共查询到19条相似文献,搜索用时 62 毫秒
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影响X射线像增强器分辨率的因素分析 总被引:3,自引:0,他引:3
对采用双近贴聚焦成像结构的MCP(Micro Channel Plate)-X射线像增强器的工作原理与结构进行了分析,对影响其空间分辨率的主要因素进行了研究.影响X射线成像系统分辨率的因素主要有X射线源焦斑的大小和X射线像增强器自身的分辨率,而影响X射线像增强器分辨率的因素主要有MCP输出面到荧光屏之间的距离、MCP输出面与荧光屏之间的电压差以及MCP自身的分辨率.通过对两种具有不同参量的X射线像增强器分辨率的理论计算及分辨率测试实验,将理论计算结果与测试实验结果对比,验证了分辨率计算公式及影响分辨率因素分析的正确性. 相似文献
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为了实现在较低剂量下获得较高的分辨率,研制了一款价格低廉的X射线CCD相机。该相机使用硫氧化钆作为转换屏、经一代像增强器增强后的图像通过光锥耦合到CCD相机上;为了提高系统的光传输效率,提出了将像增强器输出直面板或倒像器直接更换成光锥,其小端直接同CCD相机耦合的方案;通过灰度分析计算对比度曲线,拟合得出系统的本征空间分辨率为13 Lp/mm;通过拍摄实际景物,可以清晰地看到其内部的细节,显示出比较好的图像质量。 相似文献
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将X射线成像技术和微光成像技术相结合, 设计了组合新型X射线影像增强器。不同于常用的进口真空型X射线影像增强管,组合新型X射线影像增强器是由X射线屏和亮度增强器经过透镜耦合而成的非真空型组合器件。文章详细分析了组合新型X射线影像增强器的结构特点、成像原理和成像性能;并在结构特点、成像原理和成像性等方面对组合新型X射线影像增强器和常用的进口X射线影像增强管进行了详细的对比,比较的结果表明组合新型X射线影像增强器的成像性能略低于进口的医用X射线影像增强管,但是组合新型X射线影像增强器的性价比非常高,而且成像性能令人满意,正在向进口管不断靠近。它满足很多科研领域对X射线成像的要求,易于被广大用户接受,可以被广泛的应用在工业探伤,无损检测,机场安检等领域。 相似文献
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“超Ⅱ代像增强器”光电阴极成分控制原理研究 总被引:3,自引:1,他引:2
本文研究了用光电阴极反射率预测和确定多碱阴极的厚度和成分,并用反射率和光谱响应对其进行控制。如果用520nm单色光源来测量反射率和光谱响应,则“超Ⅱ代像增强器”的光电阴极的厚度应在120nm左右,即峰值RM3出现后,S/Smax约为60%时。根据(RM1,RM)和(RM,RM2)确定n、k值以及光电流在光谱响应峰值前的稳定上升和峰值后的近似线性下降规律通过调节锑、钾、钠源蒸发速率控制阴极成分。 相似文献
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In order to solve the problem of digital radiography for printed circuit board (PCB) defect inspection, a new inspection system for PCB defect inspection with high resolution X-ray is proposed and implemented in this paper. The influence of the focus size of X-ray source on imaging formation is analyzed to get the best geometrical magnification. Moreover, the relationship between the resolution of intensifier and geometrical magnification is presented by analyzing the performance of MCP-X intensifier, which results in calculating the comprehensive resolution of this system. The experiment result indicates that the measurements on defect character is achieved by inspection software, and the defect analysis accuracy on ball grid array (BGA) solder joint of circuit board achieves minimum resolution of 0.03 mm. As a result, this system succeeds in implementing invisible solder joint defect inspection on BGA. 相似文献
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微光像增强器光阴极灵敏度理论极限问题研究 总被引:2,自引:2,他引:0
光阴极灵敏度(量子效率)是微光像增强器最重要和最基本的性能参数之一,它决定着微光成像系统在低照度下的视距和图像清晰度。根据半导体光电发射物理模型及普朗克黑体辐射理论,简介了光电发射5个环节(光子不完全吸收、GaAlAs/GaAs后界面、GaAs光阴极激活层体特性缺陷、GaAs光阴极表面位垒和GaAs光阴极-MCP之间近贴电场电子隧道效应)对光阴极量子效率的影响,给出了相关数学表达式。在假定5个环节子量子效率均为100%的前提下,估算出蓝延伸GaAs光阴极在(0.41~0.93)μm波段内的极限积分灵敏度,其值为6569μA/lm。文末,对此结果的意义给予评价。 相似文献
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鉴于离子阻挡膜保证了三代像增强器的工作寿命,但增加了微通道板和三代像增强器的噪声因子,降低了三代像增强器的信噪比,削弱了NEA光阴极的优势,提出一种最新研制的微通道板。它优化了玻璃成份,提高了玻璃的工作温度,同时还改善了通道内壁工作面结构,且开口面积比达到65%~70%。通过三代像增强器制管试验证实,这种高性能微通道板具有低噪声因子特性,与标准MCP相比,可显著提高三代管的信噪比。最后指出通过进一步试验和改进,实现更高信噪比长寿命无膜三代像增强器的可能性。 相似文献
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Design of high-repetition frequency gating circuit for cathode of image intensifier北大核心CSCD 下载免费PDF全文
According to the requirements of high repetition frequency, fast edge speed and small pulse width for cathode gating signal by range-gated technology, a cathode high repetition frequency gating circuit using period and multi-stage acceleration was proposed. By combining the RC circuit and the high-speed gate circuit, the time bias circuit unit was cascaded to generate logic pulses with different time sequences, which could respectively control the intermediate stage drive MOSFET to generate three phased drive signals, and the output of the intermediate stage drive was used as input of the output-stage MOSFET to control the acceleration and retention of its on-off process. It was verified by software simulation and board-level test. The test results show that the proposed gating circuit can increase the edge time of output pulse from μs level to 2 ns, and can provide +50 V/−200 V cathode off/on voltage, so as to achieve a repetition frequency ranging from 0~350 kHZ, a duty ratio of 0~100%, a minimum pulse width of 3.7 ns, and a pulse output delay time jitter of about 0.1 ns. It has important guiding significance for improving the minimum pulse width performance of high-speed and high-voltage gating power, the highest working repetition frequency and reducing the power loss of the device. © 2022 Editorial office of Journal of Applied Optics. All rights reserved. 相似文献
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简要说明了三代像增强器的特点,分析了微通道板的离子反馈形成机理,给出有效抑制离子反馈对光阴极造成伤害的2种方法,即一种是减少和清除微通道板的吸附气体,另一种是阻止反馈离子反馈到光阴极上。介绍了国外最新的三代像增强器,以及使用优化改进的高性能微通道板显著减薄甚至彻底去除微通道板离子反馈膜的方法,该方法能维持砷化镓光阴极足够长的工作寿命,还介绍了最新发展的体导电微通道板和硅微通道板。指出高可靠性无膜选通砷化镓像增强器技术的实现,不仅需要微通道板在抑制离子反馈方面取得突破,还需要砷化镓光阴极在耐受离子反馈能力上进一步提高,同时还要结合和拓展选通电源的应用。 相似文献
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Development of afterglow time test system for nanosecond fluorescent screen of low-level-light image intensifier北大核心CSCD 下载免费PDF全文
The time characteristics of fluorescent screen is one of the important parameters to evaluate the performance of image intensifier. At present, there is no measurement method for the afterglow time of nanosecond fluorescent screen of low-level-light image intensifier. Based on the traditional test scheme of image intensifier afterglow time, a afterglow time test system for nanosecond fluorescent screen was developed. This system used a high-speed signal generator with the sampling rate of 250 MHz to complete the excitation of the laser diode light pulse, and a photomultiplier tube was used with the descending time of 0.57 ns to complete the photoelectric conversion of the fluorescent screen light signal. The weak photocurrent signal of μA magnitude was amplified and converted to a single-terminal differential circuit to complete the AD conversion in AD9684. Then the digital luminance information of the fluorescent screen was stored in the double data rate SDRAM (DDR) unit after field programmable gate array (FPGA), and the host computer sent instructions to read the DDR memory. The USB3.0 high-speed transmission protocol was used to transmit data to the host computer. In the data processing, the Kalman filtering and fast finding falling edge algorithm were used to realize the accurate measurement of noise filtering from collected data and afterglow time. The test results show that the proposed afterglow time test system for nanosecond fluorescent screen can effectively test the image intensifier with ultrafast optical characteristics. The afterglow test results of P47 phosphor reaches 118.094 4 ns, and the repeatability reaches 2.08%. © 2022 Editorial office of Journal of Applied Optics. All rights reserved. 相似文献
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紫外像增强器是紫外探测系统的核心器件,是一种电真空成像器件,可将微弱的紫外光图像转换并增强为肉眼可见、亮度可见的光图像,其研制与应用是微光夜视技术的重要发展方向。辐射灵敏度是评价紫外像增强器的重要参数,直接决定了紫外探测系统的性能。介绍了紫外像增强器辐射灵敏度的测量原理,采用紫外辐射光源、光栅单色仪系统、测试暗箱、微电流计、计算机及测量软件组建了辐射灵敏度测量系统。对3只紫外像增强器在260 nm、280 nm及320 nm波长下的辐射灵敏度进行了测量,并分析了其测量不确定度。该测量系统的建立,将辐射灵敏度测量系统的光谱范围拓展至200 nm~400 nm,弥补了现有系统的不足,具有广泛的应用前景。 相似文献