8 results about "Sinusoidal grating" patented technology

The invention discloses a high-reflective surface defect detection method based on structured light and phase deflection, which belongs to the technical field of visual inspection, and comprises the following steps: generating a multi-frequency sinusoidal grating pattern by using a structured light module, and projecting the multi-frequency sinusoidal grating pattern to the surface of a detected object; multi-frequency phase shift coding is introduced, an absolute phase is calculated through a pilot frequency unwrapping method, a depth map obtained by the structured light is calculated, and a structured light point cloud is reconstructed; a unit normal vector is calculated, a Poisson reconstruction model is adopted to obtain a depth map obtained by phase deflection, and deflection point cloud is obtained; the structured light point cloud data and the deflection point cloud data are registered through an iterative nearest point algorithm and then fused to form a fused depth map; and determining a defect area by adopting the maximum principal curvature and the minimum principal curvature combined mask. By means of the mode, the limitation of a traditional three-dimensional measurement means in high-reflection and complex-curvature surface defect recognition is solved, and submicron-level three-dimensional deformation detection precision is achieved.

This invention relates to a device and method for measuring helicopter rotor blade deformation, comprising: two semiconductor lasers, two sinusoidal gratings, two linear CCD arrays, and a data receiving and processing unit. The semiconductor lasers emit light beams as optical cutters. The sinusoidal gratings receive the light beams, which then fall onto the spanwise plane of the rotor blade, forming stripes. The linear CCD arrays collect all the stripes on the blade surface. The data receiving and processing unit receives the stripe information collected by the linear CCD arrays and applies Fourier transform profilometry to obtain the three-dimensional surface profile of the rotor blade under test. Furthermore, by comparing the three-dimensional surface profiles of the rotor blade under test at different rotor speeds, the amount of blade deformation is obtained. Determining the blade deformation at two different rotor speeds using the three-dimensional surface profile of the blade improves the accuracy of blade deformation measurement.

A visual noise exclusion ability evaluation method based on contrast modulation grating, comprising the following steps: S1, combining the constructed grating noise image; S2, obtaining the contrast modulation grating image with specific noise; S3, the display of the grating is directly opposite to the subject with a set distance, the display displays a general gray background with the brightness being the maximum brightness of the display, and the evaluation is started; S4, after the image appears, the grating is randomly oriented, appears on the screen for a set time and disappears, and then the subject answers the orientation of the grating; when the answer of the subject is consistent with the orientation of the grating, the contrast of the grating in the next test is reduced until the subject cannot judge correctly. The noise information with the same or close spatial frequency as the grating picture is superimposed on the sine grating picture, so that the visual noise information exclusion ability of the subject at the spatial frequency can be more accurately evaluated.

The focal depth lengthening intraocular lens comprises an optical body, the optical body is provided with an optical surface, the optical surface is sequentially provided with a central area, a grating area and an edge area from inside to outside, and light waves of a light source pass through the central area and the edge area to form a fundamental wave light function; the grating area is provided with a sine amplitude grating used for forming multiple harmonic waves, and the fundamental wave optical function and the optical function of the multiple harmonic waves interfere with each other at the same position. According to the intraocular lens with the extended focal depth, the sine amplitude grating is overlaid on the optical surface, multiple harmonic waves coherent with light waves of a light source are generated through fundamental wave interference of a central area and an edge area, finally, the multiple harmonic waves and the light waves form stable and continuous steady-state harmonic waves through interference, and the purpose of extending the focal depth is achieved; the intraocular lens capable of prolonging the focal depth can continuously and clearly image within the focal depth range, light energy loss is reduced, postoperative visual adaptability of a patient is improved, and the intraocular lens is simple in structure and good in stability.

The invention provides a three-dimensional reconstruction method, equipment, system and device and a storage medium. The method comprises the following steps: acquiring a coded stripe pattern which is projected to the surface of a measured object and is based on time sequence change; the coding stripe pattern comprises two groups of first sinusoidal grating stripe images with the same periodicity and at least one group of second sinusoidal grating stripe images with the periodicity less than that of the first sinusoidal grating stripe images; obtaining first three-dimensional point cloud data according to the group of first sinusoidal grating stripe images and the at least one group of second sinusoidal grating stripe images; obtaining second three-dimensional point cloud data according to the other group of first sinusoidal grating stripe images and at least one group of second sinusoidal grating stripe images; the first three-dimensional point cloud data and the second three-dimensional point cloud data are converted to the same pose and then fused, and third three-dimensional point cloud data are obtained; and determining a three-dimensional surface model of the measured object according to the third three-dimensional point cloud data. According to the method, two pieces of three-dimensional point cloud data are reconstructed according to a group of coding stripe patterns, and the three-dimensional reconstruction effect is better.

The invention provides a three-dimensional measurement method and system based on dual-frequency time domain unwrapping, and the method comprises the steps: carrying out the parameter calibration of an image collection device; performing sine correction on the grating fringes projected by the grating fringe projection device; sequentially projecting high and low sinusoidal grating stripes with different frequencies to the surface of a measured object, performing phase shift scanning on each frequency, and collecting a deformation image; recognizing and processing a projection blind area through a maximum light intensity threshold value method or a light intensity difference value self-judgment method; and calculating the three-dimensional coordinates of each point on the surface of the measured object based on a dual-frequency time domain phase unwrapping algorithm, and generating a three-dimensional data file in an STL format. According to the three-dimensional measurement method and system based on double-frequency time domain unwrapping, discontinuous and abrupt-change molded surface objects which are difficult to process by a traditional method can be measured in a high-precision mode, the stay wire phenomenon and noise interference are effectively eliminated, and compared with a three-frequency method, the number of collected images is reduced, and the measurement efficiency is improved.

An aniseikonia measurement method. Mainly the problem that the aniseikonia size of the corresponding area of the retina cannot be accurately measured at present. It is characterized by comprising the following steps: step one, calibration, a cross mark and white points in the first and third quadrants are presented in front of the left eye of the subject, and a cross mark and white points in the second and fourth quadrants are presented in front of the right eye of the subject; the subject adjusts the position of the visual stimulus through the direction key until the four white points are symmetrically distributed around the cross; step two, measurement, a circular sinusoidal grating is presented in front of the dominant eye of the subject, and a hollow circle is presented in front of the non-dominant eye; the central part of the circular sinusoidal grating and the hollow circle has a black fixation point; the subject adjusts the size of the green hollow circle through the key so that it is consistent with the size of the circular sinusoidal grating; the measurement method presents double-eye stimuli (green hollow circle and circular sinusoidal grating respectively) at the same position, and the aniseikonia size of the corresponding area of the retina of the double eyes can be measured.

The application provides a three-dimensional measurement method and system based on double-frequency time domain unwrapping, wherein the method comprises the following steps: parameter calibration is performed on an image acquisition device; sinusoidal correction is performed on grating fringes projected by a grating fringe projection device; high and low sinusoidal grating fringes of different frequencies are projected onto the surface of a measured object in sequence, phase shift scanning is performed on each frequency, and deformed images are collected; a maximum light intensity threshold method or a light intensity difference self-determination method is used to identify and process a projection blind area; and three-dimensional coordinates of each point on the surface of the measured object are calculated based on a double-frequency time domain phase unwrapping algorithm, and an STL format three-dimensional data file is generated. The three-dimensional measurement method and system based on double-frequency time domain unwrapping can not only measure discontinuous and mutant surface objects which are difficult to process by traditional methods with high precision, effectively eliminate the pull line phenomenon and noise point interference, but also reduce the number of image collection compared with a three-frequency method, and improve the measurement efficiency.