Willoughbymeldgaard8793

We show that background fringe-pattern subtraction is a useful technique for removing static noise from off-axis holographic reconstructions and can enhance image contrast in volumetric reconstructions by an order of magnitude in the case for instruments with relatively stable fringes. We demonstrate the fundamental principle of this technique and introduce some practical considerations that must be made when implementing this scheme, such as quantifying fringe stability. This work also shows an experimental verification of the background fringe subtraction scheme using various biological samples.Sensorless adaptive optics is commonly used to compensate specimen-induced aberrations in high-resolution fluorescence microscopy, but requires a bespoke approach to detect aberrations in different microscopy techniques, which hinders its widespread adoption. To overcome this limitation, we propose using wavelet analysis to quantify the loss of resolution due to the aberrations in microscope images. By examining the variations of the wavelet coefficients at different scales, we are able to establish a multi-valued image quality metric that can be successfully deployed in different microscopy techniques. To corroborate our arguments, we provide experimental verification of our method by performing aberration correction experiments in both confocal and STED microscopy using three different specimens.We report a chirped-pulse optical parametric oscillator (OPO) generating light pulses with an instantaneous-bandwidth much wider than the parametric gain-bandwidth of nonlinear crystals. Our numerical simulations show that a relatively high residual second-order-dispersion within the OPO cavity is required in order to achieve the maximum signal-bandwidth from an OPO system. Based on this principle, we constructed an OPO using a 3-mm-long PPLN crystal, which produced a signal wave with an instantaneous-bandwidth of 20 THz (at -20 dB) covering 1447-1600 nm, roughly twice as much as the phase-matching bandwidth of the nonlinear crystal. This scheme represents a promising technical route for generating high-repetition-rate, ultrashort optical pulses with a wide bandwidth at various wavelengths, which may benefit many applications, including optical coherence tomography, pulse synthesis and spectroscopy.We present a theoretical study on the plasmonic response of borophene, a monolayer 2D material that is predicted to exhibit metallic response and anisotropic plasmonic behavior in visible wavelengths. We investigate plasmonic properties of borophene thin films as well as borophene nanoribbons and nanopatches where polarization-sensitive absorption values in the order of 50% is obtained with monolayer borophene. It is demonstrated that by adding a metal layer, this absorption can be enhanced to 100%. We also examine giant dichroism in monolayer borophene which can be tuned passively (patterning) and actively (electrostatic gating) and our simulations yield 20% reflected light with significant polarization rotation. These findings reveal the potential of borophene in the manipulation of phase, amplitude and polarization of light at the extreme subwavelength scales.Structured illumination microscopy (SIM) is a widely used super resolution imaging technique that can down-modulate a sample's high-frequency information into objective recordable frequencies to enhance the resolution below the diffraction limit. However, classical SIM image reconstruction methods often generate poor results under low illumination conditions, which are required for reducing photobleaching and phototoxicity in cell imaging experiments. Although denoising methods or auxiliary items improved SIM image reconstruction in low signal level situations, they still suffer from decreased reconstruction quality and significant background artifacts, inevitably limiting their practical applications. In order to improve the reconstruction quality, second-order optimized regularized SIM (sorSIM) is designed specifically for image reconstruction in low signal level situations. In sorSIM, a second-order regularization term is introduced to suppress noise effect, and the penalty factor in this term is selected to optimize the resolution enhancement and noise resistance. Compared to classical SIM image reconstruction algorithms as well as to those previously used in low illumination cases, the proposed sorSIM provides images with enhanced resolution and fewer background artifacts. Therefore, sorSIM can be a potential tool for high-quality and rapid super resolution imaging, especially for low signal images.Superconducting nanowire-based single-photon detectors (SNSPDs) are promising devices, especially with unrivalled timing jitter ability. Necrostatin 1S ic50 However, the intrinsic physical mechanism and the ultimate limit of the timing jitter are still unknown. Here, we investigated the timing jitter of the SNSPD response to different excitation wavelengths from visible to near-infrared (NIR) as a function of the relative bias currents and the substrate temperature. We established a physical model based on a 1D electrothermal model to describe the hotspot evolution and thermal diffusion process after a single photon irradiated the nanowire. The simulations are in good agreement with the experimental results and reveal the other influencing factors and potential ways to further improve the timing jitter of SNSPDs. Finally, we introduce a new time-resolved approach, where by collecting the instrument response function (IRF) of SNSPDs, the wavelength of the incident photons can be easily discriminated with a resolution below 80 nm.Interpreting the polarimetric data from fiber-like macromolecules constitutive of tissue can be difficult due to strong scattering. In this study, we probed the superficial layers of fibrous tissue models (membranes consisting of nanofibers) displaying varying degrees of alignment. To better understand the manifestation of membranes' degree of alignment in polarimetry, we analyzed the spatial variations of the backscattered light's Stokes vectors as a function of the orientation of the probing beam's linear polarization. The degree of linear polarization reflects the uniaxially birefringent behavior of the membranes. The rotational (a-)symmetry of the backscattered light's degree of linear polarization provides a measure of the membranes' degree of alignment.