Showing papers on "Light field published in 1987"
TL;DR: The coherent interaction of femtosecond laser pulses and thin CdSe and GaAs samples is investigated experimentally and theoretically and oscillatory structures around the exciton resonance and around the pump frequency are observed.
Abstract: The coherent interaction of femtosecond laser pulses and thin CdSe and GaAs samples is investigated experimentally and theoretically Oscillatory structures in the differential probe transmission around the exciton resonance and around the pump frequency are observed when the probe pulse precedes the pump Comparison with theory attributes the oscillations to the coherent coupling between the light field and the electron-hole transitions in the semiconductor For nonresonant excitation, the oscillatory structures around the exciton are identified as the early stages of the optical Stark effect
146 citations
TL;DR: In this article, the theory of the intensity correlations between photons of different frequencies is re-examined from basic principles and is found to lead to an expression for the correlation function containing operator products which are normally ordered in time.
Abstract: The theory of the intensity correlations between photons of different frequencies is re-examined from basic principles and is found to lead to an expression for the correlation function containing operator products which are normally ordered in time. This expression leads to results which are free of certain extra contributions that arise in another version of this theory which contains non-normally ordered products. The analysis presented is based on a description of the frequency-filtering process in terms of Fabry-Perot interferometers. The mirrors of the interferometers are modelled as classical dielectrics. The EM field in the presence of these dielectrics is then quantised and the intensity correlation function defined in terms of these modified field operators. The results are examined in detail for the case of a light field radiated by a two-level atom.
26 citations
TL;DR: In this paper, the authors reviewed the development and applications of a new method of recording optical spectra that preserves full information on both the amplitude and phase relationships between the spectral components of the light field being recorded, and which thus realizes holographic spectroscopy.
Abstract: Studies are reviewed on the development and applications of a new method of recording optical spectra that preserves full information on both the amplitude and phase relationships between the spectral components of the light field being recorded, and which thus realizes "holographic spectroscopy." The method has been realized in practice in various polarization modifications of Coherent Active (anti-Stokes) Raman Spectroscopy (CARS). By using it, the problem has been solved in principle of resolving close, overlapping spectral lines not amenable to discrimination by the Rayleigh criterion in noncoherent spectra. In polarization CARS the experimenter can carry out a controlled action on the form and amplitude of an optical resonance being recorded ("multidimensionality" of spectra). However, this is not accompanied by an actual distortion of the spectrum or action from the probe field on the object of study. The principles of holographic spectroscopy have been realized experimentally, and by using them new information has been obtained on the internal structure of broad superposed Raman and light-absorption lines.
16 citations
TL;DR: In this paper, the authors present a picture of current activity in time-resolved spectroscopy with sub-picosecond resolution, in the study of hyper-Raman and other higher order effects with CARS, in extension of resonant Raman excitation in the UV region of spectrum, and in the development of Raman laser sources.
Abstract: To round out a quarter century of SRS the timing of this writing (1986) requires a look ahead of only one year into the future. The proceedings of the 10th International Conference on Raman Spectroscopy present a picture of current activity. Further progress will be made in time-resolved spectroscopy with subpicosecond resolution, in the study of hyper-Raman and other higher order effects with CARS, in extension of resonant Raman excitation in the UV region of spectrum, and in the development of Raman laser sources. During past few years extensive theoretical investigations have been made for four-wave light mixing in the case of one or more very strong light beams. The perturbation approach for those fields ceases to be valid. If only one light field is strong, the usual approach is to make a transformation to a rotating coordinate system so that the strong Hamiltonian for this light field becomes time-independent. Very recently these techniques have been extended to the case of two or more strong fields. CARS-type experiments with strong beams are likely to receive more attention. Extrapolation of the current activities instills confidence in the vitality of stimulated Raman scattering for the foreseeable future.
15 citations
TL;DR: In this paper, it was shown that bees on a horizontal comb can orient their dances by a field of polarized light in the zenith even when the degree of polarization of this light field is modulated from 0 to 100%, at frequencies between 0.05 and 25 Hz, with the direction of polarization and the intensity kept constant.
Abstract: Bees on a horizontal comb can orient their dances by a field of polarized light in the zenith even when the degree of polarization of this light field is modulated from 0 to 100%, at frequencies between 0.05 and 25 Hz, with the direction of polarization and the intensity kept constant. The result suggests that bees use a process of polarized light evaluation which probes simultaneously with three or more differently oriented analyser channels. It would follow that, in this experimental situation, time is not a component of sampling.
13 citations
TL;DR: In this article, the free propagation properties of the light field diffracted by an aperture were investigated by employing a formalism based on the orthogonal and complete set of Walsh functions, which can be used to explain the spatial filtering properties of many optical devices.
Abstract: The free-propagation properties of the light field diffracted by an aperture, have been investigated by employing a formalism based on the orthogonal and complete set of Walsh functions We found an interesting link with the well-known self-imaging phenomenon, which can be used to explain the spatial filtering properties of many optical devices An experimental result is given in order to illustrate this approach
12 citations
TL;DR: In this paper, the interaction of light with a polyatomic system is treated as a photon-scattering process in terms of time-correlation functions of transition operators, which are written as products of factors referring only to the molecule or the light field.
Abstract: The interaction of light with a polyatomic system is treated as a photon-scattering process in terms of time-correlation functions of transition operators. These are written as products of factors referring only to the molecule or the light field, so that the statistical properties of the polyatomic system and the light source can be easily incorporated. This procedure is developed for resonance absorption-emission and scattering of both thermal and coherent light.
7 citations
Patent•
28 Apr 1987
TL;DR: In this paper, a convex cylindrical lens is arranged vertically to an optical axis so that the dispersed light out of the projected light are converted into parallel light and the curvature of the lens is continuously changed so that its focus is fitted to the whole waveguide formed on the device.
Abstract: PURPOSE: To convert projected light from a waveguide type nonlinear optical device into parallel light by using a convex cylindrical lens continuously changing its curvature. CONSTITUTION: Light radiated from a light source 100 is made incident upon the waveguide type nonlinear optical device 101. The device 101 generates and projects higher harmonic of the light radiated from the light source 100, one of the projected light 103 is converted into parallel light and the other is projected as dispersed light. A light emitting point of secondary higher harmonic radiated from the incident end of the waveguide is different from that of secondary higher harmonic radiated from its projection end. A convex cylindrical lens 103 is arranged vertically to an optical axis so that the dispersed light out of the projected light are converted into parallel light. The curvature of the lens 102 is changed in accordance with the incident position of light and continuously changed so that its focus is fitted to the whole waveguide formed on the device 101. Consequently, the projected light from the device 101 can be converted into parallel light. COPYRIGHT: (C)1988,JPO&Japio
5 citations
TL;DR: In this article, it was shown that non-stationary interaction of the molecules with the light field cannot explain the inversion effect, since the transit time of molecules through the light fields was short compared to the radiative lifetime.
Abstract: Previously [1] we reported, that the inversion effect observed on NO2 cannot be explained conventionally. However, it was suggested by several scientists that nonstationary interaction of the molecules with the light field may provide a conventional explanation of this effect, because the transit time of the molecules through the light field was short compared to the radiative lifetime. In the present paper we report on investigations of the inversion effect versus the transit time. We show that nonstationary interaction of the molecules with the light field cannot explain the inversion effect.
5 citations
TL;DR: In this paper, the authors construct a mathematical model describing the structure of a light field emerging from a layer of identical particles of arbitrary shape that takes into account both coherent and incoherent scattering of the incident laser radiation.
Abstract: The authors construct a mathematical model describing the structure of a light field emerging from a layer of identical particles of arbitrary shape that takes into account both coherent and incoherent scattering of the incident laser radiation. The radiation is considered monochromatic and the layer is extrapolated to represent a reflecting film. Scattering amplitudes and distribution functions are computed.
3 citations
Patent•
08 Jul 1987
TL;DR: In this article, a surface is subjected to a light field whose intensity is periodically modulated in vertical direction to evaluate the scattered light pattern, which is obtained from interference between a first beam with vertical incidence and two symmetrical lateral beams (2a, 2c) with oblique incidence.
Abstract: A surface (1) is subjected to a light field whose intensity is periodically modulated in vertical direction to evaluate the scattered light pattern. The light field is obtained from interference between a first beam (2b) with vertical incidence and two symmetrical lateral beams (2a, 2c) with oblique incidence. All beams are focussed to a common spot if the profile is obtained by scanning the surface or are superimposed as collimated beams if large area profiling is desired. The surface (1) is imaged onto a diaphragm (4) which selects appropriate locations of the surface for measurements by a photodetector (5) to record the synusoidal intensity variation that is obtained when the light field is periodically shifted in vertical direction by phase modulating the central beam - (2b) with respect to the lateral beams.
TL;DR: In this article, the authors present a picture of current activity in time-resolved spectroscopy with sub-picosecond resolution, in the study of hyper-Raman and other higher order effects with CARS, in extension of resonant Raman excitation in the UV region of spectrum, and in the development of Raman laser sources.
Abstract: To round out a quarter century of SRS the timing of this writing (1986) requires a look ahead of only one year into the future. The proceedings of the 10th International Conference on Raman Spectroscopy present a picture of current activity. Further progress will be made in time-resolved spectroscopy with subpicosecond resolution, in the study of hyper-Raman and other higher order effects with CARS, in extension of resonant Raman excitation in the UV region of spectrum, and in the development of Raman laser sources. During past few years extensive theoretical investigations have been made for four-wave light mixing in the case of one or more very strong light beams. The perturbation approach for those fields ceases to be valid. If only one light field is strong, the usual approach is to make a transformation to a rotating coordinate system so that the strong Hamiltonian for this light field becomes time-independent. Very recently these techniques have been extended to the case of two or more strong fields. CARS-type experiments with strong beams are likely to receive more attention. Extrapolation of the current activities instills confidence in the vitality of stimulated Raman scattering for the foreseeable future.
Patent•
06 Feb 1987
TL;DR: In this paper, a light field illumination source is turned on by an instruction outputted from an operation control circuit 14 to execute the light fields illumination of a prescribed area on a circuit substrate 1 through a half mirror 6 and the illumination area is picked up by the camera 5 and the obtained image information is stored in the 2nd image memory 10b through the circuit 9.
Abstract: PURPOSE:To recognize precisely an objective substance by executing light field illumination and dark field illumination individually to the same area of an object to be detected to pickup the area and finding out the difference between two image information obtained by said image pickup on the same coordinate system. CONSTITUTION:A light field illumination source 7 is turned on by an instruction outputted from an operation control circuit 14 to execute the light field illumination of a prescribed area on a circuit substrate 1 through a half mirror 6 and the illuminated area is picked up by an image pickup camera 5. The image information obtained by said image pickup is recorded in the 1st image memory 10a through an A/D converter 9. Then, the light source is switched by an instruction outputted from an operation control circuit 13 and a dark field illuminating light source 8 is turned on to execute the dark field illumination of the same area on the substrate 1. The illumination area is picked up by the camera 5 and the obtained image information is stored in the 2nd image memory 10b through the circuit 9. When the difference between the image information stored in the memories 10a, 10b is found out by a subtractor 11 at every signal on the same coordinates, a specific density difference is generated at every substrate ground/wiring pattern and circuit parts.
01 Apr 1987
01 Jan 1987
TL;DR: In this paper, the authors measured the evolution of a longitudinal structure with time resolution τ c ≪ τ L, where τ c is the coherence time of the light field.
Abstract: Broadband (incoherent) light pulses can be characterized in the time domain by the pulse duration τ L and by the inverse of the spectral width i.e. the coherence time τ c . For standard pump-probe experiments the time resolution is governed by τ L . In a nonlinear experiment involving the autocorrelation of the light field, the ultimate time resolution is determined by the coherence time τ c . Subpicosecond time resolution has been demonstrated in the measurements of transverse relaxation time T 2 using nanosecond light pulses [1].We report on the measurement of the evolution of a longitudinal structure with time resolution τ c ≪ τ L .