基于任意偏振态的数字全息散斑去噪
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摘要
数字离轴全息图重建的物体图像会有明显的散斑噪声,本文利用降低相干度的方法来实现散斑去噪。具体方法是通过任意偏振态的物光和线偏振态参考光实现干涉记录,通过这些光场进行平均处理可以有效减少数字全息中产生的散斑噪声。通过控制三个波片的旋转实现任意偏振态,得到多种偏振态下的全息图,多偏振态下重建物体图像的散斑对比度各有不同,对各个重建图像进行对比分析得到最优结果。之后再将各偏振态下的全息图叠加进行重建,重建图像中的散斑噪声得到很好的抑制且比单偏振态下效果更好。从实验结果的分析中能看到这种方法对抑制散斑噪声的有效性。
Speckle noise is often obvious in the reconstruction of object image by digital off-axis hologram.In this paper,speckle denoising is realized by reducing the coherence.The interferometric recording is realized by arbitrary polarized object light and linear polarized reference light.The speckle noise produced in digital holography can be effectively reduced by averaging these light fields.By controlling the rotation of three wave plates to realize arbitrary polarization state,the holograms of different polarization states are obtained.The speckle contrast of reconstructed object images is different under different polarization states.The optimal results are obtained by comparing and analyzing each reconstructed image.The speckle noise in the reconstructed image is well suppressed and the effect is better than that in the single polarization state.The effectiveness of this method in suppressing speckle noise can be seen from the analysis of experimental results.
Speckle noise is often obvious in the reconstruction of object image by digital off-axis hologram.In this paper,speckle denoising is realized by reducing the coherence.The interferometric recording is realized by arbitrary polarized object light and linear polarized reference light.The speckle noise produced in digital holography can be effectively reduced by averaging these light fields.By controlling the rotation of three wave plates to realize arbitrary polarization state,the holograms of different polarization states are obtained.The speckle contrast of reconstructed object images is different under different polarization states.The optimal results are obtained by comparing and analyzing each reconstructed image.The speckle noise in the reconstructed image is well suppressed and the effect is better than that in the single polarization state.The effectiveness of this method in suppressing speckle noise can be seen from the analysis of experimental results.
引文
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[2] Schnars U,W Jüptner.Direct recording of holograms by a CCD target and numerical reconstruction[J].Applied Optics,1994,33(2):179-181.
[3] Anon.Laser speckle and related phenomena[J].Applied Optics,1984,23(16):2661.
[4] Pedrini G,Schedin S.Short coherence digital holography for 3D microscopy[J].Optik-International Journal for Light and Electron Optics,2001,112(9):427-432.
[5] Pan F,Xiao W,Liu S,et al.Coherent noise reduction in digital holographic phase contrast microscopy by slightly shifting object[J].Optics Express,2011,19(5):3862-3869.
[6] Kim M K.Tomographic three-dimensional imaging of a biological specimen using wavelength-scanning digital interference holography[J].Optics Express,2000,7(9):305-310.
[7] Nomura T,Okamura M,Nitanai E,et al.Image quality improvement of digital holography by superposition of reconstructed images obtained by multiple wavelengths[J].Applied Optics,2008,47(19):38-43.
[8] Garcia J.Reduction of speckle noise in digital holography by using digital image processing[J].Optik-International Journal for Light and Electron Optics,2005,116(1):44-48.
[9] Kang Xin.Speckle noise reduction in digital holography by multiple holograms[J].Optical Engineering,2007,46(11):115801.
[10] Kim D H,Ilev I,Kang J U.Fiber-optic Fourier-domain common-path OCT[J].Chinese Optics Letters,2008,6(12):899-901.