Global environment and climate change are the focus and frontier subjects of ecology, biogeochemistry and environmental science. Simultaneous in-situ monitoring of multiple atmospheric pollution components base on laser absorption spectroscopy technology has become an effective way for in-depth analysis and accurate identification of atmospheric pollution sources by analyzing the correlation of their concentration data. In view of the wide variety of actual atmospheric pollutants, the source, transformation mechanism, and transportation process of each component are extremely complex and overlap phenomenon, the in-depth analysis of atmospheric pollution sources is an important challenge. The depth analysis of air pollution sources is the key basis for scientific control of the air pollution. It is of great significance to carry out in situ monitoring techniques and analytical algorithms for various pollutants. In this paper, carbon monoxide (CO), a typical pollutant in the atmosphere, is firstly selected and analyzed by using HYSPLIT backward trajectory model, and the reliability of the proposed algorithm is verified. In addition, with PM2.5 as the analysis target, the backward trajectory of air mass during 72 h of pollution was simulated by HYSPLIT model for Beijing's heavy pollution during January 26-28, 2020. The potential transport channels and pollution contribution sources of PM2.5 in different areas to Beijing were analyzed by daily trajectory clustering analysis.
In recent years, Fourier transform spectrometer (FTS) with small size and low mass is required in many applications with
growing need for real-time and small platform spectral detection. In this paper, a micro Fourier transform infrared
spectrometer (μFTIR) based on spatial modulation mode was designed. This spectrometer has the advantages of high
stability and simplified configuration. It also promises optical path differences (OPD) with high precision, as MOEMS
technology is used in manufacturing the key components. The simulation and the experiments with regard to this FTIR
configuration have been done. Firstly, the diffraction effect of the micro multi-step mirrors (MMSMs) is studied. We
discuss the influence to the reversed spectrum by different mirror widths and different diffraction distances. Secondly, we
simulate and analyze the influence of the source solid angle to the spectral resolution. Thirdly, we set up the theoretical
model of the collimation error which is mainly from the defocus of the optical system and analyze the result caused by
the collimation error. Fourthly, a new discrete Fourier transform arithmetic using least-squares cosines progression
(LSCP) is proposed which can reconstruct the spectrum with nonuniform sampled signals. Finally, the MMSMs are
fabricated used the MOEMS technology and the structural parameters are tested.
This paper presents a new wavelength-selective switch by combining silicon micromaching and microassembly
techniques. The 1×8 wavelength-selective switch (WSS) based on micro electro mechanical systems (MEMS)
technology is proposed and fabricated with micro electromagnetic actuators, reflecting prisms and narrow-band thin
films filters. And a 8×8 WXC prototype node is implemented by using 1×8 WSSs as building elements. The working
principle and the configuration of the micro electromagnetic actuator are illuminated. By analysis, the property suits for
the application when the inputs are 2V, and the best fiber-to-fiber insertion loss 5dB is gotten.
Linear fiber-optic image slicer is used more and more in spatial exploration and imaging system. In this paper, a plane
arranging method of fiber-optic array based on Si-V grooves is established in order to improve the accuracy and reduce
the cost of manufacturing. Firstly, the Si-V groove array is micro-machined with anisotropic etching process, then optical
fibers are placed in the grooves orderly with plane arranging method. Secondly, the end surfaces of the device are
polished, also the linear fiber-optic image slicer is packaged. Finally, some parameters are tested, including structure
parameters, transmittivity and vibration test. Experimental results indicate that the maximum error accumulated in 2000
periods of the Si-V grooves is 0.5μm, the error of the height in
Si-V grooves is less than 0.15μm, the roughness of the
end surface is less than 0.9nm. The transmittivity of the linear fiber-optic image slicer that without optical film is 51.46%
at the wavelength of 632.8nm. After random vibration experiment, the ratio of the broken fiber increased by 0.1%. While
the temperature reached 320°C, the stress of epoxy will be 130Mpa, which is close to the limit resistance stress of
139Mpa, some cracks appeared.
Optical switch is one of key supporting technologies in all-optical-network (AON). And electrostatic MOEMS (Micro-Optical-Electro-Mechanical Systems) switch plays a very important role in all the researched switches, because of their excellent features, including low insertion, low crosstalk and scalability. But the packaging technology has been limiting the development of optical switch. In this paper, the authors study the laser beam propagating during the free space and select collimator, design the pedestal to packaging and address aspects of the insertion loss that are most important loss mechanisms for the 2D cross-connect switch.
In this paper, the authors report their resent results of the study on the epoxy resin compound X-ray refractive lens. At the first, the theoretical results of the structure parameters for such a device are given. Then, the fabrication technologies are presented. They are deep soft X-ray lithography, mold-manufacturing and molding. The material of X-ray photoresist is PMMA, the mold is made of silicone rubber, and the material of the lens is epoxy resin. Some measured results by means of optical microscope and SEM are also shown. The structure height of the epoxy resin compound lens is measured to be 500 micrometers.
Air-guiding photonic bandgag (PBG) fibers are new kind fibers which are quite different from conventional correspondence ones. In this paper, we studied the light transmission properties and light wave modes of hexagonal air-guiding PBG fibers. The fiber core is 10μm diameter air hole, surrounded by a cladding of 71.5μm diameter. The outer-cladding of the fiber is about 185μm. The experimental results show that when the wavelength ranges from 1430 to 1600 nm, there is merely no attenuation. It means that in these new fibers, light wavelength ranges widely. In addition, light wave mode and fiber core are the same in symmetrical structure. The theoretical results coincide with experimental results exactly.
Since CVD diamond film possesses desirable properties, it has been widely investigated, and much research has been made in this field. In this experiment, we mainly studied the characteristics of field emission from the CVD diamond films. The motivation for the experiment is to gain some insight into a possible emission mechanism. The diamond films are grown using a hot filament chemical vapor deposition, basing on the diamond micro-grits on silicon substrates. And the diamond micro-grits are deposited on silicon substrates using electrophoresis coat method, through a solution of diamond micro-grits in ethyl alcohol. This study has revealed that emission can be obtained at fields as low as 1.8V/μm. And the field emission measurements were carried out at a pressure of 10-4Pa.
Arrays of micro-sized LEDs which can be used as microdisplays have been demonstrated in recent years. In order to reduce the input and output connections to the arrays, we employ a matrix addressable architecture, in which all the pixels in each row are connected by a common metal line on the top of the window layer (top electrode) or at the base of substrate(bottom electrode). Decreasing the size of electrodes makes for minimizing the size of device. The optic and electronic isolation and good ohmic contact are also helpful to obtain superior optical and electrical performance. We describe a procedure of fabrication of AlGaInP-based orange micro-LED by wet etching. The structure of devices is etched using both isotropic and anisotropic solvent. The pixel size is about 16um x 20um, and there are 1000 x 818 pixels in the light emitting chip whose diagonal is 1-in.
KEYWORDS: Nitrogen, Near infrared, Solids, Spectroscopy, Chemistry, Calibration, Testing and analysis, Near infrared spectroscopy, Chemical analysis, Infrared spectroscopy
The author, Shangyu Li, engages in supervising and inspecting the quality of products. In soy sauce manufacturing, quality control of intermediate and final products by many components such as total nitrogen, saltless soluble solids, nitrogen of amino acids and total acid is demanded. Wet chemistry analytical methods need much labor and time for these analyses. In order to compensate for this problem, we used near infrared spectroscopy technology to measure the chemical-composition of soy sauce. In the course of the work, a certain amount of soy sauce was collected and was analyzed by wet chemistry analytical methods. The soy sauce was scanned by two kinds of the spectrometer, the Fourier Transform near infrared spectrometer (FT-NIR spectrometer) and the filter near infrared spectroscopy analyzer. The near infrared spectroscopy of soy sauce was calibrated with the components of wet chemistry methods by partial least squares regression and stepwise multiple linear regression. The contents of saltless soluble solids, total nitrogen, total acid and nitrogen of amino acids were predicted by cross validation. The results are compared with the wet chemistry analytical methods. The correlation coefficient and root-mean-square error of prediction (RMSEP) in the better prediction run were found to be 0.961 and 0.206 for total nitrogen, 0.913 and 1.215 for saltless soluble solids, 0.855 and 0.199 nitrogen of amino acids, 0.966 and 0.231 for total acid, respectively. The results presented here demonstrate that the NIR spectroscopy technology is promising for fast and reliable determination of major components of soy sauce.
A theoretical method for evaluating the three-dimensional focusing performances of the compound x-rays lenses is presented in the present paper. The relationship between the transverse and axial focusing behaviors is considered and a simple calculation that predicts the transverse and axial focusing behaviors of the compound x-ray lenses is also presented. As an example, the three-dimensional focusing performance of a compound x-ray lens with Al material is predicted. The dependences of the three-dimensional focusing performances on the compound lenses’ structural parameters are observed for the Al compound x-ray lens. Moreover, the approximate tolerances in the setting of the receiving planes are also considered for x-rays of 4.95keV, 14.99keV and 29.78keV.
Bragg grating has lots of use in many optical field. Especially, in dense wavelength division multiplexing system and optical filters, and so on. Holographic Bragg grating with 1800 line/mm is fabricated in this experiment. Performances of holographic Bragg gratings are measured in our lab. Results show that this holographic Bragg grating can resolve 0.26nm fine line spectrum. Diffraction efficiency of Bragg grating can get 76% in 1.55 μm wavelength. Results also show that this kind of holographic Bragg grating may use in DWDM device and can produce fine narrow width spectra.
Bulk silicon wet etching can be used to fabricate silicon gratings. Wet etching depends on the anisotropic property of monocrystalline silicon. Blazed gratings for different spectral ranges can be fabricated by this method, and facets of grooves are formed by crystallographic planes of the monocrystalline silicon wafer. We develop a method to fabricate blazed gratings using deflecting crystal orientation (111) silicon wafers. The topographies of the samples are measured by SEM and atomic force microscopy (AFM), and the results indicate that the samples have grooves of good uniformity and facets of excellent optical quality.
A theoretical method of focusing X-rays by the compound X-ray refractive lens is presented in this paper. The authors report their resent theoretical results including the material selection and structure parameters for such a device. As an example, a compound X-ray refractive lens with PMMA material is designed. The detailed fabrication process of the PMMA compound lens by LIGA technology is described. Moreover, some measured results by means of SEM are also shown. The structure height of one of the PMMA compound lens is measured to be 500μm.
We study insertion losses of optical switch when the laser beam is propagating during the free space between two single mode fibers (SMFs) and the related assemblage challenges; Then a new packaging structure is developed for the hybrid-integration of free-space MOEMS (micro-opto-electro-mechanical systems) chip with a silicon micromachined submount to improve alignment accuracy. The submount is designed to accommodate various free-space MOEMS chips with minimal active optical alignment, thus reducing the packaging cost. The silicon submount has a central recess to place the MOEMS chip in, sixteen V-grooves for optical fibers, and micropits for micro ball lenses, all bulk micromachined at the same time by a single anisotropic wet etching step. A corner compensation technique is employed to prevent erosion of the convex corners, where different geometries meet. Through this assembling method, the fiber, micro ball lens can be aligned preciously thus reduced lateral and angular misalignment between them. Then total insertion losses can be decreased.
In the present paper, a mask structure called adhering mask for excimer laser ablation is introduced. This mask is fabricated directly on the etched material, so it needn't a supporting chip and it thus has high transmission. Its absorber is made of gold and is fabricated by UV LIGA technology. Therefore the mask has more accurate structure and more smooth edges. This mask can fulfill the direct etching of the polymers by using a simpler optical system and can be a method of the mass production to some extent. The other mask is developed for X-ray lithography. It is made by UV LIGA process too. It consists of the substrate, the absorber and the supporter. The substrate is made of PI and the absorber is prepared by gold. The structure, fabrication process and experiment results of this mask are given.
In the present paper, the authors report their research on fabricating the three-dimensional microstructures on polymers by using the technology of excimer laser direct etching. A kind of mask structure called adhering mask, which can be used to fulfill the direct etching of polymers by a simpler optical system, is introduced. In addition, its fabrication process and optical system of the direct etching are also given in this paper. Finally the three-dimensional microstructures we fabricate by the technology are shown.
So far, the history of silicon gratings has more than 20 years and the development of fabrication methods and applications have improved a lot. Microfabrication process to made silicon gratings can be divided into bulk silicon and surface silicon technology. All these technologies are compatible with the process of MEMS, and this made it possible to fabricate micro spectrometers. We present the fabrication process of a grating by using (111) silicon wafer. The silicon gratings were manufactured using silicon micromachining techniques, as ultraviolet lithography and anisotropic wet etching, achieving good uniformity surface and grating facets of excellent optical quality. Some testing results on the silicon grating are presented.
Diamond maybe is an ideal electron emission material for field emission display because of its low work function and better chemistry stability. In this research, complex diamond conduct ceramic thin film is fabricated by using Ag- Bi-Pb-B-O base in organic conduct paste and diamond grains. The research aim is to find a method for making large area diamond-base electron emission material. Field emission performances of complex diamond ceramic are studied, too. The turn-on voltage and maximum stable emission current of material are 300 V and 760 (mu) A, respectively. The material also shows better emission stability at low vacuum pressure. The emitting center view is employed to explain the electron emission from diamond ceramic thin film.
This paper has advanced a kind of micro electromagnet motor with low rotational speed and high torque output: top-face- sway micro electromagnet motor. Its working principle is as following: under the rotating electromagnet's force, the motor's cone shape rotor makes pure rolling on the inner cone face of the stator and thus the output axle's rotation comes into being. Through testing, its rotation ranges is 20-860 rpm with larger than 10 (mu) Nm torque output. The result of the experiment show that with the same input power, this kind of micrometer has larger torque output than others' with the same volume. It has a wide applying prospect.
In the late of this century the great success of VSIC impacts into almost every fields of our social. Following this idea people starts to integrate microsensor microprocessor and microactuators into a small space to forming a Micro Electro and Mechanical System. Such small robot parts are applied to including satellites, computer communication, medical, chemical, biological and environment and so on research fields. The development of MEMS would strongly influence industrial revolution in the next century. LIGA technology including X-ray deep etching lithography; electroplating and plastic molding developed by Karlsruhe Nuclear Research Center, Germany since the beginning of 1980. Its advantages are: it could make three-dimensional microstructures with lateral dimension in several micron range and thickness of several hundred microns with sub-micron precision. In principle all kinds of materials such as polymer, metal and ceramic could be used as microcomponents and could be mass- produced by plastic molding to a commercially available fabrication. LIGA process has become one of the most promising Microfabrication technologies for producing micromechanical, microfluid and micro-optical elements. It opens an additional field in the microstructure market.
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