Photonic jet generated by a dielectric spheroid with Bessel beam excitation

2020 ◽  
Author(s):  
Le Zhu ◽  
Jiajie Wang ◽  
Hanghang Zhang ◽  
Tong Zhang ◽  
Jirong Guo ◽  
...  
Keyword(s):  
Bessel Beam ◽  
Photonic Jet ◽  
Beam Excitation

scholarly journals Efficient second-harmonic imaging of collagen in histological slides using Bessel beam excitation

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Nelly Vuillemin ◽  
Pierre Mahou ◽  
Delphine Débarre ◽  
Thierry Gacoin ◽  
Pierre-Louis Tharaux ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Bessel Beam ◽  
Depth Of Field ◽  
Label Free ◽  
Focal Volume ◽  
Coherent Signals ◽  
Excitation Scheme ◽  
Collagen Accumulation ◽  
Excitation Volume ◽  
Beam Excitation

Abstract Second-harmonic generation (SHG) is the most specific label-free indicator of collagen accumulation in widespread pathologies such as fibrosis, and SHG-based measurements hold important potential for biomedical analyses. However, efficient collagen SHG scoring in histological slides is hampered by the limited depth-of-field of usual nonlinear microscopes relying on focused Gaussian beam excitation. In this work we analyze theoretically and experimentally the use of Bessel beam excitation to address this issue. Focused Bessel beams can provide an axially extended excitation volume for nonlinear microscopy while preserving lateral resolution. We show that shaping the focal volume has consequences on signal level and scattering directionality in the case of coherent signals (such as SHG) which significantly differ from the case of incoherent signals (two-photon excited fluorescence, 2PEF). We demonstrate extended-depth SHG-2PEF imaging of fibrotic mouse kidney histological slides. Finally, we show that Bessel beam excitation combined with spatial filtering of the harmonic light in wave vector space can be used to probe collagen accumulation more efficiently than the usual Gaussian excitation scheme. These results open the way to SHG-based histological diagnoses.

scholarly journals Deep Learning-powered Bessel-beam Multi-parametric Photoacoustic Microscopy

2021 ◽  
Author(s):  
Yifeng Zhou ◽  
Naidi Sun ◽  
Song Hu
Keyword(s):  
Deep Learning ◽  
High Resolution ◽  
Gaussian Beam ◽  
Mouse Brain ◽  
Bessel Beam ◽  
Large Field ◽  
Depth Range ◽  
Photoacoustic Microscopy ◽  
Beam Excitation ◽  
Live Mouse

Enabling simultaneous and high resolution quantification of the total concentration of hemoglobin (CHb), oxygen saturation of hemoglobin (sO2), and cerebral blood flow (CBF), multi parametric photoacoustic microscopy (PAM) has emerged as a promising tool for functional and metabolic imaging of the live mouse brain. However, due to the limited depth of focus imposed by the Gaussian beam excitation, the quantitative measurements become inaccurate when the imaging object is out of focus. To address this problem, we have developed a hardware-software combined approach by integrating Bessel beam excitation and conditional generative adversarial network (cGAN) based deep learning. Side by side comparison of the new cGAN powered Bessel-beam multi parametric PAM against the conventional Gaussian beam multi parametric PAM shows that the new system enables high resolution, quantitative imaging of CHb, sO2, and CBF over a depth range of ~600 μm in the live mouse brain, with errors 13 to 58 times lower than those of the conventional system. Better fulfilling the rigid requirement of light focusing for accurate hemodynamic measurements, the deep learning powered Bessel beam multi parametric PAM may find applications in large field functional recording across the uneven brain surface and beyond (e.g., tumor imaging).

scholarly journals Erratum: Efficient second-harmonic imaging of collagen in histological slides using Bessel beam excitation

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Nelly Vuillemin ◽  
Pierre Mahou ◽  
Delphine Débarre ◽  
Thierry Gacoin ◽  
Pierre-Louis Tharaux ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Bessel Beam ◽  
Harmonic Imaging ◽  
Beam Excitation

Resolution, Contrast and Interpretation of HVEM Images of Crystals

1973 ◽  
Vol 31 ◽  
pp. 228-229
Author(s):  
L. E. Thomas ◽  
J. S. Lally ◽  
R. M. Fisher
Keyword(s):  
High Voltage ◽  
Chromatic Aberration ◽  
Crystalline Materials ◽  
Resolution Parameter ◽  
Instrument Resolution ◽  
Imaging Conditions ◽  
Beam Excitation ◽  
Optimum Imaging

In addition to improved penetration at high voltage, the characteristics of HVEM images of crystalline materials are changed markedly as a result of many-beam excitation effects. This leads to changes in optimum imaging conditions for dislocations, planar faults, precipitates and other features.Resolution - Because of longer focal lengths and correspondingly larger aberrations, the usual instrument resolution parameter, CS174 λ 374 changes by only a factor of 2 from 100 kV to 1 MV. Since 90% of this change occurs below 500 kV any improvement in “classical” resolution in the MVEM is insignificant. However, as is widely recognized, an improvement in resolution for “thick” specimens (i.e. more than 1000 Å) due to reduced chromatic aberration is very large.

scholarly journals Photonic nanojet generated by a spheroidal particle illuminated by a vector Bessel beam

2021 ◽  
pp. 100106
Author(s):  
Yongjie Jia ◽  
Renxian Li ◽  
Wenze Zhuang ◽  
Jiarui Liang
Keyword(s):  
Bessel Beam ◽  
Spheroidal Particle ◽  
Photonic Nanojet

scholarly journals “Perfect” Terahertz Vortex Beams Formed Using Diffractive Axicons and Prospects for Excitation of Vortex Surface Plasmon Polaritons

2021 ◽  
Vol 11 (2) ◽  
pp. 717
Author(s):  
Boris Knyazev ◽  
Valery Cherkassky ◽  
Oleg Kameshkov
Keyword(s):  
Surface Plasmon ◽  
Surface Plasmon Polaritons ◽  
Bessel Beam ◽  
Diffraction Theory ◽  
Terahertz Range ◽  
High Resistivity ◽  
Visible Range ◽  
Optical Elements ◽  
Scalar Diffraction ◽  
Plasmon Polaritons

Transformation of a Bessel beam by a lens results in the formation of a “perfect” vortex beam (PVB) in the focal plane of the lens. The PVB has a single-ring cross-section and carries an orbital angular momentum (OAM) equal to the OAM of the “parent” beam. PVBs have numerous applications based on the assumption of their ideal ring-type structure. For instance, we proposed using terahertz PVBs to excite vortex surface plasmon polaritons propagating along cylindrical conductors and the creation of plasmon multiplex communication lines in the future (Comput. Opt. 2019, 43, 992). Recently, we demonstrated the formation of PVBs in the terahertz range using a Bessel beam produced using a spiral binary silicon axicon (Phys. Rev. A 2017, 96, 023846). It was shown that, in that case, the PVB was not annular, but was split into nested spiral segments, which was obviously a consequence of the method of Bessel beam generation. The search for methods of producing perfect beams with characteristics approaching theoretically possible ones is a topical task. Since for the terahertz range, there are no devices like spatial modulators of light in the visible range, the main method for controlling the mode composition of beams is the use of diffractive optical elements. In this work, we investigated the characteristics of perfect beams, the parent beams being quasi-Bessel beams created by three types of diffractive phase axicons made of high-resistivity silicon: binary, kinoform, and “holographic”. The amplitude-phase distributions of the field in real perfect beams were calculated numerically in the approximation of the scalar diffraction theory. An analytical expression was obtained for the case of the binary axicon. It was shown that a distribution closest to an ideal vortex was obtained using a holographic axicon. The resulting distributions were compared with experimental and theoretical distributions of the evanescent field of a plasmon near the gold–zinc sulfide–air surface at different thicknesses of the dielectric layer, and recommendations for experiments were given.

Non-diffraction-length Bessel-beam femtosecond laser drilling of high-aspect-ratio microholes in PMMA

Optik ◽  
2021 ◽  
Vol 229 ◽  
pp. 166295
Author(s):  
Haoran Wang ◽  
Fan Zhang ◽  
Kaiwen Ding ◽  
Ji'an Duan
Keyword(s):  
Aspect Ratio ◽  
Femtosecond Laser ◽  
High Aspect Ratio ◽  
Bessel Beam ◽  
Laser Drilling
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