INTRAOCULARMICROLENS · Development and investigation of intraocular lenses on the basis of the diffraction optical elements

Development and investigation of intraocular lenses on the basis of the diffraction optical elements

Project objectives In our project, we investigated novel approaches to design and fabrication of three-foci intraocular lenses (IOLs), which can be used for cataract treatment and are likely to be more comfortable for patients than the currently used two-foci analogues, providing the ability for clear vision at intermediate distances, which is especially important for PC (personal computer) users. Special experimental setup has been built at the host organisation for practical realisation of designed diffractive microstructures with the optical properties required for intraocular lenses. The created setup allowed high precision fabrication, with a resolution down to 100 nm, of 3D-relief with an option of radial-symmetric forming. We have analysed the state of the art in computer design of diffractive optical elements (DOEs) and possibilities of experimental realisation of prototypes of designed three-foci intraocular lenses by means of novel two-photon polymerisation (2PP) technique. The ability of two-photon polymerisation technique to fabricate high-quality binary and four-level diffractive optical elements for different medical and technical applications has been demonstrated. The carried out investigations of the optical properties of the fabricated DOE's have shown that experimental results are in good agreement with the numerical design. We proposed novel designs of binary and sinusoidal intraocular lenses with desired three-foci light intensity distributions. According to these designs, prototypes of three-foci IOLs have been fabricated by the two-photon polymerisation technique. The measured optical properties of the fabricated DOE-based prototypes are in good correspondence with results of calculations. We investigated possible ways for improvement of diffractive (light transformation) efficiency of DOEs, forming rectangular light intensity distribution. As a result, four-level DOEs with improved efficiency have been designed and implemented. This is an important step in the development of implantable intraocular lens by means of novel two-photon polymerisation laser technology, which was one of the scientific aims of the project. The design of masters with rectangular and sinusoidal profile suitable for mass-production by embossing processes has been proposed. Different methods of master fabrication, based on applications of two-photon polymerisation and femtosecond laser ablation, as well diamond turning and ion lithography, have been studied. Optical properties of the designed and fabricated DOE-based intraocular lenses have been characterised by means of specially designed optical setup. It has been demonstrated that the measured optical properties of IOLs prototypes fabricated by 2PP-based laser technology are in good agreement with the calculation results.

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