Versatile, open-access opto-mechanics design for optical microscopes prototyping.

Prototype optical microscopes, built to pursue developments in advanced imaging techniques, need specific opto-mechanical constructions: preferably with high flexibility in the elements' arrangement, easy access to the optical paths, straightforward integration with external optical subsystems-light sources and detectors-as well as good mechanical stability. Typically they are either built around an adapted commercial microscope body or as a home-brewed setups, based on standard opto-mechanical elements, and neither solution delivers the desired characteristics. We developed a series of versatile microscope design for prototype optical microscopes in various configurations that use folding mirror(s) to maintain the optical paths horizontal throughout most of the setup.

Machine learning approach for ambient-light-corrected parameters and the Pupil Reactivity (PuRe) score in smartphone-based pupillometry.

Introduction: The pupillary light reflex (PLR) is the constriction of the pupil in response to light. The PLR in response to a pulse of light follows a complex waveform that can be characterized by several parameters. It is a sensitive marker of acute neurological deterioration, but is also sensitive to the background illumination in the environment in which it is measured.

Concept of inverted refractive-index-contrast grating mirror and exemplary fabrication by 3D laser micro-printing.

Highly reflective mirrors are indispensable components in a variety of state-of-the-art photonic devices. Typically used, bulky, multi-layered distributed Bragg (DBR) reflectors are limited to lattice-matched semiconductors or nonconductive dielectrics. Here, we introduce an inverted refractive index-contrast grating (ICG) as compact, single-layer alternative to DBR.

Ultra-long-working-distance spectroscopy of single nanostructures with aspherical solid immersion microlenses.

In light science and applications, equally important roles are played by efficient light emitters/detectors and by the optical elements responsible for light extraction and delivery. The latter should be simple, cost effective, broadband, versatile and compatible with other components of widely desired micro-optical systems. Ideally, they should also operate without high-numerical-aperture optics.

Optical fiber micro-connector with nanometer positioning precision for rapid prototyping of photonic devices.

Prototyping of fiber-coupled integrated photonic devices requires robust and reliable way of docking optical fibers to other structures, often with sub-micron accuracy. We have developed an optical fiber micro-connector 3D-printed with Direct Laser Writing on a planar substrate. The connector provides fiber core precision positioning better than 120 nm and sustains cryogenic cycling without any signs of degradation.

Highly asymmetric near infrared light transmission in an all-dielectric grating-on-mirror photonic structure.

We demonstrate a photonic structure, composed of a dielectric quarter-wavelength stack topped with a transmission phase grating, designed to exhibit a significant asymmetry in the near infrared light transmission for waves propagating in opposite directions. The asymmetry, defined as the difference between the intensity transmission coefficients, reaches 0.72 ± 0.

Transmission phase gratings fabricated with direct laser writing as color filters in the visible.

Simple diffraction structures having the form of a regular grid of pillars can generate a significant range of hues in white light transmission due to color-dependent diffraction into higher orders. We present the fabrication of such submicrometer scale structures by three dimensional laser two-photon photolithography, results of their optical properties measurements and compare the latter with numerical simulations.