44 results about "Fraunhofer diffraction equation" patented technology

The invention discloses a measuring method of little opening displacement of microcrack, belonging to the technical fields of photo mechanics, structural member deformation, displacement measurement and the like. The invention adopts a measuring system mainly consisting of a laser device, a loading device, a test specimen with a microcrack, a light intensity receiving screen and a pattern collecting system. During measurement, laser sends out light with a wave length of lambda; a Fraunhofer diffraction fringe pattern is formed on the receiving screen by the microcrack; an initial light intensity pattern of the microcrack is obtained by the pattern collecting system; the loading device is used for slowly loading the test specimen to open the microcrack; the pattern collecting system is used for recording multiple slit diffraction light intensity patterns of the microcrack on the receiving screen under different loads; digital pattern analysis and relative operation are carried out according to a light intensity pattern so as to finally obtain the little opening displacement amount of the microcrack under different loads. The method has the characteristics of convenient use, high measurement precision and the like. The deformation amount measurement of the microcrack can reach 100 mu epsilon magnitude, and the displacement measurement sensitivity can reach wavelength magnitude.

In an exposure head of the invention, plural first micro-focusing elements are arranged in a first microlens array so as to correspond to plural micromirrors in a DMD. An aperture array that includes plural apertures arranged so as to respectively correspond to the plural first micro-focusing elements is disposed. The apertures allow only main portions of Fraunhofer diffraction images to be transmitted therethrough. The main portions of the Fraunhofer diffraction images transmitted through the apertures are imaged on an exposure plane by second micro-focusing elements of a second microlens array. According to the exposure head of the invention, cross-talk light and scattered light can be effectively reduced, and beam diameters of beam spots projected on the exposure plane through the apertures can be adjusted to a required size.

The invention discloses wavefront measurement method and device based on a multiple-pinhole plate. The wavefront measurement method comprises the following steps of: irradiating a measured object wave to the multiple-pinhole plate containing one reference pinhole and multiple measurement pinholes; recording an intensity distribution pattern of a Fraunhofer diffraction light field of the object wave transmitting the multiple-pinhole plate by an image sensor, wherein the Fraunhofer diffraction light field is in direct proportion to the Fourier transform of the object wave transmitting the multiple-pinhole plate; carrying out inverse Fourier transform on the recorded intensity distribution pattern, and extracting the function values of points which correspond to the center positions of the measurement pinholes of the multiple-pinhole plate in the inverse Fourier transform pattern, wherein the function values is in direct proportion to the complex amplitude values of the measured object wave on the measurement pinholes; and reproducing an imaged object in a computer by utilizing the complex amplitude values. The invention increases the diffraction imaging speed, has simple structure, convenient regulation and low cost, is suitable for multiple different light sources and can realize the real-time wavefront sensing and the diffraction imaging of a pure-phase object and a plural object or a three-dimensional object.

The invention discloses a coherent diffraction imaging method and processing device thereof. The object wave passes through a rotary multi-pinhole plate. The Fraunhofer diffraction intensity distribution pattern of the object wave passing through the multi-pinhole plate is recorded by an image sensor. The diffraction intensity distribution is subjected to inverse Fourier transformation to obtain the correlation function pattern of the recorded object wave, the amplitude and phase information of the object wave to be measured are directly extracted from the points corresponding with each measurement pinhole center position coordinate in the correlation function pattern and the diffraction imaging of the complex amplitude object is realized in the computer. The coherent diffraction imaging method has no need of any iterative process and greatly reduces the requirement of the scanning recording process and positioning accuracy and increases the diffraction imaging speed, with other features of simple processing device, convenient adjustment, lower cost, suitable of various different light source, and the imaging of the complex object or three-dimensional object can be realized without imaging lens, especially suitable for the situation that it is difficult to prepare high-quality X-ray using the imaging lens.

The invention relates to a strength related diffraction imaging device and the image recovery method thereof, mainly comprising: obtaining object Fourier transform strength information and iterative algorithm of recovering the object transmittance function according to the strength information. And the imaging device comprises a thermal light source, a beam splitter is arranged in the advancing direction of the beam emitted by the thermal light source, in the direction of transmitted beam of the beam splitter are a to-be-detected object and an object light path plane detector, in the direction of reflected beam of the beam splitter is a reference light path, a reference light path plane detector is arranged in the light path, the output ends of the two plane detectors are simultaneously connected with a computer executing data collection and processing, the thermal light source and the two plane detectors are simultaneously triggered and controlled synchronously by a synchronous signal generator. And the invention can implement diffraction imaging of incoherent sources, and can obtain the Fourier transform strength information of the object transmittance function in the Fraunhofer diffraction region on condition of no lens and recovers the amplitude and phase of the object.

The invention, which belongs to the field of intelligent monitoring, provides a blazed-grating-based quick small angle identification method. On the basis of spectral characteristics of a first-orderdiffraction spectrum sequence of a blazed grating, quick identification of a small angle is carried out. With a Y type fiber self-alignment system, identification of a rotation angle change, being angular displacement, of a blazed grating is realized. The method comprises the following steps: establishing a Y-type-fiber-based self-collimation optical path angular displacement identification system; on the basis of a Fraunhofer diffraction principle, obtaining light intensity distribution of corresponding blazed gratings under different wavelengths on different angular displacement conditions by using a numerical simulation method and determining a blazed grating diffraction spectrum characteristics and angular displacement relationship; and putting forward a two-blazed-grating-based differential angular displacement identificaiton principle and system and determining an angular displacement identification method based on differential double-blazed-grating diffraction spectrum cross-correlation spectral analysis. The method has a simple structure; identification is done rapidly; with the differential structure, the sensitivity is improved and the external interference is reduced.

The invention relates to a solid granular foreign matter detection device and method for an automatic light examining machine. The solid granular foreign matter detection device comprises a radiation source system, a forward receiving Fourier lens, a forward photodetector array and a signal processing system which are arranged in sequence, and the radiation source system comprises a laser transmitter, a collimating and beam expanding lens, a spatial filter and a backward sending Fourier lens which are arranged in sequence. A divergent laser beam is provided by the radiation source system and forms parallel monochromatic lasers after being subjected to collimation and beam expanding, and a clean liquid medium which contains solid fine granular foreign matter is put in a transparent container which is positioned in front of the forward receiving Fourier lens. Before the detection, the liquid medium and the solid granular foreign matter are uniformly mixed and rotated at high speed, and when the parallel monochromatic lasers irradiate the solid granular foreign matter, the Fraunhofer diffraction phenomenon occurs. Scattered light which is gathered by the photodetector array is converted to a voltage signal which contains information about the solid granular foreign matter, and the solid granular foreign matter is detected by the signal processing system according to the change of the voltage signal.

The invention discloses a fast measuring system and method for laser information. The fast measuring system for the laser information comprises an optical signal detecting and receiving device and a signal converting and processing system. The optical signal detecting and receiving device comprises an optical filter used for limiting the wavelength range of a received laser, a diaphragm used for limiting the incident angle of the laser, a Fraunhofer diffraction device composed of optical gratings and a cylindrical lens and a high-speed linear array CCD arranged on the focal plane of the lens. The signal converting and processing system is a high-speed signal processing system based on a DSP. The measuring system and the measuring method have the advantages of being high in first-grade diffraction fringe efficiency and light intensity, low in system noise and high in detection precision, is suitable for visible light as well as near-infrared light, far infrared light, ultraviolet light and the like, and can effectively improve early warning rate when being applied to laser emergency reporting.

Embodiments of this invention utilize Fraunhofer diffraction to detect, locate, and characterize buried objects, and, in particular, weapons caches and/or potentially dangerous explosive devices, are to be detected and characterized according to rough size, shape, and reflectivity with respect to the probe energy (ultrasound, microwave, milliwave, etc.). Size is obtained by measuring the spatial pattern and/or width of the Fraunhofer diffraction wave. Reflectivity is obtained by normalizing the reflected energy with respect to the energy reaching the target object and the size of the reflective area of the target object.

The invention discloses a parallel digital construction method of a three-dimensional image, wherein a plurality of branch visual angle digital images of a three-dimensional object can be acquired; the parallel digital construction method is characterized in that parallel processing is performed by using a computer cluster, and comprises the following steps of: performing regularity processing and color separation processing on the image; segmenting into sub-graphs according to a set size; arranging, by a main calculation node, each sub-graph according to a visual field sequence of the main calculation node; taking the sub-graphs at the same visual field position as a group of processing objects; performing parallel processing on a task node; performing inverse Fourier transform, central transformation processing and iterative Fourier transform on the image to obtain fraunhofer diffraction optical field distribution of the group of sub-graphs and return a result to the main calculation node; gathering the main calculation nodes to obtain a holograph H1; and representing the three-dimensional image by using interference light and spatial light modulator. According to the parallel digital construction method, phase information is successfully extracted by using a multi-process mechanism, so that the operation time of the algorithm is greatly shortened, the three-dimensional imaging efficiency is increased, and probability is provided for industrial printing of the three-dimensional image.

An improved hinge for a micro-mirror device composed of a conductive doped semiconductor and immune to plastic deformation at typical to extreme temperatures. The hinge is directly connected to the micro-mirror device and facilitates the manufacturing of an optically flat micro-mirror. This eliminates Fraunhofer diffraction due to recesses on the reflective surface of the micro-mirror. In addition, the hinge is hidden from incoming light thus improving contrast and fill-factor

The invention provides an asymmetric optical image encryption method based on cylindrical diffraction transformation and equivalent mode decomposition. The method can effectively resist attacks of aniteration recovery method. According to the method, a classical asymmetric optical encryption technology based on equivalent mode decomposition is simply improved; cylindrical diffraction is used forreplacing Fresnel diffraction or Fraunhofer diffraction, and a pure amplitude ciphertext and a pure phase private key are used for replacing two complex amplitude masks, so that the security of the encryption method can be greatly improved, and particularly, the attack of an iterative recovery method can be resisted.

The invention relates to the technical field of acoustic vortex field detectors, in particular to an acoustic vortex field detector based on a Fraunhofer diffraction principle. The acoustic vortex field detector is characterized by comprising a substrate, wherein the acoustic vortex field detector is of a planar structure, diffraction holes are formed in the substrate, topological charges of an incident acoustic vortex field are controlled by means of the sizes and positions of the diffraction holes, acoustic vortex waves carrying different topological charges pass through the diffraction holes based on the Fraunhofer diffraction principle to obtain an uniquely defined far field intensity distribution diagram on a far field observation screen, and the topological charges of the incident acoustic vortex field are obtained through detection according to the comparison between different light intensity diagrams obtained on the far-field observation screen and a theoretical calculation value of the far-field intensity distribution diagram. The acoustic vortex field detector is reasonable in design, the method for measuring the topological charges of the acoustic vortex field by means of the acoustic vortex field detector is simple and easy to implement, and the acoustic vortex field detector can be combined with an existing acoustic vortex field emitter in practical application toachieve acoustic vortex wave communication.

The invention, which belongs to the technical field of measuring the diffraction width by diffraction of light, provides a micro-range measurement method based on Fraunhofer diffraction. Color information at a light intensity peak of a diffraction image, a light intensity value mode, the position of a peak point, and corresponding row and column vectors are obtained by using a maximum value searchfunction being find function; a theoretical diffraction curve is generated based on the color information at the light intensity peak, the row and column vectors of the peak point, and a diffractionequivalent focal length and exploration is performed; and the diffraction width of a diffraction object generating Fraunhofer diffraction is explored continuously based on a pseudo-dichotomy algorithmand an optimal theoretical diffraction curve is determined finally, so that the diffraction width corresponding to the optimal theoretical diffraction curve is an actual diffraction width. Therefore,the diffraction width value of the diffraction occurence can be obtained based on the Fraunhofer diffraction image and the calculation efficiency is high.

A method of performing coherent transformations of optical fields includes forming a far field distribution of the input optical field. A fraction of the formed far field is diffracted by producing localized discontinuities within said far field. A Fraunhofer diffraction pattern of the diffracted optical field is formed. The Fraunhofer diffraction pattern is modified by producing localized optical path differences within the Fraunhofer diffraction pattern. The transformed output optical field is produced in the far field with respect to the modified Fraunhofer diffraction pattern.

The invention discloses a full-automatic light wave length measuring method and device. According to the method, the raster dispersion light splitting principle is mainly used, according to the Fraunhofer diffraction theory, when a parallel light beam is projected to a raster plane, light waves can be diffracted at each slot, diffraction light at all the slots are interfered with each other, when diffraction angles meet a raster equation, light in the diffraction angle directions can be overlaid to be enhanced, and light in other directions can be counteracted. Through constant rotating speed, the angles of emit-in light on a raster are continuously changed in a circulation mode, light with different wave lengths in the emit-in light can be screened out in sequence, finally, light intensity is converted to currents according to the photoelectric effect, and accordingly the wave length of the light screened at this time by the raster and the corresponding currents can be detected. The device is simple in structure, low in manufacturing cost, strong in universality and reliable and stable in working, test condition parameter control is accurate, the device can be used for full-automatic detection on the wave length of homogeneous light in the ultraviolet band, the visible band and the infrared band, and the device can also be used for detecting the wave length range contained by polychromatic light and corresponding intensity of light waves with various wave lengths.

The invention provides a device and method for automatically measuring the refractive index of liquid, belongs to the technical field of photoelectric measurement, and aims at solving comprehensive problems of complicated operation, low relative precision, relatively large equipment size, relatively narrow measurement range and the like in the prior art. The device comprises a laser light source,a laser beam expander, a cuvette, an automatic extraction device, a camera, a driving motor, a double-slit plate, a computer and a single-slit plate, wherein a unibeam is emitted from the laser lightsource, is expanded by the laser beam expander, and is projected to the single slit of the single-slit plate to perform Fraunhofer diffraction, the diffracted light is projected to double slits of thedouble-slit plate to perform Young's double-slit interference, and an interference fringe is obtained in a camera; the cuvette is arranged behind the upper single slit of the double-slit plate, is connected with the automatic extraction device, and is used for holding the extracted liquid to be detected; and the automatic extraction device, the camera and the driving motor are connected with thecomputer, and the camera is connected with the driving motor. The device is simple in operation and high in accuracy, and can realize automatic measurement.

The invention relates to a focal length measurement method for a concave lens. The method adopts a sodium lamp, a shading plate, a first convex lens, a grating, a second convex lens, a third convex lens, the concave lens on which measurement is to be carried out, and a micrometer eyepiece, wherein a rectangular light transmission hole is formed in the shading plate; and a focal length of the concave lens on which the measurement is to be carried out can be measured through Fraunhofer diffraction. The method provided by the invention has the advantages that the structure is simple, and the operation is easy and convenient; and the focal length of the concave lens on which the measurement is to be carried out can be measured through Fraunhofer diffraction, so that only intervals among diffraction fringes, instead of an image distance and an object distance, need to be measured.

The invention discloses a plastic part surface flatness detection device based on optical diffractions; the detection device comprises a detection box and a fold curtain; a detection cavity is arranged in the detection box; a sodium lamp is arranged on one side in the detection cavity; a receiving screen is arranged on the other side in the detection cavity; one side, far away from the sodium lamp, of the receiving screen is provided with an observation mirror; one side, close to the receiving screen, of the sodium lamp is provided with an adjustable crack plate. The advantages are that the detection device employs a Fraunhofer diffraction principle; the light passes the adjustable crack plate so as to form visual light intensity, and passes the first lens so as to form parallel light beams; the parallel light beams pass the crack between a block plate and the plastic part, and pass the second lens so as to irradiate on the receiving screen; the observation mirror can observe the diffraction angle changes so as to determine whether the surface is smooth and flat or not; the plastic part surface flatness detection device is simple in structure, easy to operate, high in detection precision, and safe and portable in usage.

The invention discloses a sodium guide star uplink laser light field pre-correction system. The system comprises a sodium guided star laser, a beam expanding lens, an inclined reflector, an inclined controller, a spectroscope, a sodium guide star transmitting telescope and an inclined detection camera; the system further comprises a light field detection system and a light field pre-correction system; the light field detection system comprises a light field detector and a light field controller; the light field pre-correction system comprises a first deformable mirror, a Fourier transform lens, a light splitting mechanism and a second deformable mirror; and the Fourier transform lens is located in a Fraunhofer diffraction region of the first deformable mirror. By the adoption of the scheme, real-time compensation can be conducted on amplitude and phase disturbance generated by atmospheric turbulence at the same time, light spots obtained after pre-correction are closer to the diffraction limit, and the number of returned light of the sodium guide star is more stable, so that performance of a rear-end self-adaptive optical system can be effectively improved, and development of the self-adaptive optical system and the theory is promoted.