Shaping the on-axis intensity profile of generalized Bessel beams by iterative optimization methods

Author(s):

Runze Li and Xianghua Yu and Tong Peng and Yanlong Yang and Baoli Yao and Chunmin Zhang and Tong Ye
Abstract:

“The Bessel beam belongs to a typical class of non-diffractive optical fields that are characterized
by their invariant transverse profiles with the beam propagation. The extended and uniformed
intensity profile in the axial direction is of great interest in many applications. However, ideal
Bessel beams only rigorously exist in theory; the Bessel beams generated in the experiment are
always quasi-Bessel beams with finite focal extensions and varying intensity profiles along the
propagation axis. The ability to shape the on-axis intensity profile to meet specific needs is
essential for many applications. Here, we demonstrate an iterative optimization based approach
to engineer the on-axis intensity of Bessel beams through design and fine-tune processes.
Starting with a standard axicon phase mask, the design process uses the computed on-axis beam
profile as a feedback in the iterative optimization process, which searches for the optimal radial
phase distribution that can generate a so-called generalized Bessel beam with the desired on-axis
intensity profile. The fine-tune process repeats the optimization processing by using the adjusted
target on-axis profile according to the measured one. Our proposed method has been
demonstrated in engineering several quasi-Bessel beams with customized on-axis profiles. The
high accuracy and high energy throughput merit its use in many applications. This method is also
suitable to engineer higher-order Bessel beams by adding appropriate vortex phases into the
designed phase mask.”

Link to Publications Page

Publication: Journal of Optics

Issue/Year/DOI: Journal of Optics, Volume 20, Number 8 (2018)

DOI: 10.1088/2040-8986/aace46

Observing the cell in its native state: Imaging subcellular dynamics in multicellular organisms

Author(s):

Liu, Tsung-Li and Upadhyayula, Srigokul and Milkie, Daniel E. and Singh, Ved and Wang, Kai and Swinburne, Ian A. and Mosaliganti, Kishore R. and Collins, Zach M. and Hiscock, Tom W. and Shea, Jamien and Kohrman, Abraham Q. and Medwig, Taylor N. and Dambournet, Daphne and Forster, Ryan and Cunniff, Brian and Ruan, Yuan and Yashiro, Hanako and Scholpp, Steffen and Meyerowitz, Elliot M. and Hockemeyer, Dirk and Drubin, David G. and Martin, Benjamin L. and Matus, David Q. and Koyama, Minoru and Megason, Sean G. and Kirchhausen, Tom and Betzig, Eric

Abstract:

“True physiological imaging of subcellular dynamics requires studying cells within their parent organisms, where all the environmental cues that drive gene expression, and hence the phenotypes that we actually observe, are present. A complete understanding also requires volumetric imaging of the cell and its surroundings at high spatiotemporal resolution, without inducing undue stress on either. We combined lattice light-sheet microscopy with adaptive optics to achieve, across large multicellular volumes, noninvasive aberration-free imaging of subcellular processes, including endocytosis, organelle remodeling during mitosis, and the migration of axons, immune cells, and metastatic cancer cells in vivo. The technology reveals the phenotypic diversity within cells across different organisms and developmental stages and may offer insights into how cells harness their intrinsic variability to adapt to different physiological environments.”

 

Link to Publications Page

Publication: Science

Issue/Year/DOI: Science, Vol. 360, Issue 6386, (2018)
DOI: 10.1126/science.aaq1392

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

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.”

Link to Publications Page

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

Plasmonic computing of spatial differentiation.

Author(s):

Zhu, Tengfeng and Zhou, Yihan and Lou, Yijie and Ye, Hui and Qiu, Min and Ruan, Zhichao and Fan, Shanhui

Abstract:

“Optical analog computing offers high-throughput low-power-consumption operation for specialized computational tasks. Traditionally, optical analog computing in the spatial domain uses a bulky system of lenses and filters. Recent developments in metamaterials enable the miniaturization of such computing elements down to a subwavelength scale. However, the required metamaterial consists of a complex array of meta-atoms, and direct demonstration of image processing is challenging. Here, we show that the interference effects associated with surface plasmon excitations at a single metal-dielectric interface can perform spatial differentiation. And we experimentally demonstrate edge detection of an image without any Fourier lens. This work points to a simple yet powerful mechanism for optical analog computing at the nanoscale.”

Link to Publications Page

Publication: Nature Communications

Issue/Year/DOI: Nature Communications volume 8, Article number: 15391 (2017)
DOI: 10.1038/ncomms15391

Chromatic aberration control with liquid crystal spatial phase modulators

Author(s):

Jose L. Martinez and Enrique J. Fernandez and Pedro M. Prieto and Pablo Artal

Abstract:

“The chromatic behavior of diffractive optical elements, exhibiting 2π-wrapped phase profiles, implemented into liquid crystal spatial light modulators (LC-SLM) is described. A wrapped phase map is only equivalent to the original continuous profile for the design wavelength while at other wavelengths there are unwanted phase jumps and the profile does not correspond to a pure defocus. For those conditions the wrapped profile behaves as a multiple order lens (multi-focal lens). The optical power dispersion for each order is linearly proportional to the wavelength, while the energy of each order depends on the design wavelength and the material dispersion. For practical purposes, for most of the visible range only first order (main defocus) is relevant but two other orders may also be considered depending on the actual PSF of the system. As an application, we demonstrate that the longitudinal chromatic aberration of the eye can be compensated by the diffractive lens dispersion when the appropriate defocus is programmed into the SLM.”

Link to Publications Page

Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25, Issue 9, pp. 9793-9801 (2018)
DOI: 10.1364/OE.25.009793

 

Imaging moving targets through scattering media

Author(s):

Michelle Cua and Edward (Haojiang) Zhou and Changhuei Yang

Abstract:

“Optical microscopy in complex, inhomogeneous media is challenging due to the presence of multiply scattered light that limits the depths at which diffraction-limited resolution can be achieved. One way to circumvent the degradation in resolution is to use speckle- correlation-based imaging (SCI) techniques, which permit imaging of objects inside scattering media at diffraction-limited resolution. However, SCI methods are currently limited to imaging sparsely tagged objects in a dark-field scenario. In this work, we demonstrate the ability to image hidden, moving objects in a bright-field scenario. By using a deterministic phase modulator to generate a spatially incoherent light source, the background contribution can be kept constant between acquisitions and subtracted out. In this way, the signal arising from the object can be isolated, and the object can be reconstructed with high fidelity. With the ability to effectively isolate the object signal, our work is not limited to imaging bright objects in the dark-field case, but also works in bright-field scenarios, with non-emitting objects.”

Link to Publications Page

Publication: Optics Express

Issue/Year/DOI: Optics Express Vol. 25, Issue 4, pp. 3935-3945  (2017)

DOI: 10.1364/OE.25.003935