Showing papers on "Light field published in 1997"
TL;DR: In this paper, a quantum system composed of a cavity field interacting with a movable mirror can be used to generate a large variety of nonclassical states of both the cavity field and the mirror.
Abstract: We describe how a quantum system composed of a cavity field interacting with a movable mirror can be utilized to generate a large variety of nonclassical states of both the cavity field and the mirror. First we consider state preparation of the cavity field. The system dynamics will prepare a single mode of the cavity field in a multicomponent Schr\"odinger-cat state, in a similar manner to that in a Kerr medium. In addition, when two or more cavity modes interact with the mirror, they can be prepared in an entangled state, which may be regarded as a multimode generalization of the even and odd coherent states. We show also that near-number states of a single mode may be prepared by performing a measurement of the position of the mirror. Second we consider state preparation of the mirror and show that this macroscopic object may be placed in a Schr\"odinger-cat-like state by a quadrature measurement of the light field. In addition, we examine the effect of the damping of the motion of the mirror on the field states inside the cavity and compare this with the effect of cavity field damping.
434 citations
TL;DR: The Wigner distribution function (WDF) is a mathematical tool that correctly yields the expectation values of any function of the coordinates or the momenta as discussed by the authors, which is useful in the characterization of light fields and optical systems.
Abstract: Publisher Summary The Wigner distribution function (WDF) in quantum mechanics is a mathematical tool that correctly yields the expectation values of any function of the coordinates or the momenta. The chapter discusses WDF applications to the characterization of light fields and optical systems and to the problem of coupling optimization between sources and waveguides. Phenomena such as diffraction, interference, coherence, or polarization cannot be managed in the framework of geometrical optics but only within wave optics, where the light field is characterized by a vectorial distribution that satisfies the Helmholtz equation. The applications of the WDF support the assertion that the WDF is a valuable theoretical and experimental tool in optics and optoelectronics. Further expansion of WDF applications will probably result from the recent extension of the WDF definition as a quantum quasiprobability distribution of number and phase and as a wide-band distribution function in signal processing.
139 citations
TL;DR: In this paper, the quantum motion of a cold, trapped two-level ion interacting with a quantized light field in a single-mode cavity has been analyzed, and the system under consideration may evolve into the maximally entangled threeparticle Greenberger-Horne-Zeilinger state.
Abstract: We analyze the quantum motion of a cold, trapped two-level ion interacting with a quantized light field in a single-mode cavity. We show that in the nonclassical Lamb-Dicke limit the time evolution of the vibrational mode representing the quantized motion of the center of mass of the trapped ion is very sensitive to the quantum statistics of the light field. We also show that the system under consideration may evolve into the maximally entangled three-particle Greenberger-Horne-Zeilinger state. We briefly discuss the dynamics of a cluster of two-level ions trapped in a cavity and interacting with a quantized light field. @S1050-2947~97!07209-0#
84 citations
13 Oct 1997
TL;DR: A new representation scheme, called a spherical light field, of the plenoptic function, that is based on spheres is presented, which naturally creates a multi resolutional representation of the light flow that can be exploited effectively in the future applications.
Abstract: A plenoptic function is a parameterized function describing the flow of light in space, and has served as a key idea in building some of the recent image based rendering systems. The paper presents a new representation scheme, called a spherical light field, of the plenoptic function, that is based on spheres. While methods using spherical coordinates are thought to require substantially more computation than those using planar or cylindrical coordinates, we show that spheres can also be used efficiently in representing and resampling the flow of light. Our image based rendering algorithm is different from the previous systems, the light field and lumigraph, in that it is an "object space" algorithm that can be easily embedded into the traditional polygonal rendering system. Our method is easily accelerated by 3D graphics boards that support the primitive functionality, such as viewing and smooth shading. In addition, we introduce an encoding scheme based on wavelets for compression of the huge data resulting from sampling of the spherical light field. The proposed technique can be easily adapted to compress the light field and lumigraph data, and offers as high compression ratios as the previous methods. Furthermore, it naturally creates a multi resolutional representation of the light flow that can be exploited effectively in the future applications. We show how to access the compressed data efficiently using a modified significance map and an incremental decoding technique, and report experimental results on several test data sets.
84 citations
TL;DR: In this paper, the authors compared paraxial light and atom optics and showed that the slowly varying amplitude of a light field in a dielectric medium with a spatially dependent refractive index satisfies an equation which has the form of a Schr\"odinger equation.
Abstract: Paraxial light and atom optics are compared. To lowest order the slowly varying amplitude of a light field in a dielectric medium with a spatially dependent refractive index satisfies an equation which has the form of a Schr\"odinger equation: the ``optical Schr\"odinger equation.'' The unsystematic procedure of neglecting certain second-order derivatives is replaced by a systematic expansion which allows the calculation of consecutive corrections. The general theory is applied to harmonic motion in a graded index fiber and to tunneling between coupled fibers. The physical relations between wave evolution of massive particles and paraxially propagating waves are elucidated.
60 citations
TL;DR: In this article, a perturbation theory for the forward problem of optical transport in turbid media is developed, which is applicable to media with scattering and absorption in homogeneties and steady-state and modulated light.
Abstract: A perturbation theory for the forward problem of optical transport in turbid media is developed. It is applicable to media with scattering and absorption in homogeneties and steady-state and modulated light. Absorbing perturbations can be described by a volume distribution of virtual sources that primarily causes a monopole perturbation light field. Scattering objects have an additional contribution that, in the limiting case of sharply bounded objects, is represented by a surface distribution of virtual sources and causes a dipolelike perturbation pattern. Using the concept of virtual sources, we discuss a possible ambiguity between the perturbations from scattering and absorbing inhomogeneities and the implications for the source-detector placement in inverse problems. We show that the surface effects due to sharp boundaries of scattering objects pose both a numerical problem and a chance to improve the resolution of inverse algorithms.
51 citations
TL;DR: In this article, neutral chromium atoms were used to write periodic nanometerscale structures in a direct way using the force exerted on the induced dipole of the atom in the intensity gradient of an optical standing light field to focus an atomic beam onto a substrate.
40 citations
Patent•
07 Feb 1997
TL;DR: In this paper, the authors present an LED light source for a machine vision system, which includes a plurality of LEDs each arranged in a base plate in a predetermined manner during manufacturing, and each LED is then securely mounted to the base plate with an ultravioletly curable adhesive to remain pointed in the predetermined manner.
Abstract: The present invention relates to an LED light source for a machine vision system. The light source includes a plurality of LEDs each arranged in a base plate in predetermined manner during manufacturing. Each LED is then securely mounted to the base plate with an ultravioletly curable adhesive to remain pointed in the predetermined manner. The light source also includes an optically efficient non-lambertain diffuser which receives light from each of the LEDs and breaks the light up to provide a uniform light field to illuminate an object under inspection.
34 citations
TL;DR: In this article, a theoretical study of the effects of light field distribution on the frequency response of a resonant-cavity-enhanced p-i-n photodetector is presented.
Abstract: We present a theoretical study of the effects of light field distribution on the frequency response of a resonant-cavity-enhanced p-i-n photodetector. Taking advantage of the flexibility of cavity design, one can tailor the light field distribution in the absorption region. Because of the difference in velocities of the carriers, the speed performances of the detector depend on the field distribution and the cavity design. The results of our work indicate that when the maximum of light field intensity happens near the p/sup +/ edge of the depletion layer, the device shows the best speed performance. The frequency response, the impulse response, and the step response have been calculated for different structures to demonstrate the importance of the field distribution.
34 citations
15 Jul 1997
TL;DR: In this article, the ultrafast dissipative dynamics of molecular vibrations under the influence of strong laser pulses is studied in the framework of the density matrix theory, and the related equations of motion are solved directly with the inclusion of the light field.
Abstract: The ultrafast dissipative dynamics of molecular vibrations under the influence of strong laser pulses is studied in the framework of the density matrix theory. To circumvent any perturbational treatment of the molecule-radiation coupling the related equations of motion are solved directly with the inclusion of the light field. The theory is applied to the simulation of 20 fs two-color pump-probe experiments on the laser-dye IR 125 [S.H. Ashworth, T. Hasche, M. Woerner, E. Riedle and T. Elsaesser, J. Chem. Phys. 104 (1996) 5761]. It can be demonstrated that a three-level model of a S 0 , a S 1 , and a higher excited S n state completed by a single vibrational coordinate is sufficient to calculate the measured spectra. The main features of the spectra can be explained by the formation of a dynamical hole in the vibrational wave function of the electronic ground state. Its spatio-temporal oscillation and its dependence on the pump intensity is studied in detail.
27 citations
TL;DR: In this paper, a standing light wave appears to a highly detuned two-level atom as a sinusoidal potential, and the atom changes the phase of the light field.
Abstract: A standing light wave appears to a highly detuned two-level atom as a sinusoidal potential. This causes the atoms to be channeled to the minima of the potentials. At the same time, the atom changes the phase of the light field. Detecting this phase shift yields information about the position of the atom. In this paper we show that this information may be used to control the intensity of the light field so as to modify the effective shape of the potential ``seen'' by the atom. Our numerical simulations show that the effectiveness of the channeling may be significantly enhanced by such quantum-limited feedback. We discuss possible applications to atom lithography.
TL;DR: In this article, an analytical model which describes the drift and diffusion mechanisms for the formation of the nonlinear response (local and nonlocal nonlinearities) of photorefractive crystals on the microscopic level is constructed.
Abstract: An analytical model, which describes the drift and diffusion mechanisms for the formation of the nonlinear response (local and nonlocal nonlinearities) of photorefractive crystals on the microscopic level, is constructed. New types of stable self-consistent distributions of the light field intensity, i.e., spatial solitons, are found. The trajectories of their motion (self-bending) are calculated, and the possibility of observing a new nonlinear-optical effect in photorefractive crystals, viz., the formation of spatial shock waves, is demonstrated. The modulation instability appearing when plane waves propagate in photorefractive crystals is analyzed, and the characteristic spatial scales of the light field distribution formed as a result of self-interaction (fanning) are determined. The results of the analysis are confirmed by computer simulation data.
TL;DR: Speckle patterns in the light field scattered from the rough surface of a cylindrical object are experimentally studied and a theoretical model explains the main features of the scattered light field.
Abstract: Speckle patterns in the light field scattered from the rough surface of a cylindrical object are experimentally studied. The light speckles are elongated in the direction normal to the cylinder axis. A theoretical model explains the main features of the scattered light field. The dimensions of light speckles depend on both the surface roughness and the surface curvature.
TL;DR: The author examines the accuracy of the formulas for spherical and rectangular Lambertian sources, and applies them to obtain light gradients, and shows how to use the formulas to estimate light from uniform polygonal sources, sources with polynomially varying radiosity, and luminous textures.
Abstract: Computing the light field due to an area light source remains an interesting problem in computer graphics. The paper presents a series approximation of the light field due to an unoccluded area source, by expanding the light field in spherical harmonics. The source can be nonuniform and need not be a planar polygon. The resulting formulas give expressions whose cost and accuracy can be chosen between the exact and expensive Lambertian solution for a diffuse polygon, and the fast but inexact method of replacing the area source by a point source of equal power. The formulas break the computation of the light vector into two phases: the first phase represents the light source's shape and brightness with numerical coefficients, and the second uses these coefficients to compute the light field at arbitrary locations. The author examines the accuracy of the formulas for spherical and rectangular Lambertian sources, and applies them to obtain light gradients. The author also shows how to use the formulas to estimate light from uniform polygonal sources, sources with polynomially varying radiosity, and luminous textures.
TL;DR: The interaction of linearly and circularly polarized beams with a nematic liquid crystal doped with light absorbing dyes has been studied by light-diffraction and microprojection methods as discussed by the authors.
Abstract: The interaction of linearly and circularly polarized beams with a nematic liquid crystal doped with light-absorbing dyes has been studied by light-diffraction and microprojection methods. It has been found that there is a threshold for the emergence of light-induced anisotropic structures, which, depending on the type of dye, can be axisymmetric or extended in a direction determined by the light field. Possible mechanisms leading to the formation of the anisotropic structures are discussed.
Patent•
15 May 1997
TL;DR: In this paper, an approach for continuous detection faults according to size and type on the surface of a moving material (1) comprises: (a) a diffused radiation source for a light field (6); (b) a directing further radiation source (7) for a dark field (8); (c) radiation from the sources (4, 7) takes place separately from one another; (d) separate matrix cameras (5, 10) for radiation reflected respectively from the light and dark fields (6, 8).
Abstract: Apparatus for continuous detection faults according to size and type on the surface of a moving material (1) comprises: (a) a diffused radiation source (4) for a light field (6); (b) a directing further radiation source (7) for a dark field (8); (c) radiation from the sources (4, 7) takes place separately from one another; (d) separate matrix cameras (5, 10) for radiation reflected respectively from the light and dark fields (6, 8). Both observation systems formed by the radiation sources (4, 7) and matrix cameras (5, 10) respectively for the light and dark fields (6, 8) are designed for pulsed observation.
TL;DR: In this paper, the transient characteristics of an interband resonant light modulation process by ultrashort intersubband light pulses in semiconductor quantum wells (QW's) have been investigated by a numerical analysis of the coupled Bloch equations using a density-matrix approach.
Abstract: We explore the transient characteristics of an interband resonant light modulation process by ultrashort intersubband resonant light pulses in semiconductor quantum wells (QW's). The modulation characteristics in a three-level semiconductor QW system, including the effects due to in-plane momentum, have been investigated by a numerical analysis of the coupled Bloch equations using a density-matrix approach. We have studied the effect of the carrier density and the nature of the intersubband coupling light on the transient absorption features of the interband light. The modulation process has been compared in doped and undoped QW's. The switching behavior of the strong interband light field in presence of a train of intersubband light pulses has also been discussed.
Patent•
15 May 1997
TL;DR: In this article, a fiber-optic hydrophone with its smooth or modified end surface of a monomode or multi-mode light wave conductor is coated using one or more hard dielectric optical layers deposited by sputter, is immersed in a liquid.
Abstract: The fibre-optic hydrophone with its smooth or modified end surface of a monomode or multi-mode light wave conductor is coated using one or more hard dielectric optical layers deposited by sputter, is immersed in a liquid. The alteration of the complex coefficients of the layer or layer system is measured as a result of the pressure reaction. The alteration of the amplitude or the phase of a light field, coupled in the light wave conductor, and reflected at the end surface, is detected with a suitable optical system. Especially for shock wave tests, only one layer of a material with high optical refractive index e.g. Nb2O5 is coated.
TL;DR: In this article, the state reconstruction of an optical two-mode light field from sum quadrature distributions measured with a single balanced homodyne detector is considered, and explicit formulas for the pattern functions necessary to reconstruct the density matrix of the twomode field in the photon-number basis are derived.
Abstract: We consider the state reconstruction of an optical two-mode light field from sum quadrature distributions measured with a single balanced homodyne detector. New explicit formulas for the pattern functions necessary to reconstruct the density matrix of the two-mode field in the photon-number basis are derived. Moreover, an expression of the measured quadature distribution in terms of the two-mode normally ordered moments is given and the determination of the moments from it is discussed.
TL;DR: In this paper, the Sommerfeld diffraction theory is extended to the case of extremely short pulses and it is shown that a simple qualitative analysis and a quantitative solution of a wide class of diffraction problems are possible for pulses with durations of the order of the period of the light oscillations and an arbitrary initial distribution of light field.
Abstract: The Sommerfeld diffraction theory is extended to the case of extremely short pulses. It is shown that a simple qualitative analysis and a quantitative solution of a wide class of diffraction problems are possible for pulses with durations of the order of the period of the light oscillations and an arbitrary initial distribution of the light field.
TL;DR: In this paper, a generalized rate equation model for the array and polarization dynamics of general one- or two-dimensional arrays of vertical-cavity surface-emitting lasers (VCSELs) is presented.
Abstract: We present a generalized rate equation model for the array and polarization dynamics of general one- or two-dimensional arrays of vertical-cavity surface-emitting lasers (VCSELs). It is demonstrated that our model includes both the previous theory for edge-emitting laser arrays and the theory of polarization dynamics in quantum-well VCSELs in a single unified description. The model is based on the physical assumption of separated carrier density pools individually coupled to different light field modes. These modes, defined by the separate gain profile of each pool, interact through the coherent dynamics of the light field derived from Maxwell's equations and represented by the coefficients for index and loss guiding. The special case of two densities and two light field modes is solved and the implications of the results for large VCSEL arrays are discussed. Our analytic results show that typical solutions of the split-density model range from phase locking to chaos, depending on the magnitude of the frequency coefficients. For weak coupling, the stable supermode is always the mode of highest frequency. This indicates that anti-phase locking is the only stable phase locking possible in arrays.
TL;DR: In this article, a solution of the scattering problem for a wave packet of a three-level atom in the two standing light waves field with a spatial phase shift was presented for arbitrary intensities of the standing waves and for any interaction times between the atoms and light field.
TL;DR: In this paper, the authors proposed an atom optical amplitude grating formed by a standing wave light field, where the standing wave optically pumps all atoms except those localized near the nodes of the light field into an undetected internal state.
TL;DR: In this paper, the volume superposed holograms, recorded with the use of light waves, whose amplitudes can be described in terms of mutually orthogonal functions, are used for switching of optical channels and for expansion in Walsh functions of the light waves.
Patent•
28 Oct 1997
TL;DR: In this article, the authors propose an operating theater lamp with a light outlet opening at the bottom and a light source being arranged centrally in the housing and deflecting light all around it to a concave reflector, which reflects the incident light rays to the light outlets opening and concentrates them as uniformly as possible onto a main light field arranged at a distance from the light outlet.
Abstract: The invention relates to an operating theater lamp comprising a housing having a light outlet opening at the bottom with a light source being arranged centrally in the housing and deflecting light all around it to a concave reflector, preferably a ring-like concave reflector arranged in the housing, which reflects the incident light rays to the light outlet opening and concentrates them as uniformly as possible onto a main light field arranged at a distance from the light outlet opening. The invention hereby provides that the concave reflector, and/or at least one auxiliary concave reflector arranged in its vicinity and in particular concentric to it, is or are so designed and/or arranged that a part of the light rays transmitted from the light source is reflected into an outer light field extending around the main light field and preferably adjoining the latter, in such a way that a brightly illuminated main light field and a stepped-down, less brightly illuminated outer light field is present.
10 Dec 1997
TL;DR: In this paper, a sine light field is applied in the projected light stripe, meanwhile phase shifting technique is used to calculate phases of the light slit, thereafter wrapped phase distribution of the slit is formed and the unwrapping process is made by means of the height information based on the light sectioning method.
Abstract: A new method of 360 degree turning 3D shape measurement in which light sectioning and phase shifting techniques are both used is presented in this paper. A sine light field is applied in the projected light stripe, meanwhile phase shifting technique is used to calculate phases of the light slit. Thereafter wrapped phase distribution of the slit is formed and the unwrapping process is made by means of the height information based on the light sectioning method. Therefore phase measuring results with better precision can be obtained. At last the target 3D shape data can be produced according to geometric relationships between phases and the object heights. The principles of this method are discussed in detail and experimental results are shown in this paper.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this article, the s-parametrized characteristic function for the output light of a linear amplifier is investigated, where the input light field of the linear amplifier was assumed to be a squeezed displaced Fock state.
Abstract: The s-parametrized characteristic function for the output light is given. The s-ordered distribution functions for the output of a linear amplifier are investigated. The input light field of the linear amplifier is assumed to be a squeezed displaced Fock state. Various moments are calculated by using the s-ordered characteristic function for the output linear amplifier. The various distribution functions of the output fields are plotted as functions of the interaction time. The phase distribution for the output light is discussed.
06 Feb 1997
TL;DR: In this article, a slow scan camera equipped with a cooled area array CCD allows simultaneous recording of all nine spectra in the range from 400 nm to 850 nm, and the glass fibers are distributed into two groups.
Abstract: Sequential measurements of the light field above and under water are affected by changes in the ambient light field. For correlated measurements, a new instrument is being developed, based on an imaging spectrometer with a "flat field" grating. Nine optical fibers connected to different light collectors are attached to the entrance slit. A slow scan camera equipped with a cooled area array CCD allows the simultaneous recording of all nine spectra in the range from 400 nm to 850 nm. The glass fibers are distributed into two groups. Two fibers are relayed to a unit measuring the downwelling vector irradiance and upwelling radiance above the water to determine the remote sensing reflectance and to detect light level changes. The remaining seven fibers are connected to a submersible unit measuring the light field parameters necessary to compute the in situ absorption spectrum of the water column, the change of mean cosine with depth, the Q-factor and other important apparent optical properties.