Adaptive Detection of Wave Aberrations Based on the Multichannel Filter


Khorin, Pavel A.; Porfirev, Alexey P. & Khonina, Svetlana N.


“An adaptive method for determining the type and magnitude of aberration in a wide range is proposed on the basis of an optical processing of the analyzed wavefront using a multichannel filter matched to the adjustable Zernike phase functions. The approach is based on an adaptive (or step-by-step) compensation of wavefront aberrations based on a dynamically tunable multichannel filter implemented on a spatial light modulator. For adaptive filter adjustment, a set of criteria is proposed that takes into account not only the magnitude of the correlation peak, but also the maximum intensity, compactness, and orientation of the distribution in each diffraction order. The experimental results have shown the efficiency of the proposed approach for detecting wavefront aberrations in a wide range (from 0.1 λ to λ).”

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Publication: Photonics
Issue/Year: Photonics, Volume 9; Number 3; Pages 204; 2022
DOI: 10.3390/photonics9030204

Parametric characterization of ground surfaces with laser speckles


León Schweickhardt, Andreas Tausendfreund, Dirk Stöbener, and Andreas Fischer


“With well-known speckle measurement techniques, the root mean square height as well as the autocorrelation length of isotropic surfaces can be determined quickly and over a large area of interest. Beyond that, the present article studies the speckle-based measurement of anisotropic surfaces. For this purpose, a measurement setup and evaluation algorithm are presented that enable the characterization of unidirectionally anisotropic surfaces machined by grinding. As a result, four measurands are obtained from one speckle image: the machining direction, the autocorrelation length perpendicular to the machining direction, as well as two root mean square roughness parameters parallel and perpendicular to the machining direction. The first two measurands are obtained from a two-dimensional fast Fourier transform of the diffraction pattern resulting from the unidirectional tool marks and the latter two by a bidirectional evaluation of the speckle contrast. In addition to measurements on physical reference samples, a spatial light modulator is used to create a large number of surface topographies with known model parameters in order to quantify the measurement uncertainty.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 30; Number 8; Pages 12615; 2022
DOI: 10.1364/oe.454741

Singularities splitting phenomenon for the superposition of hybrid orders structured lights and the corresponding interference discrimination method


Mao, Baiwei; Liu, Yange; Chang, Wenzhe; Chen, Liang; Feng, Mao; Guo, Huiyi; He, Jiangyong & Wang, Zhi


“It is the basic characteristic of pure vortex light

that there is a phase singularity at the origin. Such a sin-

gularity may be multiple degenerate, which determines the

order of vortex light. Singularities splitting phenomenon

means that singularities no longer concentrate at the origin

but distribute around the space, usually occurring in

impure vortex light. In this paper, we demonstrate the

singularities splitting phenomenon and propose an anal-

ysis method, based on which one may rapidly estimate the

modal components of impure vortex light. As two common

singularity discrimination methods, the spiral and fork

wire interference patterns are compared in distinguishing

splitting singularities. The most widely used spiral inter-

ference pattern is revealed to be the worst form because of

the low resolution. Instead, the fork wire interference

pattern is with higher and easily adjusted resolution. 1‰

impurity is still able to be distinguished through fork wire

interference patterns in the experiment.”

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Publication: Nanophotonics
Issue/Year: Nanophotonics, Volume 0; Number 0; 2022
DOI: 10.1515/nanoph-2021-0814

Large depth-of-field fluorescence microscopy based on deep learning supported by Fresnel incoherent correlation holography


Wu, Peng; Zhang, Dejie; Yuan, Jing; Zeng, Shaoqun; Gong, Hui; Luo, Qingming & Yang, Xiaoquan


“Fluorescence microscopy plays an irreplaceable role in biomedicine. However,

limited depth of field (DoF) of fluorescence microscopy is always an obstacle of image quality,

especially when the sample is with an uneven surface or distributed in different depths. In

this manuscript, we combine deep learning with Fresnel incoherent correlation holography to

describe a method to obtain significant large DoF fluorescence microscopy. Firstly, the hologram

is restored by the Auto-ASP method from out-of-focus to in-focus in double-spherical wave

Fresnel incoherent correlation holography. Then, we use a generative adversarial network to

eliminate the artifacts introduced by Auto-ASP and output the high-quality image as a result.

We use fluorescent beads, USAF target and mouse brain as samples to demonstrate the large

DoF of more than 400µm, which is 13 times better than that of traditional wide-field microscopy.

Moreover, our method is with a simple structure, which can be easily combined with many

existing fluorescence microscopic imaging technology”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 30; Number 4; Pages 5177; 2022
DOI: 10.1364/oe.451409

Scalability of all-optical neural networks based on spatial light modulators


Ying Zuo, Zhao Yujun, You-Chiuan Chen, Shengwang Du & Liu, Junwei


“Optical implementation of artificial neural networks has been attracting great attention due to its potential in parallel computation at speed of light. Although all-optical deep neural networks (AODNNs) with a few neurons have been experimentally demonstrated with acceptable errors re- cently, the feasibility of large scale AODNNs remains unknown because error might accumulate inevitably with increasing number of neurons and connections. Here, we demonstrate a scalable AODNN with programmable linear operations and tunable nonlinear activation functions. We ver- ify its scalability by measuring and analyzing errors propagating from a single neuron to the entire network. The feasibility of AODNNs is further confirmed by recognizing handwritten digits and fashions respectively.”

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Publication: Physical Review Applied
Issue/Year: Physical Review Applied, 2021

Discretized continuous quantum-mechanical observables that are neither continuous nor discrete


Thais L. Silva, Łukasz Rudnicki, Daniel S. Tasca, and Stephen P. Walborn


“Most of the fundamental characteristics of quantum mechanics, such as nonlocality and contextuality, are manifest in discrete, finite-dimensional systems. However, many quantum information tasks that exploit these properties cannot be directly adapted to continuous variable systems. To access these quantum features, continuous quantum variables can be made discrete by binning together their different values, resulting in observables with a finite number, d, of outcomes. While direct measurement indeed confirms their manifestly discrete character, here we employ a salient feature of quantum physics known as mutual unbiasedness to show that such coarse-grained observables are in a sense neither continuous nor discrete. Depending on d, the observables can reproduce either the discrete or the continuous behavior, or neither. To illustrate these results, we present an example for the construction of such measurements and employ it in an optical experiment confirming the existence of four mutually unbiased measurements with d=3 outcomes in a continuous variable system, surpassing the number of mutually unbiased continuous variable observables.”

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Publication: Physical Review Research
Issue/Year: Physical Review Research, Volume 4; Number 1; Pages 013060; 2022
DOI: 10.1103/physrevresearch.4.013060

Multi-Incidence Holographic Profilometry for Large Gradient Surfaces with Sub-Micron Focusing Accuracy


Idicula, Moncy Sajeev; Kozacki, Tomasz; Józwik, Michal; Mitura, Patryk; Martinez-Carranza, Juan & Choo, Hyon-Gon


“Surface reconstruction for micro-samples with large discontinuities using digital holog-

raphy is a challenge. To overcome this problem, multi-incidence digital holographic profilometry

(MIDHP) has been proposed. MIDHP relies on the numerical generation of the longitudinal scanning

function (LSF) for reconstructing the topography of the sample with large depth and high axial

resolution. Nevertheless, the method is unable to reconstruct surfaces with large gradients due to

the need of: (i) high precision focusing that manual adjustment cannot fulfill and (ii) preserving

the functionality of the LSF that requires capturing and processing many digital holograms. In this

work, we propose a novel MIDHP method to solve these limitations. First, an autofocusing algorithm

based on the comparison of shapes obtained by the LSF and the thin tilted element approximation is

proposed. It is proven that this autofocusing algorithm is capable to deliver in-focus plane localization

with submicron resolution. Second, we propose that wavefield summation for the generation of the

LSF is carried out in Fourier space. It is shown that this scheme enables a significant reduction of

arithmetic operations and can minimize the number of Fourier transforms needed. Hence, a fast

generation of the LSF is possible without compromising its accuracy. The functionality of MIDHP for

measuring surfaces with large gradients is supported by numerical and experimental results”

Link to Publications Page

Publication: Sensors
Issue/Year: Sensors, Volume 22; Number 1; Pages 214; 2021
DOI: 10.3390/s22010214

Coded aperture correlation holography (COACH) with a superior lateral resolution of FINCH and axial resolution of conventional direct imaging systems


Bulbul, Angika; Hai, Nathaniel & Rosen, Joseph


“Fresnel incoherent correlation holography (FINCH) is a self-interference incoherent digital holography technique. It possesses a higher lateral resolution than an equivalent incoherent imaging system. However, FINCH has lower axial resolution than the direct imaging systems with the same numerical aperture. A decade after the FINCH invention, a different incoherent holographic method named coded aperture correlation holography (COACH) was developed with improved axial resolution but with the same lateral resolution as direct imaging. In this study, we propose and demonstrate a variant of COACH called coded aperture with FINCH intensity responses (CAFIR) with an improved lateral resolution that is similar to the FINCH system while maintaining its high axial resolution similar to the direct imaging system. CAFIR is implemented with coded phase masks to generate an ensemble of quasi-randomly distributed FINCH-like responses. Point spread holograms and object holograms are recorded under identical conditions, and they are cross-correlated to obtain the image reconstruction. Imaging of a multiplane object is studied to compare the axial resolution of CAFIR with FINCH and direct imaging systems.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 25; Pages 42106; 2021
DOI: 10.1364/oe.446945

Vector optical field with the polarization varying along an arbitrary circular trajectory on the Poincar’e sphere


Lü, Jia-Qi; Wang, Wen-Yue; Cheng, Tian-Yu; Lu, Zhi-Wei & Liu, Shuo


“As an inherent feature of vector optical field, the spatial distribution of polarization brings additional degrees of freedom to engineer the optical field and control the interaction between light and matters. Here we focus on the variation of polarization in single vector optical field, which can be defined by the trajectory on the Poincaré sphere. Based on the amplitude-phase-polarization joint modulation method we propose, vector optical field, whose variation of polarization follows arbitrary circular trajectory on the Poincaré sphere, can be generated. Moreover, the tightly focusing behaviors of the vector optical fields with the polarization varying along parallel circles on the Poincaré sphere are compared. Relations between the circular trajectory and the central intensity of the hollow focal field are concluded.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 24; Pages 39718; 2021
DOI: 10.1364/oe.441809

Experimental estimation of the longitudinal component of a highly focused electromagnetic field


Maluenda, David; Aviñoá, Marcos; Ahmadi, Kavan; Martínez-Herrero, Rosario & Carnicer, Artur


“The detection of the longitudinal component of a highly focused electromagnetic beam is not a simple task. Although in recent years several methods have been reported in the literature, this measure is still not routinely performed. This paper describes a method that allows us to estimate and visualize the longitudinal component of the field in a relatively simple way. First, we measure the transverse components of the focused field in several planes normal to the optical axis. Then, we determine the complex amplitude of the two transverse field components: the phase is obtained using a phase recovery algorithm, while the phase difference between the two components is determined from the Stokes parameters. Finally, the longitudinal component is estimated using the Gauss’s theorem. Experimental results show an excellent agreement with theoretical predictions.”

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Publication: Scientific Reports
Issue/Year: Scientific Reports, Volume 11; Number 1; 2021
DOI: 10.1038/s41598-021-97164-z
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