Control of femtosecond single-filament formation via feedback-based wavefront shaping

Author(s):

Li, Jing; Tan, Wenjiang; Si, Jinhai; Tang, Shiyun; Kang, Zhen & Hou, Xun

Abstract:

“We demonstrate the control of femtosecond single-filament formation via feedback-based wavefront shaping. It is observed that the optimal phase profile forms a single-filament with closed-loop genetic algorithm. Using this method, the position stability of the filament can be significantly improved, and the position of the single filament can be flexibly adjusted. Additionally, a two-step approach combining the premodulation of pinhole with wavefront shaping is presented for forming a bright single filament rapidly.”

Link to Publications Page

Publication: Optics Communications
Issue/Year: Optics Communications, Volume 490; Pages 126929; 2021
DOI: 10.1016/j.optcom.2021.126929

Comparative study on resolution enhancements in fluorescence-structured illumination Fresnel incoherent correlation holography

Author(s):

Jeon, Philjun; Kim, Jongwu; Lee, Heejung; Kwon, Hyuk-Sang & young Kim, Dug

Abstract:

“Fresnel incoherent correlation holography (FINCH) is a new approach for incoherent holography, which also has enhancement in the transverse resolution. Structured illumination microscopy (SIM) is another promising super-resolution technique. SI-FINCH, the combination of SIM and FINCH, has been demonstrated lately for scattering objects. In this study, we extended the application of SI-FINCH toward fluorescent microscopy. We have built a versatile multimodal microscopy system that can obtain images of four different imaging schemes: conventional fluorescence microscopy, FINCH, SIM, and SI-FINCH. Resolution enhancements were demonstrated by comparing the point spread functions (PSFs) of the four different imaging systems by using fluorescence beads of 1-μm diameter.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 6; Pages 9231; 2021
DOI: 10.1364/oe.417206

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.”

Link to Publications Page

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.”

Link to Publications Page

Publication: Journal of Modern Optics
Issue/Year: 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.”

Link to Publications Page

Publication: Ophthalmic and Physiological Optics (2020)
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.”

Link to Publications Page

Publication: Nature Communications
Issue/Year: 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.”

Link to Publications Page

Publication: Ultramicroscopy
Issue/Year: 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.”

Link to Publications Page

Publication: Optics Express
Issue/Year: 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.”

Link to Publications Page

Publication: Optics Expresss
Issue/Year: 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%.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 25, Issue 25, pp. 30820- 30826 (2017)
DOI: 10.1364/OE.25.030820
1 2 3 5