PRESIDENT’S REPORT 2015
Scientists from Technion -Israel Institute of Technology and the University of Colorado, Boulder have taken a closer look at how star systems and their planets grow old together.
Chaotic Evolution and the Lives of Stars
Tag Archives: physics
An optical spin – the nanoscience of electrons
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| Prof. Erez Hasman, Technion. |
The spin Hall effect – the impact of the intrinsic spin on the particle trajectory, which produces transverse deflection of the particle – is a central tenet in the field of spintronics regarding particles of electrons. Now, its optical equivalent has been observed.
The Magnus effect is seen in a wide range of systems. For example, it describes the sideways force applied to a spinning ball as it travels through the air explains Prof. Erez Hasman, head of the Micro- and Nanooptics Laboratory and an avid tennis player.
Light waves, comprising mass-less particles called photons, also demonstrate spin. Light’s spin is determined by its polarization: whether the wave vibration rotates in one direction or the opposite as it travels. Hasman, together with his PhD student Avi Niv, Dr Vladimir Kleiner – a senior scientist in the lab – and Ukrainian visiting scientist Dr Konstantin Bliokh, were the first to observe the effect of spin on the trajectories of polarized light beams.
The researchers launched a laser beam at a sliding angle to the internal surface of a glass cylinder. Once inside the cylinder the beam traveled in a helical trajectory along the glass-air interface, and was collected and analyzed at the far end using polarization optics and a camera. They observed a transverse spin-dependent deflection of the optical beam. These results have promising applications in nano-optics leading to much faster and more accurate computational data processing.
Physics Prof. Mordechai (Moti) Segev, a world leader in the area of Nonlinear Optics, comments, “Nanophotonics is a field where light is manipulated and controlled on a scale that is smaller than the optical wavelength. Erez Hasman has written a series of important papers in this area, leading to a new branch in optics – spinoptics. His discoveries offer an unprecedented ability to control light and its polarization state in nanometer-scale optical devices, thereby facilitating a variety of applications related to nanophotonics.”
Applied to other areas Hasman says, “There are a number of systems where the spin of a particle couples with its trajectory in high-energy and condensed matter physics. The math is the same in all cases, but experimentally it’s hard to understand what’s going on. Our experimental system offers a new way to get at some of these fundamental questions clearly and precisely.”
What is Photonics?
Photonics is the science of generating, controlling, and detecting photons. Photonics researchers investigate the emission, transmission, amplification, detection, and modulation of light. Applications include laser manufacturing, biological and chemical sensing, medical diagnostics and therapy, display technology, and optical computing.
Spinoptics: The Magnus effect for light, also called the optical spin Hall effect, causes the light to deflect due to the interaction between the intrinsic spin of the photons and the shape of the light’s trajectory.
An optical spin – the nanoscience of electrons
|
| Prof. Erez Hasman, Technion. |
The spin Hall effect – the impact of the intrinsic spin on the particle trajectory, which produces transverse deflection of the particle – is a central tenet in the field of spintronics regarding particles of electrons. Now, its optical equivalent has been observed.
The Magnus effect is seen in a wide range of systems. For example, it describes the sideways force applied to a spinning ball as it travels through the air explains Prof. Erez Hasman, head of the Micro- and Nanooptics Laboratory and an avid tennis player.
Light waves, comprising mass-less particles called photons, also demonstrate spin. Light’s spin is determined by its polarization: whether the wave vibration rotates in one direction or the opposite as it travels. Hasman, together with his PhD student Avi Niv, Dr Vladimir Kleiner – a senior scientist in the lab – and Ukrainian visiting scientist Dr Konstantin Bliokh, were the first to observe the effect of spin on the trajectories of polarized light beams.
The researchers launched a laser beam at a sliding angle to the internal surface of a glass cylinder. Once inside the cylinder the beam traveled in a helical trajectory along the glass-air interface, and was collected and analyzed at the far end using polarization optics and a camera. They observed a transverse spin-dependent deflection of the optical beam. These results have promising applications in nano-optics leading to much faster and more accurate computational data processing.
Physics Prof. Mordechai (Moti) Segev, a world leader in the area of Nonlinear Optics, comments, “Nanophotonics is a field where light is manipulated and controlled on a scale that is smaller than the optical wavelength. Erez Hasman has written a series of important papers in this area, leading to a new branch in optics – spinoptics. His discoveries offer an unprecedented ability to control light and its polarization state in nanometer-scale optical devices, thereby facilitating a variety of applications related to nanophotonics.”
Applied to other areas Hasman says, “There are a number of systems where the spin of a particle couples with its trajectory in high-energy and condensed matter physics. The math is the same in all cases, but experimentally it’s hard to understand what’s going on. Our experimental system offers a new way to get at some of these fundamental questions clearly and precisely.”
What is Photonics?
Photonics is the science of generating, controlling, and detecting photons. Photonics researchers investigate the emission, transmission, amplification, detection, and modulation of light. Applications include laser manufacturing, biological and chemical sensing, medical diagnostics and therapy, display technology, and optical computing.
Spinoptics: The Magnus effect for light, also called the optical spin Hall effect, causes the light to deflect due to the interaction between the intrinsic spin of the photons and the shape of the light’s trajectory.
The Pull of Light – optics innovation from Technion.
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| Distinguished Prof. Mordechai (Moti) Segev, Technion Faculty of Physics. |
Developing a real, working tractor beam has regularly been an exercise in frustration: it often relies on brute force attempts to induce a magnetic link or an air pressure gap, either of which falls a bit short of science fiction-level elegance.
The Technion-Israel Institute of Technology’s Mordechai Segev has a theory that would use the subtler (though not entirely movie-like) concept of negative radiation pressure in light to move objects. By using materials that have a negative refraction index, where the light photons and their overall wave shape move in opposite directions, Segev wants to create a sweet spot where negative radiation pressure exists and an object caught in the middle can be pushed around. His early approach would use extremely thin crystals stacked in layers to manipulate the refraction.
As it’s theorized, the technology won’t be pulling in the Millennium Falcon anytime soon — the millimeters-wide layer intervals dictate the size of what can be pulled. Nonetheless, even the surgery-level tractor beams that Segev hopes will ultimately stem from upcoming tests would bring us much closer to the future that we’ve always wanted.
Source: Optics Express
Read more about Distinguished Prof. Motti Segev at the Technion Book of Faces.
The Pull of Light – optics innovation from Technion.
|
| Distinguished Prof. Mordechai (Moti) Segev, Technion Faculty of Physics. |
Developing a real, working tractor beam has regularly been an exercise in frustration: it often relies on brute force attempts to induce a magnetic link or an air pressure gap, either of which falls a bit short of science fiction-level elegance.
The Technion-Israel Institute of Technology’s Mordechai Segev has a theory that would use the subtler (though not entirely movie-like) concept of negative radiation pressure in light to move objects. By using materials that have a negative refraction index, where the light photons and their overall wave shape move in opposite directions, Segev wants to create a sweet spot where negative radiation pressure exists and an object caught in the middle can be pushed around. His early approach would use extremely thin crystals stacked in layers to manipulate the refraction.
As it’s theorized, the technology won’t be pulling in the Millennium Falcon anytime soon — the millimeters-wide layer intervals dictate the size of what can be pulled. Nonetheless, even the surgery-level tractor beams that Segev hopes will ultimately stem from upcoming tests would bring us much closer to the future that we’ve always wanted.
Source: Optics Express
Read more about Distinguished Prof. Motti Segev at the Technion Book of Faces.
Physics research brings new strategies for brain tumor treatment.
Modeling the demise of migrating brain tumor cells
Evolution of brain tumor cells under treatment reveal that it is the peripheral tumor cells that need to be targeted
An Israeli physicist has developed a theoretical model to simulate the evolution of highly proliferating brain tumour core cells subjected to treatment by alternating radio frequency electric field. The research, by Alexander Iomin from the Technion – Israel Institute of Technology Technion in Haifa, is about to be published in EPJ E¹. In another model, the author examines the possibility of enhancing the level of treatment by targeting the outer area of the tumour.
Iomin introduced a theoretical evaluation of the effect of a standard treatment known as tumour-treating-field (TTF) on the speed of development of a type of brain tumour called glioma. To do so, he adapted a well-established model — the so-called fractal comb model, which looks like the regularly spaced teeth of a comb — based on a mathematical approach called fractional calculus. This model is based on the hypothesis that TTF treatment had limited efficiency in the outer region and would only be effective on the inner part of the tumour, which is characterised by a higher proliferation rate of cancer cells.
By contrast, the peripheral part of the tumour is characterised by high migration and low proliferation rates of cancer cells. In his second model, the author considered glioma cancer as a composite of cancer cells and normal tissue cells. Each cell type exhibits a distinctive polarisation by an electric field, following a pattern similar to fractal geometry. He established a model reflecting the difference between the two types of cells and applied fractal calculus to their geometry. Iomin suggested that because of the fractal nature of cancer cells the TTF treatment might be enhanced at certain frequencies. As a result, the cancer cells’ plasma membrane permeability would irreversibly increase, which could lead to their demise. This approach may constitute an effective non-invasive method for treating brain cancer.
Article extracted from: EurekaAlert.
Physics research brings new strategies for brain tumor treatment.
Modeling the demise of migrating brain tumor cells
Evolution of brain tumor cells under treatment reveal that it is the peripheral tumor cells that need to be targeted
An Israeli physicist has developed a theoretical model to simulate the evolution of highly proliferating brain tumour core cells subjected to treatment by alternating radio frequency electric field. The research, by Alexander Iomin from the Technion – Israel Institute of Technology Technion in Haifa, is about to be published in EPJ E¹. In another model, the author examines the possibility of enhancing the level of treatment by targeting the outer area of the tumour.
Iomin introduced a theoretical evaluation of the effect of a standard treatment known as tumour-treating-field (TTF) on the speed of development of a type of brain tumour called glioma. To do so, he adapted a well-established model — the so-called fractal comb model, which looks like the regularly spaced teeth of a comb — based on a mathematical approach called fractional calculus. This model is based on the hypothesis that TTF treatment had limited efficiency in the outer region and would only be effective on the inner part of the tumour, which is characterised by a higher proliferation rate of cancer cells.
By contrast, the peripheral part of the tumour is characterised by high migration and low proliferation rates of cancer cells. In his second model, the author considered glioma cancer as a composite of cancer cells and normal tissue cells. Each cell type exhibits a distinctive polarisation by an electric field, following a pattern similar to fractal geometry. He established a model reflecting the difference between the two types of cells and applied fractal calculus to their geometry. Iomin suggested that because of the fractal nature of cancer cells the TTF treatment might be enhanced at certain frequencies. As a result, the cancer cells’ plasma membrane permeability would irreversibly increase, which could lead to their demise. This approach may constitute an effective non-invasive method for treating brain cancer.
Article extracted from: EurekaAlert.
Imaging: a sub-wavelength revolution.
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| Prof. Moti Segev, Faculty of Physics. |
Technion Researchers Develop Computational Method for Improving the Resolution of Microscopes and Imaging Systems
Technion researchers have demonstrated an innovative method that substantially improves the resolution (the ability to distinguish between details) of microscopes. This was reported by the prestigious scientific journal Nature Materials. The method is based on innovative concepts, and scientists hail it as being a “breakthrough with the potential to change the world of microscopy, imaging systems, and other optical measurement systems”. The method is attracting great interest, both in the scientific world and in industry.
“When you look through an optical microscope at an object with features (optical information) smaller than one half the wavelength of light – you necessarily see a blurred image”, explains Distinguished Prof. Mordechai (Moti) Segev of the Technion’s Department of Physics. “The reason for this is that the information about the structure of very small features does not propagate through space and thus does not reach the eye or the microscope camera. Today, a number of methods are used to achieve a resolution under one half of the wavelength of light, but they all require point-by-point scanning of the object. Hence, these methods may be used only for a static object, which does not change during the scan”.
Scientists have attempted for many years to find algorithms to reconstruct the sub-wavelength information lost between the object and the microscope camera. But thus far all such attempts were largely unsuccessful. The main reason is noise: random scattering of light (for example, from reflections off non-ideal surfaces), which is inevitable in optical systems, has thus far prevented algorithmic reconstruction of features smaller than one half the wavelength of light from measurements of the blurred image.
Now a team of Technion researchers presented a breakthrough algorithmic method for improving the resolution of microscopes to considerably under one half the wavelength of light. To a great extent, the project was successful thanks to the collaboration between several research groups from four different Technion faculties (the groups of Prof. Moti Segev and of Dr. Oren Cohen of the Department of Physics, Prof. Yonina Eldar of the Department of Electrical Engineering, Prof. Irad Yavneh and Dr. Michael Zibulevsky of the Computer Science Department, and Prof. Shy Shoham of the Department of Biomedical Engineering).
“The algorithmic method relies on finding the most suitable reconstruction that meets two criteria: the reconstructed high-resolution image must conform to the blurred image, and it must minimize of the number of the degrees of freedom”, explains Prof. Segev. “The second criterion has to do with understanding compact (sparse) representation of information and with the effect caused by noise in the measurement system. Random noise occupies all degrees of freedom, whereas information has some structure, hence it occupies a given number of degrees of freedom and never all of them. In many cases, there is some sort of a priori knowledge about the information. In principle, in such a case the information may be presented compactly, such that mathematically it is represented by a small number of projections onto basis functions that cover all the possibilities of spatial information. It is then said that the information is sparsely represented, and the number of degrees of freedom it occupies is small. In general, there are many cases where information can be represented compactly. A well known example is file compression using JPEG, a method of compact representation through projection onto a basis where the information in the file is represented sparsely (compactly)”.
This innovative concept of improving resolution in microscopy through representation of the image in the correct basis in which the image is sparse, was developed by Prof. Moti Segev of the Department of Physics and Prof. Yonina Eldar of the Department of Electrical Engineering, graduate students Snir Gazit and Yoav Shechtman and postdoctoral researcher Alex Szameit, currently a professor at the University of Jena, Germany.
The idea was initially demonstrated in 2009. However, exhausting the full potential of the resolution improvement necessitated measuring the phase of the light reaching the microscope camera. Phase measurement requires interference-based methods (interferometric methods) which increase the complexity of the system substantially and limit the applications of this method.
About two years ago, Dr. Oren Cohen proposed adding an important layer to the algorithm, which in effect replaces the need for phase measurement, and to thus obtain image reconstruction at a higher resolution than one half the wavelength of light, through intensity measurement only (using a regular camera). In fact, Dr. Cohen proposed that two research directions be combined – Profs. Segev and Eldar’s idea of sub-wavelength imaging and “lensless imaging”, in which images are algorithmically (computationally) reconstructed from measurements of the intensity of the light at a very far distance from the image. This area – of lensless imaging – has recently become an extremely important field of science. On completion of the construction of three short pulse X-ray lasers (in the USA, Germany and Japan) at a cost of one billion dollars per laser, researchers intend to use lensless imaging to measure the structure of hundreds of thousands of single molecules (molecules that cannot be assembled into a crystallized structure). Understanding the structure of these molecules will pave the way for chemists, biologists and doctors to understand many biological processes at the molecular level. Until now, the resolution of all “lensless imaging” methods has been limited to features bigger than a wavelength. However, the methods developed by the Technion researchers could bring about a revolutionary improvement of the entire “lensless imaging” field, and allow measurement of dynamically changing molecules.
The Technion research team has demonstrated in experiments the reconstruction of details at least five times smaller than the wavelength of light, in a single-shot measurement of the light intensity at the focal plane of the microscope lens. The research work was published in the prestigious journal Nature Materials. The majority of the research work was done by postdoctoral researcher Alex Szameit and graduate students Yoav Shechtman and Eli Osherovich. The experiments, conducted by Alex Szameit and Hod Dana (graduate student at the Department of Biomedical Engineering), demonstrated reconstructions of objects with optical features 100 nanometers in size using radiation with a wavelength of 530 nanometers. In comparison, without using the new method, the resolution of this microscope is limited to features bigger than 300 nanometers.
As described above, the main part of the research is the development of the algorithm for the reconstruction of missing information: (a) reconstruction of the phase of light measured by the camera and (b) reconstruction of the part of the optical information which never reached the camera (information on features smaller than one half the wavelength of light). The initial algorithm, developed by Elad Bullkich, an undergraduate student at the time the research was conducted, and Yoav Shechtman, was based on performing the phase reconstruction algorithm followed by the algorithm for the reconstruction of sub-wavelength information. Some time later, Eli Osherovich developed a far better algorithm that reconstructs both types of “missing information” concurrently, thereby substantially increasing performance and allowing handling a wide range of images.
Technion researchers are now working on the development of similar methods for improving the resolution of other measurement systems. For example, graduate student Pavel Sidorenko has recently demonstrated breaking the resolution barrier of spectroscopic resolution: he has reconstructed spectral information at a higher resolution than the fundamental limit on spectroscopy (the time duration a photon spends in the measuring instrument). The researchers hope that these developments will lead to the improvement of spectral systems used, as an example, for the measurement of pollutants in the air of in water, detection of explosives, etc.
Imaging: a sub-wavelength revolution.
You may also like:
|
| Prof. Moti Segev, Faculty of Physics. |
Technion Researchers Develop Computational Method for Improving the Resolution of Microscopes and Imaging Systems
Technion researchers have demonstrated an innovative method that substantially improves the resolution (the ability to distinguish between details) of microscopes. This was reported by the prestigious scientific journal Nature Materials. The method is based on innovative concepts, and scientists hail it as being a “breakthrough with the potential to change the world of microscopy, imaging systems, and other optical measurement systems”. The method is attracting great interest, both in the scientific world and in industry.
“When you look through an optical microscope at an object with features (optical information) smaller than one half the wavelength of light – you necessarily see a blurred image”, explains Distinguished Prof. Mordechai (Moti) Segev of the Technion’s Department of Physics. “The reason for this is that the information about the structure of very small features does not propagate through space and thus does not reach the eye or the microscope camera. Today, a number of methods are used to achieve a resolution under one half of the wavelength of light, but they all require point-by-point scanning of the object. Hence, these methods may be used only for a static object, which does not change during the scan”.
Scientists have attempted for many years to find algorithms to reconstruct the sub-wavelength information lost between the object and the microscope camera. But thus far all such attempts were largely unsuccessful. The main reason is noise: random scattering of light (for example, from reflections off non-ideal surfaces), which is inevitable in optical systems, has thus far prevented algorithmic reconstruction of features smaller than one half the wavelength of light from measurements of the blurred image.
Now a team of Technion researchers presented a breakthrough algorithmic method for improving the resolution of microscopes to considerably under one half the wavelength of light. To a great extent, the project was successful thanks to the collaboration between several research groups from four different Technion faculties (the groups of Prof. Moti Segev and of Dr. Oren Cohen of the Department of Physics, Prof. Yonina Eldar of the Department of Electrical Engineering, Prof. Irad Yavneh and Dr. Michael Zibulevsky of the Computer Science Department, and Prof. Shy Shoham of the Department of Biomedical Engineering).
“The algorithmic method relies on finding the most suitable reconstruction that meets two criteria: the reconstructed high-resolution image must conform to the blurred image, and it must minimize of the number of the degrees of freedom”, explains Prof. Segev. “The second criterion has to do with understanding compact (sparse) representation of information and with the effect caused by noise in the measurement system. Random noise occupies all degrees of freedom, whereas information has some structure, hence it occupies a given number of degrees of freedom and never all of them. In many cases, there is some sort of a priori knowledge about the information. In principle, in such a case the information may be presented compactly, such that mathematically it is represented by a small number of projections onto basis functions that cover all the possibilities of spatial information. It is then said that the information is sparsely represented, and the number of degrees of freedom it occupies is small. In general, there are many cases where information can be represented compactly. A well known example is file compression using JPEG, a method of compact representation through projection onto a basis where the information in the file is represented sparsely (compactly)”.
This innovative concept of improving resolution in microscopy through representation of the image in the correct basis in which the image is sparse, was developed by Prof. Moti Segev of the Department of Physics and Prof. Yonina Eldar of the Department of Electrical Engineering, graduate students Snir Gazit and Yoav Shechtman and postdoctoral researcher Alex Szameit, currently a professor at the University of Jena, Germany.
The idea was initially demonstrated in 2009. However, exhausting the full potential of the resolution improvement necessitated measuring the phase of the light reaching the microscope camera. Phase measurement requires interference-based methods (interferometric methods) which increase the complexity of the system substantially and limit the applications of this method.
About two years ago, Dr. Oren Cohen proposed adding an important layer to the algorithm, which in effect replaces the need for phase measurement, and to thus obtain image reconstruction at a higher resolution than one half the wavelength of light, through intensity measurement only (using a regular camera). In fact, Dr. Cohen proposed that two research directions be combined – Profs. Segev and Eldar’s idea of sub-wavelength imaging and “lensless imaging”, in which images are algorithmically (computationally) reconstructed from measurements of the intensity of the light at a very far distance from the image. This area – of lensless imaging – has recently become an extremely important field of science. On completion of the construction of three short pulse X-ray lasers (in the USA, Germany and Japan) at a cost of one billion dollars per laser, researchers intend to use lensless imaging to measure the structure of hundreds of thousands of single molecules (molecules that cannot be assembled into a crystallized structure). Understanding the structure of these molecules will pave the way for chemists, biologists and doctors to understand many biological processes at the molecular level. Until now, the resolution of all “lensless imaging” methods has been limited to features bigger than a wavelength. However, the methods developed by the Technion researchers could bring about a revolutionary improvement of the entire “lensless imaging” field, and allow measurement of dynamically changing molecules.
The Technion research team has demonstrated in experiments the reconstruction of details at least five times smaller than the wavelength of light, in a single-shot measurement of the light intensity at the focal plane of the microscope lens. The research work was published in the prestigious journal Nature Materials. The majority of the research work was done by postdoctoral researcher Alex Szameit and graduate students Yoav Shechtman and Eli Osherovich. The experiments, conducted by Alex Szameit and Hod Dana (graduate student at the Department of Biomedical Engineering), demonstrated reconstructions of objects with optical features 100 nanometers in size using radiation with a wavelength of 530 nanometers. In comparison, without using the new method, the resolution of this microscope is limited to features bigger than 300 nanometers.
As described above, the main part of the research is the development of the algorithm for the reconstruction of missing information: (a) reconstruction of the phase of light measured by the camera and (b) reconstruction of the part of the optical information which never reached the camera (information on features smaller than one half the wavelength of light). The initial algorithm, developed by Elad Bullkich, an undergraduate student at the time the research was conducted, and Yoav Shechtman, was based on performing the phase reconstruction algorithm followed by the algorithm for the reconstruction of sub-wavelength information. Some time later, Eli Osherovich developed a far better algorithm that reconstructs both types of “missing information” concurrently, thereby substantially increasing performance and allowing handling a wide range of images.
Technion researchers are now working on the development of similar methods for improving the resolution of other measurement systems. For example, graduate student Pavel Sidorenko has recently demonstrated breaking the resolution barrier of spectroscopic resolution: he has reconstructed spectral information at a higher resolution than the fundamental limit on spectroscopy (the time duration a photon spends in the measuring instrument). The researchers hope that these developments will lead to the improvement of spectral systems used, as an example, for the measurement of pollutants in the air of in water, detection of explosives, etc.
Russia, Israel, Technion and Space Research
Israel, Russia sign space cooperation agreement
The agreement covers observation, navigation, medicine and biology in space, advanced materials and launchings.
27 March 11 19:08, Globes’ correspondent
The Israel Space Agency and the Russian Federal Space Agency today signed a framework agreement in the Prime Minister’s Office in Jerusalem.
The agreement, which was signed in the presence of Prime Minister Benjamin Netanyahu, enhances cooperation between the Israeli and Russian space agencies in the fields of space research, observation, navigation, medicine and biology in space, and research in advanced materials and launchings.
Minister of Science and Technology Daniel Hershkovitz and Russian Ambassador to Israel Pyotr Stegny, the directors of the respective space agencies, and space experts from both countries also attended the signing.
Netanyahu said that the combination of Russia’s developed industry and Israel’s developed, focused and sophisticated industry would provide major benefits to both countries, and added that today’s agreement reflects the impressive development in bilateral relations.
Published by Globes, Israel business news – www.globes-online.com – on March 27, 2011