scholarly journals A Method to Generate Vector Beams with Adjustable Amplitude in the Focal Plane

2020 ◽  
Vol 10 (7) ◽  
pp. 2313 ◽  
Author(s):  
Alexandru Crăciun ◽  
Traian Dascălu

We design and investigate an original optical component made of a c-cut uniaxial crystal and an optical system to generate cylindrical vector beams with an adjustable polarization state. The original optical component has a specific, nearly conical shape which allows it to operate like a broadband wave retarder with the fast axis oriented radially with respect to the optical axis. We show via numerical simulations, using the Debye–Wolf diffraction integral, that the focal spot changes depending on the polarization state, thus enabling the control of the focal shape. Non-symmetrical shapes can be created although the optical system and incoming beam are circularly symmetric. We explained, using Jones matrix formalism, that this phenomenon is connected with the Gouy phase difference acquired by certain modes composing the beam due to propagation to the focal plane. We present our conclusions in the context of two potential applications, namely, stimulated emission depletion (STED) microscopy and laser micromachining. The optical system can potentially be used for STED microscopy for better control of the point-spread function of the microscope and to decrease the unwanted light emitted from the surroundings of the focal point. We give an analytical expression for the shape of the original component using the aspherical lens formula for the two versions of the component: one for each potential application.

Nanophotonics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 973-981 ◽  
Author(s):  
Han Yao ◽  
Fan Shi ◽  
Zhaoyang Wu ◽  
Xinzhu Xu ◽  
Teng Wang ◽  
...  

AbstractUsing an all-fiber mode selective coupler (MSC) at the visible band, here we experimentally demonstrate a generating and wavelength multiplexing scheme for the cylindrical vector (CV) and vortex beams (VBs). The proposed MSCs act as efficient mode converters to produce spectrally insensitive high-order modes (HOMs) at the wavelength ranging from 450 to 980 nm, which have broad operation bandwidth (more than 7 nm), high mode conversion efficiency (94%), and purity (98%), and low insert loss (below 0.5 dB). By adjusting the polarization state and the phase shift of linear polarization (LP)11 mode respectively, the donut-shaped CVs and circular-polarization VBs are achieved. The focused intensity distribution of the donut beam on the cross- and axial-sections is monitored by using a confocal system. The all-fiber solution of producing and multiplexing HOMs opens a new route for stimulated emission depletion microscopy applications.


2018 ◽  
Vol 218 (1) ◽  
pp. 83-96 ◽  
Author(s):  
Lena K. Schroeder ◽  
Andrew E.S. Barentine ◽  
Holly Merta ◽  
Sarah Schweighofer ◽  
Yongdeng Zhang ◽  
...  

The endoplasmic reticulum (ER) is composed of interconnected membrane sheets and tubules. Superresolution microscopy recently revealed densely packed, rapidly moving ER tubules mistaken for sheets by conventional light microscopy, highlighting the importance of revisiting classical views of ER structure with high spatiotemporal resolution in living cells. In this study, we use live-cell stimulated emission depletion (STED) microscopy to survey the architecture of the ER at 50-nm resolution. We determine the nanoscale dimensions of ER tubules and sheets for the first time in living cells. We demonstrate that ER sheets contain highly dynamic, subdiffraction-sized holes, which we call nanoholes, that coexist with uniform sheet regions. Reticulon family members localize to curved edges of holes within sheets and are required for their formation. The luminal tether Climp63 and microtubule cytoskeleton modulate their nanoscale dynamics and organization. Thus, by providing the first quantitative analysis of ER membrane structure and dynamics at the nanoscale, our work reveals that the ER in living cells is not limited to uniform sheets and tubules; instead, we suggest the ER contains a continuum of membrane structures that includes dynamic nanoholes in sheets as well as clustered tubules.


2016 ◽  
Vol 45 (1) ◽  
pp. 118002
Author(s):  
于 洋 Yu Yang ◽  
王世勇 Wang Shiyong ◽  
蹇 毅 Jian Yi ◽  
陈 珺 Chen Jun ◽  
代具亭 Dai Juting

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Erika Günther ◽  
André Klauß ◽  
Mauricio Toro-Nahuelpan ◽  
Dirk Schüler ◽  
Carsten Hille ◽  
...  

AbstractProtein interaction and protein imaging strongly benefit from the advancements in time-resolved and superresolution fluorescence microscopic techniques. However, the techniques were typically applied separately and ex vivo because of technical challenges and the absence of suitable fluorescent protein pairs. Here, we show correlative in vivo fluorescence lifetime imaging microscopy Förster resonance energy transfer (FLIM-FRET) and stimulated emission depletion (STED) microscopy to unravel protein mechanics and structure in living cells. We use magnetotactic bacteria as a model system where two proteins, MamJ and MamK, are used to assemble magnetic particles called magnetosomes. The filament polymerizes out of MamK and the magnetosomes are connected via the linker MamJ. Our system reveals that bacterial filamentous structures are more fragile than the connection of biomineralized particles to this filament. More importantly, we anticipate the technique to find wide applicability for the study and quantification of biological processes in living cells and at high resolution.


2019 ◽  
Vol 52 (41) ◽  
pp. 415108
Author(s):  
Zhi-Jun Luo ◽  
Ya-Nan Liu ◽  
Meng-Lin Chen ◽  
Zong-Song Gan ◽  
Chang-Sheng Xie

1976 ◽  
Vol 54 (17) ◽  
pp. 1774-1780 ◽  
Author(s):  
Pierre-André Bélanger ◽  
Marc Rioux

A spherical lens and an axicon are combined to form an optical system producing a ring-shaped focalization pattern. The diameter of the ring in the focal plane depends on the angle of the axicon, on its dielectric index, and on the focal length of the spherical lens. The diffractional analysis of the lens–axicon combination, when illuminated by a plane wave, is presented. In particular, we show that, when the aperture is large, the Kirchhoff–Fresnel integral can be reduced to a known function. A close examination of the function reveals that the diffractional width of the ring is equal to approximately twice the width of the Airy pattern of the lens alone. This type of focalization is well suited for a system where a laser beam is used to drill holes.


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