Non-Telecentric 2P microscopy for 3D random access mesoscale imaging at single cell resolution

In neuroscience, diffraction limited two-photon (2P) microscopy is a cornerstone technique that permits minimally invasive optical monitoring of neuronal activity. However, most conventional 2P microscopes impose significant constraints on the size of the imaging field-of-view and the specific shape of the effective excitation volume, thus limiting the scope of biological questions that can be addressed and the information obtainable. Here, employing a non-telecentric (nTC) optical design, we present an ultra-low-cost, easily implemented and flexible solution to address these limitations, offering a several-fold expanded three-dimensional field of view that also maintains single-cell resolution. We show that this implementation also allows for straight-forward tailoring of the point-spread-function, increases effective excitation power, and achievable image brightness. Moreover, rapid laser-focus control via an electrically tunable lens allows near-simultaneous imaging of remote regions separated in three dimensions and permits the bending of imaging planes to follow natural curvatures in biological structures. Crucially, our core design is readily implemented (and reversed) within a matter of hours, and compatible with a wide range of existing 2P customizations, making it highly suitable as a base platform for further development. We demonstrate the application of our system for imaging neuronal activity in a variety of examples in zebrafish, mice and fruit flies.

Эффективное возбуждение магнитоэлектрического эффекта в структуре ферромагнетик-пьезоэлектрик током через магнитный слой

The effective excitation of the magnetoelectric effect in a planar structure amorphous ferromagnet – piezoelectric lead zirconate titanate by alternating current flowing through the magnetic layer was demonstrated. Due to orientation of the exciting magnetic field perpendicular to the constant field and absence of demagnetization, the structure generates even voltage harmonics with efficiency, several times higher than the efficiency of excitation of the effect by volume coils. It was shown that the amplitude of the second harmonic is proportional to the piezomagnetic coefficient of the magnetic layer,increases quadratically with the amplitude of the current and decreases inversely with the biasing magnetic field

Divergent excitation two photon microscopy for 3D random access mesoscale imaging at single cell resolution

ABSTACTIn neuroscience, diffraction limited two-photon (2P) microscopy is a cornerstone technique that permits minimally invasive optical monitoring of neuronal activity. However, most conventional 2P microscopes impose significant constraints on the size of the imaging field-of-view and the specific shape of the effective excitation volume, thus limiting the scope of biological questions that can be addressed and the information obtainable. Here, employing ‘divergent beam optics’ (DBO), we present an ultra-low-cost, easily implemented and flexible solution to address these limitations, offering a several-fold expanded three-dimensional field of view that also maintains single-cell resolution. We show that this implementation increases both the space-bandwidth product and effective excitation power, and allows for straight-forward tailoring of the point-spread-function. Moreover, rapid laser-focus control via an electrically tunable lens now allows near-simultaneous imaging of remote regions separated in three dimensions and permits the bending of imaging planes to follow natural curvatures in biological structures. Crucially, our core design is readily implemented (and reversed) within a matter of hours, and fully compatible with a wide range of existing 2P customizations, making it highly suitable as a base platform for further development. We demonstrate the application of our system for imaging neuronal activity in a variety of examples in mice, zebrafish and fruit flies.

Surface plasmon-polaritons in deformed graphene excited by attenuated total internal reflection

In the present work we theoretically investigated the excitation of surface plasmon-polaritons (SPPs) in deformed graphene by attenuated total reflection method. We considered the Otto geometry for SPPs excitation in graphene. Efficiency of SPPs excitation strongly depends on the SPPs propagation direction. The frequency and the incident angle of the most effective excitation of SPPs strongly depend on the polarization of the incident light. Our results may open up the new possibilities for strain-induced molding flow of light at nanoscales.

Микромагнитное моделирование спин-волновых возбуждений в гофрированных пленках ЖИГ

Particularities of the spin-wave spectrum in YIG film with the thickness of 0.4 μm and magnetization of 1.1 kG that was corrugated due to the periodical substrate relief in the form of grooves having width of 10 μm, depth of 0.5 μm, sloped walls and period of 20 μm were studied with the help of micromagnetic modelling. Calculations were carried out for the external magnetic field applied along (θ=0) and across (θ=90°) the grooves in the film plane, and showed that the anisotropy from the film form caused the spectrum quantization and localization of spin-wave excitations in the different parts of the sample. Besides that, spacial distribution of magnetization amplitude at fixed frequencies in the spectrum for θ=90° can be characterized by several spacial scales that differ by orders. This is explained by the strong inhomogeneity of equilibrium state at grooves' walls for θ=90° that leads to the effective excitation of short-wave part of the spin-wave spectrum in the periodical structure by Schlömann mechanism.