Focal Plane Research Articles

Measuring Concentration of Nanoparticles in Polydisperse Mixtures Using Interferometric Nanoparticle Tracking Analysis.

Quantitative measurements of nanoparticle concentration in liquid suspensions are in high demand, for example, in the medical and food industries. Conventional methods remain unsatisfactory, especially for polydisperse samples with overlapping size ranges. Recently, we introduced interferometric nanoparticle tracking analysis (iNTA) for high-precision measurement of nanoparticle size and refractive index. Here, we show that by counting the number of trajectories that cross the focal plane, iNTA can measure concentrations of subpopulations in a polydisperse mixture in a quantitative manner and without the need for a calibration sample. We evaluate our method on both monodisperse samples and mixtures of known concentrations. Furthermore, we assess the concentration of SARS-CoV-2 in supernatant samples obtained from infected cells.

Single 5-centimeter-aperture metalens enabled intelligent lightweight mid-infrared thermographic camera.

Existing mid-infrared thermographic cameras rely on a stack of refractive lenses, resulting in bulky and heavy imaging systems that restrict their broader utility. Here, we demonstrate a lightweight metalens-based thermographic camera (MTC) enabled by a single 0.5-mm-thick, 3.7-g-weight, flat, and mass-producible metalens. The large aperture size (5 cm) of our metalens, when combined with an uncooled focal plane array, enables thermal imaging at distances of tens of meters. By computationally removing the veiling glare, our MTC realizes the temperature mapping with an inaccuracy of less than ±0.7% within the range of 35° to 700°C and shows exceptional environmental adaptability. Furthermore, by using intelligent algorithms and spectral filtering, our uncooled MTC enables visualization and quantification of the SF6 gas leakage at a long distance of 5 m, with a remarkable minimum detectable leak rate of 0.2 sccm. Our work opens the door to the lightweight and multifunctional intelligent thermal imaging systems.

Spin–momentum properties in the gradient-index fiber

The vector characteristics of the kinetic momentum, spin angular momentum (SAM), and light field of a radially polarized vortex beam (RPVB) in the radial gradient-index (GRIN) fiber are analyzed using a unified methodology based on the generalized Huygens-Fresnel principle and the spin-momentum relationship. The kinetic momentum, SAM, transverse-type spin (t-SAM), longitudinal-type spin (l-SAM) and light field contain parallel and perpendicular components to the optical axis in the GRIN fiber. Moreover, the optical spin skyrmion from the SAM, t-SAM, and l-SAM can be observed at the semi-focal plane and the focal plane of the GRIN fiber. To the best of our knowledge, this is the first confirmation of spin skyrmions in the GRIN fiber. The analysis of spin-momentum properties of an RPVB in the GRIN fiber combined with the generalized Huygens-Fresnel principle and the spin-momentum relationship can be applied in describing the vector properties of transmission in atmospheric and optical systems.

P-269 Three-dimensional assessment of the inner cell mass is more effective at predicting implantation and live birth than Gardner grading

Abstract Study question 3-dimensional quantitative assessment of the inner cell mass (ICM) is more effective at selecting viable embryos than the widely used Gardner grading system? Summary answer 3-dimensional quantitative assessment of the ICM is significantly more predictive of implantation and live birth than the widely used Gardner grading of the ICM What is known already ICM assessment forms a key part of most widely used blastocyst grading systems. Grading under these systems, however, is often qualitative, subjective, and subject to inter/intra-operator variability. To reduce subjectivity in ICM grading, it has been suggested that quantitative criteria are used. Previous studies have focused on the assessment of such parameters (e.g. ICM area) in 2 dimensions. However, such approaches fail to account for the various embryo orientations which could lead to different measurements. Therefore, quantitative 3-dimensional analysis of the ICM is needed to improve the reliability and consistency of grading. Study design, size, duration This was a retrospective analysis of 153 randomly selected tEB embryos from two clinics. All data was captured on Embryoscope between 2018 and 2020. Data for maternal age, blastocyst grade, blastocyst ploidy, implantation and live birth rates were also recorded. Participants/materials, setting, methods Embryos were imaged at 7+ focal planes and in-focus sections of each ICM were annotated using ImageJ. These sections were combined into a 3D model using Blender, and sphericity (ψ) computed. Embryos were categorised as spheroid (ψ ≥ 0.8), ellipsoid (ψ < 0.8), crescent and irregular. Chi-squared tests were performed, comparing classification and clinical outcome. The predictive power of the system was compared to the Gardner scale (spheroid/ellipsoid classifications and A grades considered predictive of a positive outcome respectively). Main results and the role of chance Most ICM were either ellipsoid (48%) and spheroid (37%) rather than crescent (6%) or irregular (8%, p < 0.001). ICM 3D classification was associated with implantation, X2(3, N = 119)= 11.10, p = 0.01 and live birth, X2(3, N = 119)= 10.78, p = 0.01. Blastocysts with ellipsoid (70%, 28/40) and spheroid (58%, 18/31) shaped ICM had the greatest chances of implantation, whilst those with crescent (40%, 6/15) and irregularly shaped ICM (33%, 11/33) had lower chances of implantation (p < 0.011). Similarly, blastocysts with ellipsoid (58%, 23/40) and spheroid (48%, 15/31) shaped ICM had the greatest chances of live birth, whilst those with crescent (33%, 5/15) and irregularly shaped ICM (21%, 7/33) had lower chances of live birth (p < 0.013). 3D assessment of ICM outperformed Gardner ICM grading with regards to prediction of implantation (accuracy 64.7% vs 49.6%, area-under-the-curve 0.642 vs 0.486, precision 64.8% vs 51.9%, sensitivity 73% vs 65.1%, specificity 55.4% vs 32.1%, F1 score 68.7% vs 57.8%, 3D vs Gardner) and live birth (accuracy 62.2% vs 50.4%, area-under-the-curve 0.641 vs 0.531, precision 53.5% vs 44.3%, sensitivity 76% vs 70%, specificity 52% vs 36.2%, F1 score 62.2% vs 54.3%, 3D vs Gardner). Limitations, reasons for caution Manually rendering the 3D images for each ICM was time consuming, making it impractical for clinical application. Further work is now focusing on automating this process using image recognition and augmented reality. Wider implications of the findings This is a novel ICM assessment that provides an improved perspective of the 3-dimensionality of the ICM which is more consistent and effective than traditional methods of embryo assessment, potentially contributing towards improving embryo selection efficacy and time to pregnancy. Trial registration number none

O-130 The spatial conformational features of blastocysts can serve as a new basis for selection

Abstract Study question Can spatial conformational features become a new basis for blastocyst selection? Summary answer The spatial conformational features of blastocysts can be associated with clinical outcomes, which is a new basis for blastocyst selection. What is known already At present, the quality evaluation of blastocysts is two-dimensional, and there are relatively few evaluation indicators. There are now methods for exploring three-dimensional reconstruction of blastocysts, including fluorescence staining to obtain three-dimensional structures or artificial rotation to obtain images and restore three-dimensional conformations. However, one drawback of these methods is that they are far from true clinical applications. There are no reports on the reconstruction techniques that can be used in clinical blastocyst selection techniques, and there are no reports on the spatial conformational features related to them. Study design, size, duration This study included 2,141 frozen thaw single blastocyst transfer cycles at Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from 2020 to 2021. Simultaneously collect multi-focal plane (11) image data for each blastocyst (EmbryoScope+). The inclusion criteria for patients are those under 40 years old, with an endometrial thickness of 7-16mm, and a history of embryo transfer failure of less than or equal to 1 time. Participants/materials, setting, methods This study iteratively interpolated the 11 focal planes using a multi focal plane generation network model. The contour and spatial information of blastocyst TE and ICM were obtained through deep-learning and segmentation networks. Texture information was extracted using depth estimation and image fusion and mapped to a 3D model to obtain a complete blastocyst spatial model. Then calculate a series of new spatial conformational features of the blastocyst and analyze their correlation with clinical outcomes. Main results and the role of chance We validated the model using the fluorescence reconstruction of human blastocysts as the gold standard (key indicator accuracy>90%). The obtained spatial conformational parameters of blastocysts include: Blastocyst: overall volume (BOV), cystic cavity volume (BCV), surface area (BSA); ICM: volume (IV), surface area (ISA), spatial aspect ratio (ISAr), surface sphericity (ISS), relative distance from ICM to TE (IRD), contact area with TE (ICA); TE cells: number (TN), density (TD), distribution difference (TDD), TE cell roundness (TR), circumference (TC), area (TA) and variance, TE cell aspect ratio (TMM) and variance. The BOV, BCV, and BSA of the blastocyst were positively correlated with clinical pregnancy rate (CPR). The quartile results showed significant differences in CPR when the values were >179 wμm3, 165 wμm3, and 25.8 wμm2, respectively. In terms of ICM, there was no significant difference in CPR among the IV, ISA, IRD, and ICA. However, we found ISAr and ISS had higher CPR in the range of 0.715-0.912 and 0.920-0.943, respectively. In terms of TE, TN is positively correlated with CPR. TD, TDD, TR were not significantly associated with CPR. The pleasing finding is that TC, TA, TMM, and their variances are significantly correlated with CPR. Limitations, reasons for caution The overall quality of blastocysts is relatively good, which is related to the priority thawing of the best blastocysts. Some blastocysts may appear partially out of view, leading to data unavailability and potentially affecting 3D reconstruction. Further exploration and discovery are needed for the spatial conformational features of blastocysts. Wider implications of the findings This work provides a 3D reconstruction system for blastocysts that is closer to clinical applications and discovers new spatial features that are related to clinical outcomes. This enables the study of more dimensional biological characteristics of blastocysts, and our research further promotes the development of embryo reconstruction technology. Trial registration number not applicable

Noise equivalent temperature difference study of type-II superlattice MWIR focal plane arrays for high operating temperature performance.

Achieving high operating temperature (HOT) plays a crucial role in miniaturizing type-II superlattice (T2SL) mid-wavelength infrared (MWIR) focal plane arrays (FPAs). However, their full potential has yet to be realized due to a lack of complete understanding of their operation from the perspective of detection principles. Here, by investigating the photon transmission path and optoelectronic performance of the simulated devices, a detailed noise equivalent temperature difference (NETD) model of the T2SL MWIR FPAs was established. The NETD limitations in the optics-limited and detector-limited modes were revealed by studying the effects of the source, optical system, and FPA-related parameters. Although NETD exhibits sensitivity to dark currents, improvements in the quantum efficiency and well capacity can further boost its performance. When the defects and carrier lifetimes are well controlled to completely suppress the dark current, the NETD of an MWIR system with optimized integration times, which operates between 150 K and 200 K, is predicted to be below 10 mK when detecting room-temperature targets. The results provide new insights into the model and sources contributing to the NETD and demonstrate the possibility of high-temperature operation of T2SLs MWIR FPAs.

Single-pixel microscopy with optical sectioning.

Imaging with single-pixel detectors offers a valuable alternative to the conventional focal plane array strategy, especially for wavelengths where silicon-based sensor arrays exhibit lower efficiency. However, the absence of optical sectioning remains a challenge in single-pixel microscopy. In this paper, we introduce a single-pixel microscope with optical sectioning capabilities by integrating single-pixel imaging (SPI) techniques with structured illumination microscopy (SIM) methods. A spatial light modulator positioned at the microscope's input port encodes a series of structured light patterns, which the microscope focuses onto a specific plane of the 3D sample. Simultaneously, a highly sensitive bucket detector captures the light reflected by the object. Optical sectioning is achieved through a high-frequency grating positioned at the microscope's output port, which is conjugated with the spatial light modulator. Utilizing SPI reconstruction techniques and SIM algorithms, our computational microscope produces high-quality 2D images without blurred out-of-focus regions. We validate the performance of the single-pixel microscope (SPM) by measuring the axial response function and acquiring images of various 3D samples in reflected bright-field configuration. Furthermore, we demonstrate the suitability of the optical setup for single-pixel fluorescence microscopy with optical sectioning.

Investigation of the effects of polarisation and alignment method of retarders in isoSTED microscopy

Stimulated emission depletion (STED) microscopy is a powerful tool for observing subcellular structures beyond the diffraction-limited resolution. To achieve improved isotropic three-dimensional (3D) resolution in STED microscopy, 4Pi-geometry, which is equipped with two opposing objectives, is adopted; this approach is known as isoSTED microscopy. In isoSTED microscopy, constructive and destructive interference occur at the shared focal plane for lateral and axial depletion, respectively. The performance of isoSTED microscopy depends critically on the polarisation status and optical power differences of the two beams of the 4Pi cavity, which are adjusted using retarders. Misalignment of the retarders creates a nonzero core of the depletion focus owing to partial destructive interference. We analytically investigated the effects of retarder misalignments and proposed a simple and accurate alignment method for retarders. We also demonstrate that the proposed method can generate a completely destructive interference pattern and consequently achieve a sub-40-nm 3D resolution.

Fabrication of broadband HgCdTe photodetectors with biomimetic insect corneal arrays.

Broadband photodetectors are of great significance in a wide variety of technologically important areas. Inspired by bionics, insect cornea-mimicking microstructures could reduce surface reflection, thus enabling broadband detection. Here, we fabricate a broadband large-area (1280 × 1024) HgCdTe focal plane array photodetector based on biomimetic ZnS microarrays, which achieves high external quantum efficiency (> 60%, averaging 79%) across the broad wavelength range of 400 nm - 5000 nm. These results demonstrate that implementing biomimetic ZnS microstructures has effectively broadened the operational wavelength range of conventional HgCdTe infrared photodetectors to encompass the visible light spectrum. Our work achieves continuous visible-to-infrared spectral imaging and provides a beneficial route to fabricate broadband, large-area, high-performance photodetectors.

BCLA CLEAR presbyopia: Management with intraocular lenses

Cataract surgery including intraocular lens (IOL) insertion, has been refined extensively since the first such procedure by Sir Harold Ridley in 1949. The intentional creation of monovision with IOLs using monofocal IOL designs has been reported since 1984. The first reported implantation of multifocal IOLs was published in 1987. Since then, various refractive and or diffractive multifocal IOLs have been commercialised. Most are concentric, but segmented IOLs are also available. The most popular are trifocal designs (overlaying two diffractive patterns to achieve additional focal planes at intermediate and near distances) and extended depth of focus designs which leave the patient largely spectacle independent with the reduced risk of bothersome contrast reduction and glare. As well as mini-monovision, surgical strategies to minimise the impact of presbyopia with IOLs includes mixing and matching lenses between the eyes and using IOLs whose power can be adjusted post-implantation. Various IOL designs to mimic the accommodative process have been tried including hinge optics, dual optics, lateral shifts lenses with cubic-type surfaces, lens refilling and curvature changing approaches, but issues in maintaining the active mechanism with post-surgical fibrosis, without causing ocular inflammation, remain a challenge. With careful patient selection, satisfaction rates with IOLs to manage presbyopia are high and anatomical or physiological complications rates are no higher than with monofocal IOLs.

Focal plane imaging system based on CMOS terahertz detector

Abstract Terahertz technology has shown remarkable potential for application in the field of imaging since it offers several particular advantages such as great penetration capabilities, non-ionization and high instantaneous bandwidth. This paper presents a focal plane imging system based on CMOS terathertz detector for forward-looking detection. The focal plane imaging system has several advantages, including fast scanning, simple composition, low cost, and easy integration of a CMOS detector. It is composed of a terahertz radiation source, a Polytetrafluoroethylene (PTFE) lens and a broadband CMOS detector. The detector was fabricated in a 65 nm CMOS process. The operating frequency range of the detector covers 75 GHz to 1000 GHz. Measurement results have shown that the focal plane imaging system is capable of stably imaging at frequencies of 100 GHz and 220 GHz. To address the issue of missing information in measurement images, the morphological closing algorithm is employed to process the original image, successfully filling in the missing information and improving image quality.

Development of Two-Photon Super-Resolution Microscopy

Two-photon excitation microscopy enables in vivo deep-tissue imaging within organisms. This technique is based on two-photon excitation, a nonlinear optical process that uses near-infrared light for excitation, resulting in high tissue permeability. Notably, two-photon excitation occurs only near the focal plane; therefore, minimally invasive tomographic images can be obtained. Owing to these features, two-photon excitation microscopy is currently widely used in medical and life-science research, particularly in the domain of neuroscience for in vivo visualization of deep tissues. However, the use of long-wavelength excitation light in two-photon excitation microscopy has resulted in a larger focused spot size and relatively low spatial resolution, which is a limitation of this technique for further applications. Recent studies have described super-resolution microscopy techniques applied to two-photon excitation microscopy in an attempt to observe living organisms "as they are in their natural state" with high spatial resolution. We have also addressed this topic using an optical approach (two-photon stimulated emission depletion microscopy) and an image analysis approach (two-photon super-resolution radial fluctuation). Here, we describe these approaches together with a discussion of our recent accomplishments.

Controllable split polarization singularities for ultra-precise displacement sensing

The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, although effectively manipulating the singularity in an ideal manner remains challenging. In this work, we propose a theoretical approach to achieve controllable position modulation of the C-point in the focal plane, whose spatial position can be easily modulated by adjusting the relative offset factor β and the offset angle α of an azimuthal polarization beam (APB), while the interval and orientation of the C-points can be flexibly regulated. Notably, the chiral polarization state undergoes a distinct reversal along the link-line connecting the two C-points, thereby providing a promising approach for accurate displacement sensing. To evaluate its sensing characteristics, the varying pattern of the scattered field intensity is monitored when sweeping a gold helix and nanoparticle along the link-line. The results of simulation quality index Q verify that the equilibrium factor of the scattering field possesses an obvious linear relationship with the displacement, signifying a precise sub-nanometric sensitivity. This research introduces new methods for the flexible control of polarization singularities in tightly focused fields, thereby enhancing the utilization of circular polarization properties near C-points for displacement sensing. These findings not only enrich the field of nanometer measurement technology but also pave the way for new avenues of research in this domain.

Distinguishing the topological charge of vortex beam via Fourier back plane imaging with chiral windmill structure

In recent years, research on the interaction between orbital angular momentum (OAM) of light and matter has shown a continuous influx of investigations. OAM possesses distinct properties, such as a degree of freedom with multiple states, vortex characteristics, and topological properties, which expand its applications in optical communication, optical sensing, and optical manipulation. We have observed different phenomena in the chiral metal windmill structure under excitation of spin angular momentum (SAM)-OAM beam generated by Q-plate than under SAM excitation. Fourier back focal plane (FBP) imaging under SAM beam excitation easily identifies the chirality and geometric properties of the structure. When the SAM-OAM beam excites the structure, FBP not only identifies its chirality and geometric properties but also distinguishes different OAM topological charges and signs, as well as the degree of elliptic polarization. The Stokes parametric FBP imaging reveals asymmetric polarization distribution resulting from the interaction between a vortex beam and the chiral structure. Moreover, it clearly reflects the conversion process of SAM to OAM. The experimental results match well with simulation results. These findings hold valuable insights for the advancement of optical information storage and communication using OAM, opening up new possibilities for further exploration in this field.

Patterned microsphere-lens projection lithography using an electrohydrodynamic-jet-printing-assisted assembly

Microlens arrays have been widely used in the fields of micro-optics and micro- and nanofabrication. Traditional preparation methods utilize commercial photoresists and thermosetting materials, thereby restricting the optical properties of microlenses. In recent years, significant advancements have been achieved in near-field super-resolution imaging by utilizing microspheres and forming arrays of microsphere lenses via self-assembly. However, self-assembly approaches lack flexibility in terms of pattern selection. This study proposes a method that utilizes electrohydrodynamic jet (E-jet) printing to code ultraviolet (UV)-curable adhesives and assist in the assembly of patterned microsphere-lens arrays. Simulation results demonstrate that the UV-curable adhesive has little impact on the optical properties of the microsphere lens. Moreover, the microsphere lens exhibits a superior imaging resolution compared with traditional microlenses. A projection-lithography system is developed to achieve an accurate alignment between the focal plane of the microsphere lenses and the plane of the photoresist, facilitating the fabrication of patterned nanostructures. The lithographic nanostructures have a minimum feature size of 850 nm. This method enables the fabrication of arrays of microsphere lenses with arbitrary patterns and presents an inexpensive and simple strategy for fabricating micro- and nanostructure arrays with submicrometer features.

Multilayer focal plane metalens based on all-dielectric materials in the ultraviolet band

Metalens can expand optical imaging capabilities due to the ability of metasurfaces to manipulate light propagation. Multi-focal metalens have been widely used in multi-imaging systems, detectors, and laser printing. This study presents the design of a UV metalens composed of alumina nanopillars. We investigate the focusing properties of representative UVA (343 nm) at multiple focal points on the in-plane axis, off-axis, and within a single plane. In addition, we extend the focusing ability of the metalens with multiple focal planes. We design the metalens with multiple imaging capabilities and produce focuses with different shapes in four focal planes. Simulation results show that the focal points of the planes have different shapes, the location of the maximum light intensity in the xz plane is in good agreement with our designed focal length, and the average focusing efficiency is greater than 60% in each plane. To evaluate the feasibility of planar spacing detection, we calculate the error-tolerant rate (Etr) of the device to be more than 90%. This work has important implications for the integrated miniaturization of UV photonic devices and the study of optical tomography.

Measuring Fiber Positioning Accuracy and Throughput with Fiber Dithering for the Dark Energy Spectroscopic Instrument

Highly multiplexed, fiber-fed spectroscopy is enabling surveys of millions of stars and galaxies. The performance of these surveys depends on accurately positioning fibers in the focal plane to capture target light. We describe a technique to measure the positioning accuracy of fibers by dithering fibers slightly around their ideal locations. This approach also enables measurement of the total system throughput and point-spread function delivered to the focal plane. We then apply this technique to observations from the Dark Energy Survey Instrument (DESI), and demonstrate that DESI positions fibers to within 0.″08 of their targets (5% of a fiber diameter) and achieves a system throughput within about 7% of expectations.

Rotation of a Tricomi–Gaussian beam and its focusing characteristics through a thin lens system

The rotation behaviors of an asymmetric Tricomi–Gaussian beam (aTGB) propagating in free space and through a thin lens system are mainly investigated. The focusing characteristics of TGB with symmetric and asymmetric modes propagating through a thin lens system are also presented. Influences of complex constants α and β, the topological charge n, and the lens focal length f on the field distributions of TGB are studied thoroughly. The results indicate that when a symmetric TGB propagates through a thin lens system, a perfect vortex beam could be generated at the lens focal plane. TGB undergoes two focusing processes through the thin lens system, and the peak intensities at two focal planes, the rotation, and the focal characteristics of TGB can be manipulated by α,β,n, and f. Moreover, f has more significant effects on the focal depths of two foci and the self-focusing focal length than α,β, and n.

Hemiepiphysiodesis Corrects Lower Extremity Coronal Plane Deformity in Children with Skeletal Dysplasia Irrespective of Intra-Articular Malalignment

BackgroundSkeletal dysplasias (SkD) are a rare group of disorders characterized by abnormal growth and development of bone and cartilage, often causing limb deformity. Many patients also have ligamentous instability that can accentuate the malalignment. This ligamentous instability can present either a generalized ligamentous laxity or focal coronal plane intra-articular malalignment. Temporary hemiepiphysiodesis (HE) is a commonly employed minimally invasive surgical technique for correcting coronal plane limb deformities. This study evaluated the effectiveness of HE in the correction of knee coronal plane deformity in children with SkD and the correlation of concurrent joint laxity. MethodsA retrospective cohort study was conducted to evaluate radiological outcomes of HE for coronal plane knee deformities in patients with SkD (aged <18 years) who had surgery between January 1, 2008 and December 31, 2020. Changes in distal femoral and proximal tibial mechanical angles, and knee joint line congruence angles (JLCA) prior to HE and at the final follow-up were analyzed. An increased JLCA of ≥±2° was considered a knee with ligamentous instability. Preoperative and postoperative patient-reported pain status was recorded. ResultsFifty-six tibial and 42 femoral HE procedures in 32 children (mean age at HE: 9.8 ± 2.8 years) were included. The deformity was fully corrected in 23/32 (72%) children, at an average annual rate of 6.3° at the distal femur and 3.3° at the proximal tibia, over 21.9 ± 12.6 months. The overall pre-HE JLCA improved by an average of 5.3° (P < .05). The improvement was more pronounced in varus knees (n = 45; P < .05) than valgus knees (n = 12; P = .11) but regardless of the severity of joint instability, pre-HE JLCA did not impede the rate of femoral (r = −0.22) or tibial (r = −0.21) corrections. Preoperative pain was reported by 78% of patients whereas only 25% of patients reported pain postoperatively at the final follow-up (mean follow-up: 26.4 ± 13.5 months). ConclusionsThe presence of coronal plane intra-articular malalignment did not affect the rate and the magnitude of correction with HE in this cohort. Coronal plane deformities and JLCA improve with deformity correction by HE in children with SkD. Key Concepts(1)Intra-articular malalignment at the knee does not impede the success of hemiepiphysiodesis in children with skeletal dysplasia.(2)While all coronal plane knee deformities improved, a more significant improvement was noted in children with varus than valgus.(3)Joint line congruency angles improved with guided growth for coronal plane deformities. Level of EvidenceIII

Dark background correction with multivariate model fitting for infrared hyperspectral remote sensing

Dark currents in HgCdTe devices are the main factor that limit detector performance in infrared imaging systems, which may result in a reduced dynamic range and poor signal-to-noise ratio (SNR). In this paper, the theoretical limit of dark background correction is defined, and the correction effects of different methods are quantitatively evaluated. Based on accurate measurements of the focal plane array (FPA) temperature, the relationship between the FPA temperature and dark background is evaluated. The fluctuations are highly consistent; thus, the FPA temperature can be used to estimate the dark background of different pixels in real time. Moreover, the temperature of the opto-mechanical components is stabilized at 120 K to suppress instrument radiation, and the temperature of the electrical box is applied to correct gradient changes in the dark background at large time scales. As a result, the dark backgrounds of different pixels can be accurately corrected in real time.