High-accuracy misalignment measurement with a large range remains challenging in lithography. Although overlapping circular gratings generate isotropic moir & eacute; fringes capable of two-dimensional measurement, their complex phase variations limit accuracy and practical applications. We propose a novel displacement measurement method using circular gratings that eliminates the prerequisite of knowing reference centers. This method incorporates previously neglected high-order harmonics, thereby enhancing measurement accuracy. First, the intensity of moir & eacute; fringes is modeled as a polynomial amplitude-modulated sinusoidal signal, whose coefficients enable efficient phase extraction via linear least-squares algorithms. Then, maximum likelihood estimation integrates high-order angular harmonic amplitudes of the phase measured at multiple origin positions, yielding precise and robust displacement measurements. The results demonstrate that incorporation of the second harmonic significantly improves performance over linear methods based on windowed Fourier transform and wavelet transform, achieving sub-100 nm experimental accuracy and sub-10 nm theoretical accuracy. The flexible parameter selection enables a trade-off between precision and robustness across diverse grating periods and sizes. This framework expands the versatility and applicability of circular gratings, demonstrating their substantial potential for misalignment measurement.

Line laser scanning system based on high-resolution cameras (HR-LLSS) is widely applied in large-scale three-dimensional (3D) measurement scenarios owing to its high accuracy and strong anti-interference capability. However, due to the inherent trade-off between high resolution and frame rate in imaging sensors, existing large-scale HR-LLSS methods struggle to achieve high-speed without introducing additional measurement errors or high system cost. In this paper, we propose a novel laser scanning method based on spatio-temporal division multiplexing, a technique that significantly improves the exposure duty cycle of image sensors. This method utilizes a high-speed galvanometer to achieve active spatiotemporal encoding of the laser beam within a single exposure period. To decode the aliased high-density laser stripe patterns, this paper innovatively integrates a high-speed camera into the measurement system for capturing temporal characteristics and proposes a concise method that establishes a lookup table of the spatial light planes. On this basis, a multi-line laser stripe matching (MLSM) algorithm is introduced, leveraging multi-constraint fusion across temporal, spatial, and local region-level consistency. Experimental results demonstrate that the proposed system achieves an acquisition speed equivalent to a 21-line diffractive multi-line laser, while simultaneously achieving matching accuracy of 99.64% and 99.14% on the left and right high-density stripe images, respectively. This work proposes a novel scanning technique for high-speed and high-accuracy large-scale 3D measurement using HR-LLSS and presents an effective solution for the accurate order identification of high-density multi-line laser patterns.

This paper proposes a novel three-dimensional (3D) measurement system that employs multi-line structured light generated by a dual-grating diffraction scheme. By exploiting the beam-splitting characteristics of diffraction gratings, a fixed grating is used to realize light separation, while a rotating grating enables spatial scanning. This configuration allows the generation of a larger number of laser lines with a well-defined and precise spatial structure, resulting in a compact measurement setup. Meanwhile, the spatial structure of the multi-line laser produced by dual-grating diffraction is utilized to achieve high accuracy light plane calibration of the system. Furthermore, by combining the beam-splitting characteristics of the laser grating with the epipolar constraints of the dual-camera system, the search range for matching laser lines is significantly reduced, thereby improving matching efficiency. Experimental results demonstrate the effectiveness and accuracy of the proposed measurement system. Compared with conventional multi-line structured light 3D measurement methods, the proposed method achieves a measurement accuracy better than 34 mu m while improving measurement efficiency by 39%. The system features a compact structure, and gets rid of motion of the measured object, indicating application potential in practical 3D measurement scenarios.

This study focuses on the topographic structure of optical anisotropy maps (theziograms) of dehydrated blood plasma films (facies) to identify and utilize markers for diagnosing self-similarity (multifractality) in the birefringence parameters of supramolecular protein networks. The research is based on the Jones-matrix analytical framework, which describes the formation of polarization-structural speckle fields in polycrystalline blood plasma facies. In the proposed model, algorithms were developed to relate the real and imaginary parts of the complex elements of the Jones matrix to the theziograms of linear and circular birefringence. To experimentally implement these algorithms, a novel optical technology was introduced for polarization-interference registration and phase scanning of the laser speckle field of blood plasma facies. The laser-based Jones-matrix layer-by-layer theziography relies on polarization filtration and the digital recording of interference patterns from microscopic images of blood plasma facies. This process includes digital 2D Fourier reconstruction and phase-by-phase scanning of the object field of complex amplitudes, enabling the acquisition of phase sections of laser polarization-structural speckle field components scattered with varying multiplicities. Jones-matrix images of supramolecular networks, along with their corresponding theziograms of linear and circular birefringence, were obtained for each phase plane. The experimental data derived from laser layer-by-layer Jones-matrix theziography were quantitatively analyzed using two complementary approaches: statistical analysis (central moments of the 1st to 4th orders) and multifractal analysis (spectra of fractal dimension distributions). As a result, the most sensitive markers—namely asymmetry and kurtosis—were identified, highlighting changes in the statistical and scale self-similar structures of the theziograms of linear and circular birefringence in blood plasma facies. The practical aspect of this work is to evaluate the diagnostic potential of the Jones-matrix theziography method for identifying and differentiating changes in the birefringence of supramolecular networks in blood plasma facies caused by the long-term effects of COVID-19. For this purpose, a control group (healthy donors) and three experimental groups of patients, confirmed to have had COVID-19 one-to-three years prior, were formed. Within the framework of evidence-based medicine, the operational characteristics of the method—sensitivity, specificity, and accuracy—were assessed. The method demonstrated excellent accuracy in the differential diagnosis of the long-term effects of COVID-19. This was achieved by statistically analyzing the spectra of fractal dimensions of Jones-matrix theziograms reconstructed in the phase plane of single scattering within the volume of blood plasma facies.

The micro-electro-mechanical system (MEMS) has the advantages of high frequency and low size, and the uniaxial MEMS-based 3D measurement system has attracted much attention. However, the reconstruction and calibration processes of existing methods are complicated. In this paper, an efficient 3D reconstruction method is proposed. First, the MEMS coordinate system (MCS) is established according to the mathematical model of the MEMS mirror, then the simple constraint is obtained in the MCS, and the 3D points are recovered in a triangulation-like form. Furthermore, a simple calibration method for the MCS is proposed, which requires only one calibration position to complete the calibration, greatly simplifying the calibration process. Quantitative and comparative experiments verify the feasibility and effectiveness of the proposed method.

The article describes a technique for digital holographic reconstruction of complex amplitude fields in diffuse blood facies using laser polarization-interference phase scanning to isolate a single scattered component of the object field. This method serves as the basis for developing algorithms for Mueller-matrix reconstruction of linear and circular birefringence parameters in the polycrystalline architectonics of blood facies. Statistical (central moments of the 1st-4th orders) and multifractal analyses (fractal dimension spectra) are applied to study the optical anisotropy maps of polycrystalline networks during blood dehydration. The study explores a practical application in the differential diagnosis of blood loss volume, identifying higher-order central moments (skewness, kurtosis) as sensitive markers. The method achieved a maximum accuracy of 92.9% in differentiating blood loss volume.

Galvanometer line laser scanning system (GLLSS) offers the advantage of high scanning speeds in three-dimensional measurement fields. However, due to the lack of rigorous mathematical models, existing calibration methods find it difficult to realize high-accuracy measurements when the incident laser light plane is not aligned with the galvanometer axis, which restricts their applications in some complicated scenarios, such as oblique scanning, multilaser, and complex shape measurements. In this paper, we propose a universal mathematical model of GLLSS, which can reveal the dynamic relationship among the reflection light planes during galvanometer deflection. Based on the object-image transformation relationship in specular reflection, the rigorous relationship among the reflection light planes at different angles is quantitatively established by the galvanometer parameters in the form of matrices multiplication. On this basis, a calibration method for obtaining the parameters in the GLLSS model is presented. A strategy that integrates local optimization with global optimization is employed to reduce the computational complexity and enhance the calibration accuracy. The universality and accuracy of the proposed method are verified by comparative experiments. This method ensures that the root mean square errors of the standard sphere are kept within 0.07 mm, and the planeness errors are kept within 0.056 mm under different assembly conditions. Experimental results demonstrate the high accuracy and good universality of the presented method, which provides a novel practicable method for the calibration of GLLSS and expands its applications.

To date, visual analysis is mainly used to evaluate images of dehydrated films (facies) of biological fluids—microscopy at various magnifications, illumination with white or polarized light, as well as using a dark field. At the same time, important information on the architectonics of optically anisotropic supramolecular networks of facies is unknown (inaccessible). In our work, a model of optical anisotropy of the architectonics of supramolecular networks of blood facies is proposed. Algorithms and a methodology for a new multifunctional method of polarization-interference visualization of the Jones matrix and digital layer-by-layer phase reconstruction of optical anisotropy maps (theziograms) have been developed. As a result, statistically significant markers of oncological changes in the polycrystalline architectonics of supramolecular networks of blood facies samples from healthy donors and patients with papillary thyroid cancer at different stages of the oncological process have been determined and physically analyzed. A comparative study of the diagnostic efficiency of Jones matrix theziography (JT) and Mueller matrix diffusion tomography (MDT) of blood facies samples was conducted within the framework of evidence-based medicine. The main advantages of the Jones matrix method are shown: its multifunctionality (complex detection of birefringence and dichroism), high accuracy of early (stage 1: JM—90.4% and MDT—78.8%) and current (stage 2: JM—96.2% and MDT—88.5%) cancer diagnostics and an excellent level (JM—94.2% and MDT—84.6%) of differentiation of papillary thyroid cancer stages.

A new polarization-interference biomedical diagnostic three-dimensional (3D) Jones-matrix technology with digital Fourier reconstruction of layered maps of optical anisotropy (thesiograms) of dehydrated films (facies) of biological fluids of human organs is presented and experimentally tested. An original model of layered phase scanning of polycrystalline architectonics of supramolecular networks of biological fluid facies is proposed for the purpose of theoretical justification and prognostic use of the obtained results. On its basis, algorithms of Jones-matrix reconstruction of thesiograms of birefringence and dichroism of facies of synovial fluid, bile and blood are found. As a result, layered thesiograms of linear and circular birefringence and dichroism of facies with different spatial-angular architectonics of supramolecular networks are experimentally obtained for the first time. Within the framework of statistical analysis of experimental data, new objective markers (asymmetry and excess of optical anisotropy parameter distributions) for diagnostics of pathological changes in the optical anisotropy of biological fluid facies were defined and clinically tested. As a result, an excellent level of balanced accuracy of the developed polarization-interference Jones-matrix method of layer-by-layer reconstruction of thesiograms of polycrystalline supramolecular networks in differential diagnostics of bile facies (cholelithiasis), synovial fluid (reactive synovitis-septic arthritis) and whole blood (follicular adenoma-papillary thyroid cancer) was achieved.

Our goal was to develop and experimentally validate a polarization-interference method for phase scanning of laser speckle fields generated by diffuse layers of birefringent biological tissues. This method isolates and uses new diagnostic parameters related to the “phase waves of local depolarization”. We combined polarization-interference registration with phase scanning of complex amplitude distributions in diffuse laser speckle fields to detect phase waves of local depolarization in birefringent fibrillar networks of biological tissue and measure their modulation depth. This approach led to the discovery of new criteria for differentiating various necrotic changes in diffuse histological samples of myocardial tissue from deceased individuals with “ischemic heart disease (IHD) — acute coronary insufficiency (ACI)”, even in the presence of a high level of depolarized background. To evaluate the degree of necrotic changes in the optical anisotropy of diffuse myocardial layers, a new quantitative parameter — modulation depth of local depolarization wave fluctuations — has been proposed. Using this approach, for the first time, differentiation of diffuse myocardial samples from deceased individuals with IHD and ACI was achieved with a very good 90.45% and outstanding accuracy of 95.2%.

Fringe projection profilometry is a significant method for three-dimensional measurement due to its non-contact and high accuracy. However, the motion-induced error will lead to the loss of measurement accuracy in dynamic scenes due to the disruption of the phase measurement process. In this paper, we introduce a novel motion error model that considers object motion causes the misalignment of the projection points on the camera, and propose the projection points tracking method to reduce the motion-induced error. First, the speckle pattern is added to projection sequences, after which the projection point displacements are determined using the digital image correlation (DIC) method between the adjacent speckle patterns. Finally, the fringe patterns are corrected using the image remapping method to calculate the 3D shape. Quantitative analysis and dynamic measurement experiments verify the feasibility of the proposed method. Different from 3D-DIC, we use one camera-projector system to realize high-accuracy measurement in dynamic scenes.

Because derivation of retinal organoids (ROs) and transplantation are frequently split between geographically distant locations, we developed a special shipping device and protocol capable of the organoids' delivery to any location. Human embryonic stem cell (hESC)-derived ROs were differentiated from the hESC line H1 (WA01), shipped overnight to another location, and then transplanted into the subretinal space of blind immunodeficient retinal degeneration (RD) rats. Development of transplants was monitored by spectral-domain optical coherence tomography. Visual function was accessed by optokinetic tests and superior colliculus (SC) electrophysiology. Cryostat sections through transplants were stained with hematoxylin and eosin; or processed for immunohistochemistry to label human donor cells, retinal cell types, and synaptic markers. After transplantation, ROs integrated into the host RD retina, formed functional photoreceptors, and improved vision in rats with advanced RD. The survival and vision improvement are comparable with our previous results of hESC-ROs without a long-distance delivery. Furthermore, for the first time in the stem cell transplantation field, we demonstrated that the response heatmap on the SC showed a similar shape to the location of the transplant in the host retina, which suggested the point-to-point projection of the transplant from the retina to SC. In conclusion, our results showed that using our special device and protocol, the hESC-derived ROs can be shipped over long distance and are capable of survival and visual improvement after transplantation into the RD rats. Our data provide a proof-of-concept for stem cell replacement as a therapy for RD patients.

360-degree panoramic stereo profilometry has been used in many fields for its large field of view. The paper presents a panoramic stereoscopic scanning measurement system leveraging a camera equipped with a panoramic annular lens and an omnidirectional ring-shaped structured light. The ring-shaped structured light assembly comprises a collimated laser, an axicon lens, and a spherical mirror. The system facilitates a 360-degree panoramic stereo scanning measurement by a translation stage movement. Additionally, based on the calibration result of the panoramic annular camera, we propose a calibration algorithm based on the concept of the light cone to calibrate the spatial position of the ring-shaped structured light during the scanning process. Experimental validation demonstrates the calibration and measurement accuracy of the proposed system. The system features simplicity in structure, ease of calibration, and has significant application prospects.

Multi-line structured light three-dimensional (3D) scanning measurement system enables to obtain the richer 3D profile data of the object simultaneously during one frame, ensuring high accuracy while structured light is deformed for the modulation by the object. Nevertheless, current calibration methods cannot fully take advantage of its high precision. In this paper, a fast and high-accuracy 3D measurement system based on multi-line lasers with a spatially precise structure via integrating a diffraction grating was proposed. This helps achieve precise calibration results of the light planes by introducing spatial constraint relations of the diffractive light, thus improving measurement accuracy. The operating principle and the workflow of the proposed system were described in detail. The measurement accuracy of the developed prototype was verified through contrastive experiments. At a working distance of 400 mm, the results show that the root mean square error (RMSE) of the proposed system is 0.083 mm, which is improved by 37.6% compared to the traditional calibration method of light planes for the ranging system. The system utilizing a grating that facilitates the integration of the device has great application value.

The laser triangulation scanning system (LTSS) is widely employed in three-dimensional (3D) measurement fields owing to its high measurement accuracy. However, due to the limitations of the exploited motion, the traditional LTSS fails to be satisfactory for certain precise and efficient industrial applications. In this paper, a new multi-line laser triangulation scanning system (MLTSS) via integrating a rotary diffraction grating was proposed to address this problem. The image sequence of the divergent laser lines with variable angles on the object can be captured as the grating rotates. This enables to obtain the multiple profiles simultaneously during one frame. A novel method to distinguish laser lines in a single frame which enhances the measurement range was described. The measurement principle and workflow of the proposed system are explained in detail. The calibration algorithm of light planes of the proposed system utilizing the equivalent grating equation is simplified compared to the traditional algorithm. The developed setup and the measured object remain stationary throughout the whole scanning, which relieves the mechanical error caused by the motion. Moreover, the utilized grating facilitates to miniaturize the device. The experiments demonstrate the validity of the proposed system.

The full surface digitization of real samples plays a crucial role in fields such as object recognition, industrial quality control, and reverse modeling. To achieve panoramic three-dimensional (3D) reconstruction of samples in complex scenes, we propose an advanced panoramic laser scanning system, consisting of a laser rotation scanning system and a pair of plane mirrors. With the assistance of mirrors, the projected line laser beam can illuminate the sample from full angles in a single scanning sequence, and the camera can capture the 3D information of the sample from several specific viewpoints. The scanning method of rotating allows us to achieve more efficient and larger-scale 3D scanning. After obtaining the sample's 3D information from different viewpoints using the same calibration parameters, the sample's full-surface 3D data in the global coordinate can be obtained using mirror reflections. We conducted precision and effectiveness tests on samples with different sizes, materials, shapes, and textures to demonstrate the ability of the proposed method to perform full-surface 3D reconstruction under different scenarios. The experimental results of accuracy evaluation demonstrate that the proposed system can achieve a measurement accuracy at the level of 100 mu m. Additionally, the robust experimental results in different scenarios also indicate that the proposed panoramic laser scanning system is capable of accurately obtaining full-surface 3D data of various types of samples, providing a cost-effective, easy-to-use, efficient, high-resolution, and effective approach for achieving panoramic 3D reconstruction.

Phase shifting profilometry has been commonly used in three-dimensional shape measurement with the advantages of high-precision and non-contact. However, it is still challenging to measure high-reflective surface because image saturation will lead to absolute phase errors and reconstruction errors. In this paper, a dual-view multi-intensity projection method was proposed. Compared with the single-view method, the proposed method can reconstruct more points at each projection intensity especially for pixels around the specular angle and reduce the number of projections to reduce the time consumption. First, we established the dual-view structured light system consisting of two monocular systems that share the same projector. Subsequently, a dual-view saturated pixel judging method was proposed that enables the reconstruction results under two views to be combined without duplicate points. The multi-intensity projection method was adopted by reducing the input projection intensity step by step and reconstructing the remaining pixels around the specular angle. Finally, the reconstruction result can be obtained by stitching point clouds at each projection intensity. Experiments verified that the proposed method could improve the integrity of reconstructed point clouds and measurement efficiency.

360 & DEG; three-dimensional (3D) shape measurement is of great significance in the fields of defect detection and reverse modeling. Fringe projection profilometry (FPP) is widely used due to the advantages of high-accuracy and full-field measurement, but the movement of object corrupts the phase measurement. Stereo phase unwrapping (SPU) technique is adopted to improve imaging efficiency, but requires multi-cameras which resulting in high system complexity and cost. In this work, we proposed virtual stereo phase unwrapping (VSPU) method for high-speed 360 & DEG; 3D shape measurement. This method uses the virtual camera-projector systems formed by the rotation of object for phase unwrapping which only requires single camera-projector to achieve 360 & DEG; 3D shape measurement. The phase consistency checking in SPU method is modified. Experiments demonstrate that proposed method has strong robustness and can achieve 360 & DEG; 3D shape measurement in 47 s with an accuracy of 100 & mu;m during continuous rotation of the object.

The digitization of objects' full surfaces finds widespread applications in fields such as virtual reality, art and design, and medical and biological sciences. For the realization of three-dimensional full-surface digitization of objects within complex sceneries, we propose a straightforward, efficient, and robust panoramic three-dimensional optical digitization system. This system contains a laser-based optical three-dimensional measurement system and a bi-mirror. By integrating mirrors into the system, we enable the illumination of the object from all angles using the projected laser beam in a single scanning process. Moreover, the main camera employed in the system can acquire three-dimensional information of the object from several different viewpoints. The rotational scanning method enhances the efficiency and applicability of the three-dimensional scanning process, enabling the acquisition of surface information of large-scale objects. After obtaining the three-dimensional data of the sample from different viewpoints using laser triangulation, mirror reflection transformation was employed to obtain the full-surface three-dimensional data of the object in the global coordinate system. The proposed method has been subjected to precision and validity experiments using samples with different surface characteristics and sizes, resulting in the demonstration of its capability for achieving correct three-dimensional digitization of the entire surface in diverse complex sceneries.