基于反射光谱和图像的雪地伪装材料紫外检测技术研究

雪地背景伪装研究对于伪装设计与伪装识别均具有重要的意义。本文研究了高白度、高反射率的雪地型伪装材料的性能检测技术。针对冬季雪地背景和典型目标样品(白纸、白棉布和白色伪装材料),开展基于光谱曲线间相似性、基于紫外图像直方图和灰度平均对比度相似性的伪装检测技术研究。通过光谱反射因数的欧氏距离和光谱角余弦计算伪装样品与雪地背景的相似性,通过平均灰度值对比和直方图的归一化相关系数巴氏距离来判断伪装目标和雪地背景的相似程度,证明了反射光谱和紫外图像检测的可行性和有效性。研究结果对雪地型伪装装备的研制和设计定型试验有一定的指导意义。     

面向高光谱探测的伪装效果评价方法

20世纪80年代发展起来的高光谱成像技术能充分探测并利用地物的光谱信息,有着较强的伪装识别能力,而传统的伪装评价方法主要基于伪装和背景的空间特征,不适用于基于光谱特征的高光谱伪装探测技术。提出了一种面向高光谱探测的伪装效果评价方法。该方法以伪装目标和背景的光谱特征及光谱导数特征的综合相似度为评价指标,综合相似度值越大则说明伪装效果越好。同时通过实验评价了三种伪装材料的伪装效果,其中绿色棉质布料与背景综合相似度为0.976 6,伪装效果最佳。最后在高光谱图像分类技术基础上提出了错分率的概念,验证了评价方法的客观性。所提出的伪装评价方法对于面向高光谱探测的新型伪装材料的设计有一定的指导意义。     

可见光与红外融合图像反射与辐射光谱分析

可见光图像与红外图像融合是近年来热门的研究领域.根据日光的光谱分布、目标的反射系数以及黑体的红外辐射,详细分析了人体、深色涂层、高温玻璃杯等常见目标的反射辐射光谱分布和红外辐射光谱分布.利用研制的可见光与红外融合图像采集系统,采集了常见目标的可见光与红外融合图像,得到了从可见光波段到红外波段融合图像的全光谱曲线.对可见...     

可见-近红外高光谱伪装目标特性分析

传统的伪装目标探测识别大部分是依靠人眼通过光学仪器进行简单的放大观测,但是通常探测效果不佳。高光谱仪能采集一定波长范围的光谱图像,从而得到物体连续的光谱曲线,一般来说,不同物体间的光谱曲线存在差异。利用在可见光及近红外波段下获取的高光谱图像,分析伪装目标在不同背景下的伪装效果。通过光谱幅值及光谱形状变化趋势,评价伪装目标与背景光谱曲线的差异。根据实验结果综合评价,伪装目标在真实草地中的伪装效果相对塑料假草皮来说更好,符合实际需要,能为军事行动提供良好的伪装。同时,实验也表明,在可见光波段下,不同物体光谱曲线变化趋势不同,在近红外波段下,物体间的光谱反射灰度值差异较大,但是光谱变化率差异较小。在伪装目标探测时,若仅从某一方面来评价,可能得到错误的结果。所以在探测识别时,需要从各方面综合考虑。     

皮肤微区反射光谱及颜色特性的研究

本文介绍了光纤探头式皮肤反射光谱分析和颜色检测系统,该系统依据反射物体颜色测试原理,采用CCD并行处理结构,实现皮肤反射光谱快速测量,并计算出相应皮肤的颜色坐标和明度,利用该测量系统,分析了病变皮肤与正常皮肤的反射光谱和颜色,提出了实现客观识别皮肤病的对策。     

基于高光谱遥感技术的伪装材料的光谱特性分析

通过采集9种常见伪装材料及背景的光谱,进行基于反射率光谱的伪装材料的光谱分析和提取工作,然后对原始反射率光谱曲线和经包络线去除法变换后的曲线进行分析,并利用多种光谱差异算法对光谱数据进行计算,进而对伪装效果进行评估.通过实验得到了在可见光图像上难以区分的几组伪装目标的光谱特征差异,对伪装检测的波段选取及伪装材料的选择提供了参考依据.     

高光谱遥感的发展及其对军事装备的威胁

高光谱遥感融合了光谱分析和成像遥感的优点,可以利用精细光谱特征分析、识别目标的种类和表面状态,给军事装备带来了新的威胁.介绍了高光谱侦察的基本原理和发展概况.分析了高光谱在军事侦察、伪装识别和热红外探测方面的优势,并指出利用植被的光谱特征识别技术可以有效分辨林地背景中的绿色伪装目标;在热红外波段高光谱可以通过探测目标的真实温度和发射率来检测伪装.     

天然PbS（方铅矿）的远红外反射光谱

研究了天然形成的方铅矿的远红外反射光谱中低频端Ｐｌａｓｍｏｎ反射边产生的物理原因，并根据不同反射边的斜率与样品中所含杂质量的相关性，定性解释了不同样品中不同杂质组份和结构上的特点对Ｐｌａｓｍｏｎ反射边的影响。又根据不同杂质的正负相关性在自然成因上的因果关系，证明了从反射光谱特性中获得对矿物成因有一定指导意义的信息的可行性。     

多孔硅吸收光谱和反射光谱

测定了多孔硅的吸收光谱和反射光谱，结果发现其吸收边对应于可见光区域。同单昌硅要比，其吸收边发生了蓝移，并且吸收强烈。由多孔硅反射谱曲一，利用Ｋ－Ｋ关系对其光学常数进行了简单的计算和分析。     

红外内反射光谱的原理和应用

本文从波动理论的观点出发,分析了内反射光谱的形成及其基本理论。通过对几种纺织品内反射光谱的测试介绍了测试光路和测试方法,并简单介绍了内反射光谱的其它用途。     

多基色白光LED的配色研究

利用基色光混色的方法对三基色和四基色白光LED进行了配色研究。固定相关色温为(5 500±20)K的条件下,在可见光范围内将不同峰值波长、半宽的基色光进行混色,得到显色指数和光视效能与峰值波长和半宽的关系。其中,三、四基色白光LED的显色指数最高分别达到89和96.7,对应的光视效能分别为353lm/W和340lm/W。同时,计算结果表明,增加基色光的数目后,提高了白光LED的显色性及显色稳定性。     

Low-dispersion single-mode silica fibre with undoped core and three F-doped claddings

The refractive-index profile of an ideal single-mode silica fibre with undoped core and three F-doped claddings was optimised by calculation to realise two zeros of the chromatic dispersion at 1.30 and 1.55 ?m where the spectral loss has its local and absolute minima, respectively. The sensitivity of the chromatic dispersion due to different scale factors for the radial co-ordinate of the refractive-index profile is considered.     

Influence of axial chromatic aberration in projection printing

The computer simulation program SAMPLE is used to study the effects of longitudinal chromatic aberration on the resolution of projection mask aligners for microelectronics. It is shown that source spectral characteristics, filter bandwidth, and lens parameters all play a significant role in limiting image contrast in both single- and two-wavelength systems. Techniques for estimating the loss of image contrast as a function of lens and illumination parameters as well as examples including resist sensitivity and filter characteristics are given. For single-wavelength systems, appropriate filtering can make the effect of dispersion negligible usually at a slight cost of intensity available for exposure. However, in the case of two-wavelength systems, chromatic aberration can lead to a significant reduction in contrast below the diffraction-limited value. The loss in contrast can, however, be minimized by designing the lens for minimum chromatic slope at the two operating lines and by choosing a source with minimum spectral line bandwidth and minimum continuum between the two spectral lines or by using notch filtering.     

Performance evaluation of very long span direct detection intensityand polarization modulated systems

In this paper long distances very high capacity NRZ optical transmission systems adopting direct detection are considered in links with a low average chromatic dispersion. Particular attention is devoted to polarization modulated (PM-DD) systems. Polarization modulated systems results to he more degraded with respect to intensity modulated (IM-DD) systems by the light depolarization induced by the interplay among the Kerr effect, the ASE noise of the optical amplifiers and the polarization mode dispersion. The light depolarization is particularly strong in conditions of large spectral broadening that are met when the chromatic dispersion value is maintained very low along the link. On the other hand the use of a fluctuating chromatic dispersion with a mean value equal to zero, whereas the local dispersion is different from zero, shows the double advantage to reduce the chromatic dispersion impairments and to limit the spectral broadening. The advantages offered by this dispersion management technique have been already shown in several experiments for IM-DD systems: in this work we show that this technique is very important also for PM-DD systems since the limitation in the spectral broadening reduces the light depolarization. We show that adopting a suitable dispersion management and an opportune preamplifier optical filter transmissions at 5 Gb/s can be attained in transoceanic links by means of FM-DD systems     

All-fiber interferometer for chromatic dispersion measurements

An all-fiber interferometric method for chromatic dispersion measurements in meter-length single-mode fibers is presented. In a Michelson setup the physical length of a reference fiber was varied so as to obtain adjustable optical delay. Time resolution, ease of manipulation, and mechanical isolation are considerably improved with respect to conventional interferometers. Resolution of group delay measurement and chromatic dispersion over the full 1100-1700-nm spectral range are better than 5 fs and 0.1 ps/nm-km, respectively     

目标发现概率的计算方法探索

针对现代侦察包含越来越多的光谱信息，应用原来发现概率的计算方法很难满足对彩色目标伪装检测的要求．对目标的发现概率问题进行探索，提出了利用色差进行发现概率计算的方法．实验结果表明该计算方法能够反映目标的真实信息．     

Reconfigurable Dispersion Equalizer Based on Phase-Apodized Fiber Bragg Gratings

We present a novel dispersion equalizer design for the compensation of chromatic dispersion and chromatic dispersion slope in WDM systems. The device is based on a cascade of complex quasi-periodic chirped fiber Bragg gratings. We show that the use of a low chirp results in the distribution of the resonating cavities along the optical fiber length, which allows reconfiguration of the spectral characteristics by the application of a temperature profile. This paper exposes in detail the numerical techniques used in the optimization of the fiber Bragg grating filters taking into account fabrication imperfections. We present a specific design for a 32-channel dispersion equalizer for 10 Gbit/s and a 50-GHz channel spacing. We examine the spectral characterization of a device fabricated using a phase-apodized mask for various settings of the chromatic dispersion profile. We demonstrate a tuning range of $pm {800}~{rm ps}/{rm nm}$ over a bandwidth of 30 GHz. On average, the standard deviation of the phase ripple was below 0.1 rad. Finally, we evaluate the performance of this device by bit error rate measurements.      

宽光谱、大视场小畸变望远系统设计

设计了一个应用于成像光谱仪的望远系统,针对成像光谱仪的特点,由前置望远镜及后置光谱仪组成。前置望远系统的参数以及成像质量对整个成像光谱仪应用显得非常重要。设计了一个谱段范围1～2.5 m、视场为28.10.3、相对口径为1/4、焦距长度为60 mm的望远系统。系统在谱段1～2.5 m宽谱段范围内通过玻璃的匹配校正了色差及二级光谱,畸变控制在0.2%以内,很好地保证了与后续光谱仪的对接,此设计可用于航空领域进行大视场、高分辨率成像。     

Analysis of dynamic spectral width of dynamic-single-mode (DSM) lasers and related transmission bandwidth of single-mode fibers

A simple formula of the dynamic spectral width of a directly modulated dynamic-single-mode (DSM) laser, and the related maximum transmission bandwidth of a single-mode fiber limited by chromatic dispersion are theoretically given. The dynamic spectral width of a DSM laser is determined by the modulated optical shape and the linewidth enhancement factor α. The spectral width caused by the dynamic wavelength shift is shown to be larger by (1 + alpha^{2})^1/2than that caused by the sideband of the signal of the intensity modulation. Furthermore, the maximum transmission bandwidth of a conventional single-mode fiber with a DSM laser is expressed by using the parameter α and the chromatic dispersion of the fiber. The product of the maximum bit rate and the square root of the fiber length at the wavelength of 1.55 μm is estimated to be about 25 Gbit/s . km^1/2.     

硅太阳能电池板的光谱BRDF测量及色度特性的研究

实验测量了硅太阳能电池板在380～780 nm内的光谱双向反射分布函数（BRDF）,分析了光谱双向反射分布函数随波长及散射角的变化趋势,将色度学理论和光散射理论相结合,寻找到光散射理论中的双向反射系数与色度学中光谱反射率因数的联系,进而获得了一种通过光谱BRDF测量实现物体色度特性表征的方法。并且采用CIELAB均匀色空间中的明度指数和色品指数、定量地描述了几种入射条件下、不同散射方向上目标样片的颜色特性。将目标样片的光谱双向反射分布函数的研究应用到颜色光学领域中,对目标的探测、识别和颜色复现等具有重要的应用价值。