M. S. Kovalev

Bio: M. S. Kovalev is an academic researcher from Bauman Moscow State Technical University. The author has contributed to research in topics: Holography & Laser. The author has an hindex of 6, co-authored 41 publications receiving 139 citations. Previous affiliations of M. S. Kovalev include Lebedev Physical Institute.

Measurement of wavefront curvature using computer-generated holograms.

Abstract: The present article is dedicated to the problem of computer-generated holograms application for measurement of optical wavefront curvature with high precision. A holographic wavefront sensor scheme based on a phase-only spatial light modulator, which is used for CGH displaying, is proposed. The presented optical scheme and processing algorithm are validated with numerical simulations and experimental modelling.

A combination of computer-generated Fourier holograms and light guide substrate with diffractive optical elements for optical display and sighting system

Abstract: A combination of computer-generated Fourier holograms (CGFH) and light guide substrate with diffractive optical elements (DOE) is described. The experimental results show that this combination can be used in display and sighting systems.

Wave front sensor based on holographic optical elements

Abstract: A wavefront sensor (WFS) based on holographic optical elements, namely computer generated Fourier holograms is proposed as a perspective alternative to the Shack-Hartmann sensor. A possibility of single and multimode sensor and the dependence of their characteristics were investigated.

Energy deposition parameters revealed in the transition from 3D to 1D femtosecond laser ablation of fluorite at high-NA focusing

Abstract: Ultrashort-pulse laser surface and bulk nano- and micromachining of dielectrics have multiple promising applications in micro-optics, microfluidics, and memory storage. The fundamental principles relate intrinsic inter-band multi-photon (MPA) and laser-induced intra-band free-carrier absorption (FCA) to particular ablation mechanisms and features. These principles are yet to be quantified into a complete set of basic experimental laser-matter interaction parameters, describing photoexcitation, relaxation, and final ablation. In this study, we considered the characteristic double-crater structure of single-shot ablation spots on dielectric surfaces and single-shot transmission spectra to extract crucial information about the underlying basic processes of ultrafast photoexcitation and laser energy deposition. Specifically, energy-dependent crater profiles and accompanying prompt self-phase modulation (SPM) spectral broadening were studied in single-shot surface ablation experiments on fluorite (CaF2) surface photo-excited by tightly focused 515- or 1030-nm, 300-fs laser pulses. Crater size dependence demonstrated two slopes, scaling proportionally to the squared focal 1/e-radius at higher energies (intensities) for larger ablated spots, and a much smaller squared 1/e-radius at lower energies (intensities) for (sub) micron-wide ablated spots, indicating a transition from 1D to 3D-ablation. As a result, these slopes were related to lower-intensity wavelength-dependent multi-photon inter-band transitions and wavelength-independent higher-intensity linear absorption in the emerging near-critical electron-hole plasma (EHP), respectively. Crater depth dependences on the local laser intensity fitted in the corresponding ranges by multi- and one-photon absorption provided the corresponding absorption coefficients. Spectral broadening measurements indicated even values for the red and blue shoulders of the laser pulse spectrum, representing the SPM effect in the weakly excited fluorite at the leading pulse front and providing the corresponding Kerr coefficient. In the second regime, the blue-shoulder broadening value saturated, indicating the appearance of near-critical plasma screening at the trailing pulse front, which is consistent with our calculations. These complementary experiments and related analysis provided an important set of key basic parameters, characterizing not only surface ablation, but also propagation of high-intensity ultrashort laser pulses in bulk fluorite, and enabling precise forecasting of optimal energy deposition for high-efficiency ultrashort-laser micro-structuring of this dielectric material.

Investigation of Computer-Generated Fresnel Holograms for Wavefront Sensors

Abstract: The possibility of using computer-generated Fresnel holograms to determine phase aberrations of a wavefront is studied. The results of computer simulation of the propagation of an elementary signal based on the Fresnel integral transform are presented. The principle of operation of a hologram for a wavefront sensor is discussed.

The Theory of the Photographic Process

Abstract: DR. C. E. K. MEES, with the help of the Kodak Research Laboratories, has written a book that will be for many years the standard authority on the photographic process. His title describes the book as an account of the theory; but theory is not conceived in a narrow sense as the counterpart of experiment, but rather as including almost everything about photography except its practice. The first chapters deal with the emulsions, what they are made of and how they are prepared; the action of light is then described, the processes that take place in photographic materials under its influence and the large number of theories which has been advanced to account for them. Development and fixation are then discussed, again with the emphasis on the details of changes that take place in emulsions and on attempts to explain them in terms of physics and chemistry. There are further chapters on sensitometry, on the nature of the developed image and on the photographic aspects of sound recording. Finally an, account is given of the use of dyestuffs for the production of colour-sensitive film, and for desensitization. The Theory of the Photographic Process By Dr. C. E. Kenneth Mees. Pp. xi + 1124. (New York: The Macmillan Company, 1942.) 60s. net.

Digital holography and digital image processing : principles, methods, algorithms

Abstract: 1. Introduction.- 2. Optical Signals and Transforms.- 3. Digital Representation of Signals.- 4. Digital Representation of Signal Transformations.- 5. Methods and Algorithms of Digital Filtering.- 6. Fast Algorithms.- 7. Statistical Methods and Algorithms.- 8. Sensor Signal Perfecting, Image Restoration, Reconstruction and Enhancement.- 9. Image Resampling and Geometrical Transformations.- 10. Signal Parameter Estimation and Measurement. Object Localization.- 11. Target Location in Clutter.- 12. Nonlinear Filters in Signal/Image Processing.- 13. Computer Generated Holograms.

Orthonormal Polynomials in Wavefront Analysis: Analytical Solution

Abstract: This paper derives closed-form orthonormal polynomials over noncircular apertures using the Gram-Schmidt orthogonalization process. Isometric plots, interferograms, and point-spread functions are illustrated. Their use in wavefront analysis is discussed.

Measurement of wavefront curvature using computer-generated holograms.

Abstract: The present article is dedicated to the problem of computer-generated holograms application for measurement of optical wavefront curvature with high precision. A holographic wavefront sensor scheme based on a phase-only spatial light modulator, which is used for CGH displaying, is proposed. The presented optical scheme and processing algorithm are validated with numerical simulations and experimental modelling.