WISHED: Wavefront imaging sensor with high resolution and depth ranging

Author(s):

Yicheng Wu, Fengqiang Li, Florian Willomitzer, Ashok Veeraraghavan, Oliver Cossairt

Abstract:

“Phase-retrieval based wavefront sensors have been shown to reconstruct the complex field from an object with a high spatial resolution. Although the reconstructed complex field encodes the depth information of the object, it is impractical to be used as a depth sensor for macroscopic objects, since the unambiguous depth imaging range is limited by the optical wavelength. To improve the depth range of imaging and handle depth discontinuities, we propose a novel three-dimensional sensor by leveraging wavelength diversity and wavefront sensing. Complex fields at two optical wavelengths are recorded, and a synthetic wavelength can be generated by correlating those wavefronts. The proposed system achieves high lateral and depth resolutions. Our experimental prototype shows an unambiguous range of more than 1,000 x larger compared with the optical wavelengths, while the depth precision is up to 9µm for smooth objects and up to 69µm for rough objects. We experimentally demonstrate 3D reconstructions for transparent, translucent, and opaque objects with smooth and rough surfaces.”

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Publication: 2020 IEEE International Conference on Computational Photography (ICCP)
DOI: 10.1109/ICCP48838.2020.9105280

Rapid phase calibration of a spatial light modulator using novel phase masks and optimization of its efficiency using an iterative algorithm

Author(s):

Amar Deo Chandra and Ayan Banerjee

Abstract:

“We develop an improved phase calibration method of a reflective SLM using interferometry by employing novel phase masks. In the process, we definitively determine the actual maximum phase throw of our SLM which provides a recipe for users to verify supplier specifications. We generate optimised phase masks by using Iterative Fourier Transform Algorithm (IFTA) and compare their performance with global linear corrections in the look-up table (LUT) and find that the former perform with around 20% better efficiency. Besides obtaining an array of 1D/2D spots having high uniformity (90%) using IFTA, our result exemplifies the use of iterative algorithms for improving efficiency of phase limited SLMs. Finally, our improved phase calibration method enables threefold faster phase measurements, and to the best of our knowledge, is the first endeavour directed towards enabling rapid phase characterisation of an SLM using interferometric measurements. We believe that it can have very useful applications in settings which may require fast phase calibrations as well as for real-time, multi-wavelength spectroscopic applications.”

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Publication: Journal of Modern Optics

Issue/Year/DOI: Volume 67- Issue 7
DOI: 10.1080/09500340.2020.1760954

VioBio lab adaptive optics: technology and applications by women vision scientists

Author(s):

Susana Marcos, Clara Benedí‐García, Sara Aissati, Ana M Gonzalez‐Ramos, Carmen M Lago, Aiswaryah Radhkrishnan, Mercedes Romero, Shrilekha Vedhakrishnan, Lucie Sawides and Maria Vinas

Abstract:

“Purpose
Adaptive Optics allows measurement and manipulation of the optical aberrations of the eye. We review two Adaptive Optics set‐ups implemented at the Visual Optics and Biophotonics Laboratory, and present examples of their use in better understanding of the role of optical aberrations on visual perception, in normal and treated eyes.

Recent findings
Two systems (AOI and AOII) are described that measure ocular aberrations with a Hartmann‐Shack wavefront sensor, which operates in closed‐loop with an electromagnetic deformable mirror, and visual stimuli are projected in a visual display for psychophysical measurements. AOI operates in infrared radiation (IR) light. AOII is provided with a supercontiniuum laser source (IR and visible wavelengths), additional elements for simulation (spatial light modulator, temporal multiplexing with optotunable lenses, phase plates, cuvette for intraocular lenses‐IOLs), and a double‐pass retinal camera. We review several studies undertaken with these AO systems, including the evaluation of the visual benefits of AO correction, vision with simulated multifocal IOLs (MIOLs), optical aberrations in pseudophakic eyes, chromatic aberrations and their visual impact, and neural adaptation to ocular aberrations.

Summary
Monochromatic and chromatic aberrations have been measured in normal and treated eyes. AO systems have allowed understanding the visual benefit of correcting aberrations in normal eyes and the adaptation of the visual system to the eye’s native aberrations. Ocular corrections such as intraocular and contact lenses modify the wave aberrations. AO systems allow simulating vision with these corrections before they are implanted/fitted in the eye, or even before they are manufactured, revealing great potential for industry and the clinical practice. This review paper is part of a special issue of Ophthalmic & Physiological Optics on women in visual optics, and is co‐authored by all women scientists of the research team.”

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Publication: Ophthalmic and Physiological Optics
DOI: 10.1111/opo.12677

Polarization nano-tomography of tightly focused light landscapes by self-assembled monolayers

Author(s):

Eileen Otte, Kemal Tekce, Sebastian Lamping, Bart Jan Ravoo and Cornelia Denz
Abstract:

“Recently, four-dimensional (4D) functional nano-materials have attracted considerable attention due to their impact in cutting-edge fields such as nano-(opto)electronics, -biotechnology or -biomedicine. Prominent optical functionalizations, representing the fourth dimension, require precisely tailored light fields for its optimal implementation. These fields need to be like-wise 4D, i.e., nano-structured in three-dimensional (3D) space while polarization embeds additional longitudinal components. Though a couple of approaches to realize 4D fields have been suggested, their breakthrough is impeded by a lack of appropriate analysis techniques. Combining molecular self-assembly, i.e., nano-chemistry, and nano-optics, we propose a polarization nano-tomography of respective fields using the functional material itself as a sensor. Our method allows a single-shot identification of non-paraxial light fields at nano-scale resolution without any data post-processing. We prove its functionality numerically and experimentally, elucidating its amplitude, phase and 3D polarization sensitivity. We analyze non-paraxial field properties, demonstrating our method’s capability and potential for next generation 4D materials.”

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Publication: Nature Communications
Issue/Year/DOI: Nature Communications volume 10, Article number: 4308 (2019)
DOI: 10.1038/s41467-019-12127-3

Lateral position correction in ptychography using the gradient of intensity patterns

Author(s):

Priya Dwivedi and Sander Konijnenberg and Silvania Pereira and Paul Urbach

Abstract:

“Ptychography, a form of Coherent Diffractive Imaging, is used with short wavelengths (e.g. X-rays, electron beams) to achieve high-resolution image reconstructions. One of the limiting factors for the reconstruction quality is the accurate knowledge of the illumination probe positions. Recently, many advances have been made to relax the requirement for the probe positions accuracy. Here, we analyse and demonstrate a straightforward approach that can be used to correct the probe positions with sub-pixel accuracy. Simulations and experimental results with visible light are presented in this work.”

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Publication: Ultramicroscopy

Issue/Year/DOI: Ultramicroscopy, Volume 192, September 2018, Pages 29-36
DOI: 10.1016/j.ultramic.2018.04.004

Generation of focal pattern with controllable polarization and intensity for laser beam passing through a multi-mode fiber

Author(s):

Weiru Fan and Xiansheng Hu and Bamao Zhaxi and Ziyang Chen and Jixiong Pu

Abstract:

“Similar to coherent light passing through a scattering medium, the propagation of coherent light through a multi-mode fiber (MMF) will result in a random speckle field. For a non-polarization maintaining MMF, the randomization can be observed not only in the intensity distribution, but also in the polarization state. In this paper, we propose a new technique known as phase combination to control the optical field for the light passing through the MMF. We show that, based on this new technique, the random speckle pattern can be modulated into an intensity distribution of two bright focal spots with mutually perpendicular polarization by only one polarizer. In particular, the intensity distribution of these two focal spots can be quantitatively controlled. This technique may find applications in medical imaging, nonlinear optics and optical communication etc.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express Vol. 26, Issue 6, pp. 7693-7700 (2018)
DOI: 10.1364/OE.26.007693

Generation of focal pattern with controllable polarization and intensity for laser beam passing through a multi-mode fiber

Author(s):

Weiru Fan and Xiansheng Hu and Bamao Zhaxi and Ziyang Chen and Jixiong Pu

Abstract:

“Similar to coherent light passing through a scattering medium, the propagation of coherent light through a multi-mode fiber (MMF) will result in a random speckle field. For a non-polarization maintaining MMF, the randomization can be observed not only in the intensity distribution, but also in the polarization state. In this paper, we propose a new technique known as phase combination to control the optical field for the light passing through the MMF. We show that, based on this new technique, the random speckle pattern can be modulated into an intensity distribution of two bright focal spots with mutually perpendicular polarization by only one polarizer. In particular, the intensity distribution of these two focal spots can be quantitatively controlled. This technique may find applications in medical imaging, nonlinear optics and optical communication etc.”

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Publication: Optics Expresss

Issue/Year/DOI: Optics Express Volume 26, Issues 6 pp. 7693-7700 (2018)
DOI: 10.1364/OE.26.007693

Tunable third harmonic generation of vortex beams in an optical superlattice

Author(s):

Yu Wu and Rui Ni and Zhou Xu and Yaodong Wu and Xinyuan Fang and Dan Wei and Xiaopeng Hu and Yong Zhang and Min Xiao and Shining Zhu

Abstract:

“We report generation of tunable vortex beams in the blue spectral range, with a 3.3 nm spectral tuning range, by frequency tripling of the near-infrared (IR) wave at around 1.34 um in a LiTaO3 optical superlattice. The nonlinear crystal used in this work has a chirped dual-periodical structure which can provide two expanded reciprocal vectors for tunable performance of the cascaded third harmonic generation (THG). The maximum THG efficiency reaches about 1.4%.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25, Issue 25, pp. 30820- 30826 (2017)
DOI: 10.1364/OE.25.030820

Binary phase masks for easy system alignment and basic aberration sensing with spatial light modulators in STED microscopy

Author(s):

Klauss, André and Conrad, Florian and Hille, Carsten Hille

Abstract:

“The use of binary phase patterns to improve the integration and optimization of spatial light modulators (SLM) in an imaging system, especially a confocal microscope, is proposed and demonstrated. The phase masks were designed to create point spread functions (PSF), which exhibit specific sensitivity to major disturbances in the optical system. This allows direct evaluation of misalignment and fundamental aberration modes by simple visual inspection of the focal intensity distribution or by monitoring the central intensity of the PSF. The use of proposed phase masks is investigated in mathematical modelling and experiment for the use in a stimulated emission depletion (STED) microscope applying wavefront shaping by a SLM. We demonstrate the applicability of these phase masks for modal wavefront sensing of low order aberration modes up to the third order of Zernike polynomials, utilizing the point detector of a confocal microscope in a ‘guide star’ approach. A lateral resolution of ~25 nm is shown in STED imaging of the confocal microscope retrofitted with a SLM and a STED laser and binary phase mask based system optimization.”

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Publication: Scientific Reports
Issue/Year/DOI: Scientific Reports Volume 7, Article number: 15699 (2017)
DOI: 10.1038/s41598-017-15967-5

Silver Nanowires for Reconfigurable Bloch Surface Waves.

Author(s):

Zhang, Douguo and Wang, Ruxue and Xiang, Yifeng and Kuai, Yan and Kuang, Cuifang and Badugu, Ramachandram and Xu, Yingke and Wang, Pei and Ming, Hai and Liu, Xu and Lakowicz, Joseph R.

Abstract:

“The use of a single silver nanowire as a flexible coupler to transform a free space beam into a Bloch surface wave propagating on a dielectric multilayer is proposed. Based on Huygens ‘Principle, when a Gaussian beam is focused onto a straight silver nanowire, a Bloch surface wave is generated and propagates perpendicular to the nanowire. By curving the silver nanowire, the surface wave can be focused. Furthermore, the spatial phase of the incident laser beam can be actively controlled with the aid of a spatial light modulator, resulting in the reconfigurable or dynamically controlled Bloch surface waves. The low cost of the chemically synthesized silver nanowires and the high flexibility with regard to tuning the spatial phase of the incident light make this approach very promising for various applications including optical micromanipulation, fluorescence imaging, and sensing.”

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Publication: ACS Nano

Issue/Year/DOI:  ACS Nano, 2017, 11 (10), pp 10446–10451
DOI: 10.1021/acsnano.7b05638

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