59 results about "Fringe pattern" patented technology

The invention discloses a three-dimensional reconstruction method and system based on a line shift coding pattern, and the method comprises the steps: designing an original fringe pattern in a line shift manner to obtain a plurality of coding patterns, and carrying out the projection and collection of a to-be-measured object through the plurality of coding patterns and a preset Gray code pattern, respectively obtaining a plurality of fringe projection drawings and a plurality of Gray code projection drawings; synthesizing M phase shift fringe patterns according to the collected multiple fringe projection patterns; performing phase calculation on the M phase shift fringe diagrams to obtain a folded phase diagram; and combining the folded phase diagram with the plurality of Gray code projection drawings for phase unwrapping to obtain an unwrapped phase diagram, and reconstructing the to-be-measured object by using a three-dimensional reconstruction principle. According to the method, fringe synthesis is firstly carried out on the plurality of coding patterns, and then phase calculation is carried out on the M phase shift fringe patterns, so that three-dimensional reconstruction is carried out on the to-be-measured object by using the phase, relatively high reconstruction precision is achieved, the robustness is relatively high, and the method has a relatively good application effect in a high dynamic range scene.

The invention relates to a spectral separation regional adaptive fringe projection three-dimensional measurement method, which comprises the following steps of: projecting transverse and longitudinal sine phase shift fringe patterns to the surfaces of a plurality of measured objects, and acquiring a fringe sequence by using a camera; respectively obtaining an object contour mask and a saturated mask; the coordinates of the white area of the contour mask are converted into the coordinates of a projector, and a projection mask is obtained; obtaining a single object projection mask image by using a connected domain labeling algorithm; setting two groups of mask regions by using the marked regions and the saturated mask to generate a longitudinal sine phase shift fringe pattern with adaptive intensity, sequentially projecting two groups of region fringes to the surface of a measured object, and simultaneously collecting region fringe images of spectrum separation; performing independent phase demodulation and phase fusion on the fringe patterns of different channel colors corresponding to the object, and performing three-dimensional reconstruction according to a fused phase result; according to the method, the measurement efficiency is remarkably improved on the premise of eliminating stripe aliasing interference.

An objective hologram quality evaluation method is provided. The quality evaluation method, according to an embodiment of the present invention, receives an original holographic fringe pattern and a target holographic fringe pattern to be compared, calculates the respective angular spectra of the inputted original holographic fringe pattern and the inputted target holographic fringe pattern, and calculates a PSNR obtained from the calculated angular spectra as a quality value of the target holographic fringe pattern. Since the angular spectrum of the holographic fringe pattern has the same characteristics without change according to distance, even a diffraction wavefront positioned at an arbitrary distance as well as the position of the holographic fringe pattern has the same PSNR value, thereby enabling objective quality evaluation for the holographic fringe pattern.

The measurement of overlay using a microscope-based sensor is described. This provides, among several advantages, the ability to measure alignment and overlay in a single system. The signal from the sensor is an intensity-modulated fringe pattern (e.g., an interference pattern). The sensor is configured to generate an intensity-modulated fringe pattern based on diffracted radiation received from a first metronome mark on a first layer of the pattern substrate and a second metronome mark on a second layer of the pattern substrate. The intensity-modulated fringe pattern is filtered for the expected fringe period. The overlay value is determined using the amplitude, phase, and / or other parameters of the fringe in the filtered fringe pattern.

The invention discloses a detection method, device and equipment and a storage medium, which are used for bubble defect detection in a wafer bonding process and can be applied to the technical field of optics, and the method comprises the following steps: obtaining an interference fringe pattern of a to-be-detected bonding wafer; determining a three-dimensional shape graph corresponding to the to-be-detected bonding wafer based on the interference fringe graph; determining whether a bubble defect exists in the to-be-detected bonding wafer based on the interference fringe pattern; if yes, determining a target position area corresponding to the bubble defect; determining the size information of the bubble defect in combination with the three-dimensional morphology graph and the target position area; the size information comprises thickness information, length information and width information. Thus, the interference fringe pattern of the whole bonded wafer is collected by using the optical interference principle, then the three-dimensional morphology graph of the bonded wafer is calculated, then the possibly existing bubble defect and the size information of the bubble defect are visually detected through the interference fringe pattern and the three-dimensional morphology graph, the detection efficiency is improved, and the bubble size is accurately measured.

The application discloses a digital phase-shifting phase recovery method of ESPI fringe pattern based on distance mapping, which comprises the following steps: 1) extracting the direction of each pixel point of the fringe pattern, and then calculating the normal curve of the fringe according to the fringe direction to obtain the moving direction of the fringe; 2) extracting the center line of the dark fringe, calculating the width of the fringe according to the center line of the fringe, and obtaining the moving distance of the fringe through distance mapping; 3) comprehensively moving the direction and the distance, and performing digital phase-shifting on the initial fringe pattern point by point, and adopting the bilinear gray interpolation to obtain the fringe pattern after digital phase-shifting; 4) calculating the wrapped phase corresponding to the fringe pattern; and 5) performing unwrapping processing on the wrapped phase to recover the full-field phase of the fringe pattern. The application extracts the phase through the digital image processing technology on the single fringe pattern, avoids the problem of inaccurate phase-shifting existing in the traditional physical phase-shifting technology in dynamic measurement, and can effectively improve the accuracy of the phase recovery of the single fringe pattern.

There is provided a hologram quality assessment method. The quality assessment method according to an embodiment may receive an input of an original holographic fringe pattern and a target holographic fringe pattern which is a comparison target, may calculate angular spectra of the inputted original holographic fringe pattern and target holographic fringe pattern, respectively, and may calculate a PSNR as a quality value of the target holographic fringe pattern from the calculated angular spectra. Since the angular spectrum of the holographic fringe pattern has the same characteristic without a change according to a distance, not only a diffraction wavefront that is positioned at a position of the holographic fringe pattern but also a diffraction wavefront positioned at a certain distance may have the same PSNR value. Accordingly, objective quality assessment for a holographic fringe pattern is possible.

Provided is a holographic printer using a mechanical shutter having adjustable exposure time and no vibration. The holographic printer according to an embodiment of the present invention comprises: a light source; a modulator for generating a holographic fringe pattern in hogel units; a stage on which a hologram recording medium is placed; a driving part for moving the position of the stage in hogel units; and a shutter for periodically exposing an object light due to the holographic fringe pattern generated by the modulator to the hologram recording medium. The shutter comprises: a rotation plate having formed therein an arc-shaped opening which exposes the object light due to the holographic fringe pattern; and a motor for rotating the rotation plate. Therefore, the exposure period and exposure time of the shutter can be variously adjusted by adjusting the rotational state of the rotation plates having the arc-shaped opening formed therein.

This invention discloses a phase-height mapping calibration method and apparatus in fringe projection, relating to the field of three-dimensional object contour measurement technology. The method includes: controlling a projector to project a set of phase-shifted sinusoidal fringe patterns onto a micromirror array with known height values; simultaneously triggering a camera to acquire fringe image sequences; performing phase shift calculations on the fringe image sequences to obtain a wrap-around phase map; constructing a global optimization model of absolute phase using the known height value of the micromirror array as an absolute constraint; solving for the absolute phase field corresponding to the height of the micromirror array; extracting the center coordinates, absolute phase values, and known height values ​​of each micromirror element; constructing a three-dimensional control point set; fitting the three-dimensional control point set; calculating the continuous model coefficient field; and forming a phase-height lookup table. This invention can significantly improve the real-time calculation efficiency of three-dimensional measurement, meeting the practical needs of high-precision, high-stability industrial three-dimensional shape measurement.

The invention discloses a high-precision fringe phase extraction method based on a 2D-Hamming self-convolution window. The high-precision fringe phase extraction method comprises the steps of 1, discretization collection of a fringe pattern; 2, constructing a 2D-Hamming self-convolution window with better spectrum leakage suppression performance; 3, weighting the fringe pattern by adopting a 2D-Hamming self-convolution window; 4, executing 2D-FFT to obtain a frequency spectrum of the fringe pattern; 5, selecting a positive primary frequency spectrum by using a band-pass filter; 6, obtaining the time domain distribution of the positive first-order frequency spectrum through IFT (Invariant Feature Transform); 7, extracting a wrapped phase of the fringe pattern; and 8, obtaining an absolute phase by using a fast intensity transmission equation unwrapping algorithm. Aiming at the problem of spectrum leakage caused by the fringe image in the discrete sampling, asynchronous sampling and non-full-period truncation process, the weighting characteristic of the 2D-Hamming self-convolution window is utilized, the spectrum leakage error is effectively inhibited, and thus high-precision phase extraction is realized.

The invention discloses a transparent element surface shape detection method. The method mainly solves the technical problem that an existing transparent element surface shape detection method is difficult to comprehensively and efficiently eliminate parasitic reaction to achieve accurate surface shape detection. After a transparent element detection system is constructed, a display is controlled to respectively display a phase-shift fringe pattern and a multi-frequency fringe pattern, and after being reflected by a transparent element, the fringe pattern is correspondingly collected by a camera and a superposed fringe pattern is generated; then, a superposition phase is obtained through corresponding calculation of the superposition fringe pattern and converted into superposition display coordinates; and extracting the intensity value of the superposed fringe pattern, forming a time intensity sequence, and correspondingly separating parasitic reflection through correlation matching and nonlinear optimization to complete the surface shape detection of the front surface of the transparent element. The whole detection process is efficient and convenient and is not limited by types of transparent elements, and the detection accuracy is high.

The invention discloses a binary fringe phase encoding and decoding method, device, equipment and medium, and the method comprises the steps: generating a plurality of binary fringe patterns with a preset phase shift relation, sequentially projecting the binary fringe patterns to a detected object, and collecting corresponding deformed fringe images; the truncation phase of each pixel is calculated by adopting the phase calculation model based on the light intensity value of each pixel in the deformed fringe image, phase calculation after conversion into a sinusoidal signal is not needed, the reliability is high, the phase is obtained through direct calculation by utilizing the deformed fringe image collected by projecting the binary fringe pattern, and the detection accuracy is high. The time overhead for generating the sine stripe pattern is avoided, a projection system does not need to carry out gray scale modulation on the sine stripe pattern, the measurement speed is improved, the binary stripe pattern is high in anti-interference capability and high in stability, the preset phase shift relation ensures that the binary coding sequence corresponding to each pixel in the period has uniqueness, and the measurement accuracy is improved. Phase calculation ambiguity caused by coding repetition is avoided, and the measurement precision is improved.

The application discloses a variable-frequency fringe encoding and decoding method and device for rapid three-dimensional measurement and a medium, and belongs to the technical field of computer vision. The method comprises the following steps: in the fringe encoding stage, the optimal encoding pixel offset is obtained according to the target depth range, the fringe frequency and the corresponding phase are determined, the optimal fringe encoding is obtained, and the phase is stored in a lookup table; in the fringe decoding stage, the encoded fringe pattern is emitted to the surface of the object to be measured, the fringe is deformed, the deformed fringe sequence is obtained, the absolute phase is obtained by using a geometric constraint phase unwrapping method, pixel matching is performed through the lookup table established in the fringe encoding stage, and the three-dimensional shape of the object to be measured is restored. The fringe encoding method has the advantages of high precision, high speed, large range and the like.

The invention discloses a phase unwrapping method based on a space-time diagram cut algorithm, and the method comprises the following steps: 1, extracting a wrapped phase according to a result obtained through the analysis based on the fringe pattern analysis of structured light fringe projection; 2, constructing a space-time diagram based on the wrapped phase in the step 1; according to the constructed space-time diagram, defining an energy function, and using a space-time diagram cut algorithm to minimize energy; and step 3, performing phase unwrapping according to a result obtained by graph segmentation, constructing a continuous unwrapped phase graph, and completing phase unwrapping. The phase unwrapping method can adapt to complex and dynamically changing scenes, and the phase unwrapping accuracy is improved.

The invention discloses a binocular structured light transparent object three-dimensional reconstruction method and system based on a diffusion model, and belongs to the technical field of object three-dimensional reconstruction. The method comprises the following steps: acquiring a binocular aliasing stripe pattern sequence set of transparent object samples with different shapes and a corresponding binocular non-aliasing stripe pattern sequence set; obtaining a binocular aliasing stripe pattern sequence training set, a corresponding binocular non-aliasing stripe pattern sequence training set, a binocular aliasing stripe pattern sequence test set and a corresponding binocular non-aliasing stripe pattern sequence test set; the de-noised U-Net network is trained; the trained de-noised U-Net network is tested; and performing three-dimensional reconstruction on the front surface of the transparent object by adopting the tested de-noised U-Net network. According to the method, the binocular aliasing-free stripe pattern on the front surface of the transparent object can be effectively extracted from the binocular aliasing stripe pattern captured by the camera, and the reconstruction of the surface of the transparent object is realized.

In alternative embodiments, provided are moiré profilometry methods for analyzing a topography of an object comprising use of dual patterns that are simultaneously projected onto a surface of the object from two symmetric directions. In alternative embodiments, the projected dual patterns superimpose and generate a fringe pattern that contains a moiré pattern, the moiré pattern having a phase that is modulated according to the topography of the object. In alternative embodiments, the moiré pattern is extracted from the fringe pattern using a spatial or temporal method, and the phase is demodulated from the extracted moiré pattern using a spatial or temporal method.

The present application relates to a grating mark for photolithography alignment and an alignment method thereof, wherein the mark includes: a wafer alignment mark and a mask alignment mark. The method includes: etching a wafer alignment mark and a mask alignment mark on a wafer and a mask respectively; illuminating the wafer mark and the mask mark simultaneously with an alignment light source, and causing the diffracted light to interfere to generate a square moiré fringe pattern; using a computer to pre-process the outer contour of the moiré fringe pattern to achieve coarse alignment; extracting the phase information of the moiré fringe through 2D-FFT, and using an intensity equation unwrapping algorithm to calculate the absolute phase; calculating the actual misalignment between the wafer and the mask based on the phase difference of the moiré fringe; inputting the misalignment into a translation stage to implement feedback adjustment until high-precision alignment is achieved. The present invention can achieve precise alignment of multiple degrees of freedom in photolithography alignment through a single set of centrally symmetrical marks and its alignment method, greatly reducing the occupation of the effective area of ​​the wafer, and significantly improving photolithography efficiency and alignment accuracy.

The present invention is to solve the problem that the deformation of the workpiece surface can be automatically determined without the reference shape data of the workpiece. In order to solve the above problem, a workpiece quality determination system determines the quality of a workpiece based on a fringe pattern projected onto the workpiece surface, and includes: an observation angle setting section that sets an observation angle for observing a projected fringe pattern projected onto the workpiece; a fringe projection angle setting section that sets a fringe projection angle of the projected fringe pattern at the set observation angle; a reference fringe creating section that creates a reference fringe pattern based on the projected fringe pattern at the set fringe projection angle; and a quality determination section that calculates a difference between the projected fringe pattern and the reference fringe pattern at the fringe projection angle, and performs quality determination based on the difference.

The present invention provides a high dynamic range fringe projection three-dimensional measurement method based on fringe restoration, comprising the following steps: projecting a multi-step grayscale sinusoidal fringe pattern onto a highly reflective surface; dividing the captured image into a reliable area, a light saturation area, and a deep saturation area; calculating the A and B surfaces of the reliable area using the Euler formula method; finding the unsaturated lower intersection point between adjacent fringes to expand F lower The CSI-BSI interpolation method is used to complete the shallow and deep saturation areas of the three surfaces, and based on the relationship between them, the accurate A is calculated for each position. The saturated fringes are then repaired and the phase is further calculated. This invention provides a high-dynamic range fringe projection 3D measurement method based on fringe repair. This method can effectively repair saturated fringes and improve the dynamic range of the system. Using the fringe repair method, the information utilization rate of each image is increased, the number of projection patterns required for high-dynamic range measurement is reduced, and the measurement speed is effectively improved.

A holographic printer using a vibration-free mechanical shutter is provided. A holographic printer, according to an embodiment of the present invention, comprises: a light source which emits light; a modulator which modulates the light emitted from the light source to generate a holographic fringe pattern in a hogel unit; a stage on which a holographic recording medium, on which a holographic fringe pattern generated by the modulator is to be recorded in a hogel unit, is placed; a driving part which moves a position of the stage in a hogel unit; and a shutter which periodically exposes, to the holographic recording medium, object light generated by the holographic fringe pattern generated by the modulator, wherein the shutter includes a rotating plate having a slit that exposes the object light by means of the holographic fringe pattern, and a motor rotating the rotating plate. Accordingly, by applying a mechanical shutter having a structure in which vibration does not occur to the holographic printer, it is possible to prevent degradation of hologram recording quality caused by vibration generated during opening / closing of the shutter.

Eye safety and eye tracking accuracy is enhanced through pupil-aware eye tracking, where a fringe pattern projection or illumination onto the eye is locally dimmed in an area corresponding to the pupil. Fringe projection local dimming is accomplished by modifying (locally dimming) the fringe pattern at the projector. Illumination local dimming is accomplished at the light source (e.g., a laser source) before the light is provided by a micro-electromechanical system (MEMS) to the eye. An amount of light provided to non-pupil areas such as sclera may be increased to enhance a signal-to-noise ratio (SNR), which may lead to more accurate eye tracking.

The invention relates to a grating mark for photoetching alignment and an alignment method thereof, and the mark comprises a wafer alignment mark and a mask alignment mark. The method comprises the following steps: etching a wafer alignment mark and a mask alignment mark on a wafer and a mask respectively; irradiating the wafer mark and the mask mark at the same time through an alignment light source, and generating a square Moire fringe pattern through diffraction light interference; preprocessing the outer contour of the moire fringe pattern by using a computer to realize coarse alignment; phase information of the moire fringes is extracted through 2D-FFT, and an absolute phase is calculated through an intensity equation unwrapping algorithm; calculating the actual dislocation amount between the wafer and the mask according to the phase difference of the moire fringes; and inputting the dislocation quantity into a displacement table to realize feedback adjustment until high-precision alignment is realized. According to the invention, multi-degree-of-freedom fine alignment in photoetching alignment can be realized through the single group of centrosymmetric marks and the alignment method thereof, the occupation of the effective area of the wafer is greatly reduced, and the photoetching efficiency and the alignment precision are remarkably improved.

A lithographic apparatus includes an illumination system that includes a metrology system. The illumination system generates a beam of radiation to illuminate a pattern of a patterning device for projecting an image of the pattern onto a substrate. The metrology system includes an etalon, a detector having an array of pixels, and a computing system. The etalon generates a fringe pattern and a next fringe pattern respectively corresponding to a pulse and a next pulse of the beam. The array of pixels generate intensity signals based on fringe pattern intensities at positions of the pixels. The computing system determines a predicted range of pixel positions corresponding to intensity peaks of the next fringe pattern based on pixel positions of intensity peaks of the fringe pattern and performs an abbreviated analysis of the next fringe pattern. The abbreviated analysis is delimited by the predicted range of pixel positions.

The application relates to a mask and wafer leveling method, wherein the method comprises the following steps: vertically irradiating a leveling grating on a mask surface with a light source to generate a square moire fringe pattern; determining a first observation area in the lower part of the right region, calculating a fringe rotation angle and an actual fringe frequency by extracting the moire fringe phase of the first observation area; calculating the angle offset amount of the wafer in space relative to the mask when cross-section tilting and longitudinal section tilting occur respectively; and performing feedback adjustment according to the measured angle offset amount. The phase change of the first observation area in the square moire fringe pattern is measured, and then the offset amount of the wafer in space relative to the mask when cross-section tilting and longitudinal section tilting occur respectively can be accurately calculated through formula conversion, thereby solving the problem that the existing mask and wafer leveling method cannot realize high-precision detection of multi-interface tilting angles through single-point measurement, and improving the measurement efficiency and measurement precision.

A measurement device according to the present disclosure comprises a projection unit, an imaging unit, and an information processing unit. The projection unit has: a light source that emits light toward a measurement reference surface; a mask that allows transmission therethrough of light emitted from the light source and that generates a fringe pattern; and an actuator that moves the mask. The projection unit changes the phase of the fringe pattern by moving the mask. The imaging unit has an imager that acquires the amount of reflected light at each point on a projection surface on which the fringe pattern is projected from among the measurement reference surface and a surface of a measurement object. The information processing unit has: on the basis of the amount of the reflected light that is acquired a plurality of times by changing the phase of the fringe pattern, a reflected light-amount change measurement unit that measures, at each point on the projection surface, reflected light-amount change that occurs at each point on the projection surface in association with the phase change of the fringe pattern; and a height measurement unit that measures the height of each point on the surface of the object to be measured with respect to the measurement reference surface, on the basis of the reflected light-amount change at each said point on the projection surface.

The present invention discloses a method for realizing anti-counterfeiting of mobile phone screens by utilizing the moiré fringe principle. The method comprises the following steps: first, inputting a basic function through software to obtain a corresponding function image; second, modifying and deforming the basic function parameters and the stripe colors to generate rich colored stripes; third, superimposing two or more groups of colored stripes to generate a new color moiré fringe pattern in the superimposed portion; fourth, calculating an equation for generating moiré fringe by superimposing curved grids; fifth, printing patterns of different color regions on transparent paper respectively, superimposing them on each other to obtain a colored pattern, regarding the mobile phone screen as a grid, superimposing the colored pattern and the grid, different moiré fringe patterns will appear in different color regions, and printing the resulting pattern as the correct superimposed pattern in the lower right corner of the image; and sixth, taking a photo using a picture of the grid and a bottom grid, superimposing the moiré fringes in the bottom grid picture with the grid of the mobile phone screen to generate a moiré fringe pattern, and comparing the generated moiré fringe pattern with the correct moiré fringe color pattern.

There is provided a hologram quality assessment method. The quality assessment method according to an embodiment may receive an input of an original holographic fringe pattern and a target holographic fringe pattern which is a comparison target, may calculate angular spectra of the inputted original holographic fringe pattern and target holographic fringe pattern, respectively, and may calculate a PSNR as a quality value of the target holographic fringe pattern from the calculated angular spectra. Since the angular spectrum of the holographic fringe pattern has the same characteristic without a change according to a distance, not only a diffraction wavefront that is positioned at a position of the holographic fringe pattern but also a diffraction wavefront positioned at a certain distance may have the same PSNR value. Accordingly, objective quality assessment for a holographic fringe pattern is possible.

Measuring overlay using a microscope based sensor with dark-field fringe-based imaging is described. The signal from the sensor is an intensity modulated fringe pattern (e.g., an interference pattern) as generated through the cross-interference of two diffraction orders from the metrology target. A metrology target comprises a first metrology mark in a first layer of a patterned substrate (e.g., a semiconductor wafer) and a second metrology mark in a second layer. Parameters associated with the fringes of the intensity modulated fringe pattern are determined, and used to make robust overlay determinations that are compensated for in plane vibrations of the patterned substrate. Advantageously, overlay values for metrology targets are determined based on the parameters, using a multi-parameter optimization based inference of the overlay values for multiple metrology targets together with the parameters related to the diffraction model and the sensor disturbances.

The present invention discloses an interlaced phase unwrapping method that avoids periodic errors, comprising the following steps: Step 1: Obtain an N-step phase-shifted grating deformed fringe pattern modulated by an object, calculate the wrapped phase using a phase shift formula, and then construct an additional wrapped phase from the current wrapped phase; Step 2: Obtain a traditional binary Gray code deformed fringe pattern modulated by the object, establish a lookup table after image processing to determine the phase order; Step 3: Detect phase truncation points, use phase jump points to divide the forward phase unwrapping region, and combine the phase orders with the unwrapped region to perform forward and reverse phase unwrapping; Step 4: Combine the forward and reverse phase unwrapping with the phase order information to obtain the final absolute phase. Since the unstable jump region of the wrapped phase and erroneous edge order information are not used, the influence of edge order and wrapped phase jump errors can be avoided.

An eye tracking system for absolute phase unwrapping includes a fringe projector, a camera, and an illumination module. The projector provides a periodical fringe pattern onto the eye and the camera captures a reflection of the fringe pattern. Fourier transform, wavelet transform, phase shifting, and / or variants thereof may be used to determine a phase of the fringe pattern and generate a wrapped phase map. Spatial phase unwrapping is used for phase unwrapping resulting in a relative unwrapped phase map. The illumination module with a known relative position between the fringe projector and the camera is used to create glint(s) on the eye. Detected glints on the original image are used to convert the relative unwrapped phase map to an absolute unwrapped phase map.