自扫描光电二极管阵列均匀性较正

在利用自扫描光电二极管阵列 (SSPA)图像传感器进行图像处理的过程中 ,由于图像传感器存在着不均匀性问题 ,影响了图像的质量 ,为此研制了自扫描光电二极管均匀性校正电路。校正电路采用模数转换器 DAC0 80 8、存贮器 2 75 12、串行计数器 4 0 4 0等器件组成。当光强在 10 %到 90 %饱和范围内变化时 ,图像传感器的不均匀度从2 0 %校正到 3%。     

尘埃粒子检测仪校正系统的改进

一、引言 目前,国内外检测洁净环境中尘埃颗粒的仪器,即尘埃粒子计数器,是以尘埃粒子在白光束或激光束中产生的光散射现象为原理(见图1)。当空气中的尘埃粒子随采样气流穿过光敏感区时,就会产生与其粒径相关的散射光脉冲,其中的一部分散射光被收集并投射于光电倍增管或半导体光敏器件。这样,便将散射光脉冲信号变为相应的电脉冲信号。信号处理系统将电脉冲信号放大,并经幅度甄别器分档,再由机内微处理器处理,最后得到各档粒径的尘埃粒子数。     

基于平面线圈的油液磨粒监测传感器设计

为了提高油液管道直径增加后感应区磁场均匀性,减小测量误差,根据电磁感应原理,设计了一种新型的在线油液 磨粒监测传感器。传感器使用一组安匝比为15/7/15的平面线圈在直径1ｍｍ的油管中产生均匀磁场以提高传感器探测金属磨粒的性能,使用COMSOL建立线圈模型并仿真,传感器线圈产生的磁场在感应区60％范围变化率小于1％,相同磨粒在油管径向不同位置的电感变化误差平均值为5％,根据仿真设计制作线圈实物,传感器能测量和分辨粒度100μｍ 铁磨粒和100μｍ 铜磨粒,同一磨粒位于管道轴线和管壁的电感变化误差不超过6.25％。仿真研究和实验结果证明新模型在管道径向产生的磁场更加均匀,可以有效减小粒子在管道径向运动带来的误差。     

利用Arduino控制板的光引导运动小车设计

为降低生产成本、提高运输的灵活性,提出了一种以Arduino控制板为核心的光引导小车设计方案,并给出了该方案的软硬件设计方法.该方案基于光线沿直线传播的原理,通过光敏元件设计传感器并检测小车不同方向上的光强,计算出小车和光源之间的相对位置;然后,利用PWM直流电机调速技术控制小车的启动、加减速和转弯等操作;最后,利用红外线反射式脉冲编码器对小车的转速和位移进行反馈.试验证明,光引导小车在实验室中运行稳定,设计方案切实可行.     

MZI型MOEMS压力传感器的研究

集成光学压力传感器利用幅度、相位、折射率分布、光程和光波极化方式的改变来感应外部压力。设计了马赫-曾德尔干涉仪（MZI）型微型光机电系统（MOEMS）压力传感器,探讨了工作原理,分析了弹性薄膜尺寸对应力的影响和波导中TE、TM模式的光对波导折射率的影响。通过设计弹性薄膜的尺寸和选用特定波长的单模激光,得到传感器的工作特性。     

偏振控制光强调制型SPRi传感器的高灵敏检测研究

在偏振控制光强调制型SPRi传感器中,使用真实液体消光的方法实验调节困难,测量灵敏度低,线性度差.为此,提出无需真实液体消光,并将消光折射率左移的方法.首先,对在测量起点(即纯水)消光的传统方法进行光学参数的最优值仿真及其加工和调节误差仿真,结果表明,误差会引起SPRi曲线最低点在折射率轴上的左右偏移,从而影响传感器性能.接着,将消光折射率左移至1.325处,并仿真其光学参数的最优值.实验表明,与前者相比,1.325消光方法中存在的误差不会使测量曲线出现非单调的情况,此时的测量灵敏度高,线性度好,折射率分辨率达到1.85×10-6 RIU,对应NaCl溶液的检出限为35 mg/L.上述方法提高了误差存在时SPRi传感器的适用性,可以实现微量水溶液样品的高灵敏及高通量检测.     

基于单片机STM32和无线Wi-Fi的智能窗帘设计

系统以STM32单片机作为主控制器件,采用模块化设计。利用光敏电感传感器、光电开关、TFTLCD液晶显示以及Wi-Fi模块实现了对环境光强和系统工作状态的实时监测、实时显示、实时反馈。同时,单片机通过实时接收用户指令或查询用户设置的光强阈值控制窗帘的开合状态,可工作于手动拉合、自动开闭、远程遥控三种模式。     

电离总剂量效应对4T CMOS图像传感器暗电流影响的数值仿真

CMOS图像传感器是空间光学成像系统中的关键电子器件,但受到空间总剂量辐射效应影响其特性发生退化,特别是暗电流显著增大.本文利用TCAD仿真工具构建了4T CMOS图像传感器像素单元的二维仿真结构,利用总剂量效应模型计算了器件氧化层中辐射诱导氧化物陷阱电荷和界面态在不同累积剂量下的分布,并计算了器件暗电流随累积剂量的变化,以及传输栅对辐照暗电流的影响.通过分析辐照前后器件内部耗尽区的变化,以及传输栅偏置电压对器件电势分布的影响,获得了器件暗电流总剂量效应损伤机制.本文中电离总剂量效应的数值仿真方法和图像传感器暗电流损伤机制的分析可为评估器件抗辐射能力和设计加固提供技术支撑和指导.     

双波长FBG折射率变化平均值的研究

光纤Bragg光栅(FBG)是发展最为迅速的光测量器件.为解决光纤光栅传感器温度应变交叉敏感的问题,使用双波长FBG替代传统FBG是实用性较好的方案之一.通过数值计算双波长FBG的反射谱,着重分析了双波长FBG的折射率变化平均值对中心波长及其反射率的影响.     

激光光束对光幕测速系统的影响

在高精度速度测量系统中,激光光束截面形状以及光强分布影响测量结果,基于激光光束的高斯模型,计算出关于出射轴线对称的规则和非对称激光束光强变化率随位置变化的曲线,推导出设置阈值电压的最佳位置,并计算出在最佳位置处设定比较阈值对光幕测速系统的影响,提出在激光光束前添加狭缝压缩光束宽度的方法,相对距离误差减小为0.003 8%,误差减小了61.2%.     

基于双D光纤传感器的陶瓷泥浆浓度仪的设计

为了克服陶瓷泥浆浓度落后的检测技术和低效率,研制了一种新型的检测仪器.依据Mie散射理论,在入射波长、入射光强、探测距离、粒径尺寸参量、折射率,后向散射角已知时,后向散射光强就与粒子数浓度成正比.在实验中,把光信号通过双D型光纤传感器中的一支光纤射入陶瓷泥浆,另一支光纤接收陶瓷泥浆颗粒对光信号的后向散射光线.分别检测浓度为40%-60%的陶瓷泥浆样本,记录、分析这组电压值和陶瓷泥浆浓度的关系后知道:在陶土含量为40%-60%之间的数据曲线是线性的.利用这一个结果,研制了陶瓷泥浆浓度检测仪,并详细说明陶瓷泥浆浓度检测仪的结构及特点.     

基于LabVIEW搭建光纤SPR虚拟仿真设计平台

光纤表面等离子体共振(Surface plasmon resonance,SPR)传感器是一种将光纤纤芯作为激发SPR效应基体的新型传感器.本篇论文基于LabVIEW搭建虚拟仿真设计平台,依照材料参数与组件结构做理论计算,可即时改变尺寸及材料参数,了解SPR组件参数对感测效果的影响,找到最佳参数.以PMMA塑料光纤虚拟仿真结果显示,镀银薄膜40nm于光纤研磨表面上,能够制造出一个较佳的光纤SPR传感器;最后,以不同折射率的待测物进行仿真计算,得到共振波长与折射率关系.     

Searching for optimal sensitivity of single-mode D-type optical fiber sensor in the phase measurement

To improve the sensitivity of a single-mode D-type optical fiber sensor, we selected a D-type optical fiber sensor with 4 mm long and 4 μm core thickness made of a single-mode fiber, a Au-coating on the sensor with a thickness range of 15–32 nm, a light wavelength of 632.8 nm, and an incident angle of 86.5–89.5° for different refractive index (1.33–1.40) sensing. These simulations are based on the surface plasmon resonance (SPR) theory using the phase method which shows that the sensitivity is proportional to the refractive index, Au film thickness and lower incident angle on the sensing interface. The sensitivity is higher than 4000 (degree/RIU), and the resolution is better than 2.5 × 10⁻⁶(RIU) as the minimum phase variation is 0.01°. This device is used to detect the refractive index or gas or liquid concentration in real-time. The proposed sensor is small, simple, inexpensive, and provides an in vivo test.     

Integrated opto-mechanical analysis of a PMMA Fresnel lens for a concentrated photovoltaic system

This study presents the integrated opto-mechanical analysis of a polymethylmethacrylate (PMMA) Fresnel lens used in solar concentrators for concentrated photovoltaic systems. A solid model of a flat Fresnel lens made of PMMA was constructed based on the design parameters and derived formula of a Fresnel lens. Ray-tracing simulations were used to investigate the two main influences of temperature variation on the Fresnel lens: variations in the refractive index and thermal distortion. The temperature dependence of the refractive index of the PMMA lens was analyzed based on the temperature coefficient of the refractive index (dn/dT). The thermal distortion of the Fresnel lens at various temperature increases was calculated using finite element analysis. The temperature-induced effects, refractive index variation, and deformed lens geometry were then simultaneously imported into a ray-tracing simulation. Thus, this study investigates and discusses the thermal–optical effects of a flat Fresnel lens on its optical performance, including the spot size, the maximum irradiance on the receiver, and the optical efficiency at different temperature increases.     

Nanoparticles in polymer-matrix composites

Regarding the development of nanoparticles for polymer matrix composites the particle/agglomerate size and particle/agglomerate distribution in the composites, respectively, is often crucial. This is exemplarily shown for, e.g. optical applications with measurements of refractive index and transmittance. Classical blending techniques, where nanoparticles are dispersed in polymers or resins, are compared to a combination of a special gas-phase synthesis method with subsequent in-situ deposition of nanoparticles in high-boiling liquids. The particles/agglomerates were characterized regarding particle size and particle size distribution using transmission electron microscopy and dynamic light scattering. Additionally, important material properties like mechanical properties, relevant for application, or like viscosity, relevant for processing, are determined. It is shown, that with in-situ dispersed nanoparticles synthesized in a microwave plasma process composites with finely dispersed particles/agglomerates are attainable.     

Methods for counting particles in microfluidic applications

Microfluidic particle counters are important tools in biomedical diagnostic applications such as flow cytometry analysis. Major methods of counting particles in microfluidic devices are reviewed in this paper. The microfluidic resistive pulse sensor advances in sensitivity over the traditional Coulter counter by improving signal amplification and noise reduction techniques. Nanopore-based methods are used for single DNA molecule analysis and the capacitance counter is useful in liquids of low electrical conductivity and in sensing the changes of cell contents. Light-scattering and light-blocking counters are better for detecting larger particles or concentrated particles. Methods of using fluorescence detection have the capability for differentiating particles of similar sizes but different types that are labeled with different fluorescent dyes. The micro particle image velocimetry method has also been used for detecting and analyzing particles in a flow field. The general limitation of microfluidic particle counters is the low throughput which needs to be improved in the future. The integration of two or more existing microfluidic particle counting techniques is required for many practical on-chip applications.     

Refractive‐reflective optical system for realizing an ultra‐thin rear projector

Abstract— This paper presents a new optical system used in an ultra‐thin rear projector with a 1500‐mm diagonal size and 260‐mm depth. A refractive‐reflective optical system was developed to achieve a large projection angle of 136° with a small optical distortion of 0.1%. The optics consists of a convex aspherical mirror and a refractive lens. In addition, a new Fresnel screen composed of hybrid blades of refractive‐TIR (total internal reflection) elements was developed to attain good uniformity of brightness and color within the image area.     

Hand-scan OCR with a one-dimensional image sensor

We have developed a hand scanning type OCR, an optical character reader, which is applicable to POS terminals, etc. It uses a one-dimensional image sensor for small size and low cost. We developed a new recognition method which can overcome the irregularity of the hand scanning. Our method has two kinds of counters to extract the horizontal line features. One is a black occurrence counter and the other is a front shape counter. Normalizing these data reduces the influence of pattern variation. The method has been tested widely all over the world as a commercial OCR-A font reader.     

Micromachined silicon nitride solid immersion lens

We present a fabrication method for silicon nitride solid immersion lenses (SILs) integrated with atomic force microscope (AFM) cantilevers. We demonstrate a scanning optical microscope based on the microfabricated SIL that operates in reflection and transmission modes at a wavelength of /spl lambda/ = 400 nm. In this microscope, light is focused to a spot in a high refractive index SIL held close to the sample. The minimum spot size of a SIL-based microscope, which determines the transverse optical resolution, is /spl lambda//(2n) where n is the refractive index of the SIL. This is smaller than the minimum spot size of /spl lambda//2 in air. The SIL, therefore, makes possible optical resolution better than the diffraction limit in air. The full-width at half-maximum (FWHM) spot size of the SIL-based microscope is measured to be /spl sim/133 nm in transmission mode, which is /spl sim/1.98 times better than the spot size measured without the SIL (264 nm). This improvement factor is close to the refractive index of the silicon nitride SIL (n = 1.96).