mBeRFP, a versatile fluorescent tool to enhance multichannel live imaging and its applications

Cell and developmental biology increasingly require live imaging of protein dynamics in cells, tissues or living organisms. Thanks to the discovery and the development of a panel of fluorescent proteins over the last decades, live imaging has become a powerful and commonly used approach. However, multicolor live imaging remains challenging. The generation of long Stokes shift red fluorescent proteins, such as mBeRFP, offers interesting new perspectives to bypass this limitation. Here, we constructed a set of mBeRFP-expressing vectors and provided a detailed characterization of this fluorescent protein for in vivo live imaging and its applications in Drosophila. Briefly, we showed that a single illumination source is sufficient to simultaneously stimulate mBeRFP and GFP. We demonstrated that mBeRFP can be easily combined with classical green and red fluorescent protein without any crosstalk. We also showed that the low photobleaching of mBeRFP is suitable for live imaging, and that this protein can be used for quantitative applications such as FRAP or laser ablation. Finally, we believe that this fluorescent protein, with the set of new possibilities it offers, constitutes an important tool for cell, developmental and mechano biologists in their current research.

Silicon Lens Optimization to Create Diffuse, Uniform Illumination from Incoherent THz Source Arrays

Arrays of terahertz (THz) sources provide a pathway to overcoming the radiation power limitations of single sources. Several independent sources of THz radiation may be implemented in a single integrated circuit, thereby realizing a monolithic THz source array of high output power. Integrated THz sources must generally be backside-coupled to extended hemispherical dielectric lenses in order to suppress substrate modes and extract THz power. However, this lens also increases antenna gain and thereby produces several non-overlapping beams. This is because individual source pixels are relatively large. Hence, their spatial separation on-chip translates to angular separation in the far-field. In other words, there are gaps in their field of view into which very little THz power is projected. Therefore, they cannot homogeneously illuminate an imaging target. This article presents a simple, practical, and scalable method to convert arrays of incoherent THz sources into a diffuse, uniform illumination source without the need for reducing pixel size. Briefly, individual beam divergence is optimized by tailoring the dimensions of the extended hemispherical dielectric lens such that the far-field beams of adjacent source pixels overlap and combine to form a uniform far-field beam. We applied this method to an incoherent 8 × 8-pixel THz source array radiating 10.3 dBm at 0.42 THz as a proof of concept and thereby realized a 10.3-dBm 0.42-THz diffuse, uniform illumination source that was then deployed in a demonstration of THz active imaging.

Anterior Segment Examination with Slit-Lamp Biomicroscope: What Should be Highlighted?

Ocular health assessment consists of various types of examinations that aim to find pathological conditions in the eye so that it helps ophthalmologists to diagnose and provide therapy for ocular disorders suffered by the patients. Slit-lamp biomicroscope is one of the most important eye assessments and has become the standard in assessing the pathological condition of the anterior part of the eye. This examination is performed using a stereoscopic biomicroscope instrument in combination with a bright illumination source. The results of the anterior segment examination using slit-lamp biomicroscope may provide more detailed ocular findings, such as the abnormalities of the eyelid, conjunctival lesions, abnormalities of the cornea, lens, or other parts of the anterior ocular segments. Therefore, the ability to examine slit-lamp biomicroscope is essential for the ophthalmologist. This review will discuss the eye examination using slit-lamp biomicroscope and the findings that will make it easier for clinicians to determine the direction of diagnostic approach in ocular patients.

Beam Formation and Vernier Steering Off of a Rough Surface

Wavefront shaping can refocus light after it reflects from an optically rough surface. One proposed use case of this effect is in indirect imaging; if any rough surface could be turned into an illumination source, objects out of the direct line of sight could be illuminated. In this paper, we demonstrate the superior performance of a genetic algorithm compared to other iterative feedback-based wavefront shaping algorithms in achieving reflective inverse diffusion for a focal plane system. Next, the ability to control the pointing direction of the refocused beam with high precision over a narrow angular range is demonstrated, though the challenge of increasing the overall scanning range of the refocused beam remains. The method of beam steering demonstrated in this paper could act as a vernier adjustment to a coarse adjustment offered by another method.

A Closer Look at Photonic Nanojets in Reflection Mode: Control of Standing Wave Modulation

The photonic nanojet phenomenon is commonly used both to increase the resolution of optical microscopes and to trap nanoparticles. However, such photonic nanojets are not applicable to an entire class of objects. Here we present a new type of photonic nanojet in reflection mode with the possibility to control the modulation of the photonic nanojet by a standing wave. In contrast to the known kinds of reflective photonic nanojets, the reported one occurs when the aluminum oxide hemisphere is located at a certain distance from the substrate. Under illumination, the hemisphere generates a primary photonic nanojet directed to the substrate. After reflection, the primary nanojet acts as an illumination source for the hemisphere, leading to the formation of a new reflective photonic nanojet. We show that the distance between the hemisphere and substrate affects the phase of both incident and reflected radiation, and due to constructive interference, the modulation of the reflective photonic nanojet by a standing wave can be significantly reduced. The results obtained contribute to the understanding of the processes of photonic nanojet formation in reflection mode and open new pathways for designing functional optical devices.

Analysis of Reflected Metamer Light Effect on Cheese Palatability

Functional lighting can control a specific wavelength in order to emphasize a desired color signal of an object. In this study, for the purpose of designing functional lighting for cheese, the effect of lighting on the palatability of cheese was analyzed from reflected light. To investigate the palatability difference caused by different illuminants, a psychophysical experiment was conducted using five types of cheese under metameric lighting with fixed color temperature and illuminance. A total of eight observers participated in this experiment: four of them who loved eating cheese were classified as group A, and the remaining four who disliked eating it were classified as group B. The experiment revealed that observers in group A agreed that illumination sources made the cheese look most palatable, whereas observers in group B showed variability in their preferred light sources. Based on these results, guidelines for designing an illumination source that can improve cheese palatability by controlling the wavelength band were determined, under the constraint that the reflected light exists within a specific chrominance region.

Study of object image contrast and range of vision in smoke conditions

Представлены результаты исследования зависимостей контраста изображений тестового объекта от оптической плотности различных типов аэрозолей дыма при поляризационной фильтрации излучения подсветки объекта, рассеянного частицами аэрозоля в направлении назад, и в отсутствие фильтрации. Установлено, что формирование изображения объекта с применением метода поляризационной фильтрации излучения помехи обратного рассеяния (ПОР) позволяет снизить скорость уменьшения контраста изображения с увеличением оптической плотности дыма в сравнении с регистрацией изображения без фильтрации ПОР. Полученные результаты могут быть использованы при разработке оптических принадлежностей пожарного-спасателя для наблюдения объектов в неблагоприятных условиях видения: при задымлении, парообразовании, тумане. The relevance of the work is due to the need to develop effective and affordable for mass use technical means of equipping for a firefighter-rescuer, improving the conditions of his work in a smoke-filled environment in a fire. The aim of the work was to study the contrast of the image of a flat black-and-white object with a sharp border of the black-and-white transition formed through various types of smoke aerosols during polarizing filtration of the illumination radiation of the object scattered by aerosol particles in the “back” direction, and in the absence of filtration. The results of the research are presented in the form of dependencies of the object image contrast on the optical density of the smoke aerosol in two image registration schemes, when the receiving optical system is located near the object illumination source at a distance of ~150 mm and when it is located at a distance of ~800 mm from the object illumination source. It is established that the method of forming the image of the object using polarization filtering of radiation backscattering (RBS) reduces the rate of image contrast reduction with an increase in optical smoke density compared with image registration without filtering RBS. The results obtained can be used in the development of optical accessories for firefighter-rescuer to improve the conditions of object observation in adverse conditions of vision: smoke, vaporization, fog.

Contrast of Image of an Object Observed in Smoke Conditions using Polarizing Filtering of Radiation Scattered by Smoke Particles

The aim of the work was to study the contrasts of the images of an object observed in a smoky environment, using polarizing filtering of radiation scattered by smoke particles towards the observer, and without filtering. Prospects for developing optical accessories for firefighters to improve the observation of objects in smoke were evaluated by comparing image contrasts.The goal was achieved by experimentally simulating the process of transmitting images of a blackandwhite object with a sharp black/white transition boundary through various types of smoke aerosols using polarizing filtering of radiation scattered by smoke particles, and without filtering and evaluating image contrasts.Studies of image contrasts for different optical densities of smoke in two registration schemes were performed, when the receiving optical system is located near the illumination source of the object at a distance of ≈ 150 mm from it, and when it is located at a distance from the illumination source of the object at a distance of ≈ 800 mm.It is established that the method of forming the image of the object using polarization filtering of radiation backscattering (RBS) reduces the rate of image contrast reduction with an increase in optical smoke density compared to image registration without filtering (RBS).A significant difference in the contrasts of images recorded with filtration (RBS) and in the absence of it is observed for "light" fumes (smoldering of wood, cotton) at average optical densities of smoke.The results obtained can be used in the development of optical accessories for firefighter-rescuer to improve the conditions of observation of objects in adverse conditions of vision: smoke, vaporization, fog.