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1.
Based on the classical optical coherent theory and the extended Huygens-Fresnel integral, ghost imaging with partially coherent
light radiation through turbulent atmosphere has been studied. The analytical ghost-imaging formulas have been derived. Based
on these formulas and the numerical calculation results, we find that the image quality is influenced by the turbulence strength,
the propagation distance, and the coherent parameters of the partially coherent light. 相似文献
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从关联成像理论出发,提出了日光场在实际大气湍流环境中强度点对点自关联成像理论,并进行了实验验证,分析了太阳光强度二阶自关联成像和强度点对点二阶自关联成像的区别.研究结果表明,太阳光场的点对点四阶自关联,即强度的二阶点对点自关联,可实现消大气湍流成像.为验证理论有效性,利用外场实验进行了验证,获得优于17 km距离的消湍流成像结果.理论和实验均表明,太阳光强度涨落的点对点自关联可实现消大气湍流成像.相比于相机直接成像,本文成像方法消除了大气湍流影响,同时该方案极大提升了关联成像技术的实用性,可直接用于远距离消大气湍流的高质量成像,增加图像识别率.理论表明,任何成像过程中波前受相位扰动影响的波段,如红外、紫外等,均可利用本文方法消除影响,成果具有较大实用价值. 相似文献
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Based on the method of computation reference channel and the extended Huygens–Fresnel integral, the model of lens ghost imaging with fully spatially incoherent linear polarization light through a slant turbulent channel has derived. The model shows that the resolution ratio of ghost imaging decreases as the power-law exponent of non-Kolmogorov turbulence increasing or the object location departing from the source. The zenith angle of channel has little influence to the quality of the ghost imaging. The minimum distinguishable centre-separation of double slit decreases as the power-law exponent of non-Kolmogorov turbulence increasing. 相似文献
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Lensless ghost imaging has attracted much interest in recent years due to its profound physics and potential applications. In this paper we report studies of the robust properties of the lensless ghost imaging system with a pseudo-thermal light source in a strongly scattering medium. The effects of the positions of the strong medium on the ghost imaging are investigated. In the lensless ghost imaging system, a pseudo-thermal light is split into two correlated beams by a beam splitter. One beam goes to a charge-coupled detector camera, labeled as CCD2. The other beam goes to an object and then is collected in another charge-coupled detector camera, labeled as CCD1, which serves as a bucket detector. When the strong medium, a pane of ground glass disk, is placed between the object and CCD1, the bucket detector, the quality of ghost imaging is barely affected and a good image could still be obtained. The quality of the ghost imaging can also be maintained, even when the ground glass is rotating, which is the strongest scattering medium so far. However, when the strongly scattering medium is present in the optical path from the light source to CCD2 or the object, the lensless ghost imaging system hardly retrieves the image of the object. A theoretical analysis in terms of the second-order correlation function is also provided. 相似文献
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Based on the optical coherent theory and the extended Huygens–Fresnel integral, lensless ghost imaging of Multi-Gaussian Schell-model beams through the slant non-Kolmogorov turbulence channels with Z-tilt aberration correction has been studied and the theoretical models have been derived. Our results indicate that the nearer of object to illuminant plane, the larger beam width and the more beamlet number are, the more fine of image quality is. The undersize of illumination light source will cause the quality decline of ghost imaging and the image quality of the object illuminated by the incoherent light are worse than that of illuminated by partially coherent light. 相似文献
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大气湍流效应是严重影响航空光电侦察系统图像质量的重要因素之一。从大气湍流参数描述出发,研究了大气湍流对光学系统成像质量的影响机理,分析了大气湍流影响光学系统调制传递函数(modulation transfer function,MTF)的影响因素,建立了大气湍流影响光学系统成像MTF的理论模型。仿真结果表明,在大气湍流影响下,光学系统光瞳口径与大气相干直径的比值对光学系统成像MTF影响较大。通过光学系统地面外场实验图像测试对比,验证了实际光学系统受到大气湍流影响后的成像MTF理论模型。研究结果可为大气湍流影响下的航空光电侦察系统设计及提升其成像质量提供理论支持。 相似文献
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In this Letter, we propose an advanced framework of ghost edge imaging, named compressed ghost edge imaging(CGEI). In the scheme, a set of structured speckle patterns with pixel shifting illuminate on an unknown object.The output is collected by a bucket detector without any spatial resolution. By using a compressed sensing algorithm, we obtain horizontal and vertical edge information of the unknown object with the bucket detector detection results and the known structured speckle patterns. The edge is finally constructed via twodimensional edge information. The experimental and numerical simulations results show that the proposed scheme has a higher quality and reduces the number of measurements, in comparison with the existing edge detection schemes based on ghost imaging. 相似文献
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针对傅里叶望远镜系统激光在湍流大气中传输造成的成像质量下降,分析了湍流对光束传输特性的影响,指出成像质量的下降主要来自于上行传输链路中湍流造成的光束漂移与光束扩展,从而产生光束指向误差。分析了指向误差影响成像的机理。通过数值计算得出了不同强度湍流造成整条上行链路光束指向误差,并通过系统仿真,得到了不同强度大气湍流条件下的成像结果。结果显示:在弱湍流与中湍流条件下(大气折射率结构常数小于10-14 m-2/3),随机指向误差较小(偏移比小于0.06),复原图像有较好的识别性;在强湍流条件下,成像质量下降严重。因此系统应选择避开强湍流地理位置与时段进行工作。 相似文献
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针对傅里叶望远镜系统激光在湍流大气中传输造成的成像质量下降,分析了湍流对光束传输特性的影响,指出成像质量的下降主要来自于上行传输链路中湍流造成的光束漂移与光束扩展,从而产生光束指向误差。分析了指向误差影响成像的机理。通过数值计算得出了不同强度湍流造成整条上行链路光束指向误差,并通过系统仿真,得到了不同强度大气湍流条件下的成像结果。结果显示:在弱湍流与中湍流条件下(大气折射率结构常数小于10-14 m-2/3),随机指向误差较小(偏移比小于0.06),复原图像有较好的识别性;在强湍流条件下,成像质量下降严重。因此系统应选择避开强湍流地理位置与时段进行工作。 相似文献
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《中国物理 B》2020,(2)
We propose a compressed ghost imaging scheme based on differential speckle patterns,named CGI-DSP.In the scheme,a series of bucket detector signals are acquired when a series of random speckle patterns are employed to illuminate an unknown object.Then the differential speckle patterns(differential bucket detector signals) are obtained by taking the difference between present random speckle patterns(present bucket detector signals) and previous random speckle patterns(previous bucket detector signals).Finally,the image of object can be obtained directly by performing the compressed sensing algorithm on the differential speckle patterns and differential bucket detector signals.The experimental and simulated results reveal that CGI-DSP can improve the imaging quality and reduce the number of measurements comparing with the traditional compressed ghost imaging schemes because our scheme can remove the environmental illuminations efficiently. 相似文献
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In this paper it is proved that the keys to understanding the ghost imaging are the crossing symmetric (CS) photon reactions in the nonlinear media. So CS introduced a real optical path between the object and his “ghost” image, making possible to apply the geometric optics for a rigorous proof of the essential laws of the “ghost” imaging phenomena. Hence, the laws of the plane quantum mirror (QM) and that of spherical quantum mirror, observed in the ghost-imaging experiments, are shown that can be obtained as natural consequences of the energy-momentum conservation laws. So, it is proved that the ghost imaging laws depend only on the energy-momentum conservation and not on the photons entanglement. Using DFG-typical features we obtained explicit predictions of the intensities of the idler photons in terms of the intensities of the interacting photon-(p and s)-beams in the nonlinear crystal. Two fundamental experiments for a decisive test of the [SPDC-DFG]-quantum mirrors are suggested. 相似文献
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剪切光束成像(sheared-beam imaging,SBI)技术是一种利用三束剪切相干激光照明的非传统成像技术,该技术通过探测器阵列接收目标反射回波的散斑图进行计算成像,在对远距离暗弱目标高分辨率成像方面有着独特的优势.大气湍流引起的光束波前畸变是影响SBI成像质量的一个关键因素,因此本文从湍流引起的激光波前畸变对目标频谱信息提取的影响入手,建立了光束波前畸变对成像影响的理论模型.利用多层相位屏模型模拟了近地25 km大气对SBI光束传输的影响.通过计算机仿真,得到了不同激光发射孔径和不同成像距离时SBI的成像结果.仿真结果表明,选取合适的发射孔径尺寸可以有效缓解湍流对光束波前质量的影响,从而提升成像质量.在Hutchin的研究基础上,对孔径选择范围的已有研究成果进行了扩展与深化.给出了SBI系统发射孔径尺寸选取的建议,为SBI对不同高度目标成像的像质差异分析提供了参考. 相似文献
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We propose a color ghost imaging approach where the object is illuminated by three-color non-orthogonal random patterns. The object’s reflection/transmission information is received by only one single-pixel detector, and both the sparsity constraint and non-local self-similarity of the object are utilized in the image reconstruction process. Numerical simulation results demonstrate that the imaging quality can be obviously enhanced by ghost imaging via sparsity constraint and nonlocal self-similarity(GISCNL), compared with the reconstruction methods where only the object’s sparsity is used. Factors affecting the quality of GISCNL, such as the measurement number and the detection signal-to-noise ratio, are also studied. 相似文献
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The vibration is one of the important factors affecting imaging quality of conventional remote sensing imaging because the relative motion between the imaging system and the target can result in the degradation of imaging quality. The influence of the vibration of the detector in the test path on reflective ghost imaging(RGI) is investigated theoretically and experimentally. We analyze the effects of the vibrating amplitude and velocity. The results demonstrate that the microvibrations of the bucket detector have almost no impact on the imaging resolution and signal-to-noise ratio(SNR) of RGI, i.e., the degradation of imaging quality caused by the vibration of the detector can be overcome to some extent. Our results can be helpful for remote sensing imaging. 相似文献
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非柯尔莫哥洛夫湍流光束漂移的理论研究 总被引:1,自引:0,他引:1
一直以来, 大气湍流对空间光通信影响的研究都是在柯尔莫哥洛夫(Kolmogolov)湍流理论的框架内进行, 该模型已经被人们广泛接受和使用。然而, 近年来国内外众多非柯尔莫哥洛夫(Non-Kolmogolov)湍流的实验报道则表明Kolmogolov湍流理论有时不能完全正确地描述大气湍流的统计规律, 尤其在对流顶层和平流层。为了全面了解大气湍流对空间光通信的影响, 研究Non-Kolmogolov湍流对光波传输的影响成为了首先要面对的问题。基于Non-Kolmogolov湍流功率谱密度, 运用几何光学近似方法推导了弱起伏条件下准直光束和聚焦光束的光束漂移方差, 并给出了简洁的解析表达式; 然后, 利用这一表达式进行了仿真分析。 相似文献
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本文讨论了大气信道中轨道角动量纠缠光子对的纠缠度, 并利用von Karman大气湍流谱来建立双光子纠缠度的模型, 分析了大气湍流对不同轨道角动量纠缠光子对纠缠度的影响. 研究表明: 在大气信道中, 由于大气湍流的存在, 纠缠光子对的纠缠度随着传输距离z的增加而减小; 大气湍流强度越大, 纠缠光子对的纠缠度下降的越快, 纠缠光子对传输的距离越小; 在湍流强度相同的大气信道轨道角动量指数越大的纠缠光子对, 纠缠度下降得越慢, 纠缠光子对传输的距离越远. 相似文献