共查询到18条相似文献,搜索用时 593 毫秒
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为了实时抑制太阳耀光对海面目标探测的影响,基于偏振光学理论,设计并构建了一套偏振自适应滤波探测系统。本文介绍了偏振探测系统的功能和组成、偏振探测及背景抑制原理,并给出了该系统的光学设计结果;利用自适应偏振滤波探测系统,通过搭载望远镜跟踪试验平台,针对海上典型目标,开展了相关的偏振验证实验。实验结果表明:海面太阳耀光存在比较明显的偏振特性,采用常规探测手段,探测器极易出现饱和,而利用偏振探测技术则能够有效抑制太阳耀光的影响,进而实现目标的有效探测。 相似文献
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提出了两种视场偏移哈特曼波前传感器,用于探测白天条件下强背景中目标信号的波前信息.给出了哈特曼波前传感器子孔径中焦面上天光背景非均匀性分布特征的实验结果,详细分析了基于分光棱镜的双焦面视场偏移哈特曼波前传感器的探测误差,并通过基于倾斜镜的单焦面视场偏移哈特曼波前传感器实验给出了波前测量的结果,证明视场偏移哈特曼波前传感器能够精确、稳定的测量白天条件下目标信号的畸变波前信息,同时给出了其在白天条件下探测能力的估算结果及其受限因素,估算结果表明云南天文台的自适应光学系统在10 W/m2·sr天光背景条件下应用视场偏移哈特曼波前传感器能对5等星(可视星等值)目标进行准确的波前探测.
关键词:
自适应光学
波前传感器
白天工作
误差分析 相似文献
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基于地基大口径自适应望远镜构建成像偏振探测系统,可以同时获取空间目标的光强和偏振图像,将光强信息和偏振信息相结合,能为空间目标的探测和识别提供更多依据。现有的1.23m自适应望远镜在设计时并未采用保偏设计,在开展观测研究前需得到光学系统的偏振传输特性。但目前难以直接对大口径望远镜进行偏振标定,为了分析1.23m自适应望远镜光学系统的偏振传输特性,基于相干矩阵和光线追迹法建立了望远镜系统偏振传输特性分析模型。仿真得出了1.23m自适应望远镜光学系统的偏振传输特性,发现光学系统会引入较大的偏振探测偏差。为减小偏振探测偏差,给出了一个可行的保偏改进方案,并通过已建立的模型验证了该方案的有效性。 相似文献
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为了解决船载光学测量设备日间测星数量偏少的问题,研究了暗小目标电视探测技术,以保证惯导系统全天时不间断航向校准。在视频图像处理中,采用中值滤波方法提高信噪比,同时采用基于模糊理论的最大模糊熵阈值分割方法自行构建隶属度函数,自适应求取阈值,实现了星体目标检测与识别。实验结果表明:在原光学设备光学系统不变的情况下,日间可探测的恒星由大于等于3.0星等、小于等于5颗,提高到了大于等于4.5星等,大于等于250颗,满足了惯导系统全天时不间断航向校准的要求。该成果可以推广应用于电视弱小目标探测领域。 相似文献
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为了解决船载光学测量设备日间测星数量偏少的问题,研究了暗小目标电视探测技术,以保证惯导系统全天时不间断航向校准。在视频图像处理中,采用中值滤波方法提高信噪比,同时采用基于模糊理论的最大模糊熵阈值分割方法自行构建隶属度函数,自适应求取阈值,实现了星体目标检测与识别。实验结果表明:在原光学设备光学系统不变的情况下,日间可探测的恒星由大于等于3.0星等、小于等于5颗,提高到了大于等于4.5星等,大于等于250颗,满足了惯导系统全天时不间断航向校准的要求。该成果可以推广应用于电视弱小目标探测领域。 相似文献
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太阳光通过海面的镜面反射形成耀光,但其较强的光强会造成常规探测成像饱和,严重影响对海面目标的探测。基于海面耀光的偏振特性以及数字域时间延时积分互补金属氧化物半导体(TDI-CMOS)的积分特性,设计并构建了一套海面目标自适应偏振探测系统。利用该系统通过偏振相机对海面目标进行实时成像偏振测量,引导数字域TDI-CMOS相机在时域与空域两个维度上对耀光进行抑制。搭建了水面观测实验平台,针对典型目标,开展了相关的验证实验。实验结果表明:使用所构建的探测系统能够有效抑制太阳耀光对图像的影响,并且获取的耀光抑制图像相比一般图像,信杂比提升显著,该系统有效改善了运动目标对图像造成的伪影现象,针对海面目标的探测效果得到有效改善。 相似文献
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将偏振特性结合到强度信息中可有效提高天基系统对海面背景下空中目标的探测与识别性能,尤其是对于红外隐身目标。针对红外偏振特性、最优探测波段不明的问题,建立了基于天基平台的空中目标红外偏振辐射模型,分析了近红外到长波红外目标的偏振特性。采用偏振度作为评价指标,分析了目标辐射温度、飞行高度和天基探测俯仰角在红外波段中的偏振辐射规律。实验结果表明:对于不同飞行高度、辐射温度的目标而言,目标与海面背景的红外偏振特性在9μm处差异显著,该波长可作为偏振探测的最佳波段;在最佳探测波段,相较于水平偏振而言,目标和背景的差异主要体现在垂直偏振分量上;当天基平台俯仰角为大角度掠地状态时,目标与背景的偏振度差值更大,有利于提高探测性能。 相似文献
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为解决传统光强探测手段难以有效探测和识别伪装目标这一难题,基于偏振探测技术搭建了光谱偏振探测成像系统,利用该系统在位于442.0,545.5,670.5,850.5 nm的窄波段对典型草地、土壤背景下的某型深绿色和土黄色伪装涂层进行了光谱偏振探测实验研究。并通过编制的图像处理软件对测试结果进行处理分析以提取其中的偏振信息,获得了目标与背景偏振度和偏振对比度随探测波长和探测角的变化规律。研究结果表明,合理地选择偏振成像探测条件可以使伪装涂层与背景之间存在较大的偏振对比度,可以实现对传统伪装涂层涂覆的目标的有效探测和识别。 相似文献
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For the daytime adaptive optics system, a field-of-view shifted Shack-Hartmann wavefront sensor (FSWFS), which is used to measure the aberrant wavefront under daytime conditions, is proposed. Because the field angle of the object signal in adaptive optics systems is much less than that of the sky background, the effective object signal is separated from the strong sky background. Experimental results indicate that FSWFS with a single focal-plane array can precisely and stably measure the aberrant wavefront information with a strong sky background under daytime conditions. 相似文献
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We recently introduced matched filtering in the context of astronomical Shack-Hartmann wavefront sensing with elongated sodium laser beacons [Appl. Opt. 45, 6568 (2006)]. Detailed wave optics Monte Carlo simulations implementing this technique for the Thirty Meter Telescope dual conjugate adaptive optics system have, however, revealed frequent bursts of degraded closed loop residual wavefront error [Proc. SPIE 6272, 627236 (2006)]. The origin of this problem is shown to be related to laser guide star jitter on the sky that kicks the filter out of its linear dynamic range, which leads to bursts of nonlinearities that are reconstructed into higher-order wavefront aberrations, particularly coma and trifoil for radially elongated subaperture spots. An elegant reformulation of the algorithm is proposed to extend its dynamic range using a set of linear constraints while preserving its improved noise rejection and Monte Carlo performance results are reported that confirm the benefits of the method. 相似文献
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Wang D.Wang M. 《应用光学》2017,(1):106-113
Aiming at solving accuracy problem of infrared small target detection in sky and ocean background scenarios of infrared image sequences, a novel infrared small target detection based on multi-filters algorithm fusion method is presented in this paper. Firstly infrared small target and imaging, time and space characteristics of the corresponding background noise are analyzed. Tophat algorithm with improved Robinson guard filter are then integrated to highlight target and suppress clutter background by using infrared small target imaging features. Adaptive threshold segmentation is used to extract candidate targets, while Unger smoothing filter and multi-objects association filter are used to eliminate random noise and false targets in the candidate targets. Multiple experiments of infrared small target image sequences are implemented, and experimental results show that proposed method can detect infrared small targets at 99% detection rate with high reliability and good real-time performance. © 2017, Editorial Board, Journal of Applied Optics. All right reserved. 相似文献
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Real-time blind deconvolution of retinal images in adaptive optics scanning laser ophthalmoscopy 总被引:1,自引:0,他引:1
With the use of adaptive optics (AO), the ocular aberrations can be compensated to get high-resolution image of living human retina. However, the wavefront correction is not perfect due to the wavefront measure error and hardware restrictions. Thus, it is necessary to use a deconvolution algorithm to recover the retinal images. In this paper, a blind deconvolution technique called Incremental Wiener filter is used to restore the adaptive optics confocal scanning laser ophthalmoscope (AOSLO) images. The point-spread function (PSF) measured by wavefront sensor is only used as an initial value of our algorithm. We also realize the Incremental Wiener filter on graphics processing unit (GPU) in real-time. When the image size is 512 × 480 pixels, six iterations of our algorithm only spend about 10 ms. Retinal blood vessels as well as cells in retinal images are restored by our algorithm, and the PSFs are also revised. Retinal images with and without adaptive optics are both restored. The results show that Incremental Wiener filter reduces the noises and improve the image quality. 相似文献
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红外波段可以探测到足够多的星体用以导航。恒星-背景对比度是白天恒星探测时的一个重要指标,分析近红外波段,6星等恒星对比度随太阳天顶角、探测器高度和探测方位角的变化情况。结果显示,恒星-背景对比度随太阳天顶角近似于指数增长,40太阳天顶角时对比度是20时的2.69倍左右;一定高度时,对比度随探测器高度的增加近似指数增加,低于15 km时对比度仍小于3, 80 km时对比度达到60左右;随着探测方位角的增大,恒星-背景对比度基本上线性增大,30探测方位角时的对比度是0探测方位角时对比度的2.38倍。 相似文献