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扩大光学系统焦深范围的光学成象新技术研究 总被引:3,自引:3,他引:0
如何增大非相干光学系统的焦深已成为一项有意义的研究主题.对于普通光学系统,其焦深与光学系统的相对孔径平方成反比.为了增大焦深,通常的做法是缩小相对孔径,但这种做法有其缺点:会降低光学系统的光通量及调制传递函数(MTF)和分辨率.本文提出了一种新方法,通过在光学系统光路中加入一特殊设计的非球面掩模板,并用图象处理技术对相位掩模板编码后的图象进行解码得到清晰图象.保证了光学系统在维持原有相对孔径的同时扩大其焦深范围,使光学系统在离焦范围内有好的成象质量. 相似文献
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光学相干层析成像的轴向分辨率和横向分辨率是互为独立的,其轴向分辨率由系统光源带宽和探测光束的聚焦条件共同决定,而横向分辨率由系统样品臂的聚焦条件决定. 提高光学相干层析成像的轴向分辨率的方法主要基于宽带光源技术以及变迹术与相干门相结合的方法,而这些方法对于横向分辨率并没有提高. 提出了一种通过光程编码与相干合成的方法,可以同时提高其轴向分辨率和横向分辨率. 通过在光学相干层析成像系统的样品臂中加入光程编码分束器形成多种对应不同光程延迟的有效响应函数,基于光学相干层析成像术固有的光程分辨能力可以得到同一样品对应于不同有效响应函数的多幅图像. 通过数字控制不同有效响应函数的相对贡献对其进行相干合成,可以同时实现轴向和横向的超分辨效果. 与以前的方法相比,光程编码与相干合成方法简单易行、成本低廉,不仅可以避免系统复杂和价格昂贵等不足,而且可以同时较大幅度地提高系统的轴向分辨率和横向分辨率.
关键词:
光学相干层析成像
轴向超分辨
横向超分辨
光程编码 相似文献
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本文采用重叠关联迭代引擎算法, 系统地模拟研究了扫描相干衍射成像中中心挡板导致的低频信号丢失对重建图像质量的影响. 结果表明, 扫描相干衍射成像对中心挡板的承受能力远大于平面波单次相干衍射成像, 且选择小尺寸入射探针和较高重叠度(≥ 70%)可进一步降低中心丢失信号对扫描相干衍射成像的负面影响. 另外, 光斑扫描位置误差在重叠度较高时将超过中心挡板成为扫描相干衍射成像最主要的负面影响因素. 本文研究结果对扫描相干衍射成像实验中如何应用中心挡光板具有重要的指导意义, 将有助于进一步提高扫描相干衍射成像的分辨率.
关键词:
扫描相干衍射成像
位相恢复算法
低频丢失信号 相似文献
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双光栅快速扫描光学延迟线的色散补偿 总被引:1,自引:0,他引:1
光学相干层析成像(OCT)系统的纵向分辨力不仅与光源的带宽有关,而且与系统中两干涉臂间的色散匹配有关。如果色散没有得到精确匹配,将使光学相干层析成像系统的纵向分辨力达不到所预期的理论值。色散问题在超高分辨光学相干层析成像系统中尤为突出。提出了一种基于双光栅快速扫描光学延迟线(RSOD),用于光学相干层析成像系统的色散补偿。该方法中新增的光栅引入了光栅间距这一独立变量,其与常规单光栅快速扫描光学延迟线机构中的光栅离焦量一起,可使光学相干层析成像系统中的群速度色散(GVD)和三阶色散(TOD)同时得到补偿。分析了双光栅快速扫描光学延迟线的色散特性和色散调节原则,并提供了一个典型光学相干层析成像系统中的色散补偿实例。 相似文献
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Confocal enhanced optical coherence tomography for nondestructive evaluation of paints and coatings 总被引:1,自引:0,他引:1
We investigate confocal enhanced optical coherence tomography as a nondestructive evaluation tool for imaging with improved image contrast and depth resolution through a highly scattering paint layer. The depth responses provided by confocal microscopy, optical coherence tomography, and confocal enhanced optical coherence tomography for imaging through paint are investigated. We demonstrate that a new combination of confocal microscopy and optical coherence tomography provides significantly improved resolution and contrast for coherence gated imaging of substrate structures under the paint. 相似文献
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针对通过增加光源谱宽度来提高光学相干层析成像系统分辨率时样品色散特性的限制作用,分析了色散与光学相干层析成像系统纵向光程分辨率的约束关系.根据物质色散特性,采用数值变换方法对光学相干层析成像相干成像信号进行了色散补偿.实验使用了中心波长1 550 nm 自激发辐射光源和光纤迈克尓逊干涉结构,对水和光学快速扫描延迟线引入的二阶和三阶色散进行了数值补偿并通过相位修正因子来改善补偿效果.确定了一种普适的、快速的数值色散补偿方法.在对水中盖玻片和生物组织和的光学相干层析成像图像的色散补偿实验中取得了良好的效果,证明了方法的可行性. 相似文献
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Spectral domain polarization-sensitive optical coherence tomography (SDPS-OCT) is a depth-resolved polarization-sensitive interferometry which integrates polarization optics into spectral domain optical co- herence tomography (SD-OCT). This configuration can obtain birefringence information of samples and improve the imaging speed. In this paper, horizontally polarized light is used to replace natural light of the source. Then, right-rotated circularly polarized light is the incident sample light. To obtain two orthogonal components of the polarized interferogram, the reflected light of the reference arm is set to be 45° linearly polarized light. These two components are acquired by two spectrometers synchronously. The system was employed to achieve 12.8μm axial resolution and 4.36μm transverse resolution. We have imaged in vitro chicken tendon and muscle tissues with these svstem. 相似文献
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相比传统光谱仪,基于线性波数光谱仪的谱域光学相干层析(OCT)无需对非线性波数干涉光谱数据进行重采样和插值,可大大减少数据计算量并提高成像灵敏度.通过模拟计算干涉光谱信号和点扩散函数,以点扩散函数半峰全宽值的倒数作为评价准则,可以优化包括色散棱镜材料的折射率、顶角角度以及衍射光栅和色散棱镜之间旋转角角度的线性波数光谱仪的结构参数.根据优化结果,实验中选用F2玻璃等边色散棱镜,以光栅-棱镜间旋转角角度为21.8°搭建了最优化线性波数光谱仪,并引入谱域OCT成像系统.实验测得成像系统的轴向分辨率达到8.52μm,灵敏度达到91 dB,6 dB成像深度达到1.2 mm.结合具有通用并行计算能力的图形处理卡,在无需重采样和插值的情况下可实时处理和显示人手指指甲皮肤接缝处的横断面OCT图像,验证了基于最优化线性波数光谱仪的谱域OCT系统的成像性能. 相似文献
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We demonstrate inhibition of the sidelobes of the axial point spread function in optical coherence tomography by shaping the power spectrum of the light source with a remaining power of 4.54 mW. A broadband amplified spontaneous emission source radiating at 1565 +/- 40 nm is employed in a free-space optical coherence tomography system. The axial point spread functions before and after optical spectral shaping are presented. Results show that spectral shaping of the source can inhibit sidelobes of the point spread function up to 12.9 dB, with an associated small increase of 2.2 dB in noise floor in the far field. The effect of spectral shaping on axial resolution is demonstrated according to three metrics. Image quality improvement is also illustrated with optical coherence tomography images of an onion before and after spectral shaping. 相似文献
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We present an experimental demonstration of quantum-optical coherence tomography. The technique makes use of an entangled twin-photon light source to carry out axial optical sectioning. It is compared to conventional optical coherence tomography. The immunity of the quantum version to dispersion, as well as a factor of 2 enhancement in resolution, is experimentally demonstrated. 相似文献
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In vivo bidirectional color Doppler flow imaging of picoliter blood volumes using optical coherence tomography 总被引:1,自引:0,他引:1
We describe a novel optical system for bidirectional color Doppler imaging of flow in biological tissues with micrometer-scale resolution and demonstrate its use for in vivo imaging of blood flow in an animal model. Our technique, color Doppler optical coherence tomography (CDOCT), performs spatially localized optical Doppler velocimetry by use of scanning low-coherence interferometry. CDOCT is an extension of optical coherence tomography (OCT), employing coherent signal-acquisition electronics and joint time-frequency analysis algorithms to perform flow imaging simultaneous with conventional OCT imaging. Cross-sectional maps of blood flow velocity with <50-microm spatial resolution and <0.6-mm/s velocity precision were obtained through intact skin in living hamster subdermal tissue. This technology has several potential medical applications. 相似文献
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I. Abdulhalim 《Annalen der Physik》2012,524(12):787-804
Low‐coherence optical microscopy or optical coherence microscopy uses light with short coherence length. The well‐known case is: “white‐light interferometry”, which became recently more known as: “optical coherence tomography”. However, when lenses and microscope objectives are used to create interferometric images, in what is known classically as “interference microscopy” or today as “full‐field optical coherence tomography” the spatial coherence starts to play a critical role. In this article the coherence effects in low‐coherence optical microscopy are reviewed. As this technology is becoming increasingly publicized due to its importance in three‐dimensional imaging, particularly of scattering biological media and optical metrology, the understanding of the fundamental physics behind it is essential. The interplay between longitudinal spatial coherence and temporal coherence and the effects associated with them are discussed in detail particularly when high numerical apertures are used. An important conclusion of this study is that a high‐contrast, high‐resolution system for imaging of multilayered samples is the one that uses narrowband illumination and high‐NA objectives with an index‐matching fluid. Such a system, when combined with frequency‐domain operation, can reveal nearly real‐time three‐dimensional images, and is thus competitive with confocal microscopy. 相似文献
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V. M. Gelikonov I. V. Kasatkina P. A. Shilyagin 《Radiophysics and Quantum Electronics》2009,52(11):810-821
In this paper, we review methods for obtaining in vivo optical images of bio-objects with the resolution ranged from several
units to tens of micrometers, namely, the methods of spectral-domain optical coherence tomography. We focus on problems that
are specific of the spectral-domain optical coherence tomography, namely, the presence of coherent noise and mirror-symmetric
phantoms in the image. On the basis of the most important relevant publications, we analyze possibilities of eliminating these
drawbacks in modern devices. 相似文献