A new lens composed of countless annular micron channels was designed, which can not only achieves high focusing efficiency but also meets the needs of lightweight and miniaturization. Aiming at maximizing focusing efficiency, the structure design of lens was analyzed, and the mathematical relationship between optical conditions such as focal length and X-ray energy and structural parameters such as channel width, curvature radius, diameter, and channel length was deduced. According to the theoretical analysis, ideally, if the channels are equally spaced, the thickness of the lens is non-linear gradient. In order to improve the feasibility of the preparation process, three types of structure approximations were carried out. The imaging performance of lenses with different structures were simulated by Monte-Carlo ray tracing method. Taking into account the focusing efficiency and the feasibility of preparation, the lens can be divided into multiple inclined or flat planes with different channel length.
Metal-Insulator-Metal (MIM) waveguide structure is a typical surface plasmon waveguide structure. It is considered to be used in micro nano optics because of its strong mode field limitation, low transmission loss and long electromagnetic wave transmission distance The field of components and integrated circuits has a vigorous development prospect. In this paper, a new MIM waveguide coupled surface plasmon structure of rectangular connected semi-circular cavity is proposed. The wide continuous state of the straight waveguide with a metal slit interferes with the narrow-band discrete state of the rectangular connected semi-circular cavity to produce three sharp Fano resonance lines. As a refractive index sensor, the maximum sensitivity is 1100nm/RIU and the quality factor is 6900. Then, a MIM surface plasmon structure is improved to produce a triple Fano resonance effect. When the new structure is used as refractive index sensor, the sensitivity reaches 1190nm/RIU and the FOM value of formant is 7000.
Microchannel plate (MCP) is an important charged-particle electronic multiplier, whose surface roughness is one of the vital factors of high-performance multiplication. A chemical-mechanical polishing (CMP) is a planarization process assisted by chemical reactions to remove surface materials and improve surface smoothness. In this paper, atomic force microscopy (AFM) was applied to investigate the surface roughness of the MCP wafers by chemical-mechanical polishing. After chemical-mechanical polishing, the global surface roughness increased from 8.33 nm into 9.01 nm, which was contrary to the conventional chemical-mechanical polishing results. Using the surface partitioning analysis, we confirmed that the escalated global surface roughness was related to the raised surface roughness of the acid-soluble core glass (from 2.35 nm rise to 3.07 nm after CMP), which occupied more than 60% area of the MCP wafer. Moreover, the surface roughness of the etching-resistance cladding glass was notably dropped after CMP (from 6.48 nm decreased to 4.84 nm). Thus, CMP was a benefit to improve the surface finishing of the MCP multiplier despite the global surface roughness increasing after that.
Fixed pattern noise (FPN) is a kind of image defect of microchannel plate (MCP), which is manifested by uneven brightness between the boundary and inside of multi-fibers. The formation mechanism of FPN was revealed by analyzing the characteristics of FPN of the MCP. The results showed that FPN appears at the boundary of multi-fibers and three sets of opposite sides of the multi-fibers show different brightness. The cause for the formation of FPN is that the gain of the outermost mono-fibers of multi-fibers is inconsistent with that of the inner of multi-fibers. The uneven brightness in the three sets of opposite sides is because of the different morphology of them. In the drawing multi-fibers process, the outermost mono-fibers deform into an ellipse-like shape due to lack of restraint. After the MCP is sliced along a certain bias angel, the ellipticity changes. The ellipticity of one set of opposite sides increases, while that of the other two groups decrease. In the melting process, the multi-fibers rotate at a small angle, resulting in slight differences in ellipticity between the two groups. When the input electrons hit the wall in channels with different ellipticities, they will excite secondary electrons with different trajectories, thus showing FPN. In order to reduce FPN, the deformation of the outermost of monofibers should be reduced as much as possible in the drawing multi-fibers process. The study will provide fundamental insights and useful guidelines for improving the performance of MCP.
Microchannel plate (MCP) is the core material and compact multiplier of the image intensifier for two-dimensional parallel multiplication. Gain and spatial resolution are key indexes of MCP for high-performance signal multiplication. The reduction in the microchannel pore size is the most effective way to improve the limiting spatial resolution. Meanwhile, the optimum aspect ratio is needed to satisfy the requirements for high electronic gain, while a small pore means ultra-thin thickness. However, the thinner the MCP is, the easier it is to deform. Thus, the deformation has become the main bottleneck of high performance and high resolution in the ultra-thin MCP multiplier. In this paper, we manufactured the nondeformable bordered MCPs with a pore size of 4μm. Controlled the hybrid field-effect for internal stress relieving, optimized matching thermodynamic properties of solid-border glass and cladding glass of MCPs, were both considered to limit the deformation. The single MCP was tested and achieved electronic gain >104 at a bias voltage of 900V without fixed pattern noises; the limiting spatial resolution was 117 lp/mm; the dark current of the V-stacked MCPs was 0.5 pA.
The dynamic tunable performance of metamaterial absorbers generally refers to changing the response frequency or absorption rate (transmission or reflectivity) of the absorbers to the incident electromagnetic wave in real time by certain means. In the field of communication, it is necessary to make a real-time response to the incident electromagnetic wave according to the change of conditions, which requires the metamaterial absorbers to dynamically tune the spectrum, such as modulators, filters, optical switches and so on. The successful realization of the performance will be of great significance in the practical application of metamaterial absorbers. Based on the principle of VO2 phase transition, a “perfect” absorbing metamaterial with resonant frequency in infrared band is proposed. When vanadium dioxide is adjusted to the metal state, the absorber has the performances of polarization-insensitivity, wide angle, dynamic tenability and absorption up to 99.5% at 5.25μm. Furthermore, it can be tuned arbitrarily in the range of 4μm to 5.8μm with the absorption remaining above 92% by changing its geometric parameters. The absorber remains absorptivity of over 83% with incident angles below 60° under transverse magnetic (TM) polarization and that of over 89% below 50° under transverse electric (TE) polarization. Meanwhile, the absorber is polarization insensitive when the resonant wavelength is 5.25 μm and the polarization angle is between 0 and 90°. As a verification, the real part of the relative impedance of the absorber is close to 1, that is, a successful impedance matching is achieved between the resonant wavelength and the free space.
In this paper, the properties of transition metal oxide borate glass were studied. It was found that introducing a small amount of CaO and BaO into borate glass could improve the crystal resistance and chemical stability of the glass. The introduction of V2O5, ZnO, Al2O3, SiO2 and other components is beneficial to widen the glass forming range and improve the anti-crystal performance of glass. The introduction of MgO and ZrO2 can improve the acid resistance of glass. The mixed and co-mixing of Fe2O3, MnO2, V2O5 and other transition metal oxides can increase the total doping amount by more than 30%. At the same time, the introduction of multiple components can effectively prevent glass crystallization and improve the anti-crystallization ability. The developed transition metal oxide borate glass has a resistivity up to 5×1010•cm, good chemical stability and anti-crystallization ability, and is suitable for the production of large crucible melting, realizing the preparation of 100×100×1mm glass samples.
The anti-vignetting glass (AVG) is the key material for super-second and third-generation low-light image intensifiers. With the development of low-light night vision technology, the requirements of high precision and low damage are put forward to AVG. However, traditional measurement methods, such as vernier calipers, micrometers, dial indicators, etc., are all contact measurement, which will inevitably cause damage to AVG during the measurement process. They cannot meet the technical requirements for low damage. Non-contact measurement technology is a non-destructive testing method that realizes the geometric measurement of AVG by writing measurement programs and setting measurement parameters. However, due to the special structure of AVG, the non-contact measurement technology has measurement errors and cannot meet the high-precision measurement requirements. In this paper systematically analyzes the causes of errors in non-contact measurement technology by studying the characteristics of the light source, the difference in light intensity, and the way of grabbing contour edges. Through the error correction technology, the error of the non-contact measurement technology is eliminated, the AVG high-precision and low-damage non-destructive testing is realized.
The microchannel-plate-based x-ray optics is a spherical crown containing millions of square microchannels, reflecting the small incident angle light at a certain angle through the inner wall of the channels. Structure defects may exist in the square microchannel array. In this paper, the effects of structure defects on the imaging performance were studied through simulation and MPO preparation experiment. The structure defects involved in the paper include two types, chamfered channels and tilting channels. The experimental results are consistent with the simulation images, proving that the simulations are correct. The results show that the imaging of MPO with standard square channels array is a symmetrical cross. The presence of chamfers in corner of the channels results in a weak secondary small cross in the 45° direction of the obvious cross. For the case that the channels are tilted slightly, the center of the cross deviates from the imaging center, and the cross becomes an asymmetric cross. This study provides a theoretical guidance for precise control of array structures in the preparation of MPO.
Through the influence of the temperature, concentration, acid type and acid dissolution time of the acid solution on the acid etching speed of the multi-fiber and the surface quality after acid etching, the acid dissolution mechanism of the acid solution flexible optical fiber image bundle is discussed. The weight loss method was used to test the acid dissolution rate of different acid-soluble glasses, combined with the breakage of the multi-fiber after acid dissolution, to study the effect of acid-soluble glass on the image quality of the flexible optical fiber image bundle. The experimental results show that using a suitable acid solution, a suitable acid solution concentration, a suitable temperature and a reasonable acid dissolution time has obvious effects on reducing the broken wire rate of the flexible optical fiber image bundle and improving the image transmission quality.
Microchannel plate (MCP) is two dimensional arrays of microscopic channel electron multipliers. In this study, oxide thin films such as zinc oxide doped with aluminum oxide (AZO) as conductive layer and aluminum oxide (Al2O3) as secondary electron emission (SEE) layer were prepared in the pores of MCP via thermal atomic layer deposition (ALD). The bulk resistance of MCP in the suitable range (about 40~100 MΩ) was obtained by adjusting the percentage of zinc oxide (ZnO) cycles and the nano-oxide thin film thickness. As the tested voltage increased a behavior of negative temperature coefficient of the film was observed. After 5 days of continuous loading with 800 V bias, the resistance nearly doubled and stabilized. For the conduction mechanisms, the I-V curve obeys the ohmic law at low voltage region and the trap-controlled space-charge-limited conduction mechanisms as the applied voltage continue to increase. High gain performance (24000 @ 800 V) can be obtained by depositing only aluminum oxide film on traditional reduced lead glass microchannel plate. Meanwhile after the deposition of aluminum oxide film, the dark current density of the microchannel plate would increase to 1.8 picoampere in 15 minutes at DC 1000 V. Because of blocking effect the dark current density will drop to 0.03 picoampere in 50 minutes by depositing zinc oxide film with thickness of 4 nm before the SEE layer, and the resistance of MCP will reduce when the thickness of zinc oxide exceeds 4 nm.
Wolter microchannel plate (W-MCP) is a two dimensional array of capillary channel EUV/X-ray imaging precision optics. Detection efficiency and imaging quality are vital to the micro-focusing optics for X-ray. As a key factor of the detection efficiency and imaging quality, the micropore geometry of the W-MCP was investigated in the paper. The transformations of simulative imagings for different geometries were investigated both with Tracepro by the ray trace method of Monte Carlo algorithm and the real images of the specific manufactured plates were measured by the spectrometer. Symmetry axes, circular-arc structures and stacked density of layers on the focal imaging characteristics and detection efficiency of the W-MCPs were explored. The simulation results indicated that the detection efficiency of the ideal Lobster eye microchannel plate (L-MCP) was about 80% than that of the ideal W-MCP. Besides, the detection efficiency and the quality of focal imaging changing both obeyed Parabola distribution with the increasing of the numbers of symmetry axes from three to six in the W-MCP. The visible spectrum demonstrated that the detection efficiency was changed with the structural geometry of the MCP optics transforming. The standard W-MCP had an outstanding detection performance. The relative detection efficiency of the standard L-MCP was only 75% than that of the standard W-MCP. Moreover, the integrity of the outermost ring had the greatest impact on the relative detection efficiency of W-MCP, but the closest-packed-losing geometry rarely affected the detection performance.
The optical imaging system is the the core device in the extrem ultraviolet (EUV) astronomical telescope. Because of its light weight, large field of view, high resolution, the lobster-eye optical imaging system is considered to be the best imaging system for EUV. The curved square hole microchannel plate is an imitation lobster-eye type optical imaging system. The channels of the traditional curved square hole microchannel plate are generally arranged in a square shape, and the image is a cross image, which only the cross area is effectively detected, so the detection efficiency is low. In this paper, all the square hole channels are pointed to the center by radial arrangement, thereby the detection efficiency is improved. However, this arrangement cannot achieve close alignment, and there are a large number of voids in the structure, which reduces the density of the focusing unit. In this paper, the simulation of the radial arrangement of the square hole microchannel structure is carried out by Tracepro simulation software. Through the high-precision wire drawing method, radial arrangement technology, and distortion-free control, the drawing precision of the square wire is improved, the square wire structure defects are eliminated, and the square hole microchannel plate with uniform structural height is prepared.
Resistive Plate Chambers are planar, gaseous detectors made with electrodes and resistive plates, which is divided into single-gap (RPC) and multi-gap (MRPC). Such detectors have a simple structure, good time resolution, high efficiency, small dead zone, flexible signal readout mode and a relatively low cost, etc. Therefore, it has extensive and important applications in high energy physics, nuclear physics and other fields. The resistive glass plate has good stability and is less affected by the environments, which ensures the uniformity of the electric field inside the detector and makes the detector have lower dark current and noise. In this paper, the influence mechanism of resistive glass on detector performance was introduced firstly. Then the application and research status at home and abroad were summarized. On this basis, the existing problems in the research of resistive glass were expounded. Finally, according to the application requirements of RPC under the condition of high particle fluxes, the future development trend was analyzed and proposed. The author believes that it is the future development trend and direction in the field of resistive glass to carry out research on high-performance resistive glass materials and develop pure electronic conduction glass materials with volume resistivity of 109Ω•cm ~1010Ω•cm through composition design and control. At the same time, in order to meet the manufacturing requirements of large area array detectors, the strength, chemical stability and the possibility of batch manufacturing of the glass should also be fully considered in the development process of resistive glass.
The resistive plate chamber (RPC) is a gaseous parallel-plate detector, the glass resistive plate is the key element of RPC. In order to meet the requirement of high flux particle detection, it is urgent to develop low resistivity electroconductive glass. For this purpose, we designed the glass of SiO2-B2O3-P2O5-Al2O3-MxOysystem, the MxOy was chosen as Fe2O3, V2O5 and MnO2. In this paper, the formation abilities and conductive properties of glass were studied by adjusting the contents of the glass forming body and MxOy. The results showed that P2O5-Al2O3and P2O5-B2O3 built a quasi-[SiO4] tetrahedron structure as the glass forming body, the SiO2strengthened the network, which greatly improved the stability of the glass. Meanwhile, the addition of B2O3 and P2O5 could enhance the doping ability of MxOy in the whole glass system, which was benefit to reduce the resistivity of glass. Three transition metal oxides were added to the same base glass, and their resistivity was in order: ρFe<ρV<ρMn. The relationships between the oxidation-reduction atmosphere of glass melting and the resistivity of glass were investigated. The conductivity types was confirmed to be electronic conductive by testing the Seebeck coefficient and Hall effect of glass. The resistivity of the developed SiO2- B2O3-P2O5-Al2O3-Fe2O3 electronic conductive glass system was reached to1010Ω·cmlevel.
As a two dimensional arrays of micro-channel X-ray imaging precision optics, detection efficiency and imaging quality are crucial to micro-channel optics (MPO). As a key factor of the detection efficiency and imaging quality, cell packed geometries in the Wolter type micro-channel optics were investigated in the paper. The characteristics of simulative images for different cell packed geometries were compared with the software Tracepro by ray trace method of Monte Carlo algorithm. The influences for the amount of symmetry axes, chamber types and stacked density of layers on the focal imaging characteristics and detection efficiency of Wolter type micro-channel optics were explored. The results indicated that the detection efficiency and the quality of focal imaging changing both obeyed Parabola distribution with the increasing of the numbers of symmetry axis from three to six. In the cambered stacking models, focusing images showed a petaline shape dispersion background with the same symmetry axis in non-full-cambered stacking types. In the close-packed loss model, it had a minimal and maximal impact on the detection efficiency in the outmost layer and subouter layer, respectively. Besides, characteristics of simulative images for Lobster eye micro-channel optics (L-MPO) and Wolter type micro-channel optics (W-MPO) were compared by ray trace method in this paper. Results indicated that under a constant illumination with the same cell size, the simulated detection efficiency of ideal W-MPO was over 41.0%, which was 1.3 times than that of ideal L-MPO.
With the development of electronic displays becoming flat and portable, field emission displays (FED) get the widespread attention because they have the advantages of flat-panel displays and CRT displays together. At present, as one of the core components in FED, the screen is still the short board in the application of FED. With thin film phosphor as the phosphor layer, the screen will be very beneficial to the application of FED because of many advantages of extremely high resolution, strong adhesion, good smoothness, low release of gas, good conductivity and so on. That highlights the important application value and research significance of thin film phosphor in FED. In this review, we summarize the recent advances in the thin film phosphors for FED with emphasis on the film materials, preparation technology, and the main problems in the film. And the further study of thin film phosphors in FED is also presented.
The microchannel plate (MCP) as the most important component of image intensifiers and ultraviolet detectors, is avalanche two-dimensional electron multiplier device. The emission point as a pattern noise, which is characterized by a bright or a flickering point at a fixed position of the fluorescent screen, affects the visual quality and reliability of the MCP. Therefore, eliminating the emission point is an effective way to improve the performances of the MCP. In this paper, the inner wall morphology and structure defect of the channel were studied, the MCPs with different inner wall morphlogies were analyzed by SEM, and the emission point were tested by using the photoelectric imaging integrated tester. Using the above-mentioned research methods, a specific relationship between the inner wall morphology and the emission point was established. According to the field emission theory, the mechanism of the emission point was analyzed and discussed. The results show that the inner wall structure defects of the channel are the main reasons for the emission point. Furthermore, the study found that the matching of the thermal physical properties between core glass and clad glass is the main reason for the occurrence of structure defects. The structure defects of the inner wall can be effectively reduced by optimizing the composition of the glass material, make the two glasses have the suitable performance matching, avoid forming residual pores at the interface position, the inner wall of the channel will have a smooth, defect free microstructure, thereby effectively controlling the emission point of the MCP.
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