56 results about "Phase front" patented technology

A stepped reflector for being illuminated by at least one multiple-band feed is provided. The reflector includes a central region and a first annular region with an annular width of w. The first annular region is axially stepped a height h above the central region, where h is approximately equal to

where m is a positive odd integer, Φ is a desired amount of phase shift of an outer region of a phase front for reflecting off of the reflector, φ is a feed phase contribution for an angle Θ, and Θ₀ is an angle formed between an axis of the at least one feed and a line connecting a phase center of the at least one feed and an inner edge of the at least one annular region.

The central region and the annular region of the reflector may be parabolically curved or may alternately be shaped. The reflector may be fed by one or more multiple-band horn antennas.

The approximate radius of curvature of the spherical phase front at the aperture of a transmitting microwave antenna is controlled by an inner section of the aperture attached to the outer section of the aperture by a small number of programmable transducers, thereby controlling the near field shape and power distribution of the transmitted beam.

An apparatus and method for achieving a near diffraction-limited, high-average power output from a solid-state laser oscillator are provided. The solid-state laser uses multiple disk-shaped laser gain media having a large optical aperture placed in an unstable resonator. The laser gain media is provided with optical coatings for operation in the active mirror configuration and is attached to a rigid, cooled substrate, which allows it to maintain a prescribed shape even when experiencing significant thermal load. The resonator is configured so as to preferentially support low order optical modes with transverse dimensions sufficiently large to efficiently fill the gain media apertures. Resonator configurations capable of producing standing wave or traveling wave optical fields are disclosed. The resonator may include means for intracavity correction of an optical phase front by adaptive optics. Also disclosed is an arrangement of resonator gain elements in axisymmetric arrays suitable for integration into a compact and lightweight laser system.

Retrospective dynamic transmit beamformation is provided in medical ultrasound imaging. Using parallel receive beamformation, sets of data representing locations in at least a common field of view are obtained, each set in response to a transmit with a spatially distinct phase front. The common field of view receive data are time aligned and amplitude weighted for retrospective transmit focusing and retrospective transmit apodization, respectively. A time offset, such as of a cycle or more in some cases, is applied to the receive data for retrospective transmit focusing. The offset is selected to emulate shifting the transmit delay profile to be tangentially intersecting with the dynamic receive delay profile for each location which is the desired transmit delay profile. A weight is applied to the receive data for retrospective transmit apodization. The weight is selected based on the desired transmit apodization profile. The offset and weighted data representing a same location from different transmit events is coherently combined. The number of sets of data offset, weighted and combined may vary as a function of depth for dynamic transmit beamformation.

A cooling system for use in with a transmissive optical element of a high average power laser (HAP). The system includes at least one optically transmissive element (TOC) that is held by a differential pressure in thermal contact with a heat sink assembly. In one embodiment, the heat sink assembly includes an optically transparent heat conductor (THC) attached to at least one face of the TOC. A vacuum formed between adjacent faces of the TOC and THC urges the facing planar surfaces into thermal contact with one another. Waste heat generated in the TOC is conducted to the THC. The temperature gradient inside the TOC is maintained substantially parallel to the direction of a laser beam being directed through the THC so that a given phase front of the beam exposes TOC material to the same temperature. As a result, the TOC does not perturb the phase front of the laser beam.

A method of correcting for pulse reverberations in ultrasound imaging using two-dimensional transducer arrays, and uses such reduction in element signals and beam signal before estimation of corrections for phase front aberrations of the ultrasound wave. The pulse reverberation is estimated by two transmit events, where the second event is determined by measurement and processing on measurement on echoes of the first event. In a second embodiment of the invention, the reverberation is estimated by a single transmit event, using two receive beams and processing on these. In a third embodiment of the invention the reverberation from very strong scatterers is reduced by adjustment of the active transmit aperture.

A semiconductor gain medium has an optical cavity comprising a multimode region permitting propagation of light with a diverging phase front and a single mode region. An optical cavity is formed by optical feedback within the medium. Preferably, the feedback comprises a combination of a cleaved facet and a grating. The gain medium may be an amplifier or, in addition to the amplifier, may include a resonator cavity, or operate as an unstable resonator.

A method and a nonlinear frequency mixer employing the method to generate at least one output light from at least one input light with the aid of a quasi-phase-matching (QPM) grating for quasi-phase-matching the input and output light involved in a nonlinear frequency mixing operation such as three-wave mixing, four-wave mixing or other nonlinear operation mediated by a susceptibility of the nonlinear optical material. The QPM grating has a beam-modifying pattern with features for wave front shaping. More specifically, the features shape the wave fronts of the output light by diffraction or phase front shaping to thereby modify its propagation. This modification of propagation can be used to steer, focus, defocusing, split and/or collimate the output light. The features themselves can have various geometric shapes and sizes, even on the order of the wavelength of the output light, and they can include domains exhibiting a nonlinear optical susceptibility χ, such as the second-order susceptibility χ⁽²⁾, domain edges, and/or spacings between such domains.

An optical phased array including a wafer, optical waveguides, a root optical waveguide, the root optical waveguide being optically connected at one end to one optical waveguide, another end of the root optical waveguide constituting an optical port, optical couplers disposed in an array and located on the wafer, the optical waveguides optically connecting the optical couplers to the optical port via respective optical paths, one optical path per optical coupler, configurable optical delay lines; each configurable optical delay line being disposed in one respective optical path from the respective optical paths; the configurable optical delay lines being configured such that the optical couplers emit a non-planar phase front near field radiation pattern from light received from a light source coupled to the optical port.

A method for improving the mechanical dephosphorization of iron scale of a low-carbon cold heading steel wire rod belongs to the technical field of steel rolling. Processing steps and control technical parameters are as follows: finish rolling inlet temperature is controlled to be 920 DEG C-950 DEG C, and the finish rolling temperature rising range is controlled to be 80 DEG C-100 DEG C; the spinning temperature is controlled to be 880 DEG C-920 DEG C; the opening times and a heat holding cover of an air cooling line and the opening degree of a fan are regulated, the cooling rate of the phase front section of a spun steel wire rod is controlled to be 2-3 DEG C/s; the temperature of the spun steel wire rod is controlled to be 760 DEG C-740 DEG C when the spun steel wire rod enters the heat holding cover, and the heat holding cover is uncovered at the temperature being 620 DEG C-600 DEG C; and the temperature of the spun steel wire rod is controlled to be 580 DEG C-600 DEG C when the spun steel wire rod is discharged from the heat holding cover, the fan is additionally arranged when the spun steel wire rod is discharged from the heat holding cover, the cooling rate of the spun steel wire rod passing through a temperature zone being 5000 DEG C-400 DEG C rapidly is controlled to be 3-5 DEG C/s, and the passing time is controlled to be 15-25s. The method has the advantages that the phase structure conversion phenomenon in an FeO layer in the iron scale on surface of a hot rolling steel wire rod is reduced obviously, the mechanical dephosphorization is improved obviously, and the wire breaking rate and the loss of a die in the user pulling process are reduced.

The output modal content of optical fibers that contain more than one spatial mode may be analyzed and quantified by measuring interference between co-propagating modes in the optical fiber. By spatially resolving the interference, an image of the spatial beat pattern between two modes may be constructed, thereby providing information about the modes supported by the optical fiber. Measurements of the phase front exiting the optical fiber under test are advantageously performed in the far field.

A liquid crystal optical device is provided. The optical device includes a liquid crystal cell controlling optical properties of light passing therethrough and has a liquid crystal layer, a planar electrode located to one side of said liquid crystal layer, an electric field control structure located to the opposite side of the liquid crystal layer, and a wavefront adjustment structure configured to provide optical phase front adjustment. In some embodiments the wavefront adjustment structure is a conductive floating electrode. In other embodiments the wavefront adjustment structure is a weakly conductive structure having spatially variable sheet resistance. In other embodiments, the wavefront adjustment structure a weakly conductive structure having spatially variable sheet resistance having a frequency dependent characteristic.

The present invention provides a non-equal phase front correction method of a material complex permittivity quasi-optical cavity method wideband test. The sample wideband complex permittivity accuracy test can be realized. Gaussian beam electromagnetic field phase distribution in a quasi-optical cavity is analyzed, and an actual phase distribution function at the upper surface of a sample is obtained according to the upper surface of a sample to be tested, namely the matching relation of the air and a waist radius at a medium area interface. The perturbation theory is employed to solve the stored energy at the gap of the surface plane and the wavefront spherical surface so as to obtain frequency shift caused by phase mismatching of the sample surface and the wavefront. The non-equal phase surface at the upper surface of the sample is corrected through combination of a preset format; the influence of non-equal phase surface errors caused by thickness of the sample in the quasi-optical cavity method wideband test is corrected, the wideband test of the material complex permittivity through adoption of the quasi-optical cavity method can be effectively performed, and the precision of the multimode wideband test of the quasi-optical cavity method can be improved.

One embodiment relates to an optical displacement sensor for sensing relative movement between a data input device and a surface by determining displacement of optical features in a succession of frames. The sensor includes an illuminator and a detector. The illuminator has a light source and illumination optics to illuminate a portion of the surface with a planar phase-front. The detector has a plurality of photosensitive elements and imaging optics. The illuminator and the detector are configured such that the illuminated portion of the surface is less than fifty percent larger than a field of view of the photosensitive elements of the detector. Other embodiments are also described.