Vol 53, No 5 (2017)

The problems and prospects of using diffractive elements with a sawtooth relief-phase microstructure in imaging optical systems are analyzed. Particular attention is paid to minimizing the adverse side effect of diffraction orders on the quality of the image formed by an optical system with a diffractive element due to the change-over from single-layer microstructures to structures containing several layers and reliefs. Requirements are formulated for the design parameters of the microstructure and operating conditions of diffractive elements in optical systems that ensure no visible halo caused by adverse diffraction orders. It is shown by a number of examples that the use of a diffractive element in a plastic-lens imaging optical system corrects chromatic aberrations and provides high resolution in the generated image.

Manufacturing methods and design features of modern diffractive-refractive intraocular lenses are discussed. The implantation of multifocal intraocular lenses is the most optimal method of restoring the accommodative ability of the eye after removal of the natural lens. Diffractive-refractive intraocular lenses are the most widely used implantable multifocal lenses worldwide. Existing methods for manufacturing such lenses implement various design solutions to provide the best vision function after surgery. The wide variety of available diffractive-refractive intraocular lens designs reflects the demand for this method of vision correction in clinical practice and the importance of further applied research and development of new technologies for designing improved lens models.

Various issues of creation of diffractive optical elements transforming one laser beam with small divergence to a matrix of converging beams with a diffraction size of focused spots in the plane of object illumination and their application for problems of DNA sequencing and microscopy are considered. The parameters of diffractive elements are calculated and optimized in the approximation of the Fresnel–Kirchhoff diffraction theory. Diffractive elements are fabricated by the method of direct laser writing on a photoresist by using a circular laser writing system. Experimental characteristics of a diffractive element creating a matrix consisting of 33 × 33 beams, which are focused in one plane at a distance of 210 mm, are presented. The degree of nonuniformity of beam intensities determined by the ratio of beam intensities in the central region to intensities of peripheral beams is 1/2.5, which is potentially sufficient to be used in DNA sequencing problems. The maximum distortions of spot positions in the entire focusing field is <0.15%.

This paper is a review of studies carried out by the staff of the National Research University of Information Technologies, Mechanics and Optics (ITMO University, Saint-Petersburg) and the Institute of Automation and Electrometry of the Siberian Branch of the Russian Academy of Sciences (IAE SB RAS, Novosibirsk) in the field of development of laser engineering processes for the formation of the structure of diffractive optical elements (DOEs) and photomasks with amplitude binary and grayscale transmission. This paper also describes the results of the study of laser thermochemical technology for fabricating chrome DOEs and technologies for the fabrication of grayscale DOEs and photomasks based on the use of amorphous silicon and LDW glass.

This paper presents a brief overview of papers dealing with the nonparaxial effects arising from the use of the lensacon proposed by Koronkevich and coauthors in 1993, as well as its analogs in a substantially nonparaxial mode. In this case, it is necessary to take into account the vector nature of electromagnetic radiation. This allows detecting new effects, which, in turn, would extend the range of applications of the lensacon.

A comparative analysis is made of spatial variations in the energy characteristics of tightly focused, longitudinally polarized needle laser beams generated by an optical system with selective thin-film linear-to-radial polarization conversion, followed by their spatial filtering and tightannular focusing to subwavelength sizes. For the important special case of ideal radial polarization of a focused beam, longitudinal cross-sections of spatial distributions of the electric energy density and the Poynting vector modulus in the vicinity of the focus were compared by numerical simulation. It is shown that the degree of their difference increases substantially with decreasing angular zone of annular focusing and with the introduction of spatial-frequency filtering. It is established that the dimensions of the axial zone of beam focusing determined for their central lobes in the first approximation do not depend on the choice of energy characteristics used for their measurements.

This paper describes the development and manufacture of diffraction corrector and imitator for the interferometric control of the surface shape of the 6-m main mirror of the Big Azimuthal Telescope of the Russian Academy of Sciences. The effect of errors in manufacture and adjustment on the quality of the measurement wavefront is studied. The corrector is controlled with the use of an off-axis diffraction imitator operating in a reflection mode. The measured error is smaller than 0.0138λ (RMS).

A review of advanced equipment for automated interference measurements developed at the All-Russian Research Institute for Optical and Physical Measurements is given. Three types of interference microscopes based on the Linnik, Twyman–Green, and Fizeau interferometers with the use of the phase stepping method are presented.