In freeform optical metrology, wavefront fitting over non-circular apertures is hindered by the loss of Zernike polynomial orthogonality and severe sampling grid distortion inherent in standard conformal mappings. To address the resulting numerical instability and fitting bias, we propose a unified framework curve-shortening flow (CSF)-guided progressive quasi-conformal mapping (CSF-QCM), which integrates geometric boundary evolution with topology-aware parameterization. CSF-QCM first smooths complex boundaries via curve-shortening flow, then solves a sparse Laplacian system for harmonic interior coordinates, thereby establishing a stable diffeomorphism between physical and canonical domains. For doubly connected apertures, it preserves topology by computing the conformal modulus via Dirichlet energy minimization and simultaneously mapping both boundaries. Benchmarked against state-of-the-art methods (e.g., Fornberg, Schwarz–Christoffel, and Ricci flow) on representative irregular apertures, CSF-QCM suppresses area distortion and restores discrete orthogonality of the Zernike basis, reducing the Gram matrix condition number from >900 to <8. This enables high-precision reconstruction with RMS residuals as low as 3×10−3λ and up to 92% lower fitting errors than baselines. The framework provides a unified, computationally efficient, and numerically stable solution for wavefront reconstruction in complex off-axis and freeform optical systems.

Obtaining an unobscured starting point for off-axis four-mirror imaging systems is a non-trivial task that traditionally relies heavily on designer expertise and extensive trial-and-error. To address this challenge, we propose an automated framework capable of efficiently constructing initial off-axis four-mirror structures with diverse geometries. An evaluation function is formulated by combining first-order constraints, third-order aberration constraints using nodal aberration theory (NAT), and a "ray-quadrangle" obscuration error function. A hybrid global optimization strategy, named IACOR-NM, is proposed by integrating the Improved ant colony optimization for continuous domains (IACOR) with the Nelder-Mead (NM) simplex method, enabling designer-independent global exploration and rapid obtain unobscured systems. The IACOR quickly locates an unobscured, coarse global optimum, upon which NM performs refined local optimization. This framework allows designers to efficiently assess the optimization potential of different initial structures and rapidly select suitable geometries for further optimization. Using this method, a compact off-axis four-mirror freeform imaging system is constructed, achieving diffraction-limited performance. Moreover, comparative studies against other global optimizers and gradient-based local methods demonstrate the superior optimization capability of the proposed hybrid algorithm.

Chronic infection with Helicobacter pylori (H. pylori) is a major environmental risk factor for gastric carcinogenesis. Malignancy is largely driven by variations within the virulence factor CagA, with East Asian lineages exhibiting higher oncogenic potential than Western ones. However, how these variants modulate cellular crosstalk remains poorly understood. We integrated molecular dynamics (MD) simulations with single-cell transcriptomics across progressive disease stages, including chronic atrophic gastritis, intestinal metaplasia, and gastric cancer. Local niche remodeling was evaluated via cell–cell communication profiling among epithelial, stromal, and immune circuits, while simulations of MARK2 kinase bound to distinct CagA lineages determined binding affinities. Single-cell analysis revealed that H. pylori toxicity progressively dampens epithelial–stromal crosstalk, marked by severe epithelial polarity aberrations that disrupt neuroendocrine-like secretory and synaptic pathways during malignant transformation. Mechanistically, MD simulations and MM/GBSA calculations demonstrated that East Asian CagA lineages exhibit higher binding affinity toward host MARK2 than Western lineages. Specific East Asian amino acid substitutions dramatically tighten the protein interface, driving stronger signaling perturbations. This study bridges atomistic structural virulence with microenvironmental shifting, establishing geographic CagA toxicity divergence as a critical determinant for pathogen-driven gastric cancer risk.

Stacked microlens array scanning imaging systems inevitably suffer from space-variant point spread functions caused by diffraction effects, resulting in severe image blur that is difficult for traditional deconvolution methods to effectively restore. To address this, we employ a sparse matrix to efficiently represent the image degradation process and embed it into an alternating direction method of multipliers optimization framework to establish a space-variant image deblurring model. Building upon this, we design a deep unfolding network, termed the multiple space-variant kernel network (MSVKNet), and compare its restoration performance against a method based on total variation (TV) priors and conjugate gradient (CG) iteration (TV-CG). Simulation results under various system parameters indicate that MSVKNet achieves performance comparable to or better than the TV-CG method in most cases, with an inference speedup of nearly three orders of magnitude. Furthermore, experiments using a dual microlens array imaging system operating in the visible spectrum validate the accuracy and practical utility of the proposed method.

Optical metasurfaces, consisting of two-dimensional nanopillar arrays at the subwavelength scale, enable arbitrary phase manipulation for diffraction-limited imaging. Metalenses based on single or double metasurfaces are lightweight, compact, and support high-resolution imaging, but their practical application in macroscopic optics is hindered by sharply increasing design and fabrication complexity with aperture size. Here, we present a novel metalens design using a fixed-height concentric ring structure. As a demonstration, we design and simulate a wide-field-of-view double-sided metalens with an incident angle of 35 degrees and an F-number of 2, achieving a modulation transfer function (MTF) above 0.2 at 125lp/mm across the field and a central focusing efficiency of 53 %. Compared to traditional two-dimensional nanopillar arrays, this concentric ring approach reduces the number of microstructures by 4-5 orders of magnitude, significantly lowering simulation and fabrication costs and complexity, and facilitating large-aperture metalens manufacturing. This work provides a promising route for the practical deployment of metalenses in macroscopic optical imaging.

Background:Pediatric severe aplastic anemia (SAA) is a rare diagnosis characterized by pancytopenia with a hypocellular bone marrow. Patients with inherited bone marrow failure syndromes (IBMFS) need to be distinguished from those with idiopathic SAA as the underlying etiology significantly impacts treatment and long-term management decisions. However, awaiting genetic testing results before initiating therapy for idiopathic SAA risks life-threatening complications from prolonged, severe cytopenias. Prior genomic studies have reported a significant incidence of unrecognized IBMFS among patients with SAA; however, these studies did not incorporate the comprehensive clinical and laboratory testing currently used for the diagnostic workup of SAA, which has evolved with our increasing understanding of IBMFS. This study aims to investigate the incidence of cryptic IBMFS among pediatric patients with SAA who have undergone diagnostic evaluation with current standard-of-care clinical and laboratory assessments. Methods: This is a retrospective study of 149 pediatric and young adult patients (age <21 years) who underwent a comprehensive clinical evaluation for SAA from 4 pediatric institutions. All patients met Camitta criteria for SAA diagnosis. Clinical and laboratory testing including Fanconi anemia chromosomal breakage studies, telomere length testing, paroxysmal nocturnal hemagobinuria (PNH) flow cytometry, and bone marrow evaluations were extracted from medical records. Enhanced whole exome sequencing (WES) with added coverage of clinically relevant non-coding sequences was performed for all patients. Analysis focused on variants in 102 IBMFS-associated genes. Results: The median age at diagnosis was 10.15 years (range 1.28 to 20.79 years) with a median length of follow-up of 4.83 years (range 0 – 17.35 years). 98 patients (65.8%) were males. Of the 149 patients in the cohort, 113 patients lacked any clinical/family history or laboratory findings to suggest an IBMFS, and of these, none were identified by enhanced WES to have an underlying genetic IBMFS. Of the remaining 36 patients, at least one clinical feature or family history possibly suggestive of an inherited syndrome was identified. These included a history of cytopenias prior to the diagnosis of SAA, lymphocyte telomere lengths suspicious for a telomere biology disorder, low pancreatic isoamylase, congenital anomalies, short stature, dysmorphic features, recurrent infection, neurologic abnormalities, or a family history of bone marrow failure/chronic cytopenias, hematologic malignancy, or solid tumor diagnosed at an early age. Among these 36 patients with a history possibly suggestive of a germline condition, 1 patient was found to have a heterozygous likely pathogenic variant in SAMD9L (c.1877C>T, p.Ser626Leu) consistent with autosomal dominant SAMD9L syndrome. This patient had a 3-generation paternal family history of a cerebellar degenerative disorder and a personal history of mild cognitive impairment, nystagmus, and ataxia in addition to episodes of severe infection prior to the diagnosis of SAA. Another patient with a history of cytopenias prior to SAA diagnosis was found to have two pathogenic variants in ERCC6L2 (c.1930C>T, p.Arg644Ter and a splicing variant c.950+2T>G) though zygosity could not be determined and therefore affected status could not be ascertained. Conclusion:Among a large cohort of pediatric patients presenting with SAA without features of an IBMFS following a comprehensive clinical history, exam, and laboratory evaluation, none had a IBMFS identified by enhanced WES. Among those with clinical features suggestive of a possible inherited syndrome, one patient was diagnosed with SAMD9L syndrome. Another patient had pathogenic variants in ERCC6L2,but allelic phasing could not be ascertained for diagnosis. Delays in initiating SAA treatment can leave patients vulnerable to complications including infection, particularly fungal infections, from prolonged severe neutropenia or bleeding from severe thrombocytopenia. For patients with a diagnostic evaluation concerning for an IBMFS, germline genetic testing should be considered prior to proceeding with SAA therapy. For patients with a negative comprehensive IBMFS workup utilizing current diagnostic clinical and laboratory evaluations, the low likelihood of benefit gained by awaiting genetic testing results must be weighed against the risks of treatment delay for SAA.

High-resolution optical systems impose stringent requirements on manufacturing and assembly tolerances. However, lens decentration, inevitably introduced during fabrication, leads to misalignment of the optical axes between elements, breaking rotational symmetry and consequently degrading imaging performance. Existing manual centering alignment techniques heavily rely on operator experience due to the lack of specific adjustment guidance, resulting in poor precision stability and high randomness. Conversely, computer-aided alignment techniques suffer from high computational costs and a susceptibility to becoming trapped in local optima. This paper proposes an approach for precision optical axis alignment optimization in optical assembly using differentiable optics. By constructing a differentiable ray-tracing model that incorporates lens decentration, a differential correlation mechanism between lens pose parameters (decenter/tilt) and imaging performance metrics is established. Gradient- driven iterative optimization is employed to progressively adjust the pose of elements containing decentration, thereby restoring imaging quality. In validation experiments conducted on a 7-lens airborne camera lens with a large aperture, wide field of view, and large image plane, the full field of view (FOV) spot radius of the system was reduced to 16% of its pre-optimization value after optical axis alignment optimization. Ultimately, this approach yields deterministic pose adjustment parameters. This capability not only provides a quantitative basis for tolerance allocation in complex optical systems, improving lens design, but also supplies direct corrective parameters for automated alignment equipment, significantly enhancing assembly efficiency and precision. These functionalities hold substantial engineering application value in the field of precision optical manufacturing.

Metastasis, the spread of cancer cells from the primary tumor to distant organs, is the leading cause of mortality in cancer patients. This process often exhibits a preference for specific organs, a phenomenon known as tumor organotropism. This study focuses on the organotropism of breast cancer and analyzes its genomic alterations following metastasis to four organs (bone, brain, liver, and lung). The research aims to explore the intrinsic characteristics of primary breast cancer and the interactions between tumor cells and the tumor microenvironment (TME) within these target organs. Building upon this foundation, we developed a deep learning model to identify organ-specific metastatic genes, providing insights into the molecular mechanisms of metastasis. To investigate the mechanisms of organ-specific metastasis in breast cancer, we employed an integrative approach combining single-cell RNA sequencing, bulk RNA sequencing, ChIP-seq data, and deep learning techniques. Single-cell analysis provided detailed insights into cellular heterogeneity and microenvironment interactions at metastatic sites. Bulk RNA sequencing enabled the identification of gene expression patterns associated with metastatic propensity. A deep neural network (DNN) model was developed to analyze these complex datasets and identify key predictors of organ-specific metastasis. Our integrative analysis revealed distinct gene expression profiles and cellular compositions in metastatic lesions across different organs. We have identified that, regardless of the target organ, breast cancer metastasis critically depends on specific biological signaling pathways, including the MAPK signaling pathway, metabolic pathways, the PI3K-Akt signaling pathway, and the positive regulation of cell adhesion. Single-cell sequencing highlighted unique interactions between tumor cells and the microenvironment, which varied significantly depending on the metastatic site. Fibroblasts play a critical role in facilitating the colonization of breast cancer cells in metastatic organs. The deep learning models effectively identified key molecular signatures and pathways associated with organ-specific metastasis, providing insights into the metastatic process. The study underscores the importance of the tumor microenvironment in influencing breast cancer metastasis to distant organs. We also established a comprehensive framework for understanding the mechanisms driving organotropism metastasis in breast cancer. Additionally, we identified key genes and signaling pathways associated with organ-specific metastasis, providing insights that may inform future studies on risk assessment and potential therapeutic targets for metastatic breast cancer.

Laser beam shaping is widely applied in laser processing, illumination and other fields. Aiming at problems existing in previous methods, such as the difficulty in solving surface shapes, poor machinability and the difficulty in tolerance analysis, we present an entire design method for off-axis reflective freeform surface beam shaping systems. The freeform surfaces in the form of annular expansion are construct and optimized. Then, a surface tilt removal algorithm is proposed to reduce the variation amplitude of the mirror's sag, improving the machinability of the mirrors. Moreover, we established a real-time communication model between optical design software and numerical processing software, enabling the automatic statistical analysis of tolerance analysis results. The design example show that the method proposed in this paper can effectively shape Gaussian beams into circular flat-top beams. When the beam propagates from 100 mm to 500 mm, the uniformity variation range is 94.2 %-90.1 %. The surface tilt removal algorithm reduces the variation amplitude of the mirror's sag by more than 87 %. The tolerance results of irradiance uniformity at different propagation distances satisfy the demands of optical manufacture and alignment. This design method can provide valuable insight for the design, tolerance analysis and processing of freeform surface beam shaping systems.

Infrared search and track (IRST) systems demand lightweight, low-power designs to support deployment on small airborne platforms such as unmanned aerial vehicles. A microlens array scanner (MLAS) integrating dual MLAs with a long focal length objective lens enables beam scanning through millimeter-scale lateral displacements, reducing system volume and weight. However, the far-field beam intensity distribution pattern produced by the MLAs resembles that of a two-dimensional grating, which introduces side lobes in the PSF and significantly degrades image quality. Accurate degradation modeling is critical for computational restoration of diffraction-blurred images. However, the PSF is influenced by factors such as field of view, wavelength, and processing and alignment tolerances, thereby significantly increasing simulation complexity. This study presents a physics-based optical simulation platform that integrates geometric ray tracing with the Huygens-Fresnel principle to simulate PSF distributions under realistic conditions. Diffraction-blurred images are synthesized across varying FOVs and wavelengths. The similarity between the simulation and experimental results was evaluated using DISTS, with all values below 0.220, demonstrating the accuracy of the proposed image degradation model. The sensitivity of processing and alignment errors within the system was systematically analyzed. The results indicate that the relative rotational misalignment between the two MLAs exhibits the highest sensitivity to imaging performance. These results provide significant theoretical guidance for the design and optimization of high-resolution MLAS imaging systems.

To address the specific requirements of particle image velocimetry systems in microscopic imaging applications, particularly focusing on the challenges encountered when commercial microscopes fail to meet the demands for long working distance, high resolution, and integrated design, a novel 30X fluorescence detection microscope with a long-working-distance apochromatic objective lens specifically tailored for micro-PIV measurements is developed. The design process employs refractive design principles and an infinity-corrected structure to ensure high-quality imaging across a broad visible light spectrum (400 similar to 800 nm). The illumination system is designed to provide uniform and stable light, which is critical for capturing high-quality fluorescence images. The imaging components, including the objective lens, tube lens, and filters, are meticulously arranged to achieve a compact and user-friendly system. The optical design has been optimized to minimize various aberrations, including chromatic and spherical aberrations, ensuring that the overall imaging performance approaches the diffraction limit. Methods for increasing the working distance and techniques for apochromatic correction are proposed. The main way to increase the working distance is to adjust the focal length and interval of the negative light group and the positive light group. The method of apochromatism is mainly replacing glass materials and combining them. After optimization, a numerical aperture of 0.35, a working distance of 17.3 mm, and a microscopic objective with a magnification of 30 times were formed, which exceeded the limitations of conventional microscopic objectives. Additionally, the mechanical design of the microscope emphasizes robustness and ease of use, with the entire system weighing approximately 17.29 kg and measuring 360 mmX300 mmX300 mm. The entire microscope system is designed to be portable and lightweight, enabling remote operation capabilities. It features excellent sealing properties, allowing it to be deployed in complex environments while minimizing stray light interference. Additionally, the displacement stage provides a user-friendly interface for observing various microfluidic channels, enhancing the system's versatility and usability in diverse experimental settings. Upon completion of the optical and mechanical designs, the optical lens and mechanical structure of the complete system are manufactured. After assembling and building, the system undergoes rigorous testing and evaluation. Initial tests involve imaging a USAF standard resolution target to assess the optical resolution of the microscopic system. The results demonstrate that the microscope achieves a resolution greater than 228 lp/mm, corresponding to a line width of 2.2 mu m, which meets the required specifications for micro-PIV applications. Subsequently, the system is employed in micro-PIV experiments on a microfluidic chip containing fluorescent particles with a velocity of nearly 1 m/s. The particles are illuminated with a 532 nm laser, and a double-exposure camera captured the resulting fluorescence at 613 nm through a 550 nm high-pass filter. The captured images display clear and distinct particle images, even for particles as small as 1 mu m in diameter, confirming the high resolution and sensitivity of the system. These particle images are then processed using a Fourier transform-based cross-correlation algorithm to analyze the velocity field within the microfluidic chip. The algorithm calculates the displacement of particles between two consecutive frames and derives the velocity vectors based on the time interval and magnification factor. The velocity distribution obtained from the experiments shows excellent agreement with theoretical simulations, with a deviation of less than 6% between the measured velocities and the simulated values. The optical and mechanical design of the proposed microscope meets the stringent requirements for high resolution, long working distance, and integrated functionality. The experimental results validate the feasibility and effectiveness of the system, demonstrating its capability to provide clear and accurate particle images and reliable velocity measurements. This work can offer a valuable reference for the development of specialized microscopic imaging systems.

Introduction: While somatic mutations in pediatric AML risk stratification have been extensively characterized, the role of heteroplasmic missense single nucleotide variants in mitochondrial DNA (mtDNA) is undefined. These variants have been correlated with poorer cancer survival rates and mtDNA haplogroups have been shown to modify the risk of various diseases. In this context, we investigated the role of mtDNA heteroplasmic variants and haplogroup identity in pediatric AML survival outcomes. Methods: The study cohort included 1097 eligible patients enrolled in the Children's Oncology Group (COG) clinical trial AAML1031 who had germline whole genome sequencing (WGS) data available. WGS and short read RNA-Seq data were generated through the COG TARGET AML initiative. The aligned CRAM files were harmonized by the Kids First Data Resource Center (DRC) and deposited on the CAVATICA platform. We used SAMtools view to extract mtDNA-mapped reads from WGS data. BCFtools was then used to generate mtDNA consensus FASTA files, which were used for haplogroup assignments with Haplogrep3. Patients were grouped into macrohaplogroups based on the mtDNA phylogenetic tree. For mtDNA variant identification, we used the GATK Best Practices workflow designed for MT short variant discovery. Mutations with variant allele frequency (VAF) between 0.03 and 0.95 were considered heteroplasmic, and those with VAF > 0.95 were deemed homoplasmic. We restricted our analyses to missense single nucleotide variants (SNVs) in coding regions and SNVs in tRNA and rRNA genes, excluding the control region. Gene expression was quantified by the Kids First DRC using RNA-Seq by Expectation-Maximization (RSEM). We extracted 37 MT genes' TPM values from the RSEM results and performed differential gene expression (DEG) analysis using Limma. Results: For the 814 pediatric AML patients with available data on mtDNA variants, a total of 920 unique SNVs were identified. Of those, 257 (28%) were found at heteroplasmic levels. 171 patients (21%) were found to have at least one heteroplasmic SNV. Overall survival (OS) and event-free survival (EFS) probability were comparable in patients with heteroplasmy compared to those without. Moreover, when dividing patients by mtDNA haplogroup (HV, R, UK, N, L, and M), we found no significant differences in OS or EFS. We then examined patients' demographic and disease characteristics by heteroplasmy status. Notably, patients without a CBF-AML classification were significantly enriched in the group with heteroplasmy (p = 0.043), while patients with positive minimal residual disease (MRD) at end-of-induction I (p = 0.002) or belonging to a high-risk AML group (p < 0.001) were significantly over-represented among patients with heteroplasmy. When patient characteristics were analyzed across haplogroups, we found that the distribution of haplogroups varied by the presence of non-CNS extramedullary disease (EMD) (p = 0.014); patients with EMD were under-represented in haplogroup M and over-enriched in haplogroup N. Next, to characterize the potential functional consequence of heteroplasmic missense mutations on respiratory chain proteins, we evaluated the predicted deleteriousness of such mutations using PolyPhen-2 (PMID: 23315928). Of the 158 heteroplasmic missense SNVs, 47% were predicted to be damaging, in contrast to 31% for the 450 homoplasmic missense SNVs (p < 0.001). OS and EFS were comparable in patients with at least one predicted damaging homo- or heteroplasmic SNV compared to those without. Lastly, we examined the association of RNA transcript abundance of MT genes with heteroplasmy and haplogroup. Genes were considered significant if they had an adjusted p-value < 0.05, regardless of fold-change magnitude. Comparing heteroplasmy versus no heteroplasmy revealed no DEGs. In the haplogroup analysis (each haplogroup versus HV), no significant differences were observed for R vs HV or UK vs HV. Comparisons of L vs HV and N vs HV identified 12 genes with significantly decreased expression, with percent decreases ranging from 12% to 38%. The comparison of M vs HV identified 3 genes with significant decreased expression, with percent decreases up to 38%.Conclusions: Our results suggest an association between mtDNA heteroplasmy and high-risk pediatric AML phenotypes, but not differential OS or EFS. Future work on mitochondrial dysfunction in different AML disease statuses may clarify the role of mtDNA variants in risk stratification.

Stemness-associated cell states are linked to chemotherapy resistance in AML. We uncovered a direct mechanistic link between expression of the stem cell transcription factor GATA2 and drug resistance. The GATA-binding protein 2 (GATA2) plays a central role in blood stem cell generation and maintenance. We find substantial intra- and inter-patient variability in GATA2 expression across AML patient samples. GATA2 expression varies by molecular subtype and has been linked to outcome. In a murine model, KMT2A-MLL3 driven AML originating from a stem cell or immature progenitor cell population have higher Gata2 expression and are more resistant to the standard AML chemotherapy agent doxorubicin. Deletion of Gata2 resulted in more robust induction of p53 following exposure to doxorubicin. ChIP-Seq, RNA-Seq and functional studies revealed that GATA2 regulates the expression of RASSF4, a modulator of the p53 inhibitor MDM2. GATA2 and RASSF4 are anti-correlated in human cell lines and AML patient cell bulk and single cell expression datasets. Knockdown of Rassf4 in Gata2 low cells resulted in doxorubicin or nutlin-3 resistance. Conversely, overexpression of Rassf4 results in sensitization of cells expressing high levels of Gata2. Finally, doxorubicin and nutlin-3 are synergistic in Gata2-high murine AML, as well as AML patient samples. We discovered a previously unappreciated role for GATA2 in dampening p53-mediated apoptosis via transcriptional regulation of RASSF4, a modulator of MDM2. This role for GATA2 directly links the expression of a stemness associated transcription factor to chemotherapy resistance.

The depth-of-focus of traditional infrared optical system always has the limited value. Installation errors and environmental temperature changes can cause defocus, degrading the image quality of infrared optical system. Therefore, infrared system imaging with extending depth-of-focus has been a popular research area in optical design. Currently, the depth-of focus expansion methods that researchers usually use have certain drawbacks. As wavefront coding technology gradually rises, it provides a new way to effectively expand the depth-of-focus of infrared optical system. Common infrared detectors are mainly divided into two types uncooled and cooled models. Compared to them, cooled infrared detectors can effectively eliminate the influence of stray light and thermal noise, and have many advantages in applications. Cooled infrared optical system refers to an optical system that matches a cooled infrared detector. The characteristic is that the cold stop of the detector is required as the aperture stop of the infrared optical system. Due to the fact that the phase mask in wavefront coding system needs to be placed at the position of the aperture stop, in order to avoid structure contradiction and reduce design complexity, infrared optical system based on wavefront coding generally matches an uncooled detector, and hardly matches a cooled detector. Therefore, this paper proposes an optical system that matches with a cooled infrared detector. The system uses a secondary imaging structure. It uses the cold stop of the detector as the aperture stop, and makes the cold stop efficiency achieve 100%. At the same time, the parallel plate is also similar to the effect of an aperture stop by controlling the direction of the light. This structure solves the structure conflict between the required position of the phase mask and the position of the cold stop. Finally, the parallel plate changed to the extended polynomial surface type. And the phase mask surface is determined by modifying the polynomial coefficients, successfully introducing the wavefront coding technology into the cooled infrared optical system. In terms of optimizing phase mask parameter, the method of direct iterative calculation by normally combining optical software with evaluation algorithms is not adopted. Instead, the appropriate value is determined by analyzing the different effects of phase mask parameter values. The specific process is to connect the optical design software with Matlab. Firstly, we use optical design software to track the light rays. Secondly, we use Matlab to read the different MTF values corresponding to the cut-off frequency as the phase mask values change, and draw the relationship curve between them. From this, it can be concluded that the phase mask value cannot be too large. Finally, we select four defocus image plane positions within a distance range of 20 times the depth-of-focus of the original system. Taking cosine similarity as the evaluation standard and using Matlab to read and calculate the data in optical software, we can get the similarity degrees between MTF curves with different phase mask values. The relationship curve between the phase mask values and the MTF similarity of the wavefront coding systems at different defocus positions can be drawn. Based on the above conclusions, the critical value that can maintain consistency of MTF is determined as the appropriate phase mask value. After selecting the phase mask value, through comparison, it is found that the MTF of normal infrared optical system gradually decreases with the increase of defocus, and many zero positions appear within the cut-off frequency. After adding a phase mask, the MTF of wavefront coding system keeps good consistency at different defocus positions, which shows that the system is insensitive to defocus. The blurred images of the wavefront coding system are obtained through software simulation experiments. And then PSF is used as a filter in Lucy-Richardson algorithm to restore the images. The lines and characters in the restored images are clearly visible, which verifies that the cooled infrared optical system based on wavefront coding successfully expands the depth-of-focus range to 20 times that of the original system. Considering that the image results are mainly observed directly by human eyes, we not only use the common evaluation method based on root mean square error of image pixels, but also introduce an evaluation index based on human visual perception to comprehensively evaluate the qualities of the restored images. Through the comprehensive analysis of the MSE and MSSIM results, it is concluded that the qualities of the restored images are good. The main factors that cause the slight differences between the original images and the restored images are noise, artifacts, ringing, and match errors between coding and decoding. In addition, the results also reflect that the wavefront coding system can break through the diffraction limit of traditional infrared optical system to some extent, and will have more research space and prospects.

Multi-channel optical systems can provide more feature information compared to single-channel systems, making them valuable for optical remote sensing, target identification, and other applications. The division of aperture polarization imaging modality allows for the simultaneous imaging of targets in the same field of view with a single detector. To overcome the limitations of conventional refractive aperture-divided systems for miniaturization, this work proposes an off-axis catadioptric aperture-divided technique for polarization imaging. First, the design method of the off-axis reflective telescope structure is discussed. The relationship between optical parameters such as magnification, surface coefficient, and primary aberration is studied. Second, by establishing the division of the aperture optical model, the method of maximizing the field of view and aperture is determined. Finally, an off-axis catadioptric cooled aperture-divided infrared optical system with a single aperture focal length of 60 mm is shown as a specific design example. Each channel can achieve 100% cold shield efficiency, and the overall length of the telescope module can be decreased significantly. The image quality of each imaging channel is close to the diffraction limit, verifying the effectiveness and feasibility of the method. The proposed off-axis catadioptric aperture-divided design method holds potential applications in simultaneous infrared polarization imaging.

The aperture-divided optical system is a significant imaging technique that enables real-time imaging with multiple channels. However, an increasing demand for multi-channel optics presents a substantial challenge for current refractive optical systems with complex structures and a narrow wavelength band. In this paper, we propose a modified design method that combines the strengths of an off-axis reflective system and an aperture-divided optical system to achieve high levels of integration and simplified structure. A design concept of integrated optical layout and local detail optimization is proposed here. We present an analysis showing how local sub-channels' distribution affects the imaging characteristics. An integrated optical system, including a relay group constructed based on the Wassermann-Wolf differential equations and a telescope objective, is built first. The sub-aperture system utilizing distinct local surface regions is gradually established with a close connection. To demonstrate the feasibility and efficiency of the method, an integrated system with an F-number of 1.6 and an entrance pupil of 130 mm is presented with its design strategies. The aperture-divided system illustrates well imaging performance close to the diffraction limit in 3-5 µm at 33 lp/mm. The design strategy we have proposed not only has a broad application to multi-channel imaging but also provides valuable insight into to our knowledge, the new imaging technology.

A three-dimensional (3D) particle image velocimetry (PIV) system typically consists of multiple cameras. However, micro-PIV systems for measuring microscale velocity fields lack sufficient space to accommodate them. In this work we propose an alternative approach based on computational imaging, enabling monocular micro-PIV systems to perform 3D flow field measurements without additional hardware or complex structure. The microscopic objective is designed to satisfy the required parameters, and the point spread function (PSF) responses of the system to different depths of the object surface are obtained. Additionally, a particle dataset generation method based on the PSFs of the optical system is proposed, and a deep-learning network is constructed for training. To validate the feasibility, particle images are captured in experiments and inputted into the network to reconstruct depth images and build three-dimensional flow fields. Simulation and experimental results demonstrate that the measurement deviation is within 13.2%, indicating the practicality of the proposed model.

Objective The Risley prism scanning system is a useful supplement to traditional rotating frame and mirror scanning systems. It features a compact structure, low optical loss, excellent dynamic performance, and a large scanning field of view, and has broad application prospects in lidars, laser communication, and laser guidance. In the practical applications of this system, it is important to select the scanning trajectory reasonably, which will directly affect the scanning efficiency of the system and the acquisition probability of the target. When the parameters and relative positions of the Risley prism are determined, the rotation velocity ratio of the Risley prism is variable and controllable to obtain the scanning trajectories of different shapes. We aim to study the relationship between the velocity ratio with the number of scanning points and petals, then summarize the internal rules of the velocity ratio and scanning trajectory, and evaluate the scanning time and coverage rate of the scanning trajectory under different velocity ratios. Therefore, our study has a guiding significance for selecting the scanning trajectory that meets the scanning efficiency requirements. Methods Firstly, the forward problem of the Risley prism is solved by the non-axial ray tracing algorithm, and the scanning trajectories under different velocity ratios can be obtained. Secondly, the number of scanning points is calculated according to the rotation velocity of the Risley prism and sampling interval, and the number of scanning petals is calculated according to the number of minimum points of the distance curve between scanning points and coordinate origin. Then, the velocity ratio is classified according to its absolute value and fractional part, and the formula for calculating the number of scanning petals by the velocity ratio is established. The scanning trajectory rules of the 2-element Risley prism are analyzed, and the scanning time and coverage rate under different velocity ratios are evaluated. Finally, the scanning trajectory of the 3-element Risley prism is regarded as the superposition and cancellation of the scanning trajectory of the 2-element Risley prism, and the scanning time and coverage rate can be evaluated according to the scanning trajectory rules of the 2-element Risley prism. Additionally, the condition for the 3-element Risley prism to obtain a regular symmetry scanning trajectory without a large scanning blind zone is proposed by analyzing the velocity ratio. Results and Discussions The scanning trajectory of 2-element Risley prism has the following rules (Table 1 and Fig. 4). When M is positive, the scanning trajectory is inner petal, and the trajectory is outer petal under negative M. When M is an integer, the scanning time under different velocity ratios is the same, and when M is a decimal, the scanning time under each type of velocity ratio is the same if the number of decimal places is the same. Under the different numbers of decimal places, the larger number of decimal places leads to longer scanning time. Therefore, the number of decimal places should not be too large. For each type of velocity ratio, when M is of the same sign, the larger vertical bar M vertical bar brings a larger coverage rate. The scanning trajectory of 3-element Risley prism has the following rules (Table 4 and Fig. 10): only when the scanning petals of 2-element Risley prism are doubled (1-2 times) with the velocity ratio of M-1 and M-2, and the scanning points are also doubled (1-2 times), the scanning trajectory of 3-element Risley prism is regular symmetry and has no large scanning blind zone. When M-1 and M-2 are both positive, the scanning trajectory is inner petal. When M-1 and M-2 are both negative or different signs, the scanning trajectory is the outer petal. Additionally, the scanning time and coverage rate of the 3-element Risley prism can be evaluated according to the scanning trajectory rules of the 2-element Risley prism. Conclusions As the scanning trajectory of the Risley prism determines the scanning efficiency of the system and the acquisition probability of the target, it is important to study the method of selecting the scanning trajectory by analyzing the velocity ratio. Based on the non-axial ray tracing algorithm, the forward problem of the Risley prism scanning system is solved. Then the petal-shaped scanning trajectories under different velocity ratios are obtained, and the number of scanning points and scanning petals are calculated, which is then adopted to summarize the rules between the scanning trajectory and velocity ratio. The scanning time and coverage rate of the scanning trajectory under different velocity ratios are evaluated. Meanwhile, the condition for the 3-element Risley prism to obtain a regular symmetry scanning trajectory without a large scanning blind zone is proposed. The obtained rules and conclusions can be employed to reasonably determine the velocity ratio in the practical applications of the Risley prism scanning system to select the scanning trajectory that meets the scanning efficiency requirements. However, the scanning trajectory of the Risley prism is sensitive to the velocity ratio, and there will be deviations between the actual and set velocity ratios in the rotation control. Therefore, the influence of such deviations on the scanning trajectory can be further explored.

In this study, an improved iterative closest point (ICP) registration algorithm was proposed to address such problems as great time consumption of iterative calculations and relatively large registration errors in the traditional ICP algorithm within the field of 2D point cloud registration. During the iteration process, the point-to-line (PL) objective equation was simplified to solve the linear least squares fast through singular value decomposition, etc. Subsequently, this result could be further nonlinearly optimized, and the weighted objective functions for the PL distance and point-to-point (PP) distance were introduced in the optimization process. Moreover, a simulation experiment was performed using point clouds that were randomly generated multiple times. The results reveal that the improved ICP algorithm proposed in this study can improve both the registration accuracy and efficiency.