Image edge-enhancement in optical microscopy with a phase mismatched spiral phase plate

We present a spiral phase filtering system with a large tolerance for edge enhancement of both phase and amplitude objects in optical microscopy.The method is based on a Fourier 4-f spatial filtering system.A phase mismatched spiral phase plate (SPP) fabricated by electron beam lithography is employed as the radial Hilbert transform for image edge enhancement.Compared with holography,SPP is simple,economical,reliable,and easy to integrate.     

Control of the metal-semiconductor phase transition in a vanadium dioxide film with the aid of a fast-acting thermoelectric cooler. III

The pulsed-cooling dynamics of fast-acting thermoelectric coolers is analyzed. Good agreement is obtained between the theory and the experimental results on information erasure with an interference vanadium dioxide structure in the single-pulse and repetitive-pulse modes. It is shown that the actually achievable overwrite frequency with thermoelectric erasure of information is about 30 Hz, and a fast-acting thermoelectric cooler is capable of providing a temperature difference of at least 10 °C between the cold and hot junctions under such conditions. Zh. Tekh. Fiz. 68, 110–115 (February 1998)     

A study of the phase relations in ionization waves in neon with the aid of a microwave resonator method

The following paper describes the generalization of the microwave resonance method for measuring the phase between relative changes of the concentration and collision frequency of electrons. It also presents the results of measuring the phase between the above-mentioned parameters of plasma in neon, in which slow and fast ionization waves are propagated which, have been obtained by the described method.In conclusion we would like to thank Prof. Dr. V. Kunzl, head of the Department of Electronics and Vacuum Physics, at the Faculty of Mathematics and Physics, Charles University, for making this work possible, and Docent Dr. M. icha C.Sc., for much valuable advice which contributed to the successful completion of this work.     

光栅编码图像微分

采用光栅编码的方法,可以实现图像微分.该方法噪声小,微分量可变,处理面积大.     

Formation of x-ray beams with the aid of a tapered microcapillary

The possibility of obtaining x-ray microbeams with a prescribed intensity using a system containing a x-ray tube with a transmission thin-film anode and a tapered glass microcapillary is investigated. Zh. Tekh. Fiz. 68, 90–93 (May 1998)     

Measurement of magnetic susceptibility with the aid of a quantum magnetometer

A procedure is proposed for the measurement of magnetic susceptibility with the help of a quantum magnetometer without the use of reference materials. Computational formulas are given for samples of various diameters and lengths. A number of specific recommendations are given for the choice of the optimal configuration for the flux transformer, the measuring ampul, and the samples.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 40–49, February, 1984.The author is grateful to N. I. Alekseev, I. E. Kuznetsov, and M. V. Krasheninnlkov for help in performing this research.     

Probing the structure of nuclei with the aid of bound a hyperons

It is shown that the binding energy b of heavy nuclei can serve to derive information on the nuclear radius only in the form of a certain dependence of the nuclear radius upon the proposed width of the edge region of the nucleus. The experimental b values and the experimental values of the width of the edge region result in estimates of the parameter nuclear radius₀= 1.28 _–0.30 ^+0.42 F.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 82–86, March, 1976.     

A spatial filter for phase object differentiation

A spatial filter for coherent optical processing which has an amplitude transmittance proportional to the square root of the sum of the spatial frequency and a constant, is shown to produce intensity images nearly linear to the first derivative of the phase of purely phase-varying input objects. These images can then be integrated incoherently to yield the phase functions of the objects.     

Image enhancement in longwave holography by electronic differentiation

In scanned longwave holography the hologram data is available in the form of an electronic signal which lends itself to convenient processing. In this paper the effects of electronic differentiation of the hologram data in Fresnel holograms are studied. We present both theoretical and experimental results which indicate that this processing technique emphasizes the detail and edges of the object.     

Investigation of multiple ultrasmall-angle neutron scattering with the aid of a double-crystal diffractometer

A method of multiple small-angle neutron scattering (MSANS), used to obtain information about inhomogeneities of substances, is considered. Experimental schemes and theory of a double-crystal diffractometer intended for measuring multiple small-angle neutron scattering are described. Methods used to approximate MSANS angular distributions at a low concentration of inhomogeneities and based on Moliére’s theory are reviewed. Their applicability is demonstrated for the examples ofMSANS spectra of samples from ferromagnetic iron-nickel alloys, aluminum powders, and high-T _c superconductor ceramic materials. Theoretical and experimental investigations of interference effects that manifest themselves in multiple small-angle neutron scattering on systems containing high concentrations of scatterers are reported.     

Image encryption using exclusive-OR with DNA complementary rules and double random phase encoding

We propose an optical image encryption scheme based on the Deoxyribonucleic Acid (DNA) theory and the double random phase encoding (DRPE) technique. The piecewise linear chaotic map (PWLCM) is used to generate key images and random phase masks, and to determine DNA encoding rules. In order to achieve ultra-fast DNA encryption, we propose using an optical exclusive-OR (XOR) gate to achieve XOR operation in DNA encryption. Different plaintexts use different initial values of PWLCM, which are generated by Message Digest Algorithm 5 (MD5). The plaintext is encrypted by two rounds of DNA and then by DRPE to form a ciphertext. Numerical simulation and the analysis of attacks on encrypted image are implemented to demonstrate the security and validity of the proposed approach.     

Study of relaxation processes in a gas with the aid of coherent transient processes

The paper is devoted to the study of two types of coherent transient processes, viz., coherent radiation in time-separated fields (CRSF) and photon echo (PE) in a traveling wave in SF₆ gas. Study of CRSF signals produced at instants of time t = T + nT (T is the delay time between the exciting pulses and n is an integer) has made it possible to measure the relaxation rates of the polarization and of the populations in SF₆ gas and draw qualitative conclusions concerning the character of the collisions. Damping of PE signals as a function of the delay time is nonlinear in the region of short T and permits measurement of the rates of rotationally inelastic processes, as well as of the contribution of other collisions with small velocity change.Translated from Lazernye Sistemy, pp. 143–154, 1982.     

Study of temperature fields in a rectangular plate with a temperature-dependent internal source with the aid of fast expansions

The approximate analytic solution of the problem of temperature field in a rectangular plate with an internal temperature- dependent source is obtained by the method of fast expansions. The critical value of a parameter characterizing heat release, which fundamentally affects the analytic solution form, is found. The maximum solution error is shown to amount to 0.02 at the consideration of the first three terms of the Fourier series in fast expansion. Temperature fields are presented, and an analysis of the influence of the plate sizes and the heat release magnitude on their formation is given. Recommendations on the plate shape choice are given.     

Image transmission via a multimode fiber assisted by polarization preserving phase conjugation in the photorefractive crystal

Image transmission via a 2m-long multimode fiber was realized by using polarization-preserving phase conjugation in the photorefractive crystal and correcting holograms.