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“Wavelength selectivity” is an important intrinsic property of diffractive optical elements that offers significant application potential. Here, we focus on tailored wavelength selectivity, the controlled efficiency distribution into different specific diffraction orders for selected wavelengths or wavelength ranges from UV to IR using interlaced double-layer single-relief blazed gratings composed of two materials. Dispersion characteristics of inorganic glasses, layer materials, polymers, nanocomposites, and high-index liquids are taken into account to investigate the impact of especially intersecting or partially overlapping dispersion curves on diffraction efficiency in different orders, providing a guideline for material choice depending on the required optical performance. By selecting appropriate combinations of materials and adjusting the grating depth, a wide variety of small or large wavelength ranges can be assigned to different diffraction orders with high efficiency that can be beneficially applied to wavelength selective functions in optical systems also including imaging or broadband lighting applications.

This contribution presents the design and implementation of a compact and robust Echelle-inspired cross-grating spectrometer which is arranged as a double pass setup. This allows use of the employed refractive elements for collimation of the incoming light and, after diffraction at the reflective crossed diffraction grating, for imaging the diffracted light onto the detector. The crossed diffraction grating combines the two dispersive functionalities of a classical Echelle spectrometer in a single element and is therefore formed by a superposition of two blazed linear gratings which are oriented perpendicularly. The refractive elements and the plane grating are arranged in a rigid objective group which is beneficial in terms of stability and robustness. The experimental tests prove that the designed resolving power of more than 300 is achieved for the addressed spectrum ranging from 400 nm to 1100 nm by using an entrance pinhole diameter of 105 µm. The utilization of a single mode fiber increases the resolving power to more than 1000, but leads to longer acquisition times.

We compare using a prospective data collection the likelihood of infection and short-term revision in inflatable penile prosthesis (IPP) placements when using AMS 700 TM CX series versus Coloplast Titan®. The study included the first-time IPP implantations using both implants performed between January 2017 and December 2019. The surgeon alternated the implants every other week, and the patients were divided into two cohorts based on implant company for comparison and study. Data were collected on patient demographics, implant characteristics, perioperative features, and complications. Follow-up was carried out at 6 weeks, 3 months, and then annually. A total of 542 patients underwent IPP implantations during the two years, 301 (56%) were performed using AMS 700TMCX and 241 (44%) using Coloplast Titan®. There was only one (0.18%) case complicated by infection. Seven cases (1.3%) required revision, five had been done using AMS 700TM CX implants. Overall, the most common reason for revision was tube fracture (n=3). Diabetes, case time, reservoir type, and reservoir location were not significant prognostic factors for revision (p>0.05). We concluded that regarding manufacturing companies the risk of infection is not affected. Diabetes and drain placement for three days did not increase the risk of infection or overall revision.

To examine motor vehicle crash frequency and risk factors following moderate-to-severe traumatic brain injury (TBI).Eight TBI Model Systems sites. Participants: Adults (N = 438) with TBI who required inpatient acute rehabilitation.Cross-sectional, observational design.Driving survey completed at phone follow-up 1 to 30 years after injury.TBI participants reported 1.5 to 2.5 times the frequency of crashes noted in the general population depending on the time frame queried, even when accounting for unreported crashes. Most reported having no crashes; for those who experienced a crash, half of them reported a single incident. Based on logistic regression, age at survey, years since injury, and perception of driving skills were significantly associated with crashes.Compared with national statistics, crash risk is higher following TBI based on self-report. Older age and less time since resuming driving were associated with lower crash risk. When driving was resumed was not associated with crash risk. These results do not justify restricting people from driving after TBI, given that the most who resumed driving did not report experiencing any crashes. However, there is a need to identify and address factors that increase crash risk after TBI.

Background The association of social isolation or lack of social network ties in older adults is unknown. This knowledge gap is important since the risk of heart failure (HF) and social isolation increase with age. The study examines whether social isolation is associated with incident HF in older women, and examines depressive symptoms as a potential mediator and age and race and ethnicity as effect modifiers. Methods and Results This study included 44 174 postmenopausal women of diverse race and ethnicity from the WHI (Women's Health Initiative) study who underwent annual assessment for HF adjudication from baseline enrollment (1993–1998) through 2018. We conducted a mediation analysis to examine depressive symptoms as a potential mediator and further examined effect modification by age and race and ethnicity. Incident HF requiring hospitalization was the main outcome. Social isolation was a composite variable based on marital/partner status, religious ties, and community ties. Depressive symptoms were assessed using CES‐D (Center for Epidemiology Studies‐Depression). Over a median follow‐up of 15.0 years, we analyzed data from 36 457 women, and 2364 (6.5%) incident HF cases occurred; 2510 (6.9%) participants were socially isolated. In multivariable analyses adjusted for sociodemographic, behavioral, clinical, and general health/functioning; socially isolated women had a higher risk of incident HF than nonisolated women (HR, 1.23; 95% CI, 1.08–1.41). Adding depressive symptoms in the model did not change this association (HR, 1.22; 95% CI, 1.07–1.40). Neither race and ethnicity nor age moderated the association between social isolation and incident HF. Conclusions Socially isolated older women are at increased risk for developing HF, independent of traditional HF risk factors. Registration URL: http://www.clinicaltrials.gov ; Unique identifier: NCT00000611.

A method to drastically enhance detection efficiency of a linear variable filter (LVF) sensor across an extended and continuous wavelength range is presented. The efficiency is increased by a wavelength preselection concept, where the incoming light is divided into partial spectra to reduce otherwise unavoidable reflection losses of filter-based spectrometers. The simple but effective setup uses selected and successively arranged dichroic beamsplitters, which ensures an optimized compromise between efficiency enhancement and minimum increasing complexity. When connected to a two-dimensional camera and combined with a tilted LVF, this compact optical system allows the continuous recording of the full wavelength range between 450 and 850 nm with a resolution of ∼19 nm at 508.6 nm. An efficiency enhancement factor of up to 5.7 is achieved in comparison to a conventional LVF setup. The working principle was verified by measuring the reflection spectra of different natural and artificial green leaves. The proposed approach for increasing the efficiency can be miniaturized and applied to a broad range of other filter-based sensors.

Hyperchromatic systems are characterized by strong longitudinal chromatic aberrations that are quantitatively described by very small equivalent Abbe numbers. In this contribution, doublet systems are systematically studied with the aim of obtaining extreme values for the equivalent Abbe numbers. Both purely refractive combinations and hybrid systems of diffractive and refractive components are considered. Chromatic axial splitting is determined as a function of the optical powers of the individual components as well as the dispersion properties of the materials involved. In order to determine actual implementable configurations for extremely small equivalent Abbe numbers, a systematic ray-trace analysis is performed in addition to paraxial studies, taking into account geometric constraints on lens curvatures and considering also complete, continuous dispersion curves. As extreme values for systems with appropriate imaging quality, an equivalent Abbe number of υ ~ = − 2.5 is obtained for the purely refractive approach, and υ ~ = 0.4 for the hybrid case, which is more than 8 times smaller than the absolute value of a single diffractive lens.

Optical interferometric sensors have acquired significant importance in metrology and information technology, especially in terms of their potential application in launching size, selectivity, sensitivity, resolution, spectral tuning ranges, efficiency, and cost. However, these demands are often contradictory and counteract one another, and are thus difficult to simultaneously fulfill during their interaction. This review focuses on a detailed comparison of seven different strongly miniaturized sensor concepts investigating the limits of these demands. For the visible and near-infrared spectral range, seven optical sensors were reviewed based on the following methodologies: classical optical transmission and reflection gratings, arrayed waveguide gratings, static Fabry–Pérot (FP) filter arrays, MEMS tunable FP interferometers, MEMS tunable photonic crystals, plasmonic filters, and fiber tip sensors. The comparison between the selected concepts concentrates on (i) the minimum space required for a particular spectral range, (ii) resolution, (iii) the integration in optical fiber technology, (iv) tunability to save space, (v) efficiency in using available light, (vi) multiplexing, (vii) miniaturization limits, and (viii) the potential of nanoimprint for cost reduction. Technologies for enhancing efficiency to obtain more available light and their applicability to the different methodologies were studied.

Background: Obesity is associated with an increased risk of heart failure (HF); however, how metabolic weight groups relate to HF risk, especially in postmenopausal women, has not been demonstrated. Methods: We included 19 412 postmenopausal women ages 50 to 79 without cardiovascular disease from the Women’s Health Initiative. Normal weight was defined as a body mass index ≥18.5 and 2 and waist circumference 2 or waist circumference ≥88 cm. Metabolically healthy was based on Results: Among our sample, 455 (2.34%) participants experienced HF hospitalizations over a mean follow-up time of 11.3±1.1 years. Compared with metabolically healthy normal weight individuals, HF risk was greater in metabolically unhealthy normal weight (HR, 1.66 [95% CI, 1.01–2.72], P =0.045) and metabolically unhealthy overweight/obese individuals (HR, 1.95 [95% CI, 1.35–2.80], P =0.0004), but not metabolically healthy overweight/obese individuals (HR, 1.15 [95% CI, 0.78–1.71], P =0.48). Subdividing the overweight/obese into separate groups showed HRs for metabolically unhealthy obese of 2.62 (95% CI, 1.80–3.83; P P =0.06). Conclusions: Metabolically unhealthy overweight/obese and metabolically unhealthy normal weight are associated with an increased risk of HF in postmenopausal women.

We present a systematic comparison of PAM-2 (NRZ), Duobinary-PAM-2, PAM-4, and Duobinary-PAM-4 (duo-quaternary) signaling in the context of short-reach photonic communications systems using a Mach–Zehnder modulator as transmitter. The effect on system performance with a relaxed and constrained system’s opto-electronic bandwidth is analyzed for bit rates ranging from 20 to 116 Gb/s. In contrast to previous analyses, our approach employs the same experimental and simulation conditions for all modulation formats. Consequently, we were able to confidently determine the performance limits of each format for particular values of bit rate, system bandwidth, transmitter chirp, and fiber dispersion. We demonstrate that Duobinary-PAM-4 is a good signaling choice only for bandwidth-limited systems operating at relatively high speed. Otherwise, PAM-4 represents a more sensible choice. Moreover, our analysis put forward the existence of transition points: specific bit rate values where the BER versus bit rate curves for two different formats cross each other. They indicate the bit rate values where, for specific system conditions, switching from one modulation to another guarantees optimum performance. Their existence naturally led to the proposal of a format-selective transceiver, a component that, according to network conditions, operates with the most adequate modulation format. Since all analyzed modulations share similar implementation details, signaling switching is achieved by simply changing the sampling point and threshold count at the receiver, bringing flexibility to IM/DD-based optical networks.

We present an ultra-compact system approach for snapshot, multispectral imaging. It is based on a slanted linear variable spectral filter mounted in close proximity to the entrance pupil of a micro-optical, multi-aperture imaging system. A compact demonstration setup with a size of only 60 × 60 × 28 mm3 is developed, which enables the acquisition of 66 spectral channels in a single shot and offers a linear spectral sampling of approximately six nanometers over an extended wavelength range of 450-850 nm. The spatial sampling of each channel covers up to 400 × 400 pixels. First, the concept, the optical design and the fabrication are detailed. After the optical performance characterization, a comprehensive calibration strategy is developed and applied. An experimental demonstration is performed by acquiring the spatial and the spectral information of an imaged test scene.

Diffuse reflecting (white) and highly absorbing (black) fused silica based materials are presented, which combine volume modified substrates and surfaces equipped with anti-reflective moth-eye-structures. For diffuse reflection, micrometer sized cavities are created in bulk fused silica during a sol-gel process. In contrast, carbon black particles are added to get the highly absorbing material. The moth-eye-structures are prepared by block copolymer micelle nanolithography (BCML), followed by a reactive-ion-etching (RIE) step. The moth-eye-structures drastically reduce the specular reflectance on both diffuse reflecting and highly absorbing samples across a wide spectral range from 250 nm to 2500 nm and for varying incidence angles. The adjustment of the height of the moth-eye-structures allows us to select the spectral position of the specular reflectance minimum, which measures less than 0.1%. Diffuse Lambertian-like scattering and absorbance appear nearly uniform across the selected spectral range, showing a slight decrease with increasing wavelength.

To further extent our understanding of aquatic vision, we introduce a complete optical model of a goldfish eye, which comprises all important optical parameters for the first time. Especially a spherical gradient index structure for the crystalline lens was included, thus allowing a detailed analysis of image quality, regarding spot size, and wavelength dependent aberration. The simulation results show, that our realistic eye model generates a sufficient image quality, with a spot radius of 4.9 mm which is below the inter cone distance of 5.5 mm. Furthermore, we optically simulate potential mechanical processes of accommodation and compare the results with contradictory findings of previous experimental studies. The quantitative simulation of the accommodation capacity shows that the depth of field is strongly dependent on the resting position and becomes significantly smaller when shorter resting positions are assumed. That means, to enable an extended depth perception with high acuity for the goldfish an adaptive, lens shifting mechanism would be required. In addition, our model allows a clear prediction of the expected axial lens-shift, which is necessary to ensure a sufficient resolution over a large object range.

This paper presents concept, optical design, and the implementation of a novel, to the best of our knowledge, lithographic exposure tool for the fabrication of rotationally symmetric meso- and microscale optical structures using a variable ring-shaped light distribution. Compared to the conventional lithographic technique of direct writing in Cartesian coordinates, which is intrinsically suboptimal for the fabrication of rotationally symmetric optical structures, this approach allows for fast exposure and avoids disturbing stitching effects. The diameter of the exposure ring varies between 1.6 and 6.5 mm, and the ring width measures ∼ 75 µ m full width at half-maximum for all diameters. The basic capabilities of the exposure tool are demonstrated by the fabrication of exemplary meso- and microscale structures such as diffractive axicon elements, phase rings, Fresnel zone plates and zone plate arrays.

Although allocation strategies such as kidney paired donation (KPD) have helped to enhance transplant opportunities for immunologically incompatible recipient and donor pairs, further expansion and optimization of KPD is possible. This review examines Global Kidney Exchange and Deceased Donors as Chain-Initiating Kidneys, two novel strategies aimed to expand the benefits of KPD. Global Kidney Exchange offers the opportunity to utilize the mechanism of kidney exchange to overcome financial barriers to kidney transplantation, thus increasing the pool of participating pairs, unlocking more chains, avoiding costs from dialysis, and expanding kidney transplantation to serve impoverished patients. The Deceased Donors as Chain-Initiating Kidneys strategy aims to increase matching opportunities by using deceased donor kidneys to initiate KPD chains. We find that both ideas offer the promise of more kidney transplants and a reduction in the personal and economic burden caused by ESRD.

Optical nanostructures have evolved successfully in nature over millions of years. For example, such nanostructures are found on the compound eyes of night active insects. These “moth‐eye” structures offer extraordinary anti‐reflective (AR) properties and therefore allow the insects to hide from their predators. This concept has been transferred to technical applications and enables artificial AR characteristics on high‐end optical elements with performance advantages not possible with classical layer‐based AR coatings. An appropriate manufacturing technology combines self‐organization of nano‐particles with a reactive ion‐etching process.

We describe the design and set-up an array of micro-spectrometers for parallel sensing. The approach utilizes a prism – grating combination to obtain a linear light path and to achieve a high packing density. This yields 2’000 micro spectrometers of 6 mm length only when working with a 4/3” CCD image sensor.