• Photonics Research
  • Vol. 8, Issue 6, 954 (2020)
Zihao Li1、2、5、†, Zhipeng Yu1、2、†, Hui Hui3、†, Huanhao Li1、2, Tianting Zhong1、2, Honglin Liu4, and Puxiang Lai1、2、*
Author Affiliations
  • 1Deparment of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China
  • 2The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518000, China
  • 3CAS Key Laboratory of Molecular Imaging, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
  • 4Key Laboratory for Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
  • 5Currently at: Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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    DOI: 10.1364/PRJ.388062 Cite this Article Set citation alerts
    Zihao Li, Zhipeng Yu, Hui Hui, Huanhao Li, Tianting Zhong, Honglin Liu, Puxiang Lai. Edge enhancement through scattering media enabled by optical wavefront shaping[J]. Photonics Research, 2020, 8(6): 954 Copy Citation Text show less

    Abstract

    Edge enhancement is a fundamental and important topic in imaging and image processing, as perception of edge is one of the keys to identify and comprehend the contents of an image. Edge enhancement can be performed in many ways, through hardware or computation. Existing methods, however, have been limited in free space or clear media for optical applications; in scattering media such as biological tissue, light is multiple scattered, and information is scrambled to a form of seemingly random speckles. Although desired, it is challenging to accomplish edge enhancement in the presence of multiple scattering. In this work, we introduce an implementation of optical wavefront shaping to achieve efficient edge enhancement through scattering media by a two-step operation. The first step is to acquire a hologram after the scattering medium, where information of the edge region is accurately encoded, while that of the nonedge region is intentionally encoded with inadequate accuracy. The second step is to decode the edge information by time-reversing the scattered light. The capability is demonstrated experimentally, and, further, the performance, as measured by the edge enhancement index (EI) and enhancement-to-noise ratio (ENR), can be controlled easily through tuning the beam ratio. EI and ENR can be reinforced by 8.5 and 263 folds, respectively. To the best of our knowledge, this is the first demonstration that edge information of a spatial pattern can be extracted through strong turbidity, which can potentially enrich the comprehension of actual images obtained from a complex environment.
    Ih=Iref+Iprob+2cosφIref·Iprob,(1)

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    M.E.=IhIref+Iprob=1+MD·cosϕ.(2)

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    Iref(x)=a(forallx);Iprob(x)={0xm/2bm/2<x<m/20xm/2,(3)

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    Eout=TEin,(4)

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    EPB=(T)t[TEin]*=[(T)+TEin]*,(5)

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    Ih,i=Ia,i+Ib,i+2cos(Ø+i·π/2)Ia,i·Ib,i,i=0,1,2,3.(A1)

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    Øcal=arg{([Ih]0[Ih]2)+j·([Ih]1[Ih]3)},(A2)

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    Zihao Li, Zhipeng Yu, Hui Hui, Huanhao Li, Tianting Zhong, Honglin Liu, Puxiang Lai. Edge enhancement through scattering media enabled by optical wavefront shaping[J]. Photonics Research, 2020, 8(6): 954
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