Showing papers in "Optics Communications in 1981"

TL;DR: In this article, the velocity distribution in a flow field is mapped on the photograph as variations in speckle contrast, which can be converted to intensity variations by means of a simple spatial filtering technique.

TL;DR: In this article, an additional phase shift is established between the photoinduced index modulation (phase volume hologram) and the incident fringe pattern, which is introduced by either moving the crystal or the interference fringes at a constant speed.

TL;DR: In this paper, it was shown that when the incident wave is uniform and the angular semi-aperture is small, the ratio of the point of maximum intensity to the distance between the geometrical focus and the plane of the aperture depends only on the Fresnel number N of the image when viewed from the focal point.

TL;DR: An analysis of the degenerate parametric amplifier including the quantisation of pump and signal modes is presented in this article, where it is shown that the fluctuations in one quadrature of the signal mode may be reduced at most by a factor of two.

TL;DR: In this paper, the number of independent parameters of the Mueller matrix of a collimator-radiometer system has been investigated in terms of 9 nonlinear (bilinear) equations.

TL;DR: In this paper, a general expression for the coherent artifact in photoinduced absorption measured by coherent polarized pump and probe beams is derived, and conditions for its reduction in isotropic media by using cross-polarized beams are discussed.

TL;DR: In this article, a simple sufficiency condition is obtained, under which the Debye diffraction integral may be expected to give a good approximation to the solution of a boundary value problem that is generally taken to represent a field in the region of focus.

TL;DR: In this paper, a statistical ensemble of monochromatic oscillations, all of the same frequency, was constructed to obtain rigorously the spectral and cross-spectral densities of a statistically stationary source and of the field that the source generates.

TL;DR: It is shown how certain algorithms for matrix-vector multiplication can be implemented using acoustooptic cells for multiplication and input data transfer and using CCD detector arrays for accumulation and output of the results.

TL;DR: In this paper, the theory of degenerate four wave mixing in saturable absorbers is verified and imaging capabilities are demonstrated. And the phase conjugation is performed in a thin film by a cw laser.

TL;DR: In this paper, a new expression for diffraction of a converging spherical wave by a circular aperture was derived based on the Debey approximation and the paraxial approximation, which depends not only on the angular aperture, but also on the distance from the aperture to the focal point.

TL;DR: In this article, a sampling theorem for functions whose Fresnel transform has finite support is established, and its possible applications to optics are outlined, as well as its possible application to optics.

TL;DR: In this article, a new group of complex color centers with F A -type properties, involving simple center production and high thermal and optical stabilities, has been found in six Tl + -doped alkali halides: NaCl, KCl, RbCl and RbI.

TL;DR: In this article, a homogeneous optical linewidth as small as 760 Hz (fwhm) was observed in Y 2 O 3 :Eu 3+ using delayed heterodyne photon echoes.

TL;DR: In this paper, the population inversion is generated by recombination in the expansion of a carbon fibre heated by a line focussed laser pulse, and the gain is identified by observations using two calibrated spectrographs from the ratio of intensities, and by spectral line modification.

TL;DR: In this paper, the mass abaltion rate depends on the incident laser irradiance as m = 4.4 × 10 5 (I/10 14 ) 0.53 g cm -2 s -1 ; the pressure near the ablation surface increases approximately linearly with irradiance and is about 70 Mbar at 1015 W/cm2.

TL;DR: Spectral Raman amplification characteristics have been measured directly for a tunable pumping source, taking the relative polarization states of pump and signal waves into consideration as mentioned in this paper, and it has been observed, even with an orthogonal polarization pump, in a long span single mode fiber.

TL;DR: In this paper, the authors describe a scheme for rapidly introducing a periodic linear time delay to a train of picosecond laser pulses by incorporating this scheme in one arm of the Michelson interferometer of a conventional autocorrelator.

TL;DR: In this article, a real-time cross correlation between two transparencies using photorefractive Bi12SiO20 crystals is presented, where a two-lens coherent optical processor is used to simultaneously record and read a dynamic phase-volume hologram.

TL;DR: In this paper, a glass laser was used to irradiate targets of various materials at ∼5 x 1014W/cm2 and the authors reported conversion efficiencies of between 1% and 0.1% for individual X-ray lines between 1.8 and 7.8 keV.

TL;DR: In this article, two-photon absorption was used to ionize H and D atoms in the ionization chamber of a quadrupole mass filter in a crossed atomic-laser beam configuration with sub-Doppler resolution of ∼ 10 GHz.

TL;DR: In this article, an efficient frequency doubling of stabilized singlemode cw rhodamine 6G dye laser radiation in a resonant passive ring cavity is discussed and first experimental results are presented.

TL;DR: In this article, the stability of folded Fabry-Perot resonators is investigated for the case where the resonator contains a medium with a dispersive third-order nonlinearity.

TL;DR: In this paper, the performance of ring dye DCM was characterized for four laser systems: 1) continuous wave, 2) synchronously pumped (SP), 3) cavity dumped synchrompously pumped and 4) single-frequency ring dye laser.

TL;DR: In this paper, a single axial mode output from an unstable resonator Nd: YAG oscillator was obtained by controlling the Q-switch following prespiking pulses.

TL;DR: In this article, the use of a phase filter to convert a gaussian laser beam into a beam with more uniform irradiance distribution is discussed, and the phase filter is calculated by employing an iterative procedure on a computer.

TL;DR: An expression for the general form of the cross-spectral density of a field that is spatially fully coherent, throughout some region of space, at some particular temporal frequency is derived in this article.

TL;DR: In this paper, a variational method is presented to obtain the transverse electric field and the propagation constant of the fundamental mode of weakly guiding graded-index fibers for single-mode operation.

TL;DR: In this article, the BSO crystal was found to be appropriate for real-time contour holography using two wavelengths, which can be a powerful tool for contactless measurements.

TL;DR: In this article, the laser characteristics of molecules with intramolecular triplet energy transfer were investigated and an efficiency increase of up to 500% was observed, where triplet-energy transfer was considered.