摘要:
The system permits the multiplex telecommunication through the medium of an optical carrier wave. The system comprises a source of coherent light whose optical spectrum is dispersed in an optical device comprising a pair of diffraction gratings. A plurality of light modulators are disposed in the path of the spread out beams and controlled by electric signals which carry items of information. Output optical means collect the modulated spectral components.
摘要:
A piezoelectric substrate is subjected to the continuous excitations produced by a high-frequency electric field of fixed radian frequency .alpha. applied between its two opposite faces; high-frequency electrical pulses of radian frequency .alpha..sub.p are applied to the periodic network of conductors illuminated by the image; the electrical conductivity at the surface of the substrate at each point is made a function of the illumination directed towards said point, for example by the application of a photoconducting semi-conductor covering the network or by a substrate whose conductivity is directly modulated by the incident light. The non-linear interaction between the two substrate excitations induces a surface wave whose intensity is modulated by the luminous intensity and which is picked up by the transducers. Application with fixed .alpha..sub.p, to the point by point read-out of a linear optical image and with .alpha..sub.p = .alpha..sub.p (t) to the analysis of its spatial frequencies.
摘要:
A system is provided for reading acoustic images such as those obtainable in an elastic medium as a result of the focusing of, or interference between, acoustic waves. The image analysing device comprises a substrate made of piezoelectric material which is provided on one face with an interdigital array and an electro-acoustic transducer.The system permits to read acoustic images formed at the free surface on the opposite face of the substrate or at a certain distance from its free surface in contact with an elastic propagation medium.
摘要:
The invention relates to a device for compensating the temporary scattering applied to the generation of ultra-short light pulses, said device including two identical and parallel optical diffraction gratings RA, RB and two identical prisms PA, PB that are placed inside the above-mentioned optical diffraction gratings RA, RB, given that the above-mentioned optical diffraction gratings RA, RB are volume phase gratings that function, during transmission, on the principle of Bragg diffraction. The outer surfaces FeA, FeB of the above-mentioned prisms PA, PB are parallel to the above-mentioned optical diffraction gratings RA, RB, and the inner surfaces FiA, FiB of the above-mentioned prisms PA, PB are parallel therebetween.
摘要:
Device for adaptation of a programmable generator of ultra short wide spectral band light pulses, to long narrow spectral band light pulses comprising a laser source (1) of ultra-short wide spectral band pulses, a device (2) for dispersion of ultra-short pulses output from said laser source (1), a first non-linear optical mixer (4) to mix long modulated pulses output from said dispersion device (2) with long quasi-monochromatic signals output from a pure frequency pump laser (3), a generator (5) of wide spectral band light pulses placed on a first channel (V1), a second non-linear optical mixer (6) to mix the channel output from said generator (5) and a second channel (V2) emerging from said first non-linear optical mixer (4).
摘要:
An optical architecture enabling the intercorrelation of two instantaneous wideband temporal signals. The beam coming from a monomode laser is used to obtain two carriers (W1, W2) for signals R(t) and S(t) by the use of, for example, integrated optical modulators (mod1, mod2). These two carriers have orthogonal polarizations and are distributed in a 2D structure comprising spatial light modulators as well as polarization separator elements. P.times.P independent channels (Cl to Cn) are thus formed. Their detection on a matrix of photodetectors (modl to modn) makes it possible to obtain, on each of them, the intercorrelation signal for different delays of the signals R(t) and S(t).
摘要翻译:一种支持两个瞬时宽带时间信号相互关联的光学架构。 使用来自单模激光器的光束通过使用例如集成光调制器(mod1,mod2)来获得用于信号R(t)和S(t)的两个载波(W1,W2)。 这两个载体具有正交偏振并且分布在包括空间光调制器以及偏振分离器元件的2D结构中。 因此形成P * P独立通道(Cl至Cn)。 它们对光电探测器矩阵(mod1 to modn)的检测使得可以在每个光电探测器中获得信号R(t)和S(t)的不同延迟的互相关信号。
摘要:
A bidimensional imaging system by echoes including a transmitting array and a receiving array. The transmitting array includes a row of transmitters (E.sub.1, E.sub.2, . . . , E.sub.i, E.sub.N) parallel to a direction Oz and the receiving array includes a row of receivers in a direction Ox. All the transmitters simultaneously transmit signals with different codes. The signals received are demodulated and the real and imaginary components of these signals are applied to two multiplexing circuits (61.1, 61.2). After modulation the multiplexed signals are applied to a Fourier transformation circuit (63), which sequentially supplies reception channels V.sub.k (.theta..sub.k) for the direction referenced by angle .theta..sub.k and which are stored in memories (66.1, 66.2). Other memories (70.1, 70.2) contain signals S.sub.i (.phi..sub.i) transmitted in an angular direction referenced by .phi..sub.i. The two pairs of memories (66.1, 66.2 and 70.1, 70.2) are connected and the signals are applied after modulation to a convolver (61), which supplies signals of the bidimensional image. The imaging system has application to ultrasonic submarine cameras, submarine target classifiers, medical acoustic imaging and non-destructive tests.
摘要:
A device for linearly extending the duration of laser light pulses by subjecting the pulses to double diffraction based on a series of variable step gratings placed at right angles to each other. Increased power density is obtained by placing a compression grating at an angle such that each wavelength of light emerging from the compression grating travels an optical path of approximately the same distance, and focusing the emerging light with a lens. Increased amplification is obtained by placing a segmented laser amplifier, one segment aligned with each wavelength of light separated by the double diffraction of the series of variable step gratings and interposed between the series of variable step gratings and the compression grating.
摘要:
The invention relates to a programmable transverse filter required for the matched filtering of signals with very wide passband. The signals to be filtered modulate one or more optical carriers (F1) in a modulator (MOD). Each carrier is distributed over several channels by a distributor (DIV). A delay creation circuit (CR1 to CRn) is provided in each channel. These channels are next summed after having been correctly delayed and assigned a coefficient characteristic of the signal to be detected.
摘要:
A system realizing various processings of signals, depending on the nature, duration and form of these signals, by means of non-linear interactions between elastic surface waves or between elastic and electromagnetic waves. The system realizes the memorization of the correlation function between a first signal, which is an elastic surface wave, and a second signal which is either an electromagnetic or an elastic surface wave; the reading may be realized with an electromagnetic wave or an elastic surface wave whose angular frequency equals or not that which corresponds to the spatial period of the memorized signal, thus generating correlation or convolution functions.