Energy flows in polychromatic fields are considered. It is shown that for fields obtained as a result of the superposition of two waves with different frequencies with an analysis time shorter than the beat period, the behavior of the characteristics of the Poynting vector and angular momentum depend on the intermodulation components of the instantaneous vector. The Stokes parameters in this case determine not the state of polarization, but rather the value of the spin angular momentum. The magnitude of the Poynting vector modulus depends on the structure of the analyzed field and for fields of general form is at a level of 20% of the value observed for a coherent wave. Computer simulation data are presented.
The article proposes a new method for the formation of polychromatic edge dislocations with the aim of synthesizing radially and azimuthally polarized polychromatic beams. The proposed method is based on the use of computer-generated hologram technology. It has been shown that using this technology allows to obtain polychromatic edge dislocations with characteristics independent of the spectral composition of the radiation. The results of computer simulation and experimental investigation are presented, confirming the possibility of transforming smooth polychromatic beams into edge dislocations.
The article presents the results of the formation of a polychromatic edge dislocation. A complex Bragg hologram formed as a complex of two gratings with similar characteristics is used as a device employed for this purpose. It is shown that, under resonant illumination of such a grating in the direction of the zero order, two waves are formed with practically equal intensities, forming a low-frequency interference pattern, at the minima of which edge dislocations are observed. The main idea of the method for the formation of a polychromatic edge dislocation is that such a grating is illuminated by a converging radiation beam with a sufficiently wide spectrum. In this case, the structure itself chooses the resonance angles of illumination of the hologram, and identically localized partial spectral gratings are formed in the zero order. The data of experimental studies are presented. The discussion considered the prospects for the formation of polychromatic azimuthally and radially polarized beams
The transverse energy fluxes (both instantaneous and averaged) arising under the superposition of two quasi-plane waves are considered in this paper. The case of superposition when the frequencies of the interacting beams are different is analyzed. The cases of superposition of coaxial orthogonally (linearly and circularly) polarized waves are considered. The mechanisms of forming the distribution of characteristics of the resulting averaged transverse component of the Poynting vector are established. The data of computer simulation are presented.
The superposition of two plane waves with different frequencies and different polarizations is considered. It is shown that electrical vector moves along complex trajectory, which is similar to the Lissajous figures. The characteristics of possible trajectories are analyzed. The results of computer simulation are presented.
The possibility of formation of the beam with edge dislocation, which is similar to the ТЕ01(10) beam is considered. It is shown that such mode may be obtained due to the diffraction of plane wave on the complex Bragg hologram, constructed as composition of two grating recorded on the same place of registration media. These partial holograms are implemented as the gratings with constant period and close characteristics. The conditions of such operation are formulated. The experimental results are presented.
The validity of running criterion for vector and scalar fields is analyzed. It is shown that such criterion may be used for scalar fields of any kind. This criterion may be implemented for relatively simple vector fields like heterogeneously polarized beams with central symmetry of their parameters and it cannot use for vector field of general type. The results of computer simulation are presented.
The possibility of formation of the beam with edge dislocation, which is similar to the ТЕ01(10) beam is considered. It is
shown that such mode may be obtained due to the diffraction of Gaussian beam on the special binary computer generated
hologram. The conditions of such operation are formulated. The experimental results and results of computer simulation
are presented.
In the paper, we take it into one's head to show how different parameters of an optical wave are connected and what follows from this connection. The results of computer simulation are presented.
The connection between contrast changes of intensity distribution of speckle pattern, obtained for polychromatic
illumination of scattering object and coherence characteristics of wave is considered. It is shown, that changes of mean
contrast of speckle field (from center of pattern toward the periphery), obtained for quasimonochromatic illuminating
wave may by connected with spectral range of the wave. The experimental results are presented.
The new approach for experimental modeling of elementary field cells with heterogeneous polarization is proposed. It is
shown that such cells may be obtained by the superposition of orthogonally linearly polarized waves with relatively
simple phase surfaces and close intensities. The characteristics of polarization cell may be easily changed by the change
of superposed beams parameters. The results of computer simulation are presented.
Some physical aspects of role of vortices (and its networks) in formation of statistical field transporting the information
about the initial image are considered. The results of field reconstruction of object image by different chosen
reconstruction samples formed under the use of field vortices characteristics are presented.
The connection between vortex network and network of stationary points of intensity is considered. It is stated that most of current gradient lines of intensity with the origin in saddle points are positioned in the areas where phase changes quickly. The results of computer simulation are presented. The technique for determining the vortex sign in the scalar fields (including the statistical ones) under conditions when the use of the regular reference beam is impossible is described. The elaborated approach is based on the shift-interferometry technique. The conditions of the optimal vortices identification are formulated. The results of the computer simulation and experimental confirmation are presented.
It was shown that C -points are associated with the singularities of the azimuth of the transversal component of the
averaged the Poynting vector. It is established that Poynting singularity shifts relatively C -point position in depending
of relation between amplitude and phase gradients and absolute values of amplitudes associated with orthogonally
polarized field components. The mean magnitude of such shift is defined by the level of polarization homogeneity of a
field. The dynamic of Poynting singularities and polarization ones changes is considered The results of the computer
simulation and experimental results are presented.
In the paper, we take it into one's head to show how different singularity systems of different parameters of an optical
wave are connected and what follows from this connection. The results of computer simulation are presented.
The connection between vortex network and network of stationary points of intensity is considered. It is stated that most
of current gradient lines of intensity with the origin in saddle points are positioned in the areas where phase changes
quickly. The results of computer simulation are presented.
The mechanisms of formation and operation of so-called "interference trap" are presented. The formation of the
interference trap by beams with different curvature, ratio of the intensities and phase difference are shown. The results of
the computer simulation of the Poynting vector behavior in the area of the interference trap are analyzed. The
transformation of angular momentum of vortex beam under interference with smooth ones is shown. Distribution of the
transversal component of the Poynting vector for the interference trap, formed by the vortex with different topological
charge is analyzed.
The behavior of the Pointing vector in the area of elementary polarization singularities with one or two C-points, which
are bounded by regular shape s-contour is considered. It was shown that the disclinations, which move, are born and
annihilate along s-contour, correspond to the singularities of the distribution of the parameters of instantaneous Poynting
vector. C-points are associated with the "vortex" kind singularities of the averaged Pointing vector field if the
handedness factor and topological charge of C-point are characterized by the different signs. "Impassive" Pointing
singularities arise in the area, if the signs are the same. Elementary topology for the Pointing vector field is formulated.
The results of the computer simulation are presented.
Poynting vector singularities are considered for scalar and vector fields. The behavior of averaged and instantaneous
components is analyzed. The relationships between Poynting singularities and conventional optical ones, other special
sets of electromagnetic fields are established. The elementary topological regularities and reactions are formulated. The
results of computer simulation are presented.
In this paper we discuss and demonstrate the trapping and manipulating the particles by three types of single traps
(Gaussian trap, vortex trap and "vortex less" trap), which are formed by one optical device. Experimental results are
presented.
Interrelation of the fine structure of the vector field and its averaged polarization characteristics is considered. It is
shown that space averaged Stokes parameters are defined by dispersion of the phase difference in its saddle points. The
dispersion of phase difference and dimension of areas with considerable polarization changes are defied by the
averaged space between the nearest adjacent component vortices of the same sign. The results of computer simulation
and experimental investigation are presented. Good correlation between these results is observed.
The features of e m inhomogeneous polarized field, which concern an angular momentum, are considered. It is shown
that the e-m field produced by differently polarized optical beams may carry orbital angular momentum. Such angular
momentum arises in field area with the point of circular polarization (C -point). Superposition of relatively simple
orthogonally polarized beams is considered. Experimental results of particles capturing by such focused beam are
presented. On the other hand, in the vicinity of s -contour (field line with linear polarization) spin angular momentum
vanishes. At the same time such angular momentum appears when superposition of beams with different wave-length is
considered.
It is shown that the polarization singularities of vector field are connected with the presence or absence of the angular momentum of electromagnetic field. In the vicinity of C-point the orbital angular momentum is observed. Direction of influence of such orbital angular momentum is defined by the sign of topological charge of vibration phase in this area. Spin angular momentum of a field vanishes on the s-contour. At the same time similar momentum appears if the resulting field is formed by the waves with different wavelengths.
Trapping and manipulation of microparticles using optical tweezers is usually performed within a sample cell formed by two parallel microscope cover slides. In this paper we discuss and demonstrate trapping and manipulation conditions when the cell has more complex configurations like microchannels or capillary tubes. The microchannels are fabricated on the surface of the cover slide by means of lithographic techniques. Experimental results of trapping and micromanipulation for silica microspheres and biological samples immersed in water show the usefulness of our study for microfluidics and biological applications.
It is shown that polarization singularities of vector field are connected with the presence or absence of the angular momentum of electromagnetic field. Namely, in the vicinity of C-point the orbital angular momentum is observed, while the spin momentum is indefinite (vanishes) on the s-contour.
An interferometric technique for analysis of a polarization singular skeleton (s-contours and C-points) of an optical vector field is elaborated. It was shown that complete characteristics of C-points and s-contours may be reconstructed from interferometric data. Some examples of elaborated interferometric technique application to the analysis of randomly polarized speckle-fields singularities are presented.
Possibilities for creation of the vortexless dark optical traps by computer generated holograms and formation of self-converging ones on the base of elementary polarization singularities are considered. The principles of the formation of s-contours with optimal characteristics are formulated. The results of computer simulation and experimental modeling are presented.
The possibility of the vortexless optical traps and self-converging optical traps formation on the base of technique of computer generated holograms is considered. Two methods of the creation of self-converging optical traps are proposed. First of them is based on the transforming of the vortexless optical trap. The second of them is based on the formation of special kind of elementary polarization singularities. The principles of the formation of s-contours with optimal characteristics are formulated. The results of computer simulation and experimental modeling are presented.
Some physical aspects of role of vortices (and its networks) in formation of statistical field transporting the information about the initial image are considered. The results of field reconstruction of object image by different chosen reconstruction samples formed under the use of field vortices characteristics are presented.
The possibility of computer realization of information coding and decoding based on the principles of referenceless holography is considered. The results of preliminary investigations are presented.
The possibility of the self-converging optical traps formation on the base of elementary polarization singularities is considered. The principles of the formation of s-contours with optimal characteristics are formulated. The technique of creating of such field based on the computer-generated holograms is proposed. The results of computer simulation and experimental modeling are presented.
The interferometric technique of analysis of polarization singular skeleton (s contours and c points) of vector field is elaborated. It was shown that complete characteristics of c points and s contours may be reconstructed from interferometric data. The examples of elaborated interferometric technique application to the polarization speckle-field analysis are presented.
Novel approach for the analysis of singularities in vector fields has been proposed. The essence of this approach is scalar consideration of the phase vortices at the orthogonal field components. The new type of vortices are introduced, namely the phase-difference vortices. The sign principle for the phase-difference vortices is formulated. An interconnection between the characteristics of the complete system of phase vortices associated with orthogonal field components, the behavior of an azimuth of a linearly polarized electrical field at an s-contour, and the polarization singularities, dislocations is established. The feasibility for comprehensive estimation of the characteristics of temporal singularities based on the measurement of the stationary field parameters is shown both theoretically and experimentally. Some elementary polarization situations are analyzed on the basis of the developed approach. The obtained results are extended to the case of quasi-uniform in polarization fields.
Polarization structure of vectoral optical fields is investigated. Interconnection among polarization structure of the field and the vortex networks at its orthogonal components is established.
Structure of statistical optical fields is considered. It is shown that the sign and phase of optical vortices are the main their characteristics. The phases of the same sign vortices are analyzed. The topological indexes of intensity field and intensity networks are introduced. The results of computer simulation are discussed.
The approximation algorithm of multicascade system analysis with non-spheric optics is considered. The results of optical realization of scale-invariant transforms is presented.
The appearance of wave front dislocations under interference among beams with simple wave fronts is considered. It is shown, that even two beams with the smooth wave fonts is possible the formation of dislocations screw type. The screw dislocations are formed in cross point of lines of equal amplitude of beams and minimum of an interference pattern.
A theoretical method making it possible to describe scattering form waveguide structures with periodically and randomly perturbed boundary is presented. This method is based on the approximate assumption of single scattering and the geometric-optical approach for the propagation of the optical field in the waveguide. Experimental results for photoresist waveguides with holographically recorded sinusoidal gratings show that the theory can correctly predict fundamental features of the scattered field.
The polarization structure of coherent optical fields in the vicinity of minimal intensity and its connection with wave front dislocations is considered.
The results on investigation of a thin structure of optical speckle fields about a so-called zero-amplitude points are presented. Connection among the object's characteristics, on the one hand, and polarization features of the field about zero-amplitude points, on the other hand, is discussed. It is shown that the polarization state in the vicinity of zero-amplitude points is of deterministic nature. Various polarization states vs the kind of dislocation realized are considered.
The problem of vector theory of amplitude zeroes is discussed. The amplitude zeroes can be of two kinds. In the vicinity of the first kind of zeroes, polarization is linearized, the phase does not have singularity, and a wavefront does not have dislocations. In the vicinity of the second kind of zeroes, polarization is elliptical, a phase has singularity, and a wavefront has a screw dislocation. The experimental results are given.
The use of holograms without reference beam as spatial and amplitude filters in devices for coherent optical data processing and in systems for studying biological processes is discussed. The possibility of a hologram without reference beam to reconstruct the amplitude and phase of the object field with no object present is demonstrated.
The field in the correlation plane of a referenceless hologram used as a matched filter is shown to be the result of interference between different components of the reconstructed and the reconstructing fields. The intensity of the unchanged parts of the field is shown to depend on the correlation between the original field, and to be described by a mutual correlation function c(x,y). Limiting cases, c(x,y) yields 0 and c(x,y) equals 1 are considered. Also considered is the case when changes in the readout fields are limited to small changes in the secondary source phases.
A new approach to fabrication of angular position sensors based on optical ICs is proposed. Capabilities of such sensors are evaluated both theoretically and experimentally.
Recent attempts aimed at developing holographic neural networks and associative memories have stimulated interest to the problems of coherent correlation processing of optical data. Finding new approaches to the reconstruction of the optical field amplitude and phase from its intensity distribution is also a topical problem. In the present work, correlation filters, based on referenceless holograms (RH), are proposed which are the necessary components of neural networks and associative memories. The RH was first introduced as a generalized correlation filter by Van Heerden. A RH is the scattered field intensity recorded on a recording medium. Image reconstruction from such a hologram is based on its associative properties, which take effect when a field (or its part) which is the same as (or similar to) the original object field, is used as the reconstructing field.
Holographic methods have been widely used in surface testing, the principal methods being the recording and reconstruction of the information on the surface under investigation, the measurement of the changes of the surface and the surrounding medium, and the holographic interferometry. The holography without reference beam (HWRB) has received little attention in this respect, although it possesses all the advantages of the commonly used holographic methods. Some of the applications of the HWRB and the holography with a local reference beam have been reported in the literature. The present paper is an attempt to investigate the applicability of the HWRB for surface testing. The feasibility of the HWRB and the reconstruction of the object field from such a hologram has been demonstrated by Van Heerden. The reconstruction is usually performed by a part of the field scattered by an object, by virtue of the HWRB selectivity. This selectivity amounts to definition of a useful signal against the background due to coherent addition of the image points and noise intensities. The associative properties of an HWRB, i.e., the reconstruction of the entire object field from its part, have been reported. However, such an associativity reduces to a minimum the advantages of HWRB since the reconstruction of the object field requires the actual presence of the object. Moreover, the illumination conditions must be identical to those during the recording of the hologram. We propose a somewhat different approach to the above associativity. To reconstruct a field, a set of reconstructing sources whose characteristics are the same as those of a set of object field sources is required. Such a reconstructing source is characterized by its coordinates, radiation phase, size, amplitude modulation, and polarization. These characteristics affect the object field reconstruction process differently. Thus, the polarization of a source has no effect on the signal-to-noise ratio, determining only the overall intensity of the reconstructed field. The amplitude modulation is also found to be insignificant for the reconstruction of a signal from a HWRB. This is evident from the experiment where the amplitude modulation is accomplished by means of a transparency placed in an immersion liquid. During the hologram reconstruction the amplitude transparency is replaced by another one. A drop in the phantom image intensity can be attributed to the fact that the original phase relationships could not be completely retained.
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