Noise analysis and measurement of time delay and integration charge coupled device

Time delay and integration （TDI） charge coupled device （CCD） noise sets a fundamental limit on image sensor performance, especially under low illumination in remote sensing applications. After introducing the complete sources of CCD noise, we study the effects of TDI operation mode on noise, and the relationship between different types of noise and number of the TDI stage. Then we propose a new technique to identify and measure sources of TDI CCD noise employing mathematical statistics theory, where theoretical analysis shows that noise estimated formulation converges well. Finally, we establish a testing platform to carry out experiments, and a standard TDI CCD is calibrated by using the proposed method. The experimental results show that the noise analysis and measurement methods presented in this paper are useful for modeling TDI CCDs.

Charge Couple Device-Based Systemfor3-di mensional Real Ti me Positioning on the Assessment of Segmental Range of Motion of Lumbar Spine

Objective： To observe the tested results of the segmental range of motion （ROM） of lumbar spine by charge couple device （CCD）-based system for 3-dimensional real-time positioning （CCD system）, and to analyze its clinical significance. Methods： Seven patients with lumbar joint dysfunction and 8 healthy subjects were tested twice by the CCD-based system with an interval of 10 min. Results： The ROM of the patients was obviously lesser than that of the healthy subjects. The measuring data of segmental ROM of lumbar spine by CCD system is correlated significantly to the same data checked later on the same subjects in every direction of the movements. The differences between two checks are usually less than 1 degree. Conclusion： Specially designed CCD based system for 3-dimensional real-time positioning could objectively reflect the segmental ROM of lumbar spine. The system would be of great clinical significance in the assessment of the biomechanical dysfunction of lumbar spine and the effect of the treatment applied.

Investigating the Thermal Stress of Millisecond Pulsed Laser Irradiation on Charge-Coupled Devices

In this study, a two-dimensional model describing thermal stress on a charge-coupled device (CCD) induced by ms laser pulses was examined. Considering the nonlinearity of the CCD’s material parameters and the melting phase transition process of aluminum electrode materials was considered by using equivalent specific heat capacity method, the physical process where a laser pulse irradiating a CCD pixel array was simulated using COMSOL Multiphysics software. The temperature field and thermal stress field were calculated and analyzed. In order to clarify the mechanism producing damage on the CCD detector, Raman spectra from silicon were measured with a micro-Raman spectrometer to determine stress change in the CCD chip. The procedure presented herein illustrates a method for evaluating strain in a CCD after laser irradiation.

Surface contamination of the charge-coupled device

An experimental method to study the influence of surface contamination of a thinned, backside illuminated charge-coupled device(CCD) upon its quantum efficiency in soft X-ray region is suggested. A transmission grating spectrometer(TGS), in which the transmission grating is coupled to a thinned, backside illuminated charge coupled device, is used to measure the continuum X-ray emission from the end of cylindrical target irradiated by laser. In the measured spectra, only the carbon K absorption edge at wavelength of 4.4 um due to condensation of the vacuum oil oil the CCD surface is clearly seen. The surface contamination is considered as an effective "carbon filter" and the filter absorption to correct the quantum efficiency of the CCD camera is taken into account. The effective thickness of the carbon filter is determined by comparing the jump height of the measured spectra at 4.4um with those of the carbon absorption coefficient curves obtained from various carbon thickness. The accuracy of this method is tested by comparing the X-ray spectrum measured by the TGS with that obtained by a soft X-ray spectrometer.

基于线阵CCD的实验教学平台设计

在光电类课程的实验教学中,电荷耦合器件(CCD)是一个重要内容,传统的相关实验教学一般以演示性实验为主,导致学生对该器件的了解不够深入。该文提出一种适合各种线阵CCD的综合实验平台,采用该平台学生可以自主进行CCD驱动电路的设计实验、积分时间调节实验、角度测量实验和长度测量实验等。通过使用该平台,有助于提高学生的线阵CCD使用能力、单片机调试能力、基于LabVIEW的软件编程能力、电路板焊接能力和光路搭建能力。

多光谱TDICCD航天相机快视一体化地面检测系统设计与实现

针对多光谱时间延迟积分电荷耦合器件(Time Delay Integration Charge Coupled Devices,TDICCD)航天相机的产品研发,提出快视一体化地面检测系统的设计方案,并依托项目实现该设计方案。设计包括主机系统搭建、CXP(CoaXPress)高带宽数传采集卡、测控采集卡、图采测控上位机、光电参数测试、非均匀性校正以及刷新芯片重注等实现。采用一体化设计,所有软硬件全部集成于地检主机系统,方便携带和使用。采用模块化设计方法,使用通用的主机接口,实现多种采集卡在不同主机系统之间交叉使用;使用通用的数据传输接口、RS-422传输接口,使得采集卡不仅适用于本相机的接口协议,也能在修改现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)代码后适用于其他相机。经验证,该地面检测系统能有效完成多光谱TDICCD航天相机的功能测试、光电参数性能测试的要求,为项目顺利进行提供有力保障。

Measurement of cathode surface temperature using the method of CCD imaging in arc discharge

A two-wavelength pyrometry device using ordinary array CCD (charge coupled device) to collect the ra- diation data in the horizontal and vertical directions has been developed for measuring the cathode surface temperature during the arc discharge. Analyses of experimental results show that the device can make the measurement of the cathode surface temperature feasible. The cathode surface temperatures measured are lower than the melting point of tungsten (3653 K), and the arc current, cathode diameter, and the cathode length are the main influencing factors of the cathode surface temperature.

激光退火在背照式CCD图像传感器中的应用研究

激光退火是消除背照式电荷耦合器件(CCD)图像传感器背面势阱的重要工艺。文章研究了激光退火工艺中不同的激光波长、能量密度、光斑交叠率对掺杂杂质激活效率、器件表面形貌、成像质量及紫外量子效率的影响。研究结果表明,在浅结注入的情况下,355 nm波长激光激活效率要优于532 nm激光,但是355 nm激光比532 nm激光更易在较低能量密度时使硅片出现龟裂现象。采用2 J/cm^(2)能量密度、50%~65%交叠率,355 nm激光能有效激活离子注入的硼离子,背照式CCD图像传感器成像均匀性好,紫外量子效率明显提升。

CCD电荷转换因子通用测试方法研究

通过分析电荷耦合器件(CCD)图像传感器光电转换、电荷转移、电荷输出的工作原理,提出了一种通用高效的电荷转换因子(CVF)测试方法。该方法采用在CCD感光区域施加直流偏压,水平区施加连续转移的驱动时序的方式,使CCD光敏区以电荷溢出方式往水平区转移电荷,水平区以固定频率不间断转移输出电荷包,从而让CCD输出强度恒定的响应信号;然后通过复位漏电流与输出信号强度的对应关系计算出CCD器件的CVF值。根据该方法的原理设计了一种适应各种CCD器件的通用测试装置,并对多款CCD进行测试验证。结果表明,该方法有效提高了CCD电荷转换因子的测试效率、测试精度和稳定性。

Calibration and Monte Carlo simulation of a single-photon counting charge-coupled device for single-shot X-ray spectrum measurements

A Princeton Instruments PI-LCX 1300 charge-coupled device （CCD） camera used for X-ray spectrum measurements in laser-plasma experiments is calibrated using three radioactive sources and investigated with the Monte Carlo code Geant4. The exposure level is controlled to make the CCD work in single photon counting mode. A summation algorithm for obtaining accurate X-ray spectra is developed to reconstruct the X-ray spectra, and the results show that the developed algorithm effectively reduces the low-energy tail caused by split pixel events. The obtained CCD energy response shows good linearity. The detection efficiency curves from both Monte Carlo simulations and the manufacturer agree well with the experimental results. This consistency demonstrates that event losses in charge collection processes are negligible when the developed summation algorithm of sDlit Dixel events is emDloved.

Surface diffuse discharge mechanism of well-aligned atmospheric pressure microplasma arrays

A stable and homogeneous well-aligned air microplasma device for application at atmospheric pressure is designed and its electrical and optical characteristics are investigated. Current-voltage measurements and intensified charge coupled device （ICCD） images show that the well-aligned air microplasma device is able to generate a large-area and homogeneous discharge at the applied voltages ranging from 12 kV to 14 kV, with a repetition frequency of 5 kHz, which is attributed to the diffusion effect of plasma on dielectric surface. Moreover, this well-aligned microplasma device may result in the uniform and large-area surface modification of heat-sensitive PET polymers without damage, such as optimization in hydrophobicity and biocompatibility. In the biomedical field, the utility of this well-aligned microplasma device is further testified. It proves to be very efficient for the large-area and uniform inactivation of E. coli cells with a density of 103/cm2 on LB agar plate culture medium, and inactivation efficiency can reach up to 99% for 2-min treatment.

线阵CCD辅助探测天幕阵列弹丸位置解析模型

针对典型光电测试系统存在的探测光幕结构复杂,测量精度较低,靶场布设困难的问题,提出了基于探测天幕和线阵电荷耦合器件(CCD)结合测量弹丸位置的方法;根据弹丸穿过探测天幕阵列和线阵CCD的时间和图像信息,结合探测天幕阵列和线阵CCD的空间几何关系,建立了弹丸位置的计算模型;按照误差传递理论,建立弹丸位置参数的全微分误差模型,仿真分析得到弹丸位置参数的误差分布在3.5 mm之内;通过弹丸位置测试试验,与纸板靶法测量弹丸坐标进行对比,误差均小于5 mm,验证了提出的测量系统的准确性和可行性。

The nonlinearity measurement of charge-coupled device array spectrometer using colorful LED

A nonlinearity measurement of the charge-coupled device(CCD) array spectrometer using flux addition and comparison method is described. The light with various colors from the colorful light emitting diode(LED) light source is applied to measure the nonlinearity of the spectrometer at different wavelengths, respectively. An high-end CCD array spectrometer is tested. For colorful LED light sources, the nonlinearity factors of the CCD array spectrometer(absolute value) are as follows: k<0.8% for white light, k <1.1% for red light, k <2.2% for green light and k<4.7% for blue light. By using those quasi-monochromatic light sources, it is shown that the nonlinearity depends on the wavelength. It is important to be wariness about the spectral nonlinearity and related uncertainty evaluation when the narrow-band light source is tested.

CCD满阱自动化检测系统及其在相机研制中的应用

在相机研制过程中,电路参数的每次调整都伴随着对相机输出满阱的测试,参数调整繁复,满阱测试的次数过多。为获得最佳的满阱输出性能,对电路各项参数进行精确匹配,提高满阱测试的效率,设计了一套自动化满阱性能测试平台。研究了影响电荷耦合器件满阱性能的因素,建立了光子转移曲线模型,提出了一种光子转移曲线快速取点法,并讨论了模型和方法在满阱测试中的应用。搭建了包括光源系统、成像电路、和温度采集系统在内的测试平台,并完成了自动化流程的软硬件设计。将该测试平台应用于在研相机的测试,验证了平台构造和测试方法的正确性,测量精度优于±1.6%,满足科学级相机的研制使用要求。

微小卫星高分辨率相机CCD焦面组件热控制

为了保证微小卫星高分辨率遥感器相机的成像品质,需控制焦面组件的温度水平及温度稳定性,特别是焦面CCD光学探测器件的温度控制。首先提出以相变储能与超低刚度柔性导热索相结合的焦面组件精密热控方法,对相变储能装置与石墨柔性导热索的设计及参数选取进行详细介绍;然后,建立焦面组件的热仿真模型并进行温度计算;最后,在真空环境下进行了热试验。计算与试验结果表明,焦面CCD器件长期温度为15~18.5℃,工作温升速率为0.33℃/min,具有良好的温度水平与温度稳定性;热控补偿功率≤4.8 W,约为焦面组件发热功率的1/10,可节省卫星能源消耗,验证了焦面组件热控制方法的正确性。

亚像元的CCD几何超分辨方法

为了在现有CCD像元尺寸的基础上提高CCD像元分辨力,对CCD几何超分辨问题进行了研究。从研究现状入手,给出了现有算法及其不足,建立了亚像元超分辨成像数学模型,提出了亚像元的CCD几何超分辨方法。该方法将两片线阵CCD集成在同一器件中,在线阵方向上错开半个像元,同时读出时间减半,最终交织重组图像数据,以合成高分辨率图像。利用MATLAB7.0.1软件对双线性插值方法及亚像元成像方法进行了仿真,并定性定量地分析了两种方法的效果。结果显示:亚像元方法合成图像分辨率约为低分辨率图像的2倍,且两组仿真图像中的PSNR比双线性插值图像分别高出1.4864dB和2.2070dB。该方法可以显著地减轻欠采样引起的图像模糊,且实时性优于双线性插值方法。

一种新型CCD驱动电路设计方法

在结合直接数字电路驱动法与单片机口驱动法的基础上,设计了一种新型的CCD驱动电路,保留了原有两种方法各自的优点。仿真与实验结果表明该方法能提供多路驱动时序,驱动频率高,硬件电路简单,编程方便,具有较好的性价比及应用推广价值,已用于CCD图像采集系统的研制。

基于CCD的智能车导航系统研究

目前智能车导航大多采用摄像机来获取路面信息,针对这一特点研究开发了基于CCD的导航模块.详细介绍了CCD视频信号的采集及处理方法.考虑到环境光线的变化会影响导航效果,提出了一种自适应动态阈值图像处理算法;该算法运算量小,能跟踪环境光线的变化.同时给出了系统抗干扰的处理方法,从而有效解决了因外界光线和赛道变化引起的智能车跑偏问题.通过系统实验和竞赛,证明了该导航系统具有良好的智能性和抗干扰能力,即此方案是有效的.

基于HJ卫星CCD数据的冬小麦病虫害面积监测

遥感在农作物病虫害监测中广泛采用的简单植被指数阈值法难以判别冬小麦的健康状况。该研究选择二值逻辑回归法,分别建立实测光谱得到的植被指数与其健康状况之间的关系模型。结果表明,重归一化植被指数RDVI模型和三角植被指数TVI模型可信度较好。考虑到遥感监测冬小麦病虫害时,涉及的地域范围广,冬小麦生长状况存在明显的局域差异,采用了3×3邻域像元的一致性假设消除局部环境差异。将模型应用到中国新近发射的环境与灾害监测预报小卫星星座HJ-CCD传感器数据,得到提取的冬小麦受病虫害胁迫范围与枣阳市植保站普查结果相符,也与地面实测结果相一致,其中,TVI模型结果的精度达到76.47%,能够满足农作物病虫害面积遥感监测要求。

CCD光电自准直仪工作原理及误差源分析

主要介绍了CCD光电自准直仪的工作原理并进行了误差源分析。