11 results about "Phase shifting algorithm" patented technology

The invention discloses a precise measurement method for object surface out-of-plane displacement under high-frequency micro-vibration. The method comprises the following steps: exciting an object to generate high-frequency steady-state vibration through a vibration exciter, freezing a surface state at any vibration position of the object by adopting stroboscopic pulse laser with strictly same frequency as the vibration, and forming a shear speckle field by utilizing a Michelson interferometer comprising a piezoelectric ceramic driving phase-shifting mirror. The movement of the phase shift mirror and the acquisition of the high-speed camera as well as the actions of the stroboscopic laser and the vibration exciter are synchronously controlled through the double-signal controller, so that the accurate acquisition of multiple phase shift speckle interference images is realized. The image is processed based on a four-step phase shift algorithm, and the phase difference of the vibration position is calculated, so that the out-of-plane displacement derivative and the out-of-plane displacement in the shearing direction are calculated. According to the invention, the signal-to-noise ratio and the sensitivity of vibration measurement are obviously improved, and the method has full-field, non-contact and micro-nano displacement resolution capabilities, and is suitable for the fields of material nondestructive testing and structure health monitoring.

The invention relates to the technical field of optical fiber optical measurement, in particular to a multimode optical fiber temperature and stress measurement and regional demodulating method and system.The single-frequency laser emitted by a tail fiber laser enters a measuring arm multimode optical fiber and a reference arm multimode optical fiber through a beam splitter, emergent light is collimated and polarized, then combined by a polarization beam combining crystal and modulated by a quarter-wave plate, and then the single-frequency laser and the reference arm multimode optical fiber are output. And finally, the interference fringes are recorded by the polarization mask camera. A wavefront phase image is reconstructed through a four-step phase shift algorithm, and two characteristic parameters of inclination angle change and wavefront phase distribution change of interference fringes are extracted. According to the invention, two-parameter decoupling is realized by utilizing the difference of wavefront response mechanisms of the multimode optical fiber under the action of temperature and stress, and the device has the advantages of high real-time performance, light intensity interference resistance and compact structure, and is suitable for temperature and stress integrated precision measurement in the fields of industrial monitoring and aerospace.

The application discloses a precision surface three-dimensional appearance measurement device and method based on phase shift digital holography, which comprises the following modules: a light beam splitting module for generating a reference light and an object light beam irradiated to the surface of a measured object and returned; a reference light beam adjusting module for receiving the reference light generated by the light beam splitting module, generating different reference light beams based on different voltage forces, and generating different reference light beams after different brightening and increasing; a lens imaging system for receiving the object light beam generated by the light beam splitting module and performing light beam amplification; a second polarization beam splitter for receiving the different reference light beams generated by the reference light beam adjusting module and the amplified object light beam of the lens imaging system, and performing light beam combination; a linear polaroid for respectively interfering a series of light beams after combination; an image acquisition module for acquiring a series of interference images; and a computer for receiving the series of interference images transmitted by the image acquisition module, extracting phase information of the object light by using a phase shift algorithm, and realizing measurement of the three-dimensional appearance of the surface of the measured object.

This invention discloses a stripe projection 3D imaging system based on a Micro-LED array. Its 3D information acquisition module consists of an integrated packaged Micro-LED driver board, a Micro-LED array, a micro-projection module, and a CCD camera. The 3D reconstruction module utilizes a computer. The micro-projection module is equipped with a plano-convex lens and a mechanical focusing damping structure, and is separately arranged in the front and rear optical paths of the Micro-LED array. The system's workflow is as follows: the driver board reads pre-stored stripe pattern data and timing-controls the Micro-LED array to output coded structured light stripes; the focusing structure adjusts the object distance in the optical path, focusing and scaling the stripes before projecting them onto the surface of the object being measured; the CCD camera simultaneously acquires a sequence of deformed images modulated by the object's shape and transmits it to the computer; the computer combines a multi-step phase-shifting algorithm and Gray code rules to complete phase calculation and unfolding, and, combined with a preset phase-height mapping relationship, reconstructs the 3D shape and point cloud data of the object being measured. This invention enables low-cost, miniaturized, and high-performance 3D shape measurement.

According to an inverse Hartmann wavefront detection principle, the invention provides a wavefront aberration measurement method for a simplified system of a terminal optical component. According to the method, a wavefront aberration measurement system is formed by a camera and a display, phase shift stripes are displayed on the display to serve as a structured light source, the camera collects stripe patterns modulated and emitted by a to-be-measured system, phase information is obtained based on a phase shift algorithm, and then coordinates of the display are obtained; and the coordinates of the emergent surface of the to-be-measured system are obtained through ray tracing in combination with system calibration parameters, and finally the slope of the actual emergent ray of the to-be-measured optical system can be obtained, so that the wavefront aberration is obtained. The device has the advantages of simple structure, low detection cost, high precision and high resolution.

The application provides a binocular vision calibration method and system, and belongs to the technical field of lens calibration. The method comprises the following steps: controlling a left camera and a right camera to simultaneously collect dynamic target patterns displayed on a liquid crystal display screen in sequence; based on a three-step phase shift algorithm, the truncated phase of a phase target image and the encoded phase of an encoded target image are recovered, and the image coordinates and the world coordinates of target feature points are determined according to the truncated phase and the encoded phase respectively; the position or orientation of the liquid crystal display screen is adjusted for a preset number of times, and the above steps are repeated to determine a plurality of image coordinates and world coordinates; a projection equation set of the binocular vision system is constructed according to the image coordinates and the world coordinates of the target feature points, and the internal and external parameters of the double-face camera are determined according to a nonlinear optimization algorithm. The application solves the problem that there is no binocular vision calibration method with strong flexibility, strong universality and the ability to adapt to application scenarios with a small depth of field range or a small common field of view in the prior art.

The invention relates to an on-line optical interference flatness measuring method for a high-resistance silicon wafer, which belongs to the technical field of semiconductor silicon wafer processing and comprises the following operation steps: step 1, feeding and positioning are carried out, and the silicon wafer is placed at a specified position of a measuring table; and 2, starting the rapid automatic focusing system to complete the focal length adjustment of the objective lens. 3, the piezoelectric ceramic driver pushes the reference mirror to move according to the set step length, and meanwhile the high-speed camera synchronously collects a plurality of phase-shift interferograms; and 4, a built-in high-performance processor operates a phase shift algorithm in real time, reconstructs a three-dimensional morphology graph of the whole silicon wafer, and immediately calculates key flatness parameters. And fifthly, sorting and discharging are conducted. By avoiding electrical measurement, the problem that the high-resistance silicon wafer is difficult to detect by a traditional method due to poor conductivity is solved. The whole process is highly automatic, rapid focusing, synchronous phase shift acquisition, real-time calculation and automatic sorting are integrated, and efficient and accurate flatness detection on a production line is realized.

The application discloses a kind of deep hole surface topography measurement systems based on low coherence interference, including detection part and autocollimation system, detection part includes the white light interference system, specifically 1550nm ASE broadband light source, first mirror, first beam splitter prism, second mirror, reference mirror are sequentially arranged, two sides of first beam splitter prism are respectively provided with to-be-measured deep hole, near-infrared camera, and conical prism is arranged in to-be-measured deep hole;Autocollimation system is arranged between to-be-measured deep hole and first beam splitter prism, and autocollimation system includes sequentially arranged 630nm light source, dichroic prism, second beam splitter prism, third mirror, four-quadrant detector.The application can realize one-time scanning to deep hole surface topography, and multiple measurements are obtained by four-step phase shift algorithm, splicing algorithm and alignment algorithm, to realize the reconstruction of surface three-dimensional topography.In the device, autocollimation system is designed, the error generated by the deflection of the horizontal placement of the rod can be measured and error compensation is carried out.

This invention relates to the field of fiber optic measurement technology, and particularly to a method and system for measuring and modulating temperature and stress in multimode fiber optics. The method utilizes a single-frequency laser emitted from a pigtail laser, which is then split by a beam splitter and fed into the multimode fiber of the measurement and reference arms. The outgoing light is collimated, polarized, and then combined by a polarization combining crystal. After being modulated by a quarter-wave plate, interference fringes are finally recorded by a polarization mask camera. A four-step phase-shifting algorithm is used to reconstruct the wavefront phase image, extracting two characteristic parameters: the change in the tilt angle of the interference fringes and the change in the wavefront phase distribution. This invention leverages the differences in wavefront response mechanisms of multimode fibers under temperature and stress to achieve two-parameter decoupling. It offers advantages such as high real-time performance, resistance to strong light interference, and a compact structure, making it suitable for integrated precision temperature and stress measurement in industrial monitoring and aerospace fields.

The application discloses a phase-shifting interferometry method for non-iterative calculation of phase tilt parameters, which comprises the following steps: estimating a tilt term of a phase in an interferogram as an initial value; constructing a least square fitting according to the initial value of the tilt term to obtain a constant term in the phase; constructing a least square fitting according to the obtained constant term of the phase and the estimated tilt term in the x direction to obtain a tilt term in the y direction; constructing a least square fitting according to the obtained constant term of the phase and the obtained tilt term in the y direction to obtain a tilt term in the x direction; repeating the previous steps to obtain tilt parameters of a phase of a phase-shifting interferogram for each frame of the interferogram; obtaining a phase shift by subtracting the tilt parameters of the phase-shifting interferogram; obtaining a phase distribution according to a least square phase shifting algorithm to complete the phase-shifting interferometry. The application can efficiently and accurately complete the phase-shifting interferometry in a vibration environment.

This invention discloses an embryo adaptive quantitative phase imaging system and method based on real-time phase shift feedback. The system includes an illumination module, an imaging module, and a quantitative phase imaging module arranged sequentially along the optical path. The Nomaski prism in the imaging module is equipped with a mechanical transmission device, enabling high-precision displacement along the shear direction. The quantitative phase imaging module measures the sample phase difference using a spatial light modulator and a four-step phase shift algorithm. Based on the measurement results, the system calculates the required prism displacement and dynamically adjusts the prism position to maintain the total system phase difference at an optimal state of π / 2. This invention solves the problem that traditional differential interferometry systems cannot adapt to dynamic changes in sample phase due to fixed prism positions, achieving real-time optimization of imaging contrast, and is particularly suitable for dynamic observation of embryonic development.