Block face imaging is widely used in three-dimensional large biological samples imaging. However, high throughput and excellent optical sectioning cannot be achieved at the same time for imaging such large area. Here, we propose a line-scanning virtual structured modulation method to combine the advantages of optical sectioning and imaging speed in structured modulation microscopy and line-scanning microscopy. We significantly improve signal to noise ratio and throughput compared to wild-filed structured illumination microscopy. Our results also have no residual modulation artifacts. It indicates our method enables to achieve imaging 3D large biological sample with excellent optical sectioning and high throughput.
Obtaining fine structures in the whole brain is necessary for understanding brain function. Simple and effective methods for large-scale 3D imaging at optical resolution are still lacking. Here, we proposed a deep-learning-based fluorescence micro-optical sectioning tomography (DL-fMOST) method for fast, high-resolution whole-brain imaging. We utilized a wide-field microscope and a convolutional neural network for optical sectioning imaging, replacing traditional optical method. A 3D dataset of a mouse brain with a voxel size of 0.32 × 0.32 × 2 µm was acquired in 1.5 days. We demonstrated the robustness of DL-fMOST for mouse brains with labeling of different types of neurons.
Optical visualization of Alzheimer’s disease (AD) pathological changes is crucial to facilitate exploration of disease mechanism and treatment. We developed cryo-micro-optical sectioning tomography (cryo-MOST) to acquire brainwide map of senile plaques. Using intrinsic fluorescence emission intensified under ultra-low temperature, we accomplished senile plaque visualization at a micron-level resolution. A whole-brain coronal distribution of senile plaque in a transgenic mouse was successfully acquired without any exogenous dye. We believe cryo-MOST would be a potential tool for understanding neurodegenerative disease mechanism and evaluating drug efficacy.
Deciphering the fine morphology and precise location of neurons and neural circuits are crucial to enhance our understanding of brain function and diseases. Traditionally, we have to map brain images to coarse axial-sampling planar reference atlases to orient neural structures. However, this means might fail to orient neural projections at single-cell resolution due to position errors resulting from individual differences at the cellular level. Here, we present a high-throughput imaging method that can automatically obtain the fine morphologies and precise locations of both neurons and circuits, employing wide-field large-volume tomography to acquire three-dimensional images of thick tissue and implementing real-time soma counterstaining to obtain cytoarchitectonic landmarks during the imaging process. The reconstruction and orientation of brain-wide neural circuits at single-neuron resolution can be accomplished for the same mouse brain without additional counterstains or image registration. Using our method, mouse brain imaging datasets of multiple type-specific neurons and circuits were successfully acquired, demonstrating the versatility. The results show that the simultaneous acquisition of labeled neural structures and cytoarchitecture reference at single-neuron resolution in the same brain greatly facilitates precise tracing of long-range projections and accurate locating of nuclei. Our method provides a novel and effective tool for application in studies on genetic dissection, brain function and the pathology of the nervous system.
Acquiring brain-wide composite information of neuroanatomical and molecular phenotyping is crucial to understand brain functions. However, current whole-brain imaging methods based on mechnical sectioning haven’t achieved brain-wide acquisition of both neuroanatomical and molecular phenotyping due to the lack of appropriate whole-brain immunostaining of embedded samples. Here, we present a novel strategy of acquiring brain-wide structural and molecular maps in the same brain, combining whole-brain imaging and subsequent immunostaining of automated-collected slices. We developed a whole-brain imaging system capable of automatically imaging and then collecting imaged tissue slices in order. The system contains three parts: structured illumination microscopy for high-throughput optical sectioning, vibratome for high-precision sectioning and slice-collection device for automated collecting of tissue slices. Through our system, we could acquire a whole-brain dataset of agarose-embedded mouse brain at lateral resolution of 0.33 µm with z-interval sampling of 100 µm in 9 h, and automatically collect the imaged slices in sequence. Subsequently, we performed immunohistochemistry of the collected slices in the routine way. We acquired mouse whole-brain imaging datasets of multiple specific types of neurons, proteins and gene expression profiles. We believe our method could accelerate systematic analysis of brain anatomical structure with specific proteins or genes expression information and understanding how the brain processes information and generates behavior.
Knowledge of neuronal wiring and morphogenesis in Drosophila is essential to understand brain function and dysfunction. The immunoenzyme method based on horseradish peroxidase/diaminobenzidine (HRP/DAB) provides high-contrast images to resolve details underlying neuronal architecture. However, the poor staining penetration and a lack of corresponding three-dimensional imaging methodology limit its application. Herein, we modified the HRP/DAB method to stain neuronal circuits in the whole brain of Drosophila. Furthermore, we found that imaging with the micro-optical sectioning tomography system provided a fast and automatic method that could dissect cell-specific neuroanatomical architecture at a submicron voxel resolution.
Cryo-imaging techniques have been widely used to measure the metabolic state of tissues by capturing reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) autofluorescence. However, NADH and FAD fluorescence is sensitive to changes in temperature, which may result in unreliable redox ratio calculations. Here, the relationship between the measured redox ratio and sample surface temperature was analyzed using a standard phantom solution and biological tissues. The results indicated that a temperature <−100°C was a suitable cryo-imaging temperature window in which redox ratio measuring was immune to temperature fluctuations. These results may serve as a reference for designing and optimizing redox cryo-imaging experiments for quantitatively mapping the metabolic state of biological samples.
Modeling the process of ion exchange in glass requires accurate knowledge of the self-diffusion coefficients of the incoming and outgoing ions. Furthermore, correlating the concentration profile of the incoming ions to a change in refractive index requires knowledge of the correlation coefficient. A novel method of a neural network based on a particle swarm optimization algorithm is considered. In the range of training, the performance parameters of ion-exchanged waveguides in any arbitrary experiment condition can be obtained easily and quickly. This method has the advantages of reliability, accuracy, and time efficiency, which are identified by simulation. Therefore, it has promise in both fields of investigation and applications.
The configuration of polymer light waveguide electro-optical printed circuit board(EOPCB) is proposed in this paper. An
additional optical layer with light waveguide structure is used in conventional PCB to construct EOPCB. Light
waveguide core layer mould is made with SU-8 photolithograph. Polymer light waveguide layer which is embedded
between multiplayer PCB is made in experiment by Doctor-blading technology for large size application. Vertical cavity
surface emitting laser (VCSEL) array is used as optical transmitter array. PIN photodiode array is used as optical
receiver array. A MT-compatible direct coupling method is presented to couple light beam between optical
transmitter/receiver with light waveguide layer. The optical signals from a processor element chip on the PCB can
transmit to another processor element chip on the same PCB board through light waveguide interconnection in EOPCB.
So optical interconnection between chip to chip for parallel multiprocessor system can be reailzed by EOPCB.
A three-dimensional (3-D) 4×4×4 optical interconnect Mesh network scheme for parallel multiprocessor system based
on polymer light waveguide electro-optical printed circuit board(EOPCB) is proposed in this paper. The Mesh
topological structures of light waveguide interconnects for processor element chip-to-chip on a board, and board-toboard
on backplane is constructed. The system consists of 64 processor element chips interconnected in a 3-D Mesh
network configuration. Every processor board comprises 4x4 processor element chips with Mesh interconnection.
Board-to-board Mesh interconnects are established on a backplane through light waveguide Mesh interconnect
topological structure. An additional optical layer with light waveguide structure is used in conventional PCB to construct
EOPCB. Vertical cavity surface emitting laser (VCSEL) array is used as optical transmitter array. PIN photodiode array
is used as optical receiver array. A MT-compatible direct coupling method is presented to couple light beam between
optical transmitter/receiver with light waveguide layer. The optical signals from a processor element chip on a board can
transmit to another processor element chip on another board through light waveguide interconnection in the backplane.
So 3-D optical interconnection Mesh network for parallel multiprocessor system can be reailzed by EOPCB.
A star-based two-dimensional (2-D) torus inter-chip network on electro-optical printed circuit board (EOPCB) is
proposed to provide a simple and effective interconnection solution for such a real-time distributed parallel systems as
satellite image processing, which is characterized with locally intensive communication. The proposed hybrid
interconnection network has a hierarchical structure where the higher level is a 2-D torus network of 8×8 optical cross-connects
(OXCs) and the lower level is a cluster of processors connected in star topology using4×4OXCs. EOPCB is
used to eliminate the electrical bottleneck of high speed interconnection on board. OXCs are used to eliminate the
expensive E/O/E conversion of electrical routers and provide a transparent optical channel between processors. A new
approach based on combination network is proposed to construct 4×4 and 8×8OXCs with 2×2optical crossbars.
Greedy demand of high speed communication has made electrical interconnection on board a bottleneck. Electro-Optical Printed Circuit Board (EOPCB) was proposed to relieve the pressure by introducing an optical layer to common printed circuit board. Nowadays, most of the proposed EOPCB solutions focused on the design of optical transceiver structure and optical interconnection was used directly to replace high speed electrical interconnection by employing transceiver arrays. This approach would need many VCSEL-PIN pairs for a single high speed chip on board, thus increase the cost and also decrease the efficiency of optical interconnection. To defeat the weakness, a network approach, where only one VCSEL-PIN pair is required for a chip, is proposed in this paper. A novel Optoelectronic
integrated circuit (OEIC) architecture is introduced to make this network approach possible.
A wavelength 0.85μm-based optical power splitter designed with Multi Mode Interference (MMI) by ion exchange on K9 glass was introduced. The waveguide material is K9 glass made in China and formed by K+-Na+ pure melt salt ion exchange method. The grade index profile of planar ion-exchanged waveguide on K9 was studied and accorded with erfc function through compare of experimental and theoretic index profiles. The fabrication process of planar ionexchanged waveguide device was described. The basic theory of 1×8 MMI optical power splitter was illuminated by using guided-model propagation analysis. The working wavelength is 0.85μm, and the structure parameters of 1×8 MMI splitter were designed. The core pitch on this chip is chosen as 250μm to take the fiber connections into account, and the typical cladding diameter of optical fibers as 125μm. The critical parameters in the fabrication of the MMI power splitter are the multimode section width and length. In general the key performance specifications of the optical power splitter are insertion loss and uniformity. The output performances and the refractive index change's influence of the device were simulated by Bear Propagation Method (BPM). The uniformity was 0.93×10-2dB, the average insertion loss was 9.12dB, and the maximal insertion loss was 9.14dB. The result shows that the advantages of the method include low loss, ease of fabrication, and low material cost.
A chip-to-chip optical interconnection solution on PCB is presented in this paper. Both electrical and optical interconnections are used in common printed circuit board (PCB) to construct electro/optical PCB (EOPCB). An additional optical layer with waveguide structure is used in the PCB. So the EOPCB integrates the information medium "light" into the board. Optical transmitter is vertical cavity surface emitting laser (VCSEL) array. Optical receiver is PIN array. VCSEL array with its driver IC chip and PIN with its receiver IC chip are bonded with LSI chip by ball-grid array (BGA) technology. Then the LSI chips with VCSEL and PIN arrays are bonded on PCB by surface-mount technology (SMT). Multimode waveguides are used as optical layer in PCB. In order to couple light beam between optical transmitter/receiver with waveguide layer, a direct coupling method by the waveguide with 45° end face is presented. VCSEL chip is placed close to the 45° end face of the waveguide. The light beams from VCSEL array are emitted into the 45° end face directly and reflected by 90°, then coupled into the waveguide layer. No microlens arrays are needed for collimating light beam array in this configuration. A proof-of-principle experiment is made to verify the feasibility of this approach.
This paper presented a silica-based 1×8 optical power splitter at 0.85μm designed with Multi Mode Interference (MMI). The waveguide material is Si-based SiO2 doped with Ge and deposited by PECVD (Plasma Enhanced Chemical Vapor Deposition) method. The refractive index of glass substrate is 1.458, and the index difference is 0.75%. The input and output waveguides are optimized considering the characteristics of VCSEL (Vertical Cavity Surface Emitting Lasers). The core pitch on this chip is chosen as 250μm to take the fiber connections into account, and the typical cladding diameter of optical fibers as 125µm. The critical parameters in the fabrication of the MMI power splitter are the multimode section width and length. In general the key performance specifications of the optical power splitter are insertion loss and uniformity. We use a Finite Difference Beam Propagation Method (FDBPM) to simulate accurately the evolution of the fundamental mode power of the input guide incoming to the device, and analyze the relationships of various parameters in detail. The bend output waveguides are sin-bend styles. Compared with the commercial optical power splitter, the simulation results accord with the requirement of our design, containing compact size, low loss, stable splitting ratio, low crosstalk, large optical bandwidth, and good fabrication tolerances. The insertion loss and the uniformity of pilot study are 9.07dB and 0.02dB respectively.
This paper describes the design of an OIF-approved 10Gbps very short reach parallel optical interconnect demonstrated system. It is a 12x1.25Gb/s channel parallel optics solution, leveraging the low cost transceiver (850nm VCSEL), and CMOS (SERDES) technologies originally developed for Gigabit Ethernet. The demonstrator comprises of SONET/SDH serial OC-192 interface, CPLD based convert IC, 1.25Gbps 12-channel parallel optical transmitter and receiver. The transmitter includes a 12-channel array of 850nm VCSEL, a 12-channel VCSEL driver LSI, and a precise coupling structure for 12 multi-mode-fibers ribbon. The receiver consists of a 12-channel array of pin-PDs, a 12-channel receiver LSI, and a precise coupling structure for 12 multi-mode-fibers ribbon. A CPLD chip, which maps the OC-192 framer onto the parallel optical links, and reassembles it after detection, has been developed. We also present the coupling package configuration for VCSEL arrays to fiber ribbon.
This paper reported an improved optical switching network configuration based on optical interconnection technology with vertical cavity surface emitting laser (VCSEL) array. The optical switching network consists of two-level optical interconnection backplane. It can connect 64 nodes with parallel optical links. The first level of optical interconnection backplane includes eight 8×8 crossbar interconnect sub-networks. Instead of one 8×8 crossbar interconnect sub-network in the second level of the optical interconnection backplane adopted in our original configuration, the second level of optical interconnection backplane has two 8×8 Crossbar interconnect sub-networks in this improved configuration. So the blocking rate is decreased. VCSEL-based parallel optoelectronic I/O interface is used as O/E conversion. Every I/O parallel interface between optical interconnection network and every node includes 18 VCSEL emitter pixels, 18 PIN receiver pixels. In order to couple 18 signal light beam array into optical fiber array ribbon, a fabrication technique based on the high precise position slot is used for assembling optical fiber array interface. A configuration of coupling packaging for the VCSEL pixel array to the fiber array with 45° end surface is also presented in this paper. An optical data transmission rate between interconnection nodes is 5Gb/s which is transmitted by the optical fiber ribbon-based parallel optical data links with 2 channels at data rate of 2.5Gb/s per channel. The aggregate bandwidth of 360Gbps for an 8×8 Crossbar optical fiber interconnect network backplane is achieved. The reliability of the fiber array with 45° end surface is tested in our experiment.
Diffractive optical element (DOE) can be used for beam smoothing, owing to its high light efficiency, design flexibility and so on. The phase design of the DOE can be considered as an optimization problem and optimized by many kinds of algorithms. In this paper, the hybrid algorithm, merging Hill-climbing with Simulated Annealing, is adopted to design the phase of the DOE. The designed phase is the sum of many kinds of sine function with different period, amplitude and initial phase, which the continuous phase DOE is ensured. The continuous phase DOE is fabricated by ion etching, with a rotating hollowed-out mask. Experiments of beam smoothing are carried out with a pulse working Nd:YAG laser, and spots with a rather good beam smoothing performance are obtained.
KEYWORDS: Diffraction, Optical components, Binary data, Optical filters, Error analysis, Refractive index, Chemical elements, Energy efficiency, High power lasers, Laser systems engineering
This paper aims at the request of dividing harmonic waves in the high power laser system used to perform Inertial Confinement Fusion. Dividing harmonic waves is realized by introducing binary optical element. Based on scalar diffraction theory, the distribution of its diffraction field was calculated and the fabrication parameters were also optimized. The element is fabricated with RIE. We also measured the relief structure and diffraction efficiency of each harmonic wave and analyze the errors.
In this paper, the term, fractal phase structure is presented. The recurrence formulas of Fourier spectral function of the Cantor relief fractal phase structure are derived out. A series of power spectral curves of the state that several generations coexist are produced by computer. The spectral characteristics fully shows the self-similarity property of the phase fractals. The Cantor relief fractal structure is successfully made by enzyme etching. Its power spectrum is recorded with CCD camera.
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