Abstract: The efficiency of an acousto-optic modulator or deflector is increased by re-using the undiffracted beam, causing the same light beam to travel multiple times through the modulator. In order to maintain the bandwidth of the modulator, the multiple passes are made co-axial. A polarizing beam combiner and a waveplate are used to transmit the incoming beam but reflect the beam on the second pass. The gain in the efficiency of the modulator is particularly large for low efficiency modulators.

Abstract: An electronically tunable optical filter utilizing noncollinear acousto-optic interaction in an acoustically anisotropic, optically birefringent crystal. The directions of optical and acoustic waves are chosen so that the optical ray is collinear with the group velocity of the acoustic wave. The collinear beam configuration provides increased spectral resolution and reduced drive power.

Abstract: An improved, multicolored video imaging system to provide a video image on a projection surface, which system includes a red, blue and green pulsed laser as a light source to provide inlet beams, an acoustic-optical cell to receive the inlet beams, an electrical signal to a sound transducer on the cell to provide a sound-modulated outlet beam; a projection surface to display the multicolored image and a projection system to project the outlet beam onto the projection surface to display the video image. The system includes as an improvement a solid state actuator to move a distance in a 45.degree. direction to backtrack the line of image of the outlet beam and a ramp signal device to provide a ramp signal that is proportional in time to the pulse duration of the input beams when the pulse duration is longer than the pixel propagation time for a line of image to be displayed, thereby minimizing the blurring of the line of image displayed.

Abstract: A heterojunction acoustic charge transport device (HACT) having a charge transport channel 39 which is sandwiched between upper and lower charge confinement layers, 14,20, has the charge transport channel 39 made of a Strained Layer Superlattice (SLS) comprising alternating deep-well semiconductor layers 40, that provide a deep quantum well depth, and strain relief layers 42 that provide strain relief to prevent dislocations from occurring due to lattice mismatches between the InGaAs layers within the channel 39 and the charge confinement layers 14,20, thereby allowing the overall thickness of the channel 39 to be at least as wide as conventional HACT devices that use a GaAs channel. The strain relief layers 42 may be narrowly sized to allow tunneling of electrons across the entire channel 39 thereby allowing the charge to move as a single group, or alternatively, widely sized to provide separate isolated channels thereby allowing the charge to move in separate groups.

Abstract: In a reflective optical modulator light enters through an optical waveguide into a detunable optical resonator which couples it back into the optical waveguide, the modulation being effected by detuning the resonator. The resonator includes the end face of the optical waveguide through which the light enters and is coupled back, and a first reflective surface disposed opposite this face.

Abstract: An acousto-optic apparatus is described that varies the time delay of electrical signals over a continuum of delays. In the preferred embodiment, a light source, which can be either coherent or incoherent, emits an optical beam that is focused into an acousto-optic cell. An input electrical signal is used to drive the acousto-optic cell which, in turn, modulates the focused optical beam. Portions of the input optical beam are modulated and diffracted at angles proportional to the frequencies and phases contained in the input electrical signal. By appropriately choosing the cone of angles at which the light is focused into the acousto-optic cell, the diffracted optical beam can be made to overlap with portions of the undiffracted, unmodulated optical beam. All of the light exiting the acousto-optic cell is then collected onto a device for detection. Optical photomixing of the diffracted beam and the undiffracted beam is performed in order to derive the input electrical signal with a time delay.

Abstract: A compact, liquid crystal-based acousto-optical control system for large (>1000 elements) phase-based phased array antennas includes a laser source providing polarized laser beams processed in an in-line interferometric optical architecture that uses two acousto-optic deflectors (AODs) driven by a microwave signal that preferably has a frequency of one-half the desired radar carrier frequency. The AODs and associated polarization rotators generate a plurality of optical signal pairs, each pair having one positive and one negative first order doppler shifted light beam, the positive and negative doppler shifted beams being orthogonally linearly polarized. A phase delay is introduced in a predetermined one of the light beams in each optical signal pair via electrical control of an array of birefringent-mode nematic liquid crystal cells in a spatial light modulator (SLM), while the non-phase delayed light beam in each pair serves as a reference for interferometric detection.

Abstract: A compact, stable, and optically efficient two dimensional spatial light modulator-based electro-optical control system for large (>1000 elements) phase-based phased array antennas uses an acousto-optic modulator (AOM) driven by a microwave signal at the desired radar carrier. A phase delay is introduced via electrical control of an array of birefringent-mode nematic liquid crystal cells that selectively phase delays a polarized signal light beam, while a non-phase delayed doppler shifted polarized beam is used as a reference for microwave signal generation via interferometric detection through a photodiode. The optical design provides a very fast (in nsecs) wideband carrier hopping capability. An alternative embodiment of the invention uses a deformable mirror device (DMD) SLM to introduce the required phase shifts.

Abstract: A one-dimensional or two-dimensional transmission mode spatial light modulator (SLM) includes one or more heterojunction acoustic charge transport (HACT) channels 18 with surrounding layers 16,20 vertically adjacent to a multiple quantum well (MQW) region 14, grown above a thick semiconductor substrate 10 thick enough to allow a surface acoustic wave (SAW) to propagate and transparent to the incident light 40. The SAW is injected by a transducer 24, charge is carried to and from the HACT channel 18 by electrodes 32,34,36, and light 40 is applied to a surface 44 perpendicular to the MQW region 14. Each charge packet 19 in the HACT channel 18 invokes an electric field 52 within the MQW region 14 which determines the optical absorption and index-of-refraction thereof, thereby determining the intensity and/or phase of each output light beam 45. Light modulation is achieved by modulating the amount of charge injected.

Abstract: A one-dimensional or two-dimensional transmission mode spatial light modulator (SLM) includes two different mediums, one medium being a semiconductor comprising one or more heterojunction acoustic charge transport (HACT) channels 28 with surrounding layers 26, 30 vertically adjacent to a multiple quantum well (MQW) region 22, and the other being a transparent piezoelectric insulating substrate 10 thick enough to allow a surface acoustic wave (SAW) 13 to propagate therein. The SAW 13 is launched in the substrate 10 by a transducer 12 and generates electric fields which propagate the charge along the HACT channel 28 in the semiconductor medium 18. Electrodes 32, 34, 36 carry charge to and from the HACT channel 28, and light 40 is applied to a surface 44 perpendicular to the MQW region 22.

Abstract: A laser based accelerometer system uses small motion induced shifts in frequency to measure the motion of an object without contact thereof. This technique is particularly useful for determining the vibratory and velocity characteristics of objects that are otherwise inaccessible for direct motion measurement by contact sensors.

Abstract: A multi-channel/multi-layer optical gate contained within a fiber-optic housing having any number of optical cells disposed within the housing. The optical cells are made up of non-linear organic polymers surrounded by a piezoelectric crystal, which is in turn connected to a photovoltaic device. When the photovoltaic device is activated, the piezoelectric crystals cause the non-linear organic polymers to change their refractive index, causing an interruption of a reference laser beam. An output detector is disposed within the fiber-optic housing for detecting the reference laser beam.

Abstract: A process for a common deflection of at least two light beams having different wavelengths, wherein the deflection is carried out by means of an acousto-optical crystal, is characterized in that color-dependent beam dividers and deflection units are inserted in the beam path of the, at least two, light beams of different colors in such a way that deflection angles are compensated by properly adjusted longer beam paths, so that all beams coincide at a predetermined distance from the deflecting crystal.

Abstract: A method and apparatus (10) for sensing sound in a fluid medium. The apparatus (10) includes an element (12) for generating polarized light having a predetermined plane of polarization. In addition, the apparatus (10) further includes an element (14) for rotating the plane of polarized light in response to sound waves propagating in the fluid medium, as well as an element (32) for detecting the polarized light. Finally, the apparatus (10) includes an element (34) for generating a signal from the output of the detecting element (32) which is indicative of the amplitude and frequency of the sound waves.

Abstract: Disclosed herein is a method of mixing together a plurality of inputted high-frequency signals whose frequency intervals are equal to each other so as to input the thus-mixed high-frequency signals to a multi-frequency acousto-optic device for dividing incident laser beams with the density according to the amplitude of each of the inputted high-frequency signals and in the direction corresponding to the frequency of each inputted high-frequency signal so as to radiate the thus-divided laser beams therefrom. The high-frequency signals whose frequencies are free from being adjacent to each other are mixed together, and the thus-mixed high-frequency signals are further mixed into one, thereby inputting the mixture to the acousto-optic device. Since the frequencies of high-frequency signals to be mixed first are not adjacent from each other, third-order harmonic signals appear at positions where they are dispersed.

Abstract: This device comprises a photoelastic interaction medium between an incident light beam (28) and at least one acoustic or sound wave, as well as means (4, 6) for producing the acoustic or sound wave. The interaction medium is a superlattice (18), which is transparent to the light beam and whose period is close to an integral multiple of half the wavelength of the light beam in the superlattice.Application to the production of acousto-optical deflectors and modulators.

Abstract: A probe for in situ quantitative detection of the concentration of an analyte in a sample includes a hollow elongated body adapted for single ended contact with the sample. The body has at least one optical fiber extended through the body for transmitting modulated light through the body, out a window at the forward end of the body, and along an optical axis into the sample to optically excite the analyte. A pressure transducer mounted beyond the window and spaced laterally away from the optical axis detects an acoustic response of the analyte to the modulated light. This probe is particularly suitable for performing remote photoacoustic analysis of analyte concentration in a sample.

Abstract: An optical beam modulating device used for recording halftone plate duplicate images on a recording material including two multi-channel optical beam modulators, each including a rectangular parallelepiped modulator crystal which has a prescribed number of acoustic electrodes installed on one side surface. The electrodes are installed at equal pitch intervals so that Gauss beams can be directed across the electrodes separately from each other, and the positions at which the electrodes of one modulator are installed are shifted by one-half pitch with respect to the positions at which the acoustic electrodes of the other modulator are installed.

Abstract: An acousto-optical filter (AOTF) is used in a spectrometer for analysis of samples. The spectrometer provides continuous wave RF excitation through the crystal, and the spectrometer provides control and modulation for said RF source. The signal to noise ratio is improved by use of a lock-in amplifier which demodulates the modulation frequency. Fiber optics are used to connect the crystal to the source, and the source to the detection system. A digital lock-in amplifier is designed which increases the efficiency, accuracy, sensitivity and decreases the cost of conventional analog lock-in amplifier.

Abstract: The present invention is a laser system that includes an acousto-optic device (24B) having an optical medium (40B) that maintains a substantially uniform index of refraction even when subjected to nonuniform thermal or mechanical stress. The acousto-optic device provides substantially distortion-free polarized output light that can be directed accurately to strike an intended target.

Abstract: An acousto-optic correlator for wideband signals. The invention is defined by and relates to device in which a laser beam is split into two paths of a Mach-Zehnder interferometer arrangement. A first Bragg cell of which, modulated with a signal Re{S.sub.1 (t)exp(jw.sub.o t)}, receives the first beam that is reflected off a first flat mirror. A second Bragg cell of which, modulated with a signal Re{S.sub.2 (t)exp(jw.sub.o t)}, receives a beam that is reflected off a second flat mirror. The undiffracted light from both of the modulators is blocked. The diffracted light emitted from the first and second Bragg cells passes through first and second imaging lenses respectively. The two diffracted light beams are then combined with an angular separation between beams. The combined beam is incident upon a square-law detector array which is at the image plane of the imaging lenses. Due to the square-law detection process, terms of low frequency biases and complex correlation on a spatial carrier develop.

Abstract: A light beam scanning apparatus comprises an ultrasonic light deflector for diffracting a light beam of a predetermined wavelength, and a reflecting mirror position approximately normal to light deflected by the ultrasonic light deflector for reflecting the deflected light and making it again impinge upon the ultrasonic light deflector.

Abstract: An acousto-optical modulation device comprises a plurality of acousto-optic modulators arranged in series with each other, to receive a zero-order light from a previous stage of the modulators. A zero-order light emerging from the last stage is used as a modulated light of an incident light. The coefficient of extinction for the zero-order light is raised by this structure, and the acousto-optic modulation device presents a high diffraction efficiency and a high value of the coefficient of extinction at the same time.

Abstract: An acousto-optic modulator is described which comprises a first support layer and a second layer of piezoelectric semiconductor material disposed over the support layer. The second layer includes a plurality of active sublayers, each active sublayer having a planar surface and thickness dimension which is such as to enable the active layer to exhibit quantum-well effects. A surface acoustic wave structure is disposed on the second layer for creating an acoustic wave in the second layer. The acoustic wave induces electric field variations therein which are perpendicular to the planar surface of the active sublayers and alter an optical property thereof. An optical beam is directed through the second layer, which beam is modulated by the altered optical properties of the active sublayers.

Abstract: The invention comprises a laser light source for a raster laser display. The laser light source comprises a laser cavity, a lasing medium within the cavity, a lasing light source and a series of mirrors within the cavity arranged to reflect the beam of laser light repeatedly through the lasing medium. An acoustic modulator is included having an acoustic medium within the path of the beam within the cavity. Video information on each pixel of the display is converted to an RF signal and fed to a piezoelectric crystal which is coupled to the acoustic medium. The acoustic medium is arranged within the laser cavity with respect to the incident laser beam such that, in response to the acoustic information, the laser beam is either directed towards the screen, or when not needed for the display is directed towards one of the mirrors such that the beam can continue to propagate through the lasing medium.

Abstract: A light beam is introduced into an optical waveguide on a substrate of LiNbO.sub.3, and diffracted by a surface elastic wave generated by a tilted-finger chirped interdigital transducer on the optical waveguide. The direction in which the light beam is guided through the optical waveguide is substantially aligned with the z-axis of the LiNbO.sub.3 substrate. The light beam diffracted by the surface elastic wave and emitted out of the optical waveguide is applied to an optical member, such as a polarizing plate, a pinhole plate, or a light shield plate, which passes only a linear polarized component of the diffracted light beam.

Abstract: A simultaneous multi-beam optical modulator device which has first modulators for amplitude modulating a plurality of carrier waves according to a plurality of input signals to produce a plurality of modulated signals and an audio optical device for separating an incoming beam of light into a plurality of sub-beams and for, at the same time, optically modulating the sub-beam upon receiving the modulated signals from their respective first modulators, is provided, further comprising an output device for storing indicator signals corresponding to the number of input signals fed to the first modulators and for selecting from these stored signals a signal corresponding to the number of the input signals to the first modulators, a digital/analog converter for converting the signal transmitted from the output device into an analog output which is used to varies the intensity of output light, and a second modulator for amplitude modulating the plural modulated signals transmitted from the first modulators according

Abstract: There is provided by this invention an electro-optic modulator for damping acoustical energy produced by an electro-optic crystal. The modulator couples acoustic energy from the electro-optic crystal to an acoustic coupler due to the matching acoustic impedances of the coupler and the crystal. The coupler transmits the acoustic wave to the acoustic damper which dampens the acoustic energy. The coupler linearly decreases in height in a direction away from the crystal so that the acoustic wave is reflected through more than one damper prior to returning to the crystal, thus further decreasing acoustical energy. Another feature of this invention is the geometrical design of the electro-optic crystal which has two of its faces, which are not attached to a coupler, positioned not to be perpendicular with a face attached to a coupler.

Abstract: An electro-optic device, which processes by modulating, switching or gating, a light beam in response to an electrical signal utilizes an electro-optic crystal through which the beam to be processed passes. An electric field is generated by pulses which modulate the crystal's index of refraction and also causes piezoelectric ringing in the crystal. Acoustic energy absorbing material is coupled to the crystal for absorbing the piezoelectrically generated acoustic waves propagating perpendicularly to the applied electric field direction which has been found to be the dominant acoustic mode affecting the birefringence of the crystal and causing the ringing. The field is applied in short pulses (of the order of 10 nsec or less) thereby reducing lower frequencies in the acoustic energy spectrum thereby facilitating the absorption of the ringing energy.

Abstract: Nonlinear optical techniques are utilized to provide an adaptive notch filter for removing narrowband noise from broadband RF communication signals. The received RF signal is converted to a corresponding acoustic wave propagated in an acousto-optic cell. Two mutually coherent beams of light are passed through and diffracted by the acousto-optic cell. The diffracted beams are modulated by the acoustic wave, the second beam being modulated at a predetermined time delay with respect to the first beam. By proper selection of the time delay, the narrowband components of the two beams remain mutually coherent while the broadband components become mutually incoherent. The two diffracted beams are then mixed within a photorefractive crystal so that a first mixed beam comprises substantially all of the narrowband components while a second mixed beam consists essentially of only the broadband components.