Imaging Correlography Using Ptychography

Abstract

Imaging correlography, an effective method for long-distance imaging, recovers an object using only the knowledge of the Fourier modulus, without needing phase information. It is not sensitive to atmospheric turbulence or optical imperfections. However, the unreliability of traditional phase retrieval algorithms in imaging correlography has hindered their development. In this work, we join imaging correlography and ptychography together to overcome such obstacles. Instead of detecting the whole object, the object is measured part-by-part with a probe moving in a ptychographic way. A flexible optimization framework is proposed to reconstruct the object rapidly and reliably within a few iterations. In addition, novel image space denoising regularization is plugged into the loss function to reduce the effects of input noise and improve the perceptual quality of the recovered image. Experiments demonstrate that four-fold resolution gains are achievable for the proposed imaging method. We can obtain satisfactory results for both visual and quantitative metrics with one-sixth of the measurements in the conventional imaging correlography. Therefore, the proposed imaging technique is more suitable for long-range practical applications.

Acousto-optic Ptychography

“…which is free from speckle artefacts via correlography [36], in the exact same manner as demonstrated without ultrasound modulation by Edrei et al [31]. In correlography [31,34,36] the estimate for the object un-speckled intensity autocorrelation at the m-th ultrasound focus position, ÂC m (r), is calculated by averaging the Fourier transforms of the captured speckle frames intensity distribution, after subtracting their mean value [34,36]:…”

“…Another important advantage of our approach is that unlike transmission-matrix and wavefront-shaping based approaches [17,18] it does not require unrealistically long speckle decorrelation times. Similar to recent approaches that utilize random fluctuations [20,34], our approach benefits from the natural speckle decorrelation to generate independent realizations of coherent illumination, improving the estimation of the object autocorrelation [31].…”

“…This requirement usually limits speckle-correlation imaging to small and unnaturally-isolated objects. Recently, ptychography-based approaches were utilized to overcome the memory-effect FoV [33,34]. However, the implementations of all FoV-extending approaches to date required direct access to the target in order to limit the illuminated area, a requirement that is impossible to fulfill in noninvasive imaging applications.…”

Morphological variations to a ptychographic algorithm

“…Ptychography has benefited from several improvements and modifications, including-but not limited to-enhanced algorithms such as extended PIE (ePIE) [29,30], combination with a Hybrid Input-Output approach [31], a reciprocal approach in which the illumination beam is tilted instead of displaced on a sample, also known as Fourier ptychography [32][33][34][35][36][37], among others [38][39][40][41]. This technique and its variants have already found application in the context of optical imaging [42][43][44][45][46][47][48], X-ray microscopy [27,41,[49][50][51][52][53][54][55][56][57][58][59], electron microscopy [27,[60][61][62][63][64][65], optical encryption [66][67][68], and recent demonstrations show promising applications in Quantum Information Science [69][70]…”

Resolution Enhancement in Coherent Diffraction Imaging Using High Dynamic Range Image

“…Due to its advantages such as no reference light wave being required and a low requirement on optical device processing accuracy, it has been actively applied in many fields, such as nanomaterials science [7], industrial measurement [8], and biomedical science [9]. In recent years, many researchers have proposed various modifications to improve the performance of CDI to meet requirements in different applications, including ptychographic iterative engine (PIE) [10][11][12][13], coherent modulation imaging [14][15][16], Fourier ptychographic microscopy [17,18], etc. [19][20][21].…”