This PDF file contains the front matter associated with SPIE Proceedings Volume 12316, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Microsphere-assisted imaging is a label-free super-resolution optical microscopic technique. In 2021, Shang et al. found that by coating microspheres with Ag films, the super-resolution imaging performance of microspheres can be significantly enhanced. Here we reported the progress of using patchy particles for super-resolution imaging, and we showed that the performance of the imaging system can also be enhanced by coating microspheres with Al films. Using Al instead of Ag can significantly reduce the cost of fabrication, and facilitates the commercialization of this technique.

Biaxial crystals offer a huge advantage for design of acousto-optic tunable filters (AOTFs) because of a variety of two-dimensional transfer functions. Special configurations of noncritical phase matching of anisotropic Bragg diffraction offer the transfer functions suitable for tunable spatial filtering of laser beams, which can be used for phase imaging and laser beam shaping. We analyze special configurations of AOTFs in alpha-iodic acid (orthorhombic system) and potassium yttrium tungstate (monoclinic system) crystals and demonstrate unique two-dimensional transfer functions, which originate from symmetries of the biaxial crystals' refractive index surface. The results include transfer function simulations and corresponding configuration analysis for AOTF design.

Optical endoscopy is indispensable for minimally-invasive medical diagnostics and therapeutics, whereby visualization of subtle changes in the structure of tissue can be used to identify disease. Adaptive real-time zoom functionality is highly desirable for resolving mucosal microvasculature, which when visualized can be used to improve diagnostic accuracy. Realizing this functionality in state-of-the-art miniaturized endoscopic imaging, such as chip-on-tip endoscopes, is challenging: conventional zoom objectives are bulky and existing chip-on-tip systems still have far from diffraction-limited performance. Point-scanning illumination approaches have been shown to improve imaging resolution by reducing the focused spot size. Typically, this higher resolution comes at the cost of low optical throughput (efficiency) and long acquisition times due to mechanical scanning requirements, thereby limiting applicability in clinical settings. In this work, we demonstrate an innovative Diffractive Optical Element (DOE) based optical imaging system for spatial resolution enhancement without mechanical scanning. Our imaging system is based on simultaneous utilization of a custom DOE and high-speed Digital Micromirror Device (DMD). The multi-level phase-only DOE produces a single super-resolution spot in the far-field while the DMD laterally scans the spot in the object plane at kHz rates. To demonstrate resolution enhancement with high-speed acquisition, we image a resolution test target and fluorescently labelled cells. In the future, through envisioned DOE-array integration in an endoscopic module, resolution enhancement (in an adaptive zoom-mode) can be achieved through illumination modulation alone without the need for separate systems.

In recent years, endoscopic imaging has become the major diagnostic approach for early cancer. It is difficult to accurately obtain the information of lesions and components content by using conventional white light imaging (C-WLI). Multispectral imaging techniques such as narrowband imaging are widely used in endoscopic clinical because of their specificity on the surface structure of digestive tract mucosa. However, there is still a lack of multispectral techniques for tissue components specificity. Tissue components such as lipid, hemoglobin are closely related to the generation and development of tumors, but it is difficult to observe the characteristics of lipid and hemoglobin by conventional white light imaging. Therefore, we studied the multispectral endoscopic imaging technique for the analysis of digestive tract mucosal components. Based on the reflectance spectrum characteristics of these tissue components, we determined their specific wavelength, and comprehensively considered the absorption, scattering, oxygenation and others in order to determine the most appropriate optical band in the wavelength range of 365-660nm. Through experimental verification, we choose different narrow-band wavelength combinations for lipids and hemoglobin oxygen saturation respectively to achieve multispectral imaging. In order to simulate the optical properties of digestive tract surface, we made tissue optical phantom. At the same time, we tested and optimized the imaging system and algorithm by the experiments in vitro, and obtained the optimal multispectral image of tissue components, then realize the quantitative detection combined with the content analysis algorithm. Our pilots show that the multispectral imaging system can improve the contrast of endoscopy image, enhance the detail information, achieve high precision detection of tissue components content, and control the error within 10%.

A holographic technique is useful for increasing the processing speed in laser grooving and scribing. In laser grooving, depth control of the processed structure is important for performing precise processing. In this paper, in-process monitoring of the depth of a structure formed by femtosecond laser processing with a line-shaped beam using sweptsource optical coherence tomography (SS-OCT) was demonstrated. In laser grooving, the structural depth and the shape were successfully monitored. The proposed method will be effective for precise laser processing with feedback control of the laser parameters based on in-process monitoring of the processed structure.

Recently, whole slide imaging (WSI) has become the gold standard for the clinical diagnosis of various diseases. It not only strengthens the cooperation between the computer and pathologists, but also promotes the development of remote primary diagnosis. WSI usually uses 20x and 40x objective lens scanners to scan the slides. Compared with the low-magnification lens, the high-magnification lens could provide high-resolution (HR) images, while sacrificing the large field-of-view (FOV), large depth-of-field (DOF), and high scanning efficiency instead. In this paper, we propose an image super-resolution (SR) reconstruction method based on a deep residual network (DSN), which improves flexibility and recovers the effective information neglected by the conventional network. After experimental verification, our method achieves large FOV, high scanning efficiency, and HR images simultaneously for assisting the diagnosis of pathologists.

In recent years, transcorneal electrical stimulation（TES）has been regarded as a potential treatment method for degenerative retinal disease. However, the mechanism of TES therapy is still not understood till now. As one of the manifestations of retinal degenerative diseases, the fundus non-vascular perfusion area has been shown to be related to the degeneration of retinal photoreceptor cells and the attenuation of the retinal vasculature and there is a great probability to be cured by TES treatment. The purpose of this study was to analyze the variation of the intrinsic optical signal (IOS) characteristic and the retinal blood vasculature induced by TES in mice and to investigate the therapeutic mechanism of TES for retinal degenerative diseases. In this study, swept-source optical coherence tomography (SS-OCT) system was custom-built to record the IOS and fundus vascular response under TES in pre-, during, and post-stimulation periods, respectively. Results showed that the vessel density (VD) of retinal vessels slightly increased under TES, positive and negative IOS changes significantly increased in all retinal layers, and recovery of the microvascular access in the lesion area was obviously observed. This study might be useful to understanding the treatment mechanism of TES on degenerative retinal diseases and it proved that OCT and OCTA could be used as monitoring techniques for TES therapy.

As live cell imaging has become a research hotspot in the biomedical field, optical microscopy imaging has become one of its most beneficial and critical research tools. Fluorescence microscopy imaging provides an effective and direct visualization for cell observation in a specifically labeled manner. Non-invasive imaging modalities such as dark field and differential phase contrast imaging enable high contrast observation of samples. Some applications often require a combination of the advantages of these two types of microscopic imaging techniques to achieve a full view and specific detection of cells. However, there is a lack of a microscope system that combines both of these imaging modalities. We designed a miniaturized multimodal fluorescence microscopy system that couples a two-channel drop-in fluorescence microscopy light path with high brightness LED units as the illumination source and a transmission multimodal microscopy light path with programmable LED arrays as the illumination source, realizing diverse imaging methods such as fluorescence, bright-field, dark-field, Rheinberg optical staining imaging and differential phase contrast imaging in the same system. The system enables a full range of diverse observations of biological samples. Furthermore, the entire system uses multiple mirrors to reduce the size of the folded optical path and can be built into the cell culture chamber for real-time observation of live cells to avoid exogenous contact and contamination.

Synthetic aperture techniques applied to visible imaging in the direction of rapid development in recent years and have achieved initial effectiveness in the fields of remote sensing. The existing synthetic aperture technique for visible imaging mainly relies on the application of Fourier Ptychography (FP) in the far field to obtain more high- frequency information by aperture scanning. FP allows resolution enhancement for the smooth object. However, the FP strategy is not sensitive to diffuse re action imaging formed by rough objects. The conventional approach to high-resolution reconstruction of images containing speckle noise by FP is to boost the overlap rate between sub-aperture images, which increases the amount of data required by a factor of ten and affects imaging efficiency. In this work, a synthetic aperture method via Total Variation (TV) regularization is proposed to achieve less- speckle imaging. The prior distribution is imposed on the object with the assistance of TV regularization and solved by the Augmented Lagrangian method. The reconstruction results of high quality without increasing data redundancy are obtained, and the optimal signal-to-noise ratio is achieved at a 70% overlap rate. The proposed method improves the resolution by a factor of eight and further enhances the perceptual resolution of rough objects. To the best of our knowledge, the findings achieve the best imaging quality without a high overlap rate, permitting large field-of-view, high-resolution detection of targets for widespread far-field detection and remote sensing applications.

In this paper, we show a portable surface imaging system based on a dual-line fiber optic sensor array, a customized CIS, for hand-held surface imaging, e.g., skin mirroring, with low-cost and high-performance. In our system, the image is taken by the dual-line image sensor with the fashion of manually shifting; the stretched image caused by the non-uniformly shifting speed is rectified by a novel image processing algorithm. The experimental results demonstrate that the proposed imaging technique is able to take image of the surface of an object, such as solid sample and human skin, which could be a promising technique for low-cost portable surface imaging and has large potentiality in many applications, such as object surface imaging device or skin-mirror, with high portability and performance.

Phase modulation of a CW UV laser is used to modulate the intensity of the laser beam at a single frequency. The intensity modulated beam is used to excite the single crystals of methylammonium lead bromide and cesium lead bromide perovskites. The modulations in the intensity of the photoluminescence are analyzed to show the co-existence of excitons and free charges in the excited crystals. The contributions from the two excited species on the emissions are quantified and imaged over the crystal surfaces.

Fourier ptychographic microscopy (FPM) is a promising high-throughput imaging technique for biological research, medical research, and pathological diagnosis. Based on varying angle illumination and synthetic aperture, it achieves the imaging resolution beyond the diffraction limit of objective lens across a wide field-of-view (FOV). In FPM, sufficient redundant data is required to ensure the convergence of iteration. However, excessive acquisition and reconstruction time cost lead to the main limitations of FPM in imaging efficiency. In this paper, we propose efficient FPM (EFPM) that distinguishes between bright and dark field illuminations, to reduce the number of images collected by Fourier strobe imaging. In bright-field acquisition, we adopt partially coherent illumination to record a single image, reducing the accumulated time of multiple LED sequential illumination to a single exposure. In addition, sparse sampling is used in the dark-field images acquisition to significantly reduce the number of captured images. Thus, EFPM yields imaging resolution reaching 3NAobj using only 7 images. The experiment on USAF resolution sample is presented to demonstrate that EFPM achieves high resolution and wide FOV through significantly reduced data, providing a rapid means for pathological research.

Since the spectral aliasing degree of object information and background intensity affects the phase demodulation accuracy directly through the linear Fourier domain filtering, conventional holography suffers from the problem of incompatibility between high reconstruction quality and high throughput imaging. The enhancement of space-bandwidth product by slightly off-axis holography is necessarily accompanied by zero-order suppression; otherwise, artifacts will be formed on the phase image due to the residual background intensity information. We innovatively propose a zero-order suppression method for slightly off-axis digital holography based on Fourier ptychography (FP), terms as FPDH. Inspired by the FPM phase retrieval process, the hologram spectrum recovery is viewed as a nonlinear optimization problem, and the object wavefront is recovered by a method like GS algorithm. Experimental results show that FPDH can provide higher reconstruction accuracy and better image quality compared with other methods.

Fourier ptychographic microscopy (FPM) is a new quantitative phase imaging (QPI) method, which achieves highresolution and wide-field-of-view imaging by iterative reconstruction algorithm. However, its drawbacks are long acquisition time and large data set, not only a large number of images need to be taken for each reconstruction, but also long exposure time is required for dark field images. To alleviate this problem, we propose an efficiency-optimized Fourier ptychographic microscopy based on spectrum overlap percentage analysis. By adopting illumination-optimized DPC and centrosymmetric sparse illumination, the number of acquired images is reduced several times, improving the imaging efficiency of FPM. This approach promises potential for high-throughput phasing applications.

Structured illumination microscopy (SIM) is a widely available super-resolution technique for bioscience, especially for living cell research, due to its high photon efficiency. However, the quality of SIM depends extremely on the post-processing algorithms (parameter estimation and image reconstruction), where parameter estimation is the critical guarantee for successful super-resolution reconstruction. In this letter, we present a novel SIM approach based on principal component analysis (PCA-SIM) that statistically purifies experimental parameters from noise contamination to achieve high-definition super-resolution reconstruction. Experiments demonstrate that our method achieves more accurate (0.01 pixel wave vector and 0.1% of 2π initial phase) parameter estimation and superior noise immunity with an order of magnitude higher efficiency than conventional cross-correlation-based methods, offering the possibility of faster, less photon dose, longer duration living cell SIM.

Laser induced breakdown spectroscopy (LIBS) termed an effective technique to confirm the elemental composition of geologic, due to its unique elemental ‘fingerprint’ properties and qualitative or quantitative analytical performance. However, the low focusing accuracy and poor spatial resolution of traditional LIBS technology limits its application in minerals with complex topography. To address this issue, we constructed a confocal controlled LIBS (CCLIBS) microscope for three-dimensional elemental mapping of natural minerals. The CCLIBS system is an innovative fusion of confocal microscopy and LIBS technology, which significantly improves the spatial resolution and the stability of LIBS spectrum. With this system, the geometry and elemental distribution of natural agate ores are accurately obtained. Then, a common chemometric method of principal component analysis (PCA) was conducted to analyse the differences in such spectral lines. According to the differences of wavelength and intensity characteristics, the typical spectra were selected to map the elemental distribution. Finally, the three elements with the highest PC scores were selected to construct the multi-element fusion mapping, which can reflect the distribution of elements more intuitively. In this paper, we innovatively integrate three-dimensional (3D) morphology with multi-element distribution to characterize the spatial distribution of elements. Compared with single-element fusion, multi-element fusion is more intuitive and clearer, which is of great significance for the analysis of complex components of natural minerals. To solve the problems of low focusing accuracy and poor spatial resolution of traditional LIBS technology, we constructed a confocal controlled LIBS microscope for three-dimensional elemental mapping of natural minerals. The microscope is an innovative fusion of confocal microscopy and LIBS technology, which significantly improves the spatial resolution and stability of spectrum, ensuring that the system can achieve minimal ablation at focal point. Furthermore, we integrate three-dimensional (3D) morphology with multi-element distribution to characterize the spatial distribution of elements. The innovative method provides an effective way for elemental characterization in the fields of biomedicine, materials science and geological science.

Brillouin scattering is an inelastic light scattering caused by local thermal vibration of materials. It can noninvasively detect the mechanical properties of materials such as stiffness, strain and elastic constant. Combined with confocal microscopy, confocal Brillouin microscope (CBM) can be used to detect the mechanical properties of micro-region materials with a non-contact manner. Therefore, it’s widely used in biomedical detection, material science and other frontier fields. However, due to the lack of fast and high-precision axial focusing ability of traditional CBM, the spatial resolution is limited, and the system stability is poor during long-time imaging process. Interference with specular reflected light can reduce the system's extinction ratio and sensitivity. These problems directly affect the accuracy of mechanical mapping results. A new type of divided-aperture confocal Brillouin microscope (DCBM) is proposed to improve its spatial resolution, stability and extinction ratio. The reflected light and scattered light are separated in space by divided-aperture, increased the extinction ratio by 20dB, and the reflected light is used to construct a confocal system to achieve the axial focusing accuracy of 5nm. The axial focusing ability of high sensitivity also significantly improves the spatial resolution and system stability. We used sheep myocardial tissue as a sample to verify the Brillouin mapping capability of the DCBM system. The fast in-situ imaging and high precision Brillouin mapping of the morphology and mechanical information of the sheep myocardial tissue was obtained at the same time. This technology provides a powerful tool for studying new phenomena in the fields of biology and materials.

Confocal Raman microscopy can provide molecular distribution and three-dimensional topographic information of the substances, and is widely used in biomedical, material chemistry and physical science fields. However, in the traditional confocal Raman microscopes, the devices have large size, and scan lens and tube lens need conjugate placement taking up a lot of space, these make it difficult to reduce the size of the system. In order to solve the mentioned problems, we propose a scanning mechanism based on MEMS scanning mirror without scan lens and tube lens, and develop a miniature confocal Raman microscope base on this mechanism. In which the MEMS scanning mirror is used for lateral two-dimensional scanning of the laser beam, and an aspherical lens is placed directly behind the MEMS scanning mirror as the objective, as well as the MEMS mirror is positioned at the back focal plane of the aspherical lens to obtain a better spatial resolution. Compared with the traditional confocal Raman microscope based on galvanometer scanning, a miniaturized MEMS scanning mirror is used in our system, and scan lens and tube lens are omitted, which greatly reduces the size of this system. Meanwhile, the reduction of optical components and the shortening of the optical length improve the signal detection efficiency, which is very beneficial for the detection of relatively weak Raman spectral signals. The preliminary experimental results demonstrate the system lateral resolution and axial resolution are about 0.8 μm and 5.5 μm, respectively, and the Raman spectral resolution is 0.2 nm, which is basically consistent with the theoretical analysis.

In modern single pixel microscopy techniques, like Nano-Illumination Microscopy, long measurement times can become a major issue, especially when imaging biological tissues with large field of view. Usually, light intensity measurements are performed with CMOS pixels, with typical integration times around tens of milliseconds. In this work, we propose to obtain a light intensity measurement indirectly by applying statistical techniques to the photon arrival times gathered with an SPAD photodetector. We will present how the different statistical measurements can be used to minimize the total acquisition time and minimize also the hardware required. In this work, with captures of 256 SPAD measurements, reducing measurement time from 50ms to 50us. The dynamic range is extended by combining multiple statistical techniques with standard intensity measurements. This paves the way to practical Nano-Illumination Microscopy and other single pixel microscopy techniques.