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Reducing/cancelling the effects of vitreous floaters using a phase retrieval method based on coded diffraction patterns (2017 - 2020)
Last Update
15.06.2018

 

Project leader Varis Karitans

Agreement No 1.1.1.2/16/I/001

Research application No 1.1.1.2/VIAA/1/16/199

The project goal is to develop a non-invasive optical system and method for reduction/cancellation of the undesired effects of the vitreous floaters. The vitreous floaters manifest themselves as chains, bubbles and other structures floating in the field of view. These structures are actually transparent phase diffraction gratings. This problem causing the visual discomfort is experienced by about 80 % of all people. The problem will be solved using the method of coded diffraction patterns to measure the structure of these objects and modulate the light so that the effects of the floaters are reduced. The method of coded diffraction patterns is one of the most popular numerical methods for measuring the phase and structure of objects. This method is suited for measuring the optical aberrations, determining the structure of complexes of proteins, structure of crystals and other purposes. During the project the applicability of this method for designing a new type of wavefront sensors in astronomy and determining the structure of objects floating in microfluidic systems will be evaluated. Such studies are essential for Latvian industry by facilitating development of high-tech products and companies.

The project will be realized at the Institute of Solid State Physics (ISSP) in collaboration with the optics laboratiry at the Dublin University College. The project will be multidisciplinary and will be realized in the field of innovative materials and technologies – natural sciences (1.1 Mathematics, 1.3 Physical sciences, 1.4 Chemical sciences) and engineering sciences and technologies (2.5 Materials engineering). The project activities are related to RIS3 as its goal corresponds to the specified directions of transformation of national economy and the 1st, 2nd, 3rd and 6th priority of the economic growth. The project matches the following specialization areas: 1) advanced materials, technologies and engineering systems; 2) Information and communication technologies and key technologies identified by EC (nanotechnologies, micro- and nano-electronics, photonics, advanced materials and manufacturing systems, biotechnologies).

The total duration of the project is 36 months, the total cost is 133,805.88 EUR.


Project progress

June 15, 2018

Studies on the method of coded diffraction patterns and aberrometry have been continued. Structures of various size and shape to be used for phase retrieval of the vitreous floaters in a model eye have been designed. Applicability of Zernike polynomials for filtering out the optical noise in the calculated wavefront has been studied. Results on analysis of aberrations have been presented in the 34th scientific conference of ISSP on 21.02.2018. and the scientific seminar of ISSP on 29.03.2018.

A research paper has been submitted to the proceedings of a SPIE conference “Optical Systems Design” (Frankfurt, Germany from 14.05.2018. to 17.05.2018.). The paper was published on 28.05.2018.

Varis Karitans; Edgars Nitiss; Andrejs Tokmakovs; Kaspars Pudzs. “Optical phase retrieval using four rotated versions of a single binary mask – simulation results”. Proc. SPIE 10694. DOI: 10.1117/12.2311861

Results on a study investigating detection of the vitreous floaters have been presented in the conference “Developments in Optics and Communications” (an invited talk: Simulation of Vitreous Floaters using an Eye Model with Microfluidics System).


Project progress

March 15, 2018

During the initial stages of the project the method of coded diffraction patterns has been customized to measure the structure of microoptical elements designed in a photoresistive layer. A good relation between the method of coded diffraction patterns and the non-contact profilometry has been proven. The method of coded diffraction patterns is realized using the photolithography method while the non-contact profilometry employs MATLAB tool LightPipes providing possibility to simulate propagation of a wavefront in a free space. In very near future a manuscript will be submitted to a journal of the Optical Society of America (OSA). In the manuscript, both methods will be compared.

Up to now, applicability of different plastics (PET, PVC etc.) for forming microfluidics contacts has also been analyzed. The strength of contacts between different plastics and polydimethylsiloxane (PDMS) has been determined. It has been observed that a good contact can be achieved using a non-modified polycarbonate (PC). Polyurethane bonds are formed on the PC surface and after being inserted in an ozone cleaner -OH groups are formed. In order to reduce aberrations in the microfluidics system, the eye model incorporating the microfluidics system has also been improved.

An optical system using 4 CMOS cameras are being developed so that 4 coded diffractions patterns can be measured at the same time thus reducing the measurement time. The MATLAB code calculating the structure of the object based on the intensity measurements has also been optimized. After optimization the computational time has been reduced very significantly.

The results obtained have been presented at the 34th annual conference of the Institute of Solid State Physics (ISSP). Thesis has also been submitted to a conference “Optical Systems Design” being held in May 2018 in Frankfurt, Germany. The thesis has been approved and the results will be reported in an oral presentation.