Abstract: A method can include receiving seismic traces associated with a geologic environment; determining time domain stretch values for individual wavelets in at least a portion of the seismic traces with respect to a spatial dimension of the geologic environment; and estimating at least one Q-factor value for at least a portion of the geologic environment via a comparison of the time domain stretch values to a Q-factor model.

Abstract: A system for the reduction of a laser equivalent surface area and for the optical protection of an optical device including a first polarizer and a first multiple wavelength quarter-wave plate placed in series in the path of a multiple wavelength light beam between the polarizer and the optical device. This system brings into play polarized light, and associates a liquid crystal shutter with it, providing for protection against optical aggression. The entire unit may take the form of a detachable optical attachment.

Abstract: Optical information recording/reading medium including at least one transparent layer (2) for recording or reading information in various strata (S1 to S3) distributed through the thickness of the medium. The medium includes, recorded in a principal plane at least the transparent layer with one or more information items (5) for carrying out either tracking, focusing, synchronization or addressing or any combination. Also included in each stratum is one more guidance information items (4).

Abstract: The invention relates to an illumination device for illuminating a display device. In a preferred embodiment, non-polarized light from a non-polarized light source is polarized by a holographic polarization beam splitting device and focused onto a liquid crystal display device by a holographic focusing device. The invention is operable with monochrome and color display devices, and allows for a high light yield independent of the useful surface area of each detector element of the display device.

Abstract: Method, system and recording medium in which the writing of information is achieved by the use of a write beam including the superposition of a first optical beam at a first wavelength and of a second beam at a second wavelength less than the first wavelength. Reading is done by the use of a second optical beam at the second wavelength. The material of the recording medium is a non-linear material exhibiting a recording threshold situated between the maximum of the sum of the energies of the two beams and an energy level situated in the vicinity of the maximum energy of the first beam.

Abstract: Disclosed is a system for the recording of data on optic disks. Presently used optic disks, which can be read with lasers working in wavelengths of the visible region (between 0.5 and 0.8 microns), have a maximum surface storage density of the order of one data bit per elementary zone having an area of about one square micrometer. Beyond this limit, the diffraction does not allow the neighboring zones to be distinguished. A means is proposed to considerably increase the storage capacities: in an elementary zone of a layer, an information bit is written not in the form of a point of absorption of a laser light but in the form of a diffraction grating with a determined pitch. Several diffraction gratings, having pitches different from one another, may be superimposed at the same position, enabling the recording, in one and the same zone, of several information bits. The diffraction gratings are made by a periodic local variation of the optic index of the layer.

Abstract: Modulation mirrors including the deformable cells (CD1 to CDn) locally modified the planarity of a reflecting surface 18. The deformable cells deform under the effect of a voltage and the control of these deformable cells is such that a control voltage V.sub.c is applied between a first and a second electrode 17, 26. A photoconductor element P1 to Pn is inserted between the second electrode 26 and the deformable cell (CD1 to CDn). A light beam (MF1 to MFn) illuminates the photoconductor element in order to obtain an elongation of the deformable cell.

Abstract: The invention relates to an illumination device in which a holographic device (HP.sub.i) separates the polarizations of an incident beam. The resulting polarized beam is transmitted to a holographic device (HL.sub.i) focusing the beam at various points of a screen. This screen may be a liquid-crystal screen (LCD).Applications: Liquid-crystal display.

Abstract: A three-color image projector, of the type using several colored light beams with primary colors, with improved luminous efficiency. The projector employs spatial rather than temporal beam modulation. The projector includes a generator producing light in the three spectral bands corresponding to the primary colors (red, green, blue). The generator has at least two light sources (S1, S2), one of which produces multi-spectral band light, and the other is a monochromatic source. By comparison with the prior art, where the white light is produced by a single source, this arrangement avoids, in particular, the elimination of a significant quantity of lumens in the excess primary color.

Abstract: Power laser includes a non-linear medium (NL1) within which a first beam of fixed direction (I1) and a second beam of orientable direction interfere with each other, an amplifying medium (2) placed along the direction of the first beam for amplifying the received light for transmitting an amplified beam towards the non-linear medium (NL1), which retransmits this bean in the direction of the second beam, and therefore in an orientable direction.

Abstract: A laser is capable of working at a wavelength L.sub.2 from an active material capable of generating radiating emissions at at least two wavelengths L.sub.1 and L.sub.2, through the presence of a semiconductor plate in the laser cavity. Notably, the laser can generate wavelengths ranging from 1.4 .mu.m to 2 .mu.m, a range in which the optical damage threshold of the eye is high, from an Nd.sup.3+ doped YAG having numerous radiating emission wavelengths ranging from 0.946 .mu.m to 1.8 .mu.m.

Abstract: A laser includes a gas enclosure placed in an optical cavity and receiving a pump beam to generate at least one first-order and one second-order Stokes wave. One of the mirrors of the cavity is transparent to wavelengths which are higher than the first-order Stokes wave.

Abstract: A coherent light power source comprising an oscillator and an amplifying optical fiber, both optically excited by the same pumping source, the beam of wave length L.sub.S output by the oscillator being amplified in the optical fiber.

Abstract: A method for the optical writing of information elements uses a material (Ma) that is highly non-linear optically, on which it is possible to record information elements with sizes several times smaller than the writing wavelength. Also disclosed is a method for the reading of information elements recorded on a material (Ma) deposited on a material (Mb) capable of being the site of a stimulated emission generating the reading of the recorded information elements. Applications: high definition television, digital sound.

Abstract: A laser having a glass enclosure placed in an optical cavity receives a pump beam and generates at least one first-order and one second-order Stokes wave. The construction is such that an optical waveguide placed in the gas enclosure is used to select the first and the second-order Stokes wave.

Abstract: A system for the display of images comprising:a spatial modulator of light receiving a first light beam and retransmitting a modulated beam;an energy transfer device receiving the modulated beam and a second light beam and transferring the energy from the second light beam towards the modulated beam.

Abstract: Disclosed is an image projector in which a spatial modulation of light is carried out on the two orthogonal components of polarization of light in order to increase the luminous efficiency of the projector. The image projector of the invention includes a light source, a projection screen, a splitter of polarizations splitting the light into two polarized beams having complementary polarizations, two mirrors reflecting the two polarized beams, firstly so as to give them opposite directions and superimpose them on one and the same axis on which a spatial light modulator is positioned and, secondly, to make them pass again through the polarization splitter by which they are superimposed on one and the same axis with one and the same direction and oriented towards the projection screen and/or the light source as a function of their modulation by the spatial modulator.

Abstract: The invention relates to a solid laser with an emission wavelength lying between 0.5 and 0.65 .mu.m. A chromium-doped Mg.sub.2 SiO.sub.4 (forsterite) laser rod is pumped by a laser diode emitting between 0.75 and 0.8 .mu.m, this laser diode having an active layer which is Ga.sub.1-x Al.sub.x As based, with x lying between 0.1 and 0.18. The laser device finds particular application in the isotopic separation of uranium.

Abstract: Disclosed is a laser source with beam scanning, of the type comprising: a pump laser source emitting a pump beam with a determined wavelength; a pressurized gas cell receiving the pump beam and emitting, by Raman effect, an output beam with a wavelength called a Stokes wavelength; a control light source transmitting a control beam to the gas cell, this control beam having a wavelength that is substantially equal to the Stokes wavelength; wherein said light source includes means for the spatial and/or temperal modification of the injection of the control photons of the control beam into said cell constituted by a multiple-laser strip structure, forming a power slave laser and cooperating with means for modifying the radiation pattern of said multiple-laser strip structure, so as to prompt the emission of the output beam in a variable direction.

Abstract: A tunable laser source comprising a laser source emitting a pump beam towards a Raman cell. It transmits a beam at a Stokes wavelength to a non-linear crystal. Depending on the angle of this beam with the optical axis of the crystal, the non-linear crystal transmits two output waves at wavelengths that are different from the Stokes wavelength.