Optical Microscope System Research Articles

Nonlinear Optical Microscopy and Plasmon Enhancement.

Improving nonlinear optics efficiency is currently one of the hotspots in modern optical research. Moreover, with the maturity of nonlinear optical microscope systems, more and more biology, materials, medicine, and other related disciplines have higher imaging resolution and detection accuracy requirements for nonlinear optical microscope systems. Surface plasmons of metal nanoparticle structures could confine strong localized electromagnetic fields in their vicinity to generate a new electromagnetic mode, which has been widely used in surface-enhanced Raman scattering, surface-enhanced fluorescence, and photocatalysis. In this review, we summarize the mechanism of nonlinear optical effects and surface plasmons and also review some recent work on plasmon-enhanced nonlinear optical effects. In addition, we present some latest applications of nonlinear optical microscopy system research.

3D Volume Rendering of Invertebrates Using Light-Sheet Fluorescence Microscopy

Light-Sheet Fluorescence Microscopy has recently emerged as the technique of choice for obtaining high quality three-dimensional (3D) images of whole organisms, with low photo-damage and fast acquisition rates. Unlike conventional optical and confocal microscopy or scanning electron microscopy systems, it offers the possibility of obtaining multiple views of the sample by rotating it. We show that the use of light-sheet fluorescence microscopy, for the analysis of invertebrates, provides a fair compromise compared to scanning electron microscopy in terms of resolution, but avoids some of its drawbacks, such as sample preparation or limited three-dimensional perspectives. In this paper, we will show how LSFM techniques can provide a cheap, high quality, multicolor, 3D alternative to classic microscopes, for the study of the morphological structure of insects and invertebrates in morphogenesis studies of the whole animal.

Measurement of three-dimensional track profiles on CR-39s based on the photometric stereo method.

To obtain more information about incident particles, a new method for measuring three-dimensional track profiles formed on CR-39s based on the photometric stereo method was developed. A new optical microscope system with 16 lasers and a complementary metal-oxide-semiconductor camera was built to automatically capture the reflecting track images illuminated by the laser beams from different angles, and the track profiles were three-dimensionally reconstructed using a self-developed software. To verify the reconstruction results of the track profiles, both the openings and depth were measured with an atomic force microscope. The results showed that the relative deviations between the two methods of the openings were about 5.5% and the deviations of the depth were about 8.0%. At present, the reconstruction speed of a three-dimensional track profile is a factor of 400 greater than that of the atomic force microscope. The new method shows great potential for rapid reconstruction of numerous track morphologies. It is expected to be helpful for further studies on the energy and angle discrimination of incident particles in the field of nuclear measurements.

Study on bending fatigue failure behaviors of end-fixed wire ropes

Torsional fatigue always exists after a wire rope is put into use, which results in damage aggravation and lifespan reduction. This study is aimed at exploring the comprehensive tribo-fatigue behaviors of wire rope considering torsional fatigue. To achieve this aim, a new type of self-made fatigue testing machine was introduced, and the bending fatigue tests were carried out. Furthermore, the diameter shrinkage ratio, the number and distribution of broken wires under different fatigue times were studied by means of manual detection and non-destructive testing. Moreover, the fractures and wear scars were investigated with the aid of the LW200-4JT optical microscope system. For the thicker outer wire of spiral strand (SS), the influences of bending fatigue times on the evolution of wear parameters were comparatively analyzed. The research results are as follows. With the increase of bending fatigue times, the diameter shrinkage ratio increases, and the increase decelerates gradually. The artificial statistical results agree well with the non-destructive testing results. To be specific, the broken wire develops slowly in the early stage of fatigue, whereas it develops rapidly when the fatigue times exceed 60,000. The broken wire is highly concentrated in the thicker outer wire of SS 1. The maximum width and depth of wear scars of the thicker outer wire of SS 1 increase with the increase of cycles. The values of the two parameters at different contact positions follow the order: contact with the pulley > contact with the adjacent SS 1 > contact with the SS 2 > contact with the wire in the adjacent layer in the same strand. This study is expected to find the fatigue failure rules of end-fixed hoisting wire rope, thus providing a basis for improving the safety of mine hoisting.

Study of the Off-Axis Fresnel Zone Plate of a Microscopic Tomographic Aberration

A tomographic microscopy system can achieve instantaneous three-dimensional imaging, and this type of microscopy system has been widely used in the study of biological samples; however, existing chromatographic microscopes based on off-axis Fresnel zone plates have degraded image quality due to geometric aberrations such as spherical aberration, coma aberration, and image scattering. This issue hinders the further development of chromatographic microscopy systems. In this paper, we propose a method for the design of an off-axis Fresnel zone plate with the elimination of aberrations based on double exposure point holographic surface interference. The aberration coefficient model of the optical path function was used to solve the optimal recording parameters, and the principle of the aberration elimination tomography microscopic optical path was verified. The simulation and experimental verification were carried out utilizing a Seidel coefficient, average gradient, and signal-to-noise ratio. First, the aberration coefficient model of the optical path function was used to solve the optimal recording parameters. Then, the laminar mi-coroscopy optical system was constructed for the verification of the principle. Finally, the simulation calculation results and the experimental results were verified by comparing the Seidel coefficient, average gradient, and signal-to-noise ratio of the microscopic optical system before and after the aberration elimination. The results show that for the diffractive light at the orders 0 and ±1, the spherical aberration W040 decreases by 62–70%, the coma aberration W131 decreases by 96–98%, the image dispersion W222 decreases by 71–82%, and the field curvature W220 decreases by 96–96%, the average gradient increases by 2.8%, and the signal-to-noise ratio increases by 18%.

Wide-field-of-view and high-resolution HiLo optical sectioning microscopy system

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Cutting forces and tool wear studies on machining of Hastelloy X

Hastelloy based nickel materials are hard to cut category due to their properties like high strength during elevated temperature and excellent stress corrosion resistance. The machinability of such alloy is very much essential during fitment meanwhile tool wear need to be considered with utmost care. This study focused on turning operation of Hastelloy X using different cutting tools under dry conditions with different sets of cutting speeds and feeds. The impact of input cutting conditions on tool wear have been investigated experimentally with three different cutting tools. The turning operation was carried out at two different feeds 0.111 & 0.127 mm/rev and three different cutting speeds 23.86, 37.69 & 57.80 m/min with three different tool inserts. The cutting tool inserts involve an uncoated carbide tool and two coated carbide tools with Titanium Aluminium Nitride (TiAlN) coating and Titanium Nitride (TiN) coating. Optical microscopy and machine vision system were employed to analyze the crater and flank wear. The cutting forces were monitored for different conditions with lathe tool dynamometer. TiAlN coated insert shown better response when compared with other two inserts.

Fast and Lightweight Network for Single Frame Structured Illumination Microscopy Super-Resolution

Structured illumination microscopy (SIM) is an important super-resolution-based microscopy technique that breaks the diffraction limit and enhances optical microscopy systems. With the development of biology and medical engineering, there is a high demand for real-time and robust SIM imaging under extreme low-light and short-exposure environments. Existing SIM techniques typically require multiple structured illumination frames to produce a high-resolution image. In this article, we propose a single-frame SIM (SF-SIM) based on deep learning. Our SF-SIM only needs one shot of a structured illumination frame and generates similar results compared with the traditional SIM systems that typically require 15 shots. In our SF-SIM, we propose a noise estimator that can effectively suppress the noise in the image and enable our method to work in the low-light and short-exposure environment without the need for stacking multiple frames for nonlocal denoising. We also design a bandpass attention module that makes our deep network more sensitive to the change of frequency and enhances the imaging quality. Our proposed SF-SIM is almost 14 times faster than traditional SIM methods when achieving similar results. Therefore, our method is significantly valuable for the development of microbiology and medicine.

Investigation into the catalytic gasification of coal gasification fine slag residual carbon by the leachate of biomass waste: Gasification reactivity, structural evolution and kinetics analysis

In this study, the applicability of chicken manure leachate (CML) to catalytic gasification of coal gasification fine slag residue carbon (RC) was investigated in order to guide the large-scale application of RC as a potential gasification feedstock. Firstly, the effects of different CML loading amount and gasification temperature on RC reactivity were investigated. The structural evolution of RC loaded with CML in gasification was deeply analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and in-situ high temperature stage coupled with optical microscope system (HSOM). The results showed that CML is rich in water-soluble alkali and alkaline earth metallic species, especially potassium, which can significantly improve the gasification reactivity of RC. The gasification activity increased with the increase loading amount of CML, but higher gasification temperature will weaken the catalytic ability of CML. The model free method can well predict the kinetics of RC gasification reaction. The existence of CML reduced the activation energy of gasification obviously. The activation energy of RC20CML was 100.96 kJ/mol, which was 37.81 kJ/mol lower than that of RC. Furthermore, the surface complexes produced during RC gasification were determined by temperature programmed desorption (TPD) technique. The results showed that CML loaded RC released more CO during TPD process, which indicated that CML promoted the formation of more active sites on the RC surface, thus accelerating the gasification reaction. This work will contribute to the classification and resource utilization of coal gasification fine slag.

Leading morphological dominants of stroke as a basis for the morbid psychotype in cardiosurgical patients with postoperative hypoxic-ischemic injuries

Leading morphological dominants of stroke as a basis for the morbid psychotype in cardiosurgical patients with postoperative hypoxic-ischemic injuries

Fiber optics offer better photoacoustic detection

An optical coherence photoacoustic microscopy system uses a fiber-based dome sensor to noninvasively image zebrafish larvae.

An optical coherence photoacoustic microscopy system using a fiber optic sensor

In this work, a novel fiber optic sensor based on Fabry–Pérot interferometry is adopted in an optical coherence photoacoustic microscopy (OC-PAM) system to enable high-resolution in vivo imaging. The complete OC-PAM system is characterized using the fiber optic sensor for photoacoustic measurement. After characterization, the performance of the system is evaluated by imaging zebrafish larvae in vivo. With a lateral resolution of 3.4 μm and an axial resolution of 3.7 μm in air, the optical coherence microscopy subsystem visualizes the anatomy of the zebrafish larvae. The photoacoustic microscopy subsystem reveals the vasculature of the zebrafish larvae with a lateral resolution of 1.9 μm and an axial resolution of 37.3 μm. As the two modalities share the same sample arm, we obtain inherently co-registered morphological and vascular images. This OC-PAM system provides comprehensive information on the anatomy and vasculature of the zebrafish larvae. Featuring compactness, broad detection bandwidth, and wide detection angle, the fiber optic sensor enables a large field of view with a static sensor position. We verified the feasibility of the fiber optic sensor for dual-modality in vivo imaging. The OC-PAM system, as a non-invasive imaging method, demonstrates its superiority in the investigation of zebrafish larvae, an animal model with increasing significance in developmental biology and disease research. This technique can also be applied for functional as well as longitudinal studies in the future.

Multimodal microscopy for the simultaneous visualization of five different imaging modalities using a single light source.

Optical microscopy has been widely used in biomedical research as it provides photophysical and photochemical information of the target in subcellular spatial resolution without requiring physical contact with the specimen. To obtain a deeper understanding of biological phenomena, several efforts have been expended to combine such optical imaging modalities into a single microscope system. However, the use of multiple light sources and detectors through separated beam paths renders previous systems extremely complicated or slow for in vivo imaging. Herein, we propose a novel high-speed multimodal optical microscope system that simultaneously visualizes five different microscopic contrasts, i.e., two-photon excitation, second-harmonic generation, backscattered light, near-infrared fluorescence, and fluorescence lifetime, using a single femtosecond pulsed laser. Our proposed system can visualize five modal images with a frame rate of 3.7 fps in real-time, thereby providing complementary optical information that enhances both structural and functional contrasts. This highly photon-efficient multimodal microscope system enables various properties of biological tissues to be assessed.

Three-dimensional virtual histology in unprocessed resected tissues with photoacoustic remote sensing (PARS) microscopy and optical coherence tomography (OCT)

Histological images are critical in the diagnosis and treatment of cancers. Unfortunately, current methods for capturing these microscopy images require resource intensive tissue preparation that may delay diagnosis for days or weeks. To streamline this process, clinicians are limited to assessing small macroscopically representative subsets of tissues. Here, a combined photoacoustic remote sensing (PARS) microscope and swept source optical coherence tomography system designed to circumvent these diagnostic limitations is presented. The proposed multimodal microscope provides label-free three-dimensional depth resolved virtual histology visualizations, capturing nuclear and extranuclear tissue morphology directly on thick unprocessed specimens. The capabilities of the proposed method are demonstrated directly in unprocessed formalin fixed resected tissues. The first images of nuclear contrast in resected human tissues, and the first three-dimensional visualization of subsurface nuclear morphology in resected Rattus tissues, captured with a non-contact photoacoustic system are presented here. Moreover, the proposed system captures the first co-registered OCT and PARS images enabling direct histological assessment of unprocessed tissues. This work represents a vital step towards the development of a rapid histological imaging modality to circumvent the limitations of current histopathology techniques.

Direct observation of wetting behavior of water drops on single micro-scale roughness surfaces of rose petal effect

Hypothesis: It has been verified that a surface of single micro-scale structures with certain roughness could exhibit petal effect. That is, water drops with a contact angle larger than 150° would pin on the petal effect surface. It is conjectured that the water drop could pin on the single micro-scale roughness petal effect surface by totally infiltrating into spaces (or grooves) between micro-pillars.Experiments: An inverted optical microscopy system is synchronically applied in the process of advancing/receding contact angle (ACA/RCA) measurements to directly observe the wetting behavior of water droplets on hydrophobic patterned surfaces with regular arrays of square micro-pillars.Findings: A sequence of wetting behavior evolution, Wenzel → petal → pseudo-lotus → lotus, is observed on the hydrophobic patterned surfaces along with increasing surface roughness. It is interesting to observe a Cassie-Wenzel transition for water drops on a petal substrate during the ACA measurement (embedded needle method), leading to two ACAs, one before (in Cassie state) and one after the transition (in Wenzel state). Thus, the petal substrates have large contact angle hysteresis (CAH) (with both ACA and RCA in Wenzel state) to pin the water drop in Wenzel state. A Cassie-Wenzel transition is consistently observed during the evaporation process of water drops on pseudo-lotus substrates, leading to two RCAs: one in Cassie state and one in Wenzel state. The pseudo-lotus substrates have CAH (with both ACA and RCA in Cassie state) small enough to make water drops easily slide off.

Optical superoscillatory waves without side lobes along a symmetric cut

Optical superoscillation refers to an intriguing phenomenon of a wave packet that can oscillate locally faster than its highest Fourier component, which potentially produces an extremely localized wave in the far field. It provides an alternative way to overcome the diffraction limit, hence improving the resolution of an optical microscopy system. However, the optical superoscillatory waves are inevitably accompanied by strong side lobes, which limits their fields of view and, hence, potential applications. Here, we report both experimentally and theoretically a new superoscillatory wave form, which not only produces significant feature size down to deep subwavelength, but also completely eliminates side lobes in a particular dimension. We demonstrate a new mechanism for achieving such a wave form based on a pair of moonlike sharp-edge apertures. The resultant superoscillatory wave exhibits Bessel-like forms, hence allowing long-distance propagation of subwavelength structures. The result facilitates the study of optical superoscillation and on a fundamental level eliminates the compromise between the superoscillatory feature size and the field of view.

Fluorescent Imaging and Multifusion Segmentation for Enhanced Visualization and Delineation of Glioblastomas Margins

This study investigates the potential of fluorescence imaging in conjunction with an original, fused segmentation framework for enhanced detection and delineation of brain tumor margins. By means of a test bed optical microscopy system, autofluorescence is utilized to capture gray level images of brain tumor specimens through slices, obtained at various depths from the surface, each of 10 µm thickness. The samples used in this study originate from tumor cell lines characterized as Gli36ϑEGRF cells expressing a green fluorescent protein. An innovative three-step biomedical image analysis framework is presented aimed at enhancing the contrast and dissimilarity between the malignant and the remaining tissue regions to allow for enhanced visualization and accurate extraction of tumor boundaries. The fluorescence image acquisition system implemented with an appropriate unsupervised pipeline of image processing and fusion algorithms indicates clear differentiation of tumor margins and increased image contrast. Establishing protocols for the safe administration of fluorescent protein molecules, these would be introduced into glioma tissues or cells either at a pre-surgery stage or applied to the malignant tissue intraoperatively; typical applications encompass areas of fluorescence-guided surgery (FGS) and confocal laser endomicroscopy (CLE). As a result, this image acquisition scheme could significantly improve decision-making during brain tumor resection procedures and significantly facilitate brain surgery neuropathology during operation.

Anterior Chamber Characteristics, Endothelial Parameters, and Corneal Densitometry After Descemet Stripping Automated Endothelial Keratoplasty in Patients With Fuchs Dystrophy.

PurposeTo compare anterior segment parameters in patients with Fuchs endothelial dystrophy (FED) who underwent Descemet stripping automated endothelial keratoplasty (DSAEK) in one eye and no corneal surgery in the fellow eye.MethodsThis prospective study was conducted on 28 eyes of 14 patients with FED who underwent DSAEK in one eye at least one year prior (DSAEK group) and no corneal surgery in the fellow eye (control group). Each eye was analyzed with the anterior segment optical coherence tomography, specular microscopy, and Scheimpflug imaging systems. Data were compared between the two groups.ResultsThe mean age of the patients was 76.9 7.0 years. There were no statistically significant differences in the mean central corneal thickness (CCT), central anterior chamber depth, anterior chamber angle parameters, cylinder and keratometry values between two groups (all P-values 0.05). The paracentral corneal thickness, corneal volume, endothelial cell density, and hexagonal cell ratio measurements were statistically significantly higher in the DSAEK group than the control (all P-values < 0.05), and anterior chamber volume in the DSAEK group was significantly less than the control (P = 0.046). While posterior and total corneal densitometry values in the DSAEK group were statistically significantly lower than the control (P < 0.001 and P = 0.011, respectively), there were no statistically significant differences in the anterior or middle corneal densities (P = 0.108 and P = 0.134, respectively).ConclusionWe found that total corneal densitometry value decreased in DSAEK group. Although DSAEK surgery did not affect the anterior chamber angle parameters, it reduced the anterior chamber volume and increased the corneal volume and paracentral corneal thickness due to the addition of the DSAEK graft.

Direct axial plane imaging of particle manipulation with nondiffracting Bessel beams.

Optical manipulation with nondiffracting beams has been attracting great interest and finding widespread applications in many fields such as chemistry, physics, and biomedicine. Generally, optical manipulation is conducted in an optical microscopy system, which, in general, only allows for imaging motions of particles in the transverse plane, rendering the observation of dynamics processes occurring in the axial plane impractical. We propose and demonstrate an optical manipulation system that incorporates an axial plane imaging module. With this system, the trapping behavior in the transverse plane and the transportation process in the axial plane of a particle immersed in a Bessel beam were acquired simultaneously in real time.

Developing Low-Profile Deflectometer for Combined Scanning Probe and Optical Microscopy Systems

Developing Low-Profile Deflectometer for Combined Scanning Probe and Optical Microscopy Systems