222 results about "Fresnel zone" patented technology

A micro-miniature x-ray apparatus comprises: a first chip subassembly including a source of x-rays including both Bremsstrahlung photons and characteristic x-rays; a second chip subassembly including a filter for transmitting the characteristic x-rays and blocking the Bremsstrahlung photons; a third chip subassembly including a movable element for focusing or collimating the transmitted characteristic x-rays into a beam and means for controlling the position of the focusing element. In one embodiment, the controlling means include a micro-electromechanical system (MEMS). In another embodiment, the position of the movable element determines how the x-ray beam is steered to the focal area. In still another embodiment, the x-ray source includes a field emitter electron source and a target responsive to the electrons for generating x-rays. In this case, the x-ray beam is also steered by selectively energizing the anode segments. In yet another embodiment, the movable element includes a Fresnel zone plate; in still another embodiment it includes an array of poly-capillaries. Advantageously, our x-ray source, including its focusing, collimating and steering components, can be fabricated small enough to be mounted at the end of a catheter. In addition, in some embodiments it can also fabricated sufficiently inexpensively to be disposable after each use.

An extreme ultraviolet (EUV) AIM tool for both the EUV actinic lithography and high-resolution imaging or inspection is described. This tool can be extended to lithography nodes beyond the 32 nanometer (nm) node covering other short wavelength radiation such as soft X-rays. The metrology tool is preferably based on an imaging optic referred to as an Achromatic Fresnel Optic (AFO). The AFO is a transmissive optic that includes a diffractive Fresnel zone plate lens component and a dispersion-correcting refractive lens component. It retains all of the imaging properties of a Fresnel zone plate lens, including a demonstrated resolution capability of better than 25 nanometers and freedom from image distortion. It overcomes the chromatic aberration of the Fresnel zone plate lens and has a larger usable spectral bandwidth. These optical properties and optical system designs enable the development of the AFO-based AIM tool with improved performance that has advantages compared with an AIM tool based on multilayer reflective mirror optics in both performance and cost.

A mask blank inspection tool includes an AFO having a diffractive lens and a refractive lens formed on a common substrate. The diffractive lens is a Fresnel zone plate and the refractive lens is a refractive Fresnel lens. The AFO is used to image light from a defect particle on a multilayer mask blank or the surface of the multilayer mask blank to a detector.

A lithography apparatus having achromatic Fresnel objective (AFO) that combines a Fresnel zone plate and a refractive Fresnel lens. The zone plate provides high resolution for imaging and focusing, while the refractive lens takes advantage of the refraction index change properties of appropriate elements near absorption edges to recombine the electromagnetic radiation of different energies dispersed by the zone plate. This compound lens effectively solves the high chromatic aberration problem of zone plates. The lithography apparatus allows the use of short wavelength radiation in the 1-15 nm spectral range to print high resolution features as small as 20 nm.

A method for assessing data coverage in a three dimensional marine seismic survey includes determining at least one Fresnel zone for at least one of a plurality of seismic data traces. A contribution is determined for each of the seismic data traces to each one of a set of bins in a defined pattern. Each contribution is based on the Fresnel zone associated with each seismic data trace. The contributions from all seismic data traces contributing to each bin are summed. The summed contribution for each bin are stored or displayed and the summed contributions in each bin are compared to a selected threshold to determine coverage.

The invention relates to a spectral-domain optical coherence tomography imaging system based on a Fresnel spectrometer, which is characterized by comprising a Michelson interferometer, the Fresnel spectrometer and a Fourier transformation module. The Michelson interferometer sends coherent light which is formed by superposing sample light returned from various layers of a sample with reference light into the Fresnel spectrometer, the coherent light is emitted onto a Fresnel zone plate parallelly through a collimating lens and an expanded beam lens respectively, and is expanded at the same interval according to the wave number and then projected to a linear array CCDs (charge coupled devices) by the Fresnel zone plate, frequency spectrum data of the coherent light are read by the linear array CCDs and sent to the Fourier transformation module, and then recovered into information of spatial position of the sample by means of discrete Fourier transformation through the Fourier transformation module. The spectral-domain optical coherence tomography imaging system based on the Fresnel spectrometer can be applied to not only spectral-domain optical coherence tomography imaging but also spectral analysis having requirements for wavelength-wave number conversion and resampling for imaging or detecting and required to be expanded uniformly according to the wave number, and especially can be applied to the biomedical imaging process.

A multifocal intraocular lens is provided having two external refractive surfaces and a longitudinal axis, and a diffractive structure superimposed on one of the surfaces in the form of a Fresnel zone. To reduce eye traumatism during surgery, to shorten post-surgical time period, to increase visual acuity, and to ensure a constant quality image at any distance from an object, a multifocal intraocular lens is proposed in which at least one additional refractive surface is inserted between the two external refractive surfaces, wherein the at least one additional refractive surface divides the lens volume into zones made of materials having different refraction coefficients.

An optical waveguide for a see-through display system using Fresnel lenses is disclosed. This invention enables high efficiency of light utilization, wavelength independence, high resolution and very small form factor. This display system is suitable for head-up-display and wearable display.

The invention discloses a three-dimensional dip angle domain stationary phase pre-stack time migration method and system. The method comprises the steps that pre-stack seismic data are read, and a migration speed field and a stretching and removing parameter are determined; according to the migration speed field and the stretching and removing parameter, two dip angle channel sets corresponding to dip angles in the directions parallel to and perpendicular to a measuring line respectively are generated through a selected imaging line; based on the two dip angle channel sets on the selected imaging line, Fresnel zones in the two dip angle directions are picked up, and the Fresnel zones of all imaging points on a quasi imaging block are obtained through interpolation; through the obtained Fresnel zones of all the imaging points, three-dimensional stationary phase pre-stack time migration is carried out, and migration results corresponding to different migration distances are obtained; the migration results of three-dimensional stationary phase pre-stack time migration are collected, and a three-dimensional imaging data body is formed; the three-dimensional imaging data body is converted into a profile image of an underground reflection structure. According to the method and system, the problem that when a high dip angle structure exists, the signal to noise ratio of the migration image obtained through an existing migration imaging technology is low is effectively solved.

The invention relates to a scattered wave pre-stack imaging method for identifying small-fault throw breakpoints, which is applied to processing of seismic reflection information in seismic exploration and is of a seismic imaging method of a micro-small fault for identifying the underground geological structure. According to the method, scattered waves of the breakpoints of the fault are utilized for independent imaging of the breakpoints with the fault throw of less than 1/4 wavelength, which are difficult to identify by conventional reflected wave migration. According to the method, the existing seismic reflection information is utilized, and the independent imaging of the small breakpoints is realized by pressing the energy of transmitted waves in pre-stack migration calculation and utilizing the polarity inversion characteristic of the scattered waves of the breakpoints. Pre-stack time migration is taken as the basis, an angle gather is generated by migration of single-shot information, and a Fresnel zone corresponding to an inphase axis of reflected waves is excised so as to eliminate the transmitted waves. According to the method, the small fault and breakpoints of the underground structure can be indicated in a fine manner, migration and plugging of underground oil gas can be better known, and the method further has an important application value for exploration and development of oil gas resources. The ability to identify the underground deep fissures and fault of the seismic exploration method is significantly improved.

A volume Fresnel zone plate and a method of producing such a device using a femtosecond laser for direct writing of zone plates. A volume zone plate has a number of Fresnel zone plate layers designed to focus light coherently to a single spot. Embodiments include both low numerical aperture (NA) and high NA zone plates, and provide a significant increase in overall diffraction efficiency over a single Fresnel zone plate.

The invention discloses a Fresnel lens device, belonging to the technical field of optical devices. The device comprises a first transparent substrate, a second transparent substrate and a liquid crystal layer filled between the first and second transparent substrates, wherein the first transparent substrate is a Fresnel lens; grooves distributed at intervals according to a Fresnel zone are formed in the side, facing the liquid crystal layer, of the Fresnel lens; the second transparent substrate is used for controlling the states of liquid crystals in the liquid crystal layer to enable the refractive index of the polarized light entering the liquid crystals when passing through the liquid crystals to switch between the first refractive index of the liquid crystals and the second refractive index of the liquid crystals; the first refractive index is greater than the second refractive index; the refractive index of the Fresnel lens is equal to the first refractive index of the liquid crystals in the liquid crystal layer. The device has the beneficial effect that switching of the function of the Fresnel lens between condensation and transmission is achieved by controlling the states of the liquid crystals with the second transparent substrate.

The invention discloses a near-surface tomographic velocity analysis method. The near-surface tomographic velocity analysis method comprises the following steps: picking up travel time of first arrival by aiming at pre-stack data, and obtaining an initial model reflecting underground medium velocity distribution by pre-stack processing; performing a shortest path ray tracing method on the model to obtain simulated travel time; performing wave field simulation on the model by utilizing a frequency domain wave equation to obtain a sensitive kernel function reflecting disturbance of a medium to the travel time; establishing a corresponding inversion equation and solving to obtain a slowness updating amount. According to the tomographic velocity analysis based on the Fresnel zone, the problem that the solution of a large-scale sparse matrix is instable during the traditional temographic velocity analysis based on the ray theory is solved, and the seismic wave propagation rule is more truly portrayed; the near-surface tomographic velocity analysis method has the advantages that the physical geography significance is obvious, the stability is strong, the efficiency is high, and calculation results are more real and reliable.

A Fresnel lens-integrated optical fiber that can be easily aligned and manufactured in miniature, and a method of fabricating the same are provided. The Fresnel lens-integrated optical fiber includes a light transmission section transmitting incident light, a light expansion section coupled to the light transmission section and expanding light provided from the light transmission section, and a Fresnel lens surface formed on a section of the light expansion section and focusing by passing through the light expanded in the light expansion section at a predetermined focal length. Accordingly, since the Fresnel lens surface has no curvature, arrangement of an optical coupling system is easy, manufacture is easy, and the optical coupling system can be miniaturized.

A method for fabrication of diffractive optics by batch processing is disclosed, having applicability to high resolution ultra-high aspect ratio Fresnel Zone Plates for focusing of X-rays or gamma-rays having energies up to hundreds of keV. An array of precursor forms is etched into a planar substrate. Sidewalls of the forms are smoothed to a required surface roughness. A sequence of alternating layers of different complex refractive index, for binary or higher order diffractive optics, are deposited on the precursor forms by atomic layer deposition (ALD), to provide diffractive line patterns. Thinnest layers may have nanometer thicknesses. After front surface planarization and thinning of the substrate to expose first and second surfaces of the diffractive line patterns of the diffractive optic, the height h in the propagation direction provides a designed absorption difference and/or phase shift difference between adjacent diffractive lines. Optionally, post-processing enhances mechanical, thermal, electrical and optical properties.

The invention discloses a high-resolution optical scanning holographic slice imaging method based on variable pupils, belongs to the field of optical scanning and mainly solves problems of large out-of-focus noises existing when images of any two-dimensional slice are reconstructed in the prior art. According to the method, a two-dimensional scanning mirror is used for controlling deflection of a first Fresnel zone plate so as to achieve primary two-dimensional scanning of an object to be detected to obtain a first matrix equation; after a second pupil is deflected, the two-dimensional scanning mirror controls deflection of a second Fresnel zone plate so as to achieve secondary two-dimensional scanning of the object to be detected to obtain a second matrix equation; and the two matrix equations are combined, and a conjugate gradient algorithm is introduced to achieve slice imaging. According to the high-resolution optical scanning holographic slice imaging method based on the variable pupils, by means of the technical scheme, high-accuracy slice imaging is achieved, the out-of-focus noises are greatly reduced, and the method is applicable to each optical field for acquiring slice imaging.

The invention discloses a method for realizing varifocal lens based on a liquid crystal space optical modulator. The method comprises the following steps: according to the phase modulating principle of the liquid crystal space optical modulator, controlling the liquid crystal space optical modulator to modulate an incident light wave to generate a kinoform, diffracting the incident light wave into a converging spherical wave, and changing radius and zone number of a Fresnel zone plate in the kinoform to realize the variable focus of a program-control varifocus imaging system established by the liquid crystal space optical modulator. The method provided by the invention can be used for improving the automatic varifocus precision and the varifocus response speed of the varifocus imaging system, so that the focal distance of the lens is variable and easy to control.