Real-time and high-transmission middle-infrared optical imaging system based on a pixel-wise metasurface micro-polarization array

Real-time polarization medium-wave infrared(MIR)optical imaging systems enable the acquisition of infrared and polarization information for a target.At present,real-time polarization MIR devices face the following problems:poor real-time performance,low transmission and high requirements for fabrication and integration.Herein,we aim to improve the performance of real-time polarization imaging systems in the MIR waveband and solve the above-mentioned defects.Therefore,we propose a MIR polarization imaging system to achieve real-time polarization-modulated imaging with high transmission as well as improved performance based on a pixel-wise metasurface micro-polarization array(PMMPA).The PMMPA element comprises several linear polarization(LP)filters with different polarization angles.The optimization results demonstrate that the transmittance of the center field of view for the LP filters is up to 77%at a wavelength of4.0μm and an extinction ratio of 88 d B.In addition,a near-diffraction-limited real-time MIR imaging optical system is designed with a field of view of 5°and an F-number of 2.The simulation results show that an MIR polarization imaging system with excellent real-time performance and high transmission is achieved by using the optimized PMMPA element.Therefore,the method is compatible with the available optical system design technologies and provides a way to realize real-time polarization imaging in MIR wavebands.

Research on the model of high robustness computational optical imaging system

Computational optical imaging is an interdisciplinary subject integrating optics, mathematics, and information technology. It introduces information processing into optical imaging and combines it with intelligent computing, subverting the imaging mechanism of traditional optical imaging which only relies on orderly information transmission. To meet the high-precision requirements of traditional optical imaging for optical processing and adjustment, as well as to solve its problems of being sensitive to gravity and temperature in use, we establish an optical imaging system model from the perspective of computational optical imaging and studies how to design and solve the imaging consistency problem of optical system under the influence of gravity, thermal effect, stress, and other external environment to build a high robustness optical system. The results show that the high robustness interval of the optical system exists and can effectively reduce the sensitivity of the optical system to the disturbance of each link, thus realizing the high robustness of optical imaging.

Observing single cells in whole organs with optical imaging

Cells are the basic unit of human organs that are not fully understood.The revolutionary advancements of optical imaging alowed us to observe single cells in whole organs,revealing the complicated composition of cells with spatial information.Therefore,in this review,we revisit the principles of optical contrast related to those biomolecules and the optical techniques that transform optical contrast into detectable optical signals.Then,we describe optical imaging to achieve threedimensional spatial discrimination for biological tisutes.Due to the milky appearance of tissues,the spatial information burred deep in the whole organ.Fortunately,strategies developed in the last decade could circumvent this issue and lead us into a new era of investigation of the cells with their original spatial information.

Imaging assessment of photosensitizer emission induced by radionuclide-derived Cherenkov radiation using charge-coupled device optical imaging and long-pass filters

BACKGROUND Radionuclides produce Cherenkov radiation(CR),which can potentially activate photosensitizers(PSs)in phototherapy.Several groups have studied Cherenkov energy transfer to PSs using optical imaging;however,cost-effectively identifying whether PSs are excited by radionuclide-derived CR and detecting fluorescence emission from excited PSs remain a challenge.Many laboratories face the need for expensive dedicated equipment.AIM To cost-effectively confirm whether PSs are excited by radionuclide-derived CR and distinguish fluorescence emission from excited PSs.METHODS The absorbance and fluorescence spectra of PSs were measured using a microplate reader and fluorescence spectrometer to examine the photo-physical properties of PSs.To mitigate the need for expensive dedicated equipment and achieve the aim of the study,we developed a method that utilizes a chargecoupled device optical imaging system and appropriate long-pass filters of different wavelengths(manual sequential application of long-pass filters of 515,580,645,700,750,and 800 nm).Tetrakis(4-carboxyphenyl)porphyrin(TCPP)was utilized as a model PS.Different doses of copper-64(^(64)CuCl_(2))(4,2,and 1 mCi)were used as CR-producing radionuclides.Imaging and data acquisition were performed 0.5 h after sample preparation.Differential image analysis was conducted by using ImageJ software(National Institutes of Health)to visually evaluate TCPP fluorescence.RESULTS The maximum absorbance of TCPP was at 390-430 nm,and the emission peak was at 670 nm.The CR and CRinduced TCPP emissions were observed using the optical imaging system and the high-transmittance long-pass filters described above.The emission spectra of TCPP with a peak in the 645-700 nm window were obtained by calculation and subtraction based on the serial signal intensity(total flux)difference between^(64)CuCl_(2)+TCPP and^(64)CuCl_(2).Moreover,the differential fluorescence images of TCPP were obtained by subtracting the^(64)CuCl_(2)image from the^(64)CuCl_(2)+TCPP image.The experimental results considering different^(64)CuCl_(2)doses showed a dosedependent trend.These results demonstrate that a bioluminescence imaging device coupled with different longpass filters and subtraction image processing can confirm the emission spectra and differential fluorescence images of CR-induced TCPP.CONCLUSION This simple method identifies the PS fluorescence emission generated by radionuclide-derived CR and can contribute to accelerating the development of Cherenkov energy transfer imaging and the discovery of new PSs.

Association of colorectal cancer with pathogenic Escherichia coli: Focus on mechanisms using optical imaging

AIM: To investigate the molecular or cellular mechanisms related to the infection of epithelial colonic mucosa by pks-positive Escherichia coli(E. coli) using optical imaging.METHODS: We choose to evaluate the tumor metabolic activity using a fluorodeoxyglucose analogue as 2-deoxyglucosone fluorescent probes and to correlate it with tumoral volume(mm^3). Inflammation measuring myeloperoxidase(MPO) activity and reactive oxygen species production was monitored by a bioluminescent(BLI) inflammation probe and related to histological examination and MPO levels by enzyme-linked immunosorbent assay(ELISA) on tumor specimens. The detection and quantitation of these two signals were validated on a xenograft model of human colon adenocarcinoma epithelial cells(HCT116) in nude mice infected with a pks-positive E. coli. The inflammatory BLI signal was validated intra-digestively in the colitisCEABAC10 DSS models, which mimicked Crohn's disease. RESULTS: Using a 2-deoxyglucosone fluorescent probe, we observed a high and specific HCT116 tumor uptake in correlation with tumoral volume(P = 0.0036). Using the inflammation probe targeting MPO, we detected a rapid systemic elimination and a significant increase of the BLI signal in the pks-positive E. coli-infected HCT116 xenograft group(P < 0.005). ELISA confirmed that MPO levels were significantly higher(1556 ± 313.6 vs 234.6 ± 121.6 ng/m L P = 0.001) in xenografts infected with the pathogenic E. coli strain. Moreover, histological examination of tumor samples confirmed massive infiltration of pks-positive E. coli-infected HCT116 tumors by inflammatory cells compared to the uninfected group. These data showed that infection with the pathogenic E. coli strain enhanced inflammation and ROS production in tumors before tumor growth. Moreover, we demonstrated that the intra-digestive monitoring of inflammation is feasible in a reference colitis murine model(CEABAC10/DSS).CONCLUSION: Using BLI and fluorescence optical imaging, we provided tools to better understand hostpathogen interactions at the early stage of disease, such as inflammatory bowel disease and colorectal cancer.

In Vivo Tumor-Targeted Dual-Modality PET/Optical Imaging with a Yolk/Shell-Structured Silica Nanosystem

Silica nanoparticles have been one of the most promising nanosystems for biomedical applications due to their facile surface chemistry and non-toxic nature. However, it is still challenging to effectively deliver them into tumor sites and noninvasively visualize their in vivo biodistribution with excellent sensitivity and accuracy for effective cancer diagnosis. In this study, we design a yolk/shell-structured silica nanosystem ^(64) Cu-NOTAQD@HMSN-PEG-TRC105, which can be employed for tumor vasculature targeting and dual-modality PET/optical imaging, leading to superior targeting specificity, excellentimaging capability and more reliable diagnostic outcomes.By combining vasculature targeting, pH-sensitive drug delivery, and dual-modality imaging into a single platform,as-designed yolk/shell-structured silica nanosystems may be employed for the future image-guided tumor-targeted drug delivery, to further enable cancer theranostics.

ACTIVATABLE SMART PROBES FOR MOLECULAR OPTICAL IMAGING AND THERAPY

Recent years have seen the design and implementation of many optical activatable smart probes.These probes are activatable because they change their optical properties and are smart because they can identify specific targets.This broad class of detection agents has allowed previously unperformed visualizations,facilitating the study of diverse biomolecules including enzymes,nucleic acids,ions and reactive oxygen species.Designed to be robust in an in vivo environment,these probes have been used in tissue culture cells and in live small animals.An emerging class of smart probes has been designed to harness the potency of singlet oxygen generating photosensitizers.Combining the discrimination of activatable agents with the toxicity of photosensitizers represents a new and powerful approach to disease treatment.This review highlights some applications of activatable smart probes with a focus on developments of the past decade.

Determining the imaging plane of a retinal capillary layer in adaptive optical imaging

Even in the early stage,endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 μm.However,the fundus cameras used in clinic diagnosis can only obtain images of vessels larger than 20 μm in diameter.The human retina is a thin and multiple layer tissue,and the layer of capillaries less than10 μm in diameter only exists in the inner nuclear layer.The layer thickness of capillaries less than 10 μm in diameter is about 40 μm and the distance range to rod＆cone cell surface is tens of micrometers,which varies from person to person.Therefore,determining reasonable capillary layer（CL） position in different human eyes is very difficult.In this paper,we propose a method to determine the position of retinal CL based on the rod＆cone cell layer.The public positions of CL are recognized with 15 subjects from 40 to 59 years old,and the imaging planes of CL are calculated by the effective focal length of the human eye.High resolution retinal capillary imaging results obtained from 17 subjects with a liquid crystal adaptive optics system（LCAOS） validate our method.All of the subjects＇ CLs have public positions from 127 μm to 147 μm from the rod＆cone cell layer,which is influenced by the depth of focus.

Fast in vivo bioluminescence tomography using a novel pure optical imaging technique

Bioluminescence tomography(BLT)is a novel opt ical molecular imaging technique that advanced the conventional planar bioluminescence imaging(BLI)into a quantifiable three-dimensional(3D)approach in preclinical living animal studies in oncology.In order to solve the inverse problem and reconstruct tumor lesions inside animal body accurately,the prior structural information is com-monly obtained from X ray computed tomography(CT).This strategy requires a complicated hybrid imaging system,extensive post imaging analysis and involvement of ionizing radiation.Moreover,the overall robustness highly depends on the fusion accuracy between the optical and structural information.Here,we present a pure optical bioluminescence tomographic(POBT)system and a novel BLT workfow based on multi-view projection acquisition and 3D surface reconstruction.This met hod can reconstruct the 3D surface of an imaging subject based on a sparse set of planar white-light and bioluminescent images,so that the prior structural information can be offered for 3D tumor lesion reconstruction without the involvement of CT.The performance of this novel technique was evaluated through the comparison with a conventional dual-modality tomo-graphic(DMT)system and a commercialized optical imaging system(IVIS Spectrum)using three breast cancer xenografts.The results revealed that the new technique offered comparable in vivo tomographic accuracy with the DMT system(P>0.05)in much shorter data analysis time.It also offered significantly better accuracy comparing with the IVIS system(P<0.04)without sacrificing too much time.

Enhanced optical imaging and fluorescent labeling for visualizing drug molecules within living organisms

The visualization of drugs in living systems has become key techniques in modern therapeutics.Recent advancements in optical imaging technologies and molecular design strategies have revolutionized drug visualization.At the subcellular level,super-resolution microscopy has allowed exploration of the molecular landscape within individual cells and the cellular response to drugs.Moving beyond subcellular imaging,researchers have integrated multiple modes,like optical near-infrared II imaging,to study the complex spatiotemporal interactions between drugs and their surroundings.By combining these visualization approaches,researchers gain supplementary information on physiological parameters,metabolic activity,and tissue composition,leading to a comprehensive understanding of drug behavior.This review focuses on cutting-edge technologies in drug visualization,particularly fluorescence imaging,and the main types of fluorescent molecules used.Additionally,we discuss current challenges and prospects in targeted drug research,emphasizing the importance of multidisciplinary cooperation in advancing drug visualization.With the integration of advanced imaging technology and molecular design,drug visualization has the potential to redefine our understanding of pharmacology,enabling the analysis of drug micro-dynamics in subcellular environments from new perspectives and deepening pharmacological research to the levels of the cell and organelles.

Experimental Study on the Variation of Optical Imaging Characteristics with Zenith Angle due to Internal Solitary Waves in Sunglint

Internal solitary waves(ISWs)change the roughness of the sea surface,thus producing dark and bright bands in optical images.However,reasons for changes in imaging characteristics with the solar zenith angle remain unclear.In this paper,the optical imaging pattern of ISWs in sunglint under different zenith angles of the light source is investigated by collecting optical images of ISWs through physical simulation.The experiment involves setting 10 zenith angles of the light source,which are divided into area a the optical images of ISWs in the three areas show dark-bright mode,single bright band,and bright-dark mode,which are consistent with those observed by optical remote sensing.In addition,this study analyzed the percentage of the dark and bright areas of the bands and the change in the relative gray difference and found changes in both areas under different zenith angles of the light source.The MODIS and ASAR images display a similar brightness-darkness distance of the same ISWs.Therefore,the relationship between the brightness-darkness distance and the characteristic half-width of ISWs is determined in accordance with the eKdV theory and the imaging mechanism of ISWs of the SAR image.Overall,the relationship between them in the experiment is almost consistent with the theoretical result.

Whole-brain Optical Imaging:A Powerful Tool for Precise Brain Mapping at the Mesoscopic Level

The mammalian brain is a highly complex network that consists of millions to billions of densely-interconnected neurons.Precise dissection of neural circuits at the mesoscopic level can provide important structural information for understanding the brain.Optical approaches can achieve submicron lateral resolution and achieve“optical sectioning”by a variety of means,which has the natural advantage of allowing the observation of neural circuits at the mesoscopic level.Automated whole-brain optical imaging methods based on tissue clearing or histological sectioning surpass the limitation of optical imaging depth in biological tissues and can provide delicate structural information in a large volume of tissues.Combined with various fluorescent labeling techniques,whole-brain optical imaging methods have shown great potential in the brain-wide quantitative profiling of cells,circuits,and blood vessels.In this review,we summarize the principles and implementations of various whole-brain optical imaging methods and provide some concepts regarding their future development.

Surpassing the standard quantum limit of optical imaging via deep learning

The sensitivity of optical measurement is ultimately constrained by the shot noise to the standard quantum limit.It has become a common concept that beating this limit requires quantum resources.A deep-learning neural network free of quantum principle has the capability of removing classical noise from images,but it is unclear in reducing quantum noise.In a coincidence-imaging experiment,we show that quantum-resource-free deep learning can be exploited to surpass the standard quantum limit via the photon-number-dependent nonlinear feedback during training.Using an effective classical light with photon flux of about 9×10^(4) photons per second,our deep-learning-based scheme achieves a 14 dB improvement in signal-to-noise ratio with respect to the standard quantum limit.

NIR-II fluorescence imaging in liver tumor surgery: A narrative review

In liver tumor surgery,the recognition of tumor margin and radical resection of microcancer focis have always been the crucial points to reduce postoperative recurrence of tumor.However,naked-eye inspection and palpation have limited effectiveness in identifying tumor boundaries,and traditional imaging techniques cannot consistently locate tumors in real time.As an intraoperative real-time navigation imaging method,NIRfluorescence imaging has been extensively studied for its simplicity,reliable safety,and superior sensitivity,and is expected to improve the accuracy of liver tumor surgery.In recent years,the research focus of NIRfluorescence has gradually shifted from the-rst near-infrared window(NIR-I,700–900 nm)to the second near-infrared window(NIR-II,1000–1700 nm).Fluorescence imaging in NIR-II reduces the scattering effect of deep tissue,providing a preferable detection depth and spatial resolution while signi-cantly eliminating liver autofluorescence background to clarify tumor margin.Developingfluorophores combined with tumor antibodies will further improve the precision offluorescence-guided surgical navigation.With the development of a bunch offluorophores with phototherapy ability,NIR-II can integrate tumor detection and treatment to explore a new therapeutic strategy for liver cancer.Here,we review the recent progress of NIR-IIfluorescence technology in liver tumor surgery and discuss its challenges and potential development direction.

Wide-spectrum optical synthetic aperture imaging via spatial intensity interferometry

High resolution imaging is achieved using increasingly larger apertures and successively shorter wavelengths.Optical aperture synthesis is an important high-resolution imaging technology used in astronomy.Conventional long baseline amplitude interferometry is susceptible to uncontrollable phase fluctuations,and the technical difficulty increases rapidly as the wavelength decreases.The intensity interferometry inspired by HBT experiment is essentially insensitive to phase fluctuations,but suffers from a narrow spectral bandwidth which results in a lack of effective photons.In this study,we propose optical synthetic aperture imaging based on spatial intensity interferometry.This not only realizes diffraction-limited optical aperture synthesis in a single shot,but also enables imaging with a wide spectral bandwidth,which greatly improves the optical energy efficiency of intensity interferometry.And this method is insensitive to the optical path difference between the sub-apertures.Simulations and experiments present optical aperture synthesis diffraction-limited imaging through spatial intensity interferometry in a 100 nm spectral width of visible light,whose maximum optical path difference between the sub-apertures reaches 69λ.This technique is expected to provide a solution for optical aperture synthesis over kilometer-long baselines at optical wavelengths.

Optical coherence tomography enhanced depth imaging of chorioretinal folds in patients with orbital tumors

AIM:To characterize spectral-domain optical coherence tomography(SD-OCT)features of chorioretinal folds in orbital mass imaged using enhanced depth imaging(EDI).METHODS:Prospective observational case-control study was conducted in 20 eyes of 20 patients,the uninvolved eye served as a control.All the patients underwent clinical fundus photography,computed tomography,EDI SDOCT imaging before and after surgery.Two patients with cavernous hemangiomas underwent intratumoral injection of bleomycin A5;the remaining patients underwent tumor excision.Patients were followed 1 to 14mo following surgery(average follow up,5.8mo).RESULTS:Visual acuity prior to surgery ranged from 20/20 to 20/200.Following surgery,5 patients’visual acuity remained unchanged while the remaining 15 patients had a mean letter improvement of 10(range 4 to 26 letters).Photoreceptor inner/outer segment defects were found in 10 of 15 patients prior to surgery.Following surgical excision,photoreceptor inner/outer segment defects fully resolved in 8 of these 10 patients.CONCLUSION:Persistence of photoreceptor inner/outer segment defects caused by compression of the globe by an orbital mass can be associated with reduced visual prognosis.Our findings suggest that photoreceptor inner/outer segment defects on EDI SD-OCT could be an indicator for immediate surgical excision of an orbital mass causing choroidal compression.

Detecting early changes in choroidal vascularity and thickness using optical coherence tomography in patients with corneal crosslinking for keratoconus

AIM:To investigate changes in choroidal thickness and vascularity in keratoconus patients treated with corneal crosslinking.METHODS:This study evaluated 28 eyes of 22 patients with keratoconus who underwent corneal crosslinking.The choroidal thicknesses were evaluated on enhanced depth imaging optical coherence tomography at the preoperative and postoperative 3d,1,and 3mo.Choroidal thickness in the four cardinal quadrants and the fovea were evaluated.The choroidal vascularity index was also calculated.RESULTS:There was no significant difference in central choroidal thickness between the preoperative and postoperative 3d,1mo(P>0.05).There was a significant increase in the 3mo(P=0.034)and a significant decrease in the horizontal choroidal vascularity index on the postoperative 3d(P=0.014),there was no statistically significant change in vertical axes and other visits in horizontal sections(P>0.05).CONCLUSION:This study sheds light on choroidal changes in postoperative corneal crosslinking for keratoconus.While it suggests the procedure’s relative safety for submacular choroid,more extensive research is necessary to confirm these findings and their clinical significance.

Multi-aperture optical imaging systems and their mathematical light field acquisition models

Inspired by the compound eyes of insects,many multi-aperture optical imaging systems have been proposed to improve the imaging quality,e.g.,to yield a high-resolution image or an image with a large field-ofview.Previous research has reviewed existing multi-aperture optical imaging systems,but few papers emphasize the light field acquisition model which is essential to bridge the gap between configuration design and application.In this paper,we review typical multi-aperture optical imaging systems(i.e.,artificial compound eye,light field camera,and camera array),and then summarize general mathematical light field acquisition models for different configurations.These mathematical models provide methods for calculating the key indexes of a specific multiaperture optical imaging system,such as the field-of-view and sub-image overlap ratio.The mathematical tools simplify the quantitative design and evaluation of imaging systems for researchers.

Recent advances of optical imaging in animal stroke model

Stroke is a major health concern and an intensive research subject due that it is the major cause of death and the leading cause of disability worldwide. The past three decades of clinical disappointments in treating stroke must compel us to rethink our strategy. New effective protocol for stroke could greatly benefit from the advances in optical imaging technologies. This review focuses on the latest advance of applications of three optical imaging techniques in animal model of stroke, such as photoacoustic （PA） imaging, laser speckle contrast imaging （LSCI） and two-photon microscopy （TPM）. The potential roles of those techniques in the future of stroke management are also discussed.

Magnetic-Optical Imaging for Monitoring Chemodynamic Therapy

Chemodynamic therapy kills cancer cells with reactive oxygen species generated by endogenous triggers in the tumor microenvironment.Although chemodynamic therapy is blossoming in recent years,their therapy process still faces a series of hampers.The unknown catalytic activity of chemodynamic therapy reagents may lead to unpredictable therapy effects,so it is necessary to reveal the therapeutic mechanism of chemodynamic therapy and develop self-monitoring probes.In this mini-review,we summarize and illustrate the most recent progress of chemodynamic therapy,focusing on the applications of magnetic imaging and optical imaging probe for monitoring cancer chemodynamic therapy.Furthermore,we also discuss the potential challenges and the further directions of this field.