凝视型红外光电系统噪声等效温差测量

噪声等效温差(NETD)是一个用以标志红外光电系统灵敏度的广泛使用的参数.本文采用三维噪声模型对凝视型红外光电系统噪声进行分析,将系统噪声按时间和空间三维划分为七个噪声分量,提出了一种系统噪声等效温差(NETD)的测量方法.对目标图像进行多帧采集,建立七个与噪声有关的数据集,提取出与系统各噪声相关的分量,用最小二乘法对系统信号传递函数(SiTF)进行拟合.通过实验,研究了系统的积分时间、增益等参数对噪声等效温差的影响.采用此方法对热像仪进行了实验分析,取得了较好的测量效果.并通过不同测量方法间的比较,说明了本文采用方法的正确性.     

关于提高红外筛检仪测量精度的研究

本文从非制冷焦平面探测器成像技术、参考黑体、温度标定三个方面,说明了在较低温度下提高红外筛检仪测量精度的方法.     

利用FPGA实现红外焦平面阵列实时非均匀性校正

实时非均匀性校正是红外成像的一项关键技术。根据红外焦平面阵列探测元光谱响应的特点和基于参照源的两点温标非均匀性校正理论，提出一种利用FPGA硬件实现红外焦平面阵列实时非均匀性两点校正的新方法。该方法动态范围大、处理速度快，适用于红外成像系统实时图像处理场合。仿真和实验结果证明是可行的。     

带温度补偿结构的高灵敏度光读出红外成像阵列器件设计

本文提出了一种光读出红外成像阵列器件的结构设计,该设计提高了器件的热-机械灵敏度,同时能有效降低周围环境温度变化所带来的影响.理论计算表明,该阵列器件的关键性能指标热-机械灵敏度和噪声等效温差分别为2.39×10-3和2.42,此外,ANSYS模拟仿真的结果验证了该设计能抑制周围环境温度波动对器件红外目标探测的影响.     

国外PtSi-SBIRFPA的技术进展及市场前景

本文全面深入地介绍了PtSi肖特基势垒红外焦平面阵列(PtSi-SBIRFPA)的技术进展及市场前景．从制作技术、像元集成度、NETD、光响应均匀性、量子效率、成品率和成本方面把PtSi单片式红外焦平面陈列(PtSi-MIRFPA)与InSb和HgCdTe混合式红外焦平面阵列(InSb和HgCdTeHIRFPA)技术作了详细的比较，评述了PtSi-MIRFPA技术的发展现状和面临的现实，分析了PtSi-MIRFPA技术的应用范围，目前的市场状况和今后的技术前景。     

非均匀校正技术算法分析与实时系统设计

为获得良好的红外焦平面阵列非均匀校正效果,讨论了非均匀性的来源、噪声类型和目前基于定标,基于场景的常用非均匀校正方法.对修正的时域高通滤波、改进的神经元网络等利用场景信息来估计探测器参数的校正算法进行了仿真效果和实时性能的分析与评价.同时设计了一种以TMS320DM642为处理核心的小型低功耗DSP硬件系统平台,描述了系统流程和实时实现策略,为红外焦平面系统提供了一条有效的实现路径.     

基于读出电路结构的红外焦平面图像非均匀校正算法

为了改善基于图像配准的红外焦平面迭代非均匀校正算法的性能,在此基础上提出了一种新的红外焦平面图像非均匀校正算法.首先分析了真实图像的噪声规律,利用红外焦平面的读出电路结构特性建立了噪声模型.而后分两部分对算法原理进行分析,最后用仿真数据对算法的有效性给予了验证.通过与其他算法的校正结果比较,证实该算法具有收敛速度快、计算复杂度低,数据存储量小等优点.     

红外焦平面阵列非均匀性嵌入式实时校正技术

红外焦平面阵列（IRFPA）成像是当今红外成像技术发展的主流方向,然而IRFPA特有的非均匀性严重地限制了系统的成像质量。针对红外焦平面阵列在进行非均匀性校正中所涉及的运算量和数据量庞大、实时处理难于实现的特点,本文提出采用高速TMS320C6000系列DSP为核心的嵌入式硬件系统,结合分段线性和分段二次多项式算法,阐述了硬件设计和实现步骤,并给出实验结果,结果表明本系统完全满足实时高精度校正的要求。     

基于维纳滤波的红外焦平面非均匀性校正算法

针对焦平面阵列上各探测单元光电响应的非均匀性,本文使用了维纳滤波技术来实现红外焦平面阵列非均匀校正.该方法首先根据实际情况确定一个输出延迟,然后采用维纳滤波并借助前后帧信息对当前帧进行多次估计,最后取其均值作为此帧的最终校正结果.文中使用了真实红外图像对算法性能进行验证,由于能够充分利用过去和将来的场景信息,因而本算法可以有效地去除原图像上的固定图案噪声.     

热红外偏振成像的目标探测技术研究

当目标与背景辐射强度接近时,传统的热红外成像系统无法有效区分背景与目标.基于光的偏振信息的目标探测技术国外已进行大量研究,在国内也越来越受重视,但尚处于初步研究阶段.采用非制冷热红外焦平面阵列,搭建热红外偏振成像系统,对特定场景中的典型目标开展了偏振成像实验,对图像进行了配准并对偏振度图像和强度图进行了融合.结果表明:热红外偏振成像较传统热红外成像对目标的探测有明显优势；采用基于HSI的偏振信息融合算法能综合反应目标特征,有利于提高图像质量,有利于远距离目标的探测与识别.     

Design of a Novel Substrate-Free Double-Layer-Cantilever FPA Applied for Uncooled Optical-Readable Infrared Imaging System

This paper describes the design and performances of a novel focal-plane array (FPA) containing pixels of double bimaterial-layer cantilevers without silicon (Si) substrate for being applied in the uncooled optical-readable infrared (IR) imaging system. The top layer of the cantilever pixels is made of two materials with large mismatching thermal expansion coefficients: silicon nitride (SiN_x) and gold (Au), which convert IR heat into mechanical deflection. The bottom layer is SiN_x cantilever, which partially serves thermal isolation legs. The top and bottom pads form the resonant cavity, which can dramatically enhance the absorption of incident IR irradiation, and the substrate-free configuration enables reducing the loss of incident IR energy. Responding to the IR source with spectral range from 8 to 14 mum, the IR imaging system may receive an IR images through visible optical readout method. A thermal-mechanical model for such cantilever microstructure is proposed, and the thermal and thermal-mechanical coupling field characteristics of the cantilever microstructure are optimized through numerical analysis method and simulation by using the finite-element method. The thermal-mechanical deflection simulated is 7.2 mum/K, generally in good agreement with what the thermal-mechanical model and numerical analysis forecast. The analysis suggests that the detection resolution of current design is 0.03 K, whereas the noise analysis from FPA indicates the current resolution to be around 100 muK and the limit noise-equivalent temperature difference (NETD) of the IR imaging system can reach to 7 mK.     

From the channel model of an InSb-based superresolution optical disc system to impulse response and resolution limits

The signal model of a superresolution optical channel can be an efficient tool for developing components of an associated high-density optical disc system. While the behavior of the laser diode, aperture, lens, and detector are properly described, a general mathematical model of the superresolution disc itself has not yet been available until recently. Different approaches have been made to describe the properties of a mask layer, mainly based on temperature- or power-dependent nonlinear effects. A complete signal-based or phenomenological optical channel model--from non-return-to-zero inverted input to disc readout signal--has recently been developed including the reflectivity of a superresolution disc with InSb used for the mask layer. In this contribution, the model is now extended and applied to a moving disc including a land-and-pit structure, and results are compared with data read from real superresolution discs. Both impulse response and resolution limits are derived and discussed. Thus the model provides a bridge from physical to readout signal properties, which count after all. The presented approach allows judging of the suitability of a mask layer material for storage density enhancement already based on static experiments, i.e., even before developing an associated disc drive.     

宽温度环境下光数据存储的不稳定性分析

本文分析了磁光存储系统读出不稳定性和温度的关系,导出了信号和噪声随温度变化的函数关系,指出半导体激光器和光电探测器是导致读出不稳定的主要原因,提出了在宽温度环境下改善系统读出稳定性所应采取的措施。     

Optical learning neural network with a pockels readout optical modulator

We have constructed an optical neural-network system with learning capability by using a Pockels readout optical modulator. The system has a two-dimensional structure that permits easy optical alignment and can handle images without scanning. Learning signals are calculated optically with two liquid-crystal devices by a matrix-matrix outer-product method. The calculated learning signals are added directly to the weights memorized on the Pockels readout optical modulator. A two-layer network is implemented, and the learning and recognition of four alphabetical characters are realized according to the delta rule.     

Three-dimensional time-resolved optical tomography of a conical breast phantom

A 32-channel time-resolved imaging device for medical optical tomography has been employed to evaluate a scheme for imaging the human female breast. The fully automated instrument and the reconstruction procedure have been tested on a conical phantom with tissue-equivalent optical properties. The imaging protocol has been designed to obviate compression of the breast and the need for coupling fluids. Images are generated from experimental data with an iterative reconstruction algorithm that employs a three-dimensional (3D) finite-element diffusion-based forward model. Embedded regions with twice the background optical properties are revealed in separate 3D absorption and scattering images of the phantom. The implications for 3D time-resolved optical tomography of the breast are discussed.     

TES microcalorimeter readout via transformer

Readout configuration for Transition Edge Sensor (TES) electrically coupled to a low noise warm front-end via transformer is studied. The study was aimed at the implementation of the readout involved in imaging with microcalorimeter detector arrays using frequency multiplexing technique (Appl. Phys. Lett. 81(1) (2002) 159). A model describing both TES electrothermal reaction and the readout response is investigated. Contribution of electronic noise to TES energy resolution is calculated. Prospective readout architecture with TES electrical biasing from the warm readout side is introduced. The architecture allows building of large imaging detector arrays with TES. It is shown that an unprecedented combination of imaging and spectrometry features can be achieved with TES readout via transformer.     

The noise of coated cantilevers

In atomic force microscopy, cantilevers with a reflective coating are often used to reduce optical shot noise for deflection detection. However, static AFM experiments can be limited by classical noise and therefore may not benefit from a reduction in shot noise. Furthermore, the cantilever coating has the detrimental side-effect of coupling light power fluctuations into true cantilever bending caused by time-varying thermal stresses. Here, we distinguish three classes of noise: detection, force, and displacement noise. We discuss these noises with respect to cantilever coating in the context of both static and dynamic AFM experiments. Finally, we present a patterned cantilever coating which reduces the impact of these noises.     

Miniature Accelerometer and Multichannel Signal Processor for Fiberoptic Fabry–Pérot Sensing

A miniature accelerometer based on silicon microelectromechanical systems (MEMS) fabrication technology has been developed. Using a beam-suspended proof mass and a Fabry-Peacuterot sensing gap, this accelerometer is fiber coupled to a miniature, multichannel, optical readout system which was developed for application in compact optical sensor systems. The approximately 4 mmtimes7 mmtimes2 mm accelerometer can be tailored to cover milli-g to kilo-g acceleration ranges. The miniature readout system is enclosed in approximately a 2 cmtimes8 cmtimes1 cm package, one of the smallest ever reported, and implements the complete optical path for a three-channel embodiment of a multichannel, highly sensitive and accurate, in-phase and quadrature (IQ) optical measurement system for Fabry-Peacuterot sensors. A variety of fiber-based sensors (temperature, strain, pressure, etc.) are commercially available using this Fabry-Peacuterot technique. The complete measurement system with the accelerometer was tested using a shaker table. Sample results are presented for 100 Hz, 10-g peak-peak acceleration     

Vector diffraction analysis of optical disk readout

The optical disk readout signals from ROM disks are presented by use of a rigorous three-dimensional vector diffraction method. The optical disk is modeled as a crossed metal grating without restriction on the form of the information marks, and the permittivity of the metal is taken into account. The diffracted field from the disk is obtained by means of decomposing the focused incident beam into a spectrum of plane waves and then calculating the diffracted plane waves for each respective incident component. The readout signal is obtained by integration of the energy-flux density of the diffracted field according to the detection scheme of the optical disk system. A typical digital versatile disk (DVD) system is applied with this theory, and the result is far from that of scalar diffraction theory.     

Interlayer cross talk in dual-layer read-only optical disks

Volumetric optical disks comprising multiple data layers have been proposed to multiply recording density. Owing to the presence of out-of-focus data layers, interlayer cross talk is induced in readout. An optical model was developed to study the readout process and the effect of interlayer cross talk on the readout of dual-layer read-only optical disks. Schemes to improve the readout characteristics by suppression of the interlayer cross talk were proposed. Experiments that agreed well with the simulation resulted.