(photo credit: Marretao22/Wikimedia Commons)
Haifa’s Technion-Israel Institute of Technology has registered a patent for a
new technique that improves tenfold the performance of any type of sophisticated
microscope and imaging system without making hardware changes.
discovery, which has just been published in the Nature Materials journal, has
aroused great interest in the scientific world and industry, being described as
a “breakthrough with the potential to change” these fields.
innovative method substantially improves the resolution – the ability to
distinguish between details – of images seen through microscopes.
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,” explained Prof. Moti Segev of the Technion’s physics
department. “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.”
Methods exist to achieve a
resolution under one-half of the wavelength of light, he said, but they all
require point-by-point scanning of the object, meaning that these approaches may
be used only for a static object, which does not change during the
Scientists have tried for many years to find algorithms to
reconstruct the subwavelength information lost between the object and the
microscope camera. But until now, all such attempts were largely unsuccessful.
The main reason is that “noise” – random scattering of light, 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 the Technion team has presented a
breakthrough algorithmic method for improving the resolution of microscopes to
considerably under one-half the wavelength of light.
The project was
successful due to interdisciplinary collaboration between several research
groups from four different Technion faculties: those of Segev and Dr. Oren Cohen
of the physics department; Prof. Yonina Eldar of the electrical engineering
department; Prof. Irad Yavneh and Dr. Michael Zibulevsky of the computer science
department; and Prof. Shy Shoham of the 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 the number of the
degrees of freedom,” Segev explained.
“The second 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.”
He continued: “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.”
About two years ago, 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, using a regular
In fact, Cohen proposed that two research directions be combined
– Segev and Eldar’s idea of sub-wavelength imaging and “lensless imaging,” in
which images are algorithmically reconstructed from measurements of the
intensity of the light at a very far distance from the image.
of lensless imaging has recently become a central field in science. When the
construction of three short pulse X-ray lasers in the US, Germany and Japan are
completed at a cost of $1 billion dollars per laser, researchers intend to use
lensless imaging to measure the structure of hundreds of thousands of single
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 the Technion researchers have developed
could bring about a revolutionary improvement in the entire lensless imaging
field, and allow measurement of dynamically changing molecules, Segev said.