Abstract
Recently introduced angular-memory-effect based techniques enable non-invasive imaging of objects hidden behind thin scattering layers. However, both the speckle-correlation and the bispectrum analysis are based on the statistical average of large amounts of speckle grains, which determines that they can hardly access the important information of the point-spread-function (PSF) of a highly scattering imaging system. Here, inspired by notions used in astronomy, we present a phase-diversity speckle imaging scheme, based on recording a sequence of intensity speckle patterns at various imaging planes, and experimentally demonstrate that in addition to being able to retrieve the image of hidden objects, we can also simultaneously estimate the pupil function and the PSF of a highly scattering imaging system without any guide-star nor reference.
Highlights
The interaction between light and complex samples with inhomogeneous refractive index in many imaging scenarios induces light scattering, which is always seen as an obstacle for imaging objects hidden inside or behind such samples and makes direct observation impossible, instead, generates a complex speckle pattern [1]
The angular signal is the convolution between the object that is placed within the range determined by the angular-memory-effect and the system’s pointspread-function (PSF), which is a highly complex speckle pattern, as generated by any light point source on the object
Since the autocorrelation of the PSF is close to a function, the Fourieramplitude of object is retrieved from a large speckle pattern by calculating its autocorrelation, and the lost phase information is recovered via an iterative phase-retrieval algorithm [15]
Summary
The interaction between light and complex samples with inhomogeneous refractive index in many imaging scenarios induces light scattering, which is always seen as an obstacle for imaging objects hidden inside or behind such samples and makes direct observation impossible, instead, generates a complex speckle pattern [1]. The angular signal is the convolution between the object that is placed within the range determined by the angular-memory-effect and the system’s pointspread-function (PSF), which is a highly complex speckle pattern, as generated by any light point source on the object.
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