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Armenian scientists, Hakob Margaryan, Nune Hakobyan, David Hovhannisyan, Tigran Sargsyan, and Valeri Abrahamyan got Armenian President’s 2014 technical sciences and information technology award for the development of a spectro-polaremeter based on a new generation optical element.

In his conversation with the news.am correspondent one of the co-designers of this new device, senior research associate of the Center for Semiconducting Devices and Nanotechnologies at the Yerevan State University, Hakob Margaryan explained that the device functions thanks to a fourth generation optical element.  Production of these new elements became possible in recent years owing to the synthesis of liquid crystal photo-orienting polymeric compounds.

A Historic Background 

In 1888 a German researcher Reithzinger found out that the substance he had synthesized melted into a foggy as opposed to a clear liquid.  The crystal nature of this liquid gave rise to a new class of substances for which a new name was coined – liquid crystals.  Liquid crystals were destined to set off a revolution in technology in the 20th century. 

In 1924 V.K. Fredericks researched the effects of external electric and magnetic fields on the orientation of molecules in liquid crystals. In about forty years after Fredericks’ findings the first liquid crystal screen was introduced in commercial electronic watches.  Despite being liquids, this new class of substances has many features of crystals.  Liquid crystals occupy an intermediate position in-between regular crystals and liquids.

Polymers are substances in which relatively small molecules manage to gather to form long and flexible chains.  Polymers are noteworthy for their omnipresence; one can find this class of substances literally everywhere.  For instance, human body consists of polymers including DNA, RNA polysaccharides, and cellulose in addition to other constituent materials. 

Liquid crystal polymers feature a combination of optical double-refraction – a quality of liquid crystals- with mechanical properties of polymers. Until recently, the orientation of liquid crystal molecules was achieved using several methods of which the most common used to be the method mechanical treatment of a substrate surface.  Obviously this contact method featured a number of shortcomings including highly possible contamination and accumulation of a static charge.  With the creation of photo-orienting polymers, it became possible to align the molecules of a liquid crystal using a contactless technique namely one utilizing light.

“It needs to be noted – told Hakob Margaryan – that already in 1950s a renowned Indian physicist S. Pancharatnam and after him a British researcher M. Berry published theoretical papers related to the topic at hand. And yet practical implementation of their ingenious ideas became only possible after liquid crystal photo-orienting polymers were synthesized.  The ability to gradually and continuously regulate the alignment of the molecules in a liquid crystal affords the opportunity to develop practically           any optical element thus putting in practice Pancharatnam-Berry theoretical predictions.”

Employing liquid crystal polymers one develop optical elements which do not have any precedent.  Modern technology research has launched an exploration of these new materials with the view of putting these elements to some practical use. Compared with the standard optical elements the new ones have a number of advantages.  Consider, for instance, such as smaller size, wider optical spectrum, multiple uses, the possibility of depositing materials on larger size flexible substrate bases, simple technological production cycle and lower production costs.

The group headed by H. Margaryan got its Presidential Award specifically for developing a device whose core element was a liquid crystal polarizing diffraction grate (LC PDG).  “LC PDG produces optic beam patterns in the +1 and -1 diffraction orders.  This means that such diffraction grate has 100 percent efficiency.  At that, with one of the orders a light beam characterized by left circular polarization is associated, while the other order a beam with right circular polarization.  This effect confirms that we are dealing with a fundamentally new optical element.” – continued his narrative H. Margaryan.  The newly designed device measures circular dichroism of biological objects.

Significance of Measuring of Circular Dichroism

In physics, circular dichroism is associated with optical anisotropy, which in turn exhibits itself in the different light absorption coefficients associated with the left and right circular light polarizations.  It is a known fact that human body responds differently to the injected molecules with left and right spins.  Doctors and biologists have been aware of this phenomenon.  Drugs with absolutely identical chemical composition may have different effect on human boies that can be attributed to difference in concentration of molecules with left and right spins.

Then it is obvious that production of medicine should incorporate an intermediate controls and a final check of the circular dichroism of the output substance.  However, only large research centers can afford spectral polarimeters present in the market owing to their high price and big size.  This sort of devices are used extremely infrequently in the mass production biological and pharmaceutical preparations.  The equipment developed by Armenian scientists can solve this problem.

Key Differences Between Margaryan’s Group Polarimeter and Those Currently in the Market

“The instrument for measuring circular dichroism developed and assembled in our lab is compact, easy to use, and with measurements are conducted in real time.  Employing this device allows to incorporate step-by-step testing into the technological cycle of drug manufacturing” – noted Hakob Margaryan

Polarimeters based on traditional optical elements require around thirty minutes before reaching the operational mode, consume much power, are bulky and do not allow real time measurements.  The device for which Margaryan’s group got its Presidential Award is small in size, is powered by a regular compact battery, attains its operational mode shortly after being turned on and allows conducting real time measurements. In addition, traditional polarimeters use powerful xenon light bulbs.  In contrast, the new device uses a simple light emitting diode (LED).

Prospects

Presently Margaryan’s group is involved with the research and development of new generation optical elements.  It is also is in search for the avenues of putting this new element base to practical uses.  Practical applications are enormously promising.  For instance, the discovered optical element can be put to use in innovative ellipsometers as well as in medical instruments that allow non-invasive determination of blood glucose content. 

“Blood is a multi-component substance.  Therefore, arriving mathematically at precise glucose content numbers in blood based on the spectral measurement of the latter is very challenging.  However, glucose is the only blood component that features dichroism.  Employing our new generation optical elements it is realistic to design yet another device for non-invasive glucose blood content measurement.  These elements could also be put to use for the creation of optical pincers utilized in genetic engineering, for cooling the atomic motion several degrees Kelvin (practically absolute zero temperature), and in the field of quantum communications.

Yet another interesting point is as follows.  The group used to obtain photo-orienting liquid crystal polymers and photo-orietants for its experiments from a Swiss company Rolic.  However, a global leader in liquid crystal display manufacturing bought Rolic.  Since then it has become impossible to obtain the aforementioned materials from Rolic.  Fortunately, our compatriot and longtime business partner, Nelson Tabiryan, the president of the U.S Company Beam Co. has set up synthesis of such polymers at this outfit. “ BEAM Co., is the only commercial manufacturer of these substances.  The company regularly makes available the polymers to us for experimentation needs.  We feel fortunate that thanks to our partner that we can continue working with the new polymer substances and stay on the cutting edge of the modern science in the discussed field”, told us the head of the group.

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