46 results about "Fringe pattern" patented technology

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 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.

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 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.

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.

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.

The invention discloses a self-adaptive multi-exposure fusion three-dimensional measurement method for a high dynamic range scene. The method comprises the following steps: firstly, acquiring high-frequency phase shift fringe patterns at different exposure times, and finding out initial exposure time for preventing effective measurement areas in all phase shift patterns from overexposure through time domain light intensity overexposure detection operation; taking the high-frequency phase shift fringe pattern of the initial exposure time as an initial image of multi-exposure fusion, adaptively reserving a fringe region with high phase quality according to a modulation degree condition through a noise-modulation degree model, and introducing a time domain superposition principle to estimate the next exposure time of the multi-exposure fusion; and finally, calculating an effective measurement area of the current fused fringe image by using a reference plane phase based on depth constraint, and continuing to perform multi-exposure fusion until the effective measurement area meets a modulation degree condition, thereby completing three-dimensional measurement of the whole high dynamic range scene. According to the invention, the high-quality fringe pattern is obtained through adaptive multi-exposure fusion, the total exposure time is significantly reduced by introducing the time domain superposition technology, and high-precision and high-efficiency full-automatic three-dimensional measurement of a high-dynamic-range scene is realized.

The application discloses an automatic multi-exposure selection method based on fringe projection. Firstly, a projector is used to project a phase-shift fringe pattern to a measured scene, and a camera synchronously collects a group of fringe images with a preset exposure value. A pseudo-white image is obtained by using a highest-frequency fringe image. An overexposure area with a brightness greater than a preset threshold value in the pseudo-white image is found, and a seed filling algorithm is used to divide the overexposure area into a plurality of sub-areas. The pixel number and average brightness of the largest overexposure sub-area are used to iteratively calculate an optimal initial exposure time, so that the initial exposure is as large as possible and the measured scene has no obvious overexposure area under the initial exposure. An automatic multi-exposure algorithm based on a fringe image modulation degree is used to calculate a multi-exposure number and automatically iterate subsequent exposure times, high-quality absolute phases under the exposure times are fused to obtain a multi-exposure fusion absolute phase. The calibration parameters of a binocular camera are used to perform stereo rectification on the absolute phases of left and right cameras. The absolute phases of the left and right cameras are phase-matched to obtain a two-dimensional disparity map, and high-speed and high-precision three-dimensional topography measurement is realized.

Measurement of overlay using a microscope-based sensor is described. This provides, among other advantages, the ability to measure alignment and overlay with 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 metrology mark in a first layer of the patterned substrate and a second metrology mark in a second layer of the patterned substrate. The intensity modulated fringe pattern is filtered for an expected fringe period. Amplitude, phase, and / or other parameters of fringes of the filtered fringe pattern are used to determine overlay values.

A projector may project a fringe pattern onto a deposited layer from an additive manufacturing printer. A camera may capture set of fringe images of the deposited layer. Then, a system may compute a two-dimensional absolute phase map that encodes surface height information of the deposited layer. The system may generate a threshold phase map corresponding to an intended geometry of the deposited layer. The system may compare the absolute phase map to the threshold phase map on a pixel-by-pixel basis to detect error regions in the deposited layer. The comparison may be performed in the two-dimensional phase domain without reconstructing a complete three-dimensional point cloud. The system may selectively reconstruct three-dimensional data only for pixels corresponding to the detected regions, thereby reducing computational resources required for in-situ process monitoring.

A method for inspecting a photomask includes scanning the photomask with an interferometric fringe pattern generated by an interferometer, generating an interferogram associated with the photomask in response to scanning the photomask using the interferometer, and detecting one or more geometric parameters of the photomask using the generated interferogram.

This measurement device comprises a projection unit, an imaging unit, and an information processing unit. A fringe pattern in this device is a waveform pattern having down edges or rise edges. The information processing unit includes: a projection control unit that controls the projection unit so that the phase of the fringe pattern moves; a reflected-light-amount change measurement unit that measures, using the pixels of an imager, changes in the amounts of reflected light at points on the surface of an object under measurement that accompany phase changes of the fringe pattern; a phase calculation unit that detects the down edges or the rise edges from a time series of the measured values of the amounts of reflected light at the points on the surface of the object under measurement to detect the origin of the period of the fringe pattern, and that calculates initial phases of the pixels on the basis of the detected origin of the period; and a height calculation unit that, on the basis of the phases of the pixels, calculates the heights of the points on the surface of the object under measurement that correspond to said pixels.

A three-dimensional shape measurement device includes: a projector to project a fringe pattern; multiple cameras having a measurable working distance range, respectively; and a processing circuitry to analyze the fringe pattern captured by the multiple cameras, using a phase shift method, to acquire three-dimensional information of an object. The multiple cameras are all arranged on one side of the projector. A projector optical axis of the projector and camera optical axes of the multiple cameras are arranged in the same plane. The camera optical axes are arranged such that interior angles between the camera optical axes and the projector optical axis are different from each other.

The present invention relates to the technical field of fruit optical property detection, specifically: a method for predicting fruit optical properties based on a double-layer network using a single multi-frequency image, comprising the following steps: Step 1, the host computer generates multiple structured light fringe patterns, including a completely black image, a completely white image, a single-frequency fringe pattern, and a double-frequency orthogonal fringe pattern, and then projects the fringe patterns onto the fruit surface through a projector; Step 2, a CCD camera is used to collect the reflected light intensity distribution on the fruit surface under fringe illumination, and the collected images are saved in BMP format; Step 3, the completely black and completely white images are projected onto a standard diffuse reflection plate respectively, and the dark field and white board light intensity distributions of the standard reference light field are collected by the CCD camera, and then the collected fringe images are corrected for the black and white boards; The present invention realizes the prediction of fruit optical properties at different spatial frequencies through a single multi-frequency image. It solves the deficiencies in real-time performance, anti-interference ability, and information integrity in traditional detection methods.

The invention discloses a surface topography measurement method and system based on multi-intensity projection and a medium, and the measurement method comprises the steps: adjusting to form fringe light with different intensities, thereby forming at least four fringe patterns with different phases under each intensity; calculating to obtain original height data of all pixel positions under the current intensity; analyzing the gray value difference of two fringe patterns of which the phase difference is pi at the same pixel position under the current intensity, and carrying out square extraction operation on the sum of squares of a plurality of gray value differences so as to serve as a weight; and performing weighted average to obtain final height data of each pixel position. According to the invention, through a multi-intensity adaptive projection and weighted data fusion mechanism, inherent defects of a traditional phase deflection technology in high dynamic range surface measurement are effectively overcome, full-automatic, high-precision and high-robustness three-dimensional shape measurement is realized, various surfaces with complex reflection characteristics can be intelligently adapted, and the measurement precision is improved. And the practicability, the reliability and the accuracy of the measurement system are remarkably improved.

The invalid point removal method and system for structured light three-dimensional measurement provided by the present application obtain the wrapping phase, background intensity and modulation intensity of the fringe pattern; obtain the discreteness between the sequence points of each fringe pattern coordinate and the ideal cosine curve based on the wrapping phase, background intensity and modulation intensity; correct point by point and establish a new error energy function based on the discreteness; and remove invalid points based on the new error energy function. The invalid point removal method and system for structured light three-dimensional measurement provided by the present application are easy to implement and can be used for invalid point removal tasks of complex objects in different scenarios. They are not only insensitive to the reflectivity or modulation of the object, but also effectively solve the problem of difficult edge segmentation of the measured object.