technique can reduce tissues scattering properties by using high refractive index chemicals, thus making the tissue transparent by equalizing the refractive index through that medium. In this paper, theory and techniques of optical clearing method are illustrated utilizing its benefits for deep imaging of different body tissues and organs.

Multipath Artifact Corrections in Ultrasonic Transmission Tomography

1982 ◽  
Vol 4 (3) ◽  
pp. 234-266 ◽  
Author(s):  
C. R. Crawford ◽  
A. C. Kak
Keyword(s):  
Refractive Index ◽  
Attenuation Coefficient ◽  
Arrival Time ◽  
Imaging Techniques ◽  
Biological Tissues ◽  
Median Filtering ◽  
Transmission Tomography ◽  
Cross Sectional ◽  
Tissue Equivalent

This paper deals with computed imaging techniques for ultrasonic transmission tomography. Cross-sectional images of the refractive index in soft biological tissues can be obtained by measuring the arrival-time of signals that propagate between two transducers. An alternative method to obtain images is to measure the attenuation in the path between the pair of transducers. In practice, images of the refractive index exhibit a better quality than images of the attenuation coefficient. In this report we have shown through computer simulation that some of the degradations in images of the attenuation coefficient are due to the existence of multiple rays that link the transmitting and the receiving transducers. This condition is known as multipath. We have demonstrated two methods to reduce the influence of multipath on reconstructions of the attenuation coefficient. The first method employs homomorphic signal processing to estimate the attenuation coefficient for one of the linking rays. The second method applies median filtering in the projection space to remove the artifacts caused by multipath. The correction techniques were tested on data obtained by scanning tissue equivalent phantoms. Results obtained indicate that the correction methods significantly improve the quality of images of the attenuation coefficient.

scholarly journals SARS-CoV-2 diagnosis using medical imaging techniques and artificial intelligence: A review

2021 ◽  
Vol 76 ◽  
pp. 6-14
Author(s):  
Narjes Benameur ◽  
Ramzi Mahmoudi ◽  
Soraya Zaid ◽  
Younes Arous ◽  
Badii Hmida ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Medical Imaging ◽  
Imaging Techniques

scholarly journals Continuous-Wave THz Imaging for Biomedical Samples

2020 ◽  
Vol 11 (1) ◽  
pp. 71
Author(s):  
Yaya Zhang ◽  
Chuting Wang ◽  
Bingxin Huai ◽  
Shiyu Wang ◽  
Yating Zhang ◽  
...  
Keyword(s):  
Medical Imaging ◽  
Biomedical Imaging ◽  
Continuous Wave ◽  
Biological Tissues ◽  
Thz Spectroscopy ◽  
Label Free ◽  
Thz Imaging ◽  
Malignant Tumours ◽  
Advantages And Disadvantages ◽  
Imaging Application

In the past few decades, the applications of terahertz (THz) spectroscopy and imaging technology have seen significant developments in the fields of biology, medical diagnosis, food safety, and nondestructive testing. Label-free diagnosis of malignant tumours has been obtained and also achieved significant development in THz biomedical imaging. This review mainly presents the research status and prospects of several common continuous-wave (CW) THz medical imaging systems and applications of THz medical imaging in biological tissues. Here, we first introduce the properties of THz waves and how these properties play a role in biomedical imaging. Then, we analyse both the advantages and disadvantages of the CW THz imaging methods and the progress of these methods in THz biomedical imaging in recent ten years. Finally, we summarise the obstacles in the way of the application of THz bio-imaging application technology in clinical detection, which need to be investigated and overcome in the future.

Differential ray tracing in inhomogeneous media

1997 ◽  
Vol 14 (10) ◽  
pp. 2824 ◽  
Author(s):  
Bryan D. Stone ◽  
G. W. Forbes
Keyword(s):  
Ray Tracing ◽  
Inhomogeneous Media

Vibrational energy distribution in plate excited with random white noise

2021 ◽  
Vol 263 (6) ◽  
pp. 965-969
Author(s):  
Tyrode Victor ◽  
Nicolas Totaro ◽  
Laurent Maxit ◽  
Alain Le Bot
Keyword(s):  
Boundary Conditions ◽  
Energy Distribution ◽  
White Noise ◽  
Numerical Simulations ◽  
Ray Tracing ◽  
Energy Analysis ◽  
Vibrational Energy ◽  
Statistical Energy Analysis ◽  
Vibrational Energy Distribution ◽  
Tracing Method

In Statistical Energy Analysis (SEA) and more generally in all statistical theories of sound and vibration, the establishment of diffuse field in subsystems is one of the most important assumption. Diffuse field is a special state of vibration for which the vibrational energy is homogeneously and isotropically distributed. For subsystems excited with a random white noise, the vibration tends to become diffuse when the number of modes is large and the damping sufficiently light. However even under these conditions, the so-called coherent backscattering enhancement (CBE) observed for certain symmetric subsystems may impede diffusivity. In this study, CBE is observed numerically and experimentally for various geometries of subsystem. Also, it is shown that asymmetric boundary conditions leads to reduce or even vanish the CBE. Theoretical and numerical simulations with the ray tracing method are provided to support the discussion.

Nonlinear Optical Investigation of Biochemical Analytes in Blood Serum via Z-Scan Technique

2021 ◽  
Author(s):  
Samane Raji ◽  
Mohammad Ali Haddad ◽  
Seyed Mohammad Moshtaghioun ◽  
Zahra Dehghan
Keyword(s):  
Refractive Index ◽  
Blood Serum ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Diagnostic Procedures ◽  
Biological Tissues ◽  
Optical Characteristics ◽  
Closed Aperture ◽  
Optical Investigation ◽  
Medical Diagnoses

Background and Aims: Biomolecules' optical and nonlinear optical properties are widely used for different medical diagnoses and applications in biophotonic devices. These properties are essential in studying biological processes in living tissues. Aside from biomolecules' linear optical characteristics, their nonlinear optical characteristics have lately been considered. Materials and Methods: In this paper, the nonlinear optical responses of three biochemical analytes in blood serum, including glucose, triglycerides, and cholesterol are examined using the laser-based Z-Scan technique. Hence, different laboratory samples of blood serum with various concentrations of biochemical analytes are taken from patients for this purpose. Results: The normalized transmission curves were taken and analyzed in a closed aperture configuration of the Z-Scan technique and led to evaluating the nonlinear refractive index (n2) as an indicator of nonlinear responses of samples. The results show significant nonlinear optical behaviors of the samples under a strong electrical field of the laser, which leads to the measurement of the nonlinear refractive index (n2) of the samples with an error of less than ̴ 0.5 × 10-8 cm2/w. It is found that the values of nonlinear refractive index (n2) vary proportionally as a function of their concentration in blood serum. Conclusion: The findings of this study imply that the above sample's nonlinear optical response and, probable, those of other biological tissues might be used in medical diagnoses. In addition, the Z-Scan technique might be considered as a complementary method with other conventional diagnostic procedures due to its simplicity and quick experimental approach.

scholarly journals Bent Laue crystal anatomy: new insights into focusing and energy-dispersion properties

2021 ◽  
Vol 54 (2) ◽  
pp. 409-426
Author(s):  
Peng Qi ◽  
Xianbo Shi ◽  
Nazanin Samadi ◽  
Dean Chapman
Keyword(s):  
Ray Tracing ◽  
Imaging Techniques ◽  
Point Of View ◽  
Energy Dispersion ◽  
General Behaviour ◽  
X Ray ◽  
Spatial Properties ◽  
X Ray Imaging ◽  
Special Cases ◽  
Intuitive View

X-ray Laue-type monochromators are common and essential optical components at many high-power X-ray facilities, e.g. synchrotron facilities. The X-ray optics of bent Laue crystals is a well developed area. An incident X-ray beam penetrating a bent Laue crystal will result in a diffracted beam with different angles and energies. There is a need for a way of organizing the rays that allows one to sort out the energy and spatial properties of the diffracted beam. The present work introduces a new approach for describing the general behaviour of bent Laue crystals from a ray-tracing point of view. This quasi-monochromatic beam approach provides an intuitive view of bent-crystal diffraction and leads to deeper understanding. It explains the energy and spatial properties of common and special cases of bent Laue optics, predicts phenomena that can improve energy-dispersion-related X-ray imaging techniques and provides a theoretical framework that makes ray-tracing simulation easier to realize.

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