基于场景的红外探测器非均匀性校正方法的分析

红外探测器中的非均匀性校正是红外成像系波器法三种基于场景的非均匀性校正算法,通过利用图像序列并依赖帧间运动对焦平面阵列的非均匀行进行校正,并与两点法比较,分析三种方法的优缺点.     

基于FPGA的两点非均匀校正模块的设计与实现

两点校正算法是一种行之有效的红外图像非均匀校正方法.本文对两点校正算法进行了分析,并推导出了该算法的定点表示形式.利用FPGA在硬件上实现了该算法,内部采用流水线技术,校正系数存储在FPGA的片内存储器中并实现了盲元补偿.仿真和实验结果证明该设计是可行的,达到了预期效果。     

基于DSP的红外图像非均匀性校正技术的研究

分析了导致红外成像系统非均匀性的机理,介绍了红外焦平面阵列非均匀性校正的基本方法。采用两点校正和积分时间校正相结合的方法,利用TMS320VC5509A DSP完成了对红外图像的非均匀性实时校正。实验结果表明,本系统具有实时性好,实用性强的特点,能够满足红外焦平面成像系统的要求。     

基于DSP红外图像非均匀校正设计

由于红外焦平面探测器各点的响应度不一致,需要对红外图像进行非均匀校正。目前许多红外成像设备非均匀校正均通过后台PC机完成,需要专门设计与PC机的接口,提高了成本,而且不利于脱机运行。系统使用红外图像处理板自身的DSP完成非均匀校正系数的计算,设计简洁,操作方便,取得了理想的效果。文中分析了两点校正的原理,介绍了实现方法,对其中涉及的关键技术进行了详细描述。     

一种新型的非制冷红外机芯组件图像校正算法研究

非制冷红外探测器由于其结构简单、响应快等优势,在诸多领域得到广泛应用。然而由于结构和制作工艺等的限制,传统的非制冷红外焦平面阵列非均匀性校正方法并不能很好完成非均匀性校正任务,在挡片打开后画面会出现一层蒙纱感,严重影响图像质量,限制探测器的应用范围。从试验数据出发,对蒙纱感可能的来源进行分析,并针对其来源提出一种针对非理想因素的新型非均匀性校正方法,较好地对蒙纱感进行处理和补偿,极大提高成像质量。该方法操作简单,容易实现,在红外成像相关的应用上有重大意义。     

基于运动指导的红外焦平面非均匀性校正方法

针对红外焦平面阵列(IRFPA)非均匀性校正算法中基于场景类自适应校正算法存在的目标退化和伪像等问题,提出一种新的基于运动检测指导的自适应校正算法。该算法首先通过预处理为实时校正准备背景帧图像和坏元模板,接着根据前后两帧场景信息的运动方差,自适应地调整迭代步长,最后结合运动幅度更新增益校正系数,对图像实施校正。以含有弱小目标的实际红外图像序列进行仿真的结果表明,新算法有效地抑制了目标退化,消除了伪像;去除了固定图案噪声,具有自适应性。     

红外焦平面阵列非均匀性校正算法研究

红外焦平面阵列( IRFPA)的非均匀性校正是提升红外系统成像质量的重要环节。非均匀性校正算法主要分为基于参考辐射源的标定类校正算法和基于场景的校正算法。将基于参考辐射源的标定类校正算法按线性模型与非线性模型进行详细分类,基于场景的校正算法按空域和时域进行详细分类。针对不同类特点,分别对上述算法进行了详细的分析及比较,为今后非均匀性校正算法的选择提供理论基础,并根据现有两类算法特点,提出算法未来的研究方向。     

基于时域高通滤波的非均匀性校正算法研究

实现红外焦平面阵列非均匀性自适应校正是红外探测系统研究中追求的重要目标,对提高红外探测系统的空间分辨率、温度分辨率、探测距离以及辐射量的正确度量具有重要意义.分析基于时域高通滤波的红外焦平面自适应非均匀校正算法的视觉神经机制以及滤波器的幅频特性.通过对实际红外图像的实验,提出正确选取时间常数是影响该校正方法最重要的因素.     

一种新型非制冷红外焦平面读出电路的设计

非制冷红外焦平面读出电路具有低功耗、高分辨率等特点,并且具有电路结构简单、低功耗、高清晰度的电路芯片,其主要用于红外成像设备。基于TSMC 0.18 μm工艺,研究并设计了一种384×288像元阵列非制冷红外焦平面读出电路,包含非均匀消除模块、像元电路模块和电容反馈互导放大器(CTIA)。对电路进行仿真,结果显示积分电压具有较好的线性和放大效果。     

基于DSP的红外焦平面阵列实时非均匀性校正技术

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,采用TMS320C6000系列DSP两路数据通道的优势,输入输出数据采用不同的数据通道并行传输,利用EDMA传输方式无需CPU介入,充分利用DSP硬件的并行性和流水线进行非均匀性校正,以分段线性插值算法为例,详细阐述了硬件设计和实现步骤,并给出仿真结果,结果表明:基于DSP的实时非均匀性校正系统完全可以达到实时校正的要求.     

Design,simulation and validation of a novel uncooled infrared focal plane array

This paper describes a novel single-layer bi-material cantilever microstructure without silicon (Si) substrate for focal plane array (FPA) application in uncooled optomechanical infrared imaging system (UOIIS). The UOIIS, responding to the radiate infrared (IR) source with spectral range from 8 to 14 μm, may receive an IR image through visible optical readout method. The temperature distribution of the IR source could be obtained by measuring the thermal–mechanical rotation angle distribution of every pixel in the cantilever array, which is consisted of two materials with mismatching thermal expansion coefficients. In order to obtain a high detection to the IR object, gold (Au) film is coated alternately on silicon nitride (SiN_x) film in the flection beams of the cantilevers. And a thermal–mechanical model for such cantilever microstructure is proposed. The thermal and thermal–mechanical coupling field characteristics of the cantilever array structure are optimized through numerical analysis method and simulated by using the finite element simulation method. The thermal–mechanical rotation angle simulated and thermal–mechanical sensitivity tested in the experiment are 2.459 × 10⁻³ and 3.322 × 10⁻⁴ rad/K, respectively, generally in good agreement with what the thermal–mechanical model and numerical analysis forecast, which offers an effective reference for FPA structure parameters design in UOIIS.     

An uncooled optically readable infrared imaging detector

This paper presents a design and fabrication of bi-material micro-cantilever array (focal plane array, FPA) made of silicon nitride (SiN_x) and gold (Au) for uncooled optical readout infrared (IR) imaging system, in which silicon (Si) substrate is removed. Compared with the conventional thermal imaging detectors where the FPA must be put in high vacuum, IR thermal images can be obtained even though the cantilever array is placed in the atmosphere. The reason is the elimination of air gap (∼2 μm) between the cantilever beam and substrate, which introduces the air conduction of high temperature gradient. The preliminary experimental results with the micro-cantilever array of 140 × 98 elements and a 12-bit charge-coupled device (CCD) indicate that objects at temperature of higher than 120 °C can be detected and the noise-equivalent temperature difference (NETD) is ∼7 K. Also, the experimental results are well accordant with the thermomechanical analysis of designed micro-cantilever array.     

基于ADN8830的非制冷焦平面探测器温度控制系统设计

高精度的温控系统是实现高性能非制冷红外焦平面热像仪设计的关键。针对非制冷焦平面阵列像元温度保持恒定可以提高测试精度的问题,提出了基于ADN8830单芯片热电制冷器控制器的温控系统设计。通过可编程逻辑器件CPLD来控制数模转换芯片DAC为ADN8830提供不同的目标温度设置电压,从而实现不同环境温度下的焦平面阵列像元温度的恒定。最后,通过对所设计电路进行测试表明,相比于由单片机m cu实现的电路,该电路具有温度控制精度高,配置灵活,功耗低、体积小等优点。     

A Low-Cost 128 × 128 Uncooled Infrared Detector Array in CMOS Process

This paper discusses the implementation of a low-cost 128 times 128 uncooled infrared microbolometer detector array together with its integrated readout circuit (ROC) using a standard 0.35 mum n-well CMOS and post-CMOS MEMS processes. The detector array can be created with simple bulk-micromachining processes after the CMOS fabrication, without the need for any complicated lithography or deposition steps. The array detectors are based on suspended p⁺-active/n-well diode microbolometers with a pixel size of 40 mum times 40 mum and a fill factor of 44%. The p⁺-active/n-well diode detector has a measured dc responsivity (R) of 4970 V/W and a thermal time constant of 36 ms at 50 mtorr vacuum level. The total measured rms noise of the diode type detector is 0.69 muV for an 8 kHz bandwidth, resulting in a detectivity (D*) of 9.7 times 10⁸ cm ldr Hz^1/2/W. The array is scanned by an integrated 32-channel parallel ROC including low-noise differential preamplifiers with an electrical bandwidth of 8 kHz. The 128 times 128 focal plane array (FPA) has one row of infrared-blind reference detectors that reduces the effect of FPA fixed pattern noise and variations in the operating temperature relaxing the requirements for the temperature stabilization. Including the noise of the reference and array detectors together with the ROC noise, the fabricated 128 times 128 FPA has an expected noise equivalent temperature difference (NETD) value of 1 K for f/1 optics at 30 frames/s (fps) scanning rate. This NETD value can be decreased to 350 mK by improving the post-CMOS fabrication steps and increasing the number of readout channels.     

Optomechanical uncooled infrared imaging system: design,microfabrication, and performance

This paper presents the design, fabrication and performance of an uncooled micro-optomechanical infrared (IR) imaging system consisting of a focal-plane array (FPA) containing bi-material cantilever pixels made of silicon nitride (SiNx) and gold (Au), which serve as infrared absorbers and thermomechanical transducers. Based on wave optics, a visible optical readout system is designed to simultaneously measure the deflections of all the cantilever beams in the FPA and project the visible deflection map onto a visible charge-coupled device (CCD) imager. The IR imaging results suggest that the detection resolution of current design is 3-5 K, whereas noise analysis indicates the current resolution to be around 1 K. The noise analysis also shows that the theoretical noise-equivalent temperature difference (NETD) of the system can be below 3 mK     

基于圆柱面映射的快速图像拼接算法

针对现有基于圆柱面映射的全景图像拼接算法无法实现自动估计焦距的问题,为满足实时性要求,提出了一种基于预测的快速特征点匹配算法,在基于纯旋转运动的自动焦距估计算法基础上,提出了一种基于单应矩阵的焦距修正算法。该算法首先从待拼接图像中提取Harris角点,然后提取方向梯度直方图(Histogram of Oriented Gradient, HOG)描述子进行特征点匹配,基于前一帧图像获得的图像映射关系采用一种基于预测的快速特征点匹配算法,然后使用简化的基于纯旋转运动的焦距估计算法估计出焦距初值,并采用基于单应矩阵的焦距修正算法得到更精确的焦距值,最后将平面图像投影至圆柱平面,使用加权平均融合算法进行拼接,合成全景图像。采用多个测试序列图像对算法进行测试,特征点匹配速度较传统方法提高了10倍以上,自动焦距估计算法能够准确估计摄像机焦距,且耗时仅50毫秒左右。实验结果表明,提出的算法能够快速地合成高质量的全景图像,拼接后的图像畸变小,具有较高的实用价值。     

Line integration HgCdTe focal plane array

Line integration 384 × 288 Focal Plane Array (FPA) consists of HgCdTe (MCT) photodiodes array formed in the mercury cadmium telluride p-type epitaxial layers grown both by liquid phase epitaxy (LPE) or molecular beam epitaxy (MBE). Grown by these methods MCT layers have multilayer compound structure. Silicon readout integration circuit (ROIC) performs the photocurrents integration during one line signals output (one row of pixels) period, and signals multiplexing in two output channels from the focal plane. The photodiodes array pitch in each direction is 28 μm. The influence of MCT surface irregularities and imperfections of MCT epitaxial layers on number of defective elements is investigated. The text was submitted by the authors in English.