16 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 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.

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.

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.

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.

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 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 invention provides a transparent element surface shape decoupling method based on ROOT-MUSIC, and the method comprises the steps: employing a pinhole camera and a display to form a reflection deflection technology detection system, enabling a plurality of groups of fringe patterns to be projected to the display based on the principle of phase measurement deflection technology, and enabling the fringe patterns to be reflected by a detected element and then to be received by the camera; according to the collected data, a shot superposed fringe pattern is separated by using a ROOT-MUSIC algorithm to obtain corresponding display coordinates; and obtaining the front surface shape of the transparent element according to a light reflection principle and a least square optimization algorithm. The method has the advantages of rapidness, flexibility, low cost and large detection dynamic range.

The present disclosure relates to relates to a system and method for measuring a real-time three dimensional shape using a diagonal fringe pattern. Particularly, in the deflectometry applied to real-time three dimensional shape measurement of freeform surfaces, a system for acquiring a real-time three dimensional phase using a diagonal fringe pattern includes: a pattern generation portion that generates a single-direction pattern in the diagonal direction and project the generated pattern onto a measurement object; a detector that obtains an image of a deformed pattern reflected from the measurement object; and a phase acquisition portion that partially differentiates and integrates a phase of the diagonal pattern in the x axis direction and y axis direction respectively, to obtain an x axis direction phase component and a y direction phase component.

The present application relates to a gap measurement method based on central symmetric grating modulation. The method comprises constructing a first grating and a second grating which are complementary in period on two surfaces of a gap to be measured to form a central symmetric grating assembly; adjusting a light source to be aligned with the normal direction of the first grating, so that the light source is vertically incident on the central symmetric grating assembly to obtain a moire fringe pattern formed by interference of diffracted light; dividing the moire fringe pattern along a diagonal line into four regions, each region having misaligned phase regions, for at least one region, calculating a phase difference of the misaligned phase regions, and calculating a gap change amount according to the phase difference. The method estimates the gap between the two parallel gratings by using the phase difference of the diffracted fringes formed by the gratings of different structures in the same region of the diffracted fringes formed by the central symmetric grating assembly, can realize high-precision measurement of the gap between the mask and the wafer in a complex lithography environment, and has the characteristics of high precision and strong anti-interference ability.

The application discloses a composite fringe phase-shifting phase demodulation method and device and a storage medium, and the method comprises the following steps: combining a phase-shifting method and a cosine function to generate a group of fringe patterns; wherein the fringe patterns contain two frequency components; projecting a measured object based on the fringe patterns and collecting a projection image; calculating two groups of phases from the projection image, and unfolding the two groups of phases according to a double-frequency heterodyne principle to obtain a phase unfolding result. The two groups of fringe patterns of the double-frequency heterodyne are combined into one group, two groups of phases are obtained through mathematical principles, an additional projection of a gray code pattern or a fringe pattern of a second group of frequencies is not needed, the number of projection patterns and the number of collected fringe patterns are greatly reduced, the phases of all pixel points are independently calculated, error accumulation is avoided, the efficiency is greatly improved while a certain precision is ensured, and the purpose of quickly and completely and accurately obtaining a phase unfolding result is achieved.

A defect detection system includes a light source configured to project a fringe pattern onto a surface. The fringe pattern includes a ratio of dark portions to light portions of at least 1.5 and a fringe pattern having a period of at least 1 millimeter. The defect detection system further includes an image capturing device configured to capture an image of the projected fringe pattern. The defect detection system further includes a movement mechanism configured to move the image capturing device at an angle of between 30° and 90°, measured from perpendicular to the surface. The defect detection system further includes an image analyzer configured to detect a defect on the surface, based on the captured image. The defect detection system further includes a defect characterizer configured to provide a defect characteristic. The defect detection system further includes a communication component configured to report the defect characteristic.