Macroscopic Lens Research Articles

Wet Chemical Engineering of Nanostructured GRIN Lenses

AbstractGradient‐index (GRIN) lenses have long been recognized for their importance in optics as a result of their ability to manipulate light. However, traditional GRIN lenses are limited on a scale of tens of microns, impeding their integration into nanoscale optical devices. This study presents a groundbreaking self‐assembled method that overcomes this limitation, allowing for constructing GRIN lenses at an extremely small dimension. The self‐assembly process offers several advantages, including creating highly precise, scalable, cost‐effective, and complex structures that eliminate the need for intricate and time‐consuming manual assembly. By engineering densely packed arrays of metallic nanoparticles, exceptional control over the local refractive index has been achieved. This is accomplished by layer‐by‐layer assembly of gold nanoparticles of different sizes over silica beads. A GRIN lens light‐sink is built where light is preferentially directed toward the center, which is corroborated by measuring the fluorescence of Rhodamine B (RhB) in the inside. Unlike traditional bulky macroscopic GRIN lenses, light‐sinks boast a size under 2.5 µm. Notably, the self‐focusing effects of this design allowed us to track the growth of single‐nanoparticle layers using SERS (Surface‐Enhanced Raman Spectroscopy). These results pave the way for designing and developing lens‐like devices at the nanoscale, allowing unprecedented light manipulation.

Spectral characterization of optical aberrations in fluidic lenses

We report an extensive numerical study and supporting experimental results on the spectral characterization of optical aberrations in macroscopic fluidic lenses with tunable focal distance and aperture shape. By using a Shack–Hartmann wavefront sensor, we experimentally reconstruct the near-field wavefront transmitted by the fluidic lenses, and we characterize the chromatic aberrations in terms of Zernike polynomials in the visible range. Moreover, we further classify the spectral response of the lenses using clustering techniques, in addition to correlation and convolution measurements. Experimental results are in agreement with numerical results based on our theoretical model of the nonlinear deformation of thin elastic membranes.

Cell biology through the macroscopic lens

Cell biology through the macroscopic lens

Reflections on the asymmetry of causation.

The most immediately salient asymmetry in our experience of the world is the asymmetry of causation. In the last few decades, two developments have shed new light on the asymmetry of causation: clarity in the foundations of statistical mechanics, and the development of the interventionist conception of causation. In this paper, we ask what is the status of the causal arrow, assuming a thermodynamic gradient and the interventionist account of causation? We find that there is an objective asymmetry rooted in the thermodynamic gradient that underwrites the causal asymmetry: along a thermodynamic gradient, interventionist causal pathways-scaffolded intervention-supporting probabilistic relationships between variables-will propagate influence into the future, but not into the past. The reason is that the present macrostate of the world, in the presence of a low entropy boundary condition, will screen off probabilistic correlations to the past. The asymmetry, however, emerges only under the macroscopic coarse-graining and that raises the question of whether the arrow is simply an artefact of the macroscopic lenses through which we see the world. The question is sharpened and an answer proposed.

Joseph II’s 1782 Edict of Toleration for the Jews of Lower Austria and its Economic and Secular Underpinnings and Effects

Joseph II’s 1782 Edict of Toleration is an important piece of legislation within Austrian and Jewish history. The Edict was a series of statements issued regarding the inclusion of Jewish citizens into larger towns, marking what was permitted, what was to change, and what was prohibited. Created by Holy Roman Emperor Joseph II, son of the notoriously anti-Jewish Empress Maria Theresia, the legislation was institutionalized in order to make Jewish people more useful economically to the state by granting them access to cities and towns, Christian schools and universities, and by allowing them to set up their own factories. It created secular subjects to achieve economic gains. The Edict can be analyzed for its economic underpinnings and effects, which can be further examined through a micro- and macroscopic lens, as well as viewing the role it had in promoting the toleration and assimilation of Jews. The Edict, despite its failure to achieve its steep economic goals or to fully assimilate Austria’s Jewish community, nonetheless is key to understanding the political, economic, and religious climate of Lower Austria at this time.

Implementation of structurally pre-stressed piezo actuator based active vibration isolation system for micro milling

This paper presents the implementation of a structurally pre-stressed piezo actuator based active vibration isolation system incorporated with tool based micromachining setup for analyzing and comparing the milled pocket depth surface before and after isolation. A carbide micro end mill tool with 1 mm diameter and 4 flutes has been used for carrying out pocket milling experiments with and without vibrations on copper work pieces having 3 mm thickness. The machining parameters selected were spindle speed of 16,000 rev/min with 64 mm/min feed rate and 50 μm depth of cut. Two sets of pocket milling experiments were carried out using the proposed vibration isolation setup one with vibration and the other without vibration. In the first set of experiment, the source actuator was actuated for generating vibrations during pocket milling whereas in the second set of experiment, both source and isolator actuators were actuated for nullifying the vibrations generated during pocket milling. The macroscopic lens output images of the pocket depth surfaces before and after isolation were then compared corresponding to various actuation voltages at different frequencies using the proposed vibration isolation setup. Based on the macroscopic lens output images it was observed that the milled pocket depth surface obtained by actuating only source actuator showed distinct rings wherein the ring count matched with frequency and feed rate that has been provided during machining. However, the milled pocket obtained by actuating both source and isolator actuators resulted in surface characteristics with less pronounced rings similar to that of regular machining. Also the rings that has been formed showed more defined edges with the increase in actuator voltage indicating that these distinct patterns were caused due to the vibrations generated by the source actuator alone and not other factors.

Non‐invasive on‐site method for thickness measurement of transparent ceramic glazes based on depth from focus

AbstractGlazed ceramics are a common material analyzed through geochemistry, whether in the form of tableware collected during excavations or tiles observed as part of architectural features. Within the framework of these studies, measuring the thickness of the transparent glaze is one of the useful variables available for the characterization of the ceramic, contributing to searches for provenance as well as serialization. However, this task often requires invasive methods performed in the laboratory, which may not always be possible. This paper develops a non‐invasive and portable on‐site system for measuring the thickness of ceramic glazes. Based on the depth from focus technique, this method makes use of a classical camera, a macroscopic lens, a translation stage, and a laptop for system control. In this article, we test this method through the measurement of glaze for ten samples as compared to results obtained for sections through scanning electron microscopy.

Hierarchical macro to nano press molding of optical glasses by using metallic glasses

The fabrication of ideal optical components is a world-wide grand challenge facing us. Benefiting from the unique thermoplastic nature, precision glass molding (PGM) is considered as a promising method for rapid and precise fabrication of optical components. The success and proliferation of such methods critically rely on the manufacturing of robust and durable master molds. Although silicon-based molds relying on photolithographic forming are facile to manufacture, they are brittle and have limited longevity when used as the molds. To address this challenge, here, we propose a hierarchical macro to nano mold preparation method based on the thermoplastic forming ability of metallic glasses (MGs), which excels in micro and nano scale fabrication. After subsequently crystallizing the as-formed MG, we demonstrate that the crystalline MG is suitable as an excellent mold for molding optical glasses with service temperature up to 600 °C. Using this ‘spawning’ process, several metallic molds including macroscopic lens arrays, microscale gratings, and nano-lens arrays were successfully prepared, respectively. The minimum feature size of the mold is 300 nm and the optimum surface roughness is 7.43 nm. Correspondingly, we prepared hierarchical optical glass components with excellent optical properties using MG as molds.

The Political Imperative of World Cinema

Abstract This paper argues for the political urgency of the project of World Cinema, and an understanding of World Cinema as a dynamic totality. Totality here is not a generic, macroscopic lens, but a system that accounts for the co-existence of all cinemas as well as the uneven power relationships that determine the relative visibility or invisibility of cinemas in the global system. This structural inequity, a condition that underlies the differentiated cinematic flows, is also a methodological ruse in that it can only point to unequal relationships in discourses that define the current conceptions of World Cinema. An awareness of totality, we argue, makes it possible to return to films themselves as nodal points from which to begin the mapping of World Cinema through its complex networks of financing, distribution, and its circuits of legitimation (film festivals, academic discourses) which shape world cinema as a body of knowledge.

Entrepreneurship

In this paper, we reconsider the various states of rest within Austrian market process theory. While this theory certainly embodies a superior representation of market processes to the neoclassical general equilibrium theory, it falls short of producing a holistic theory of human action. The analysis left out those human actions that produce changes to the so-called ‘final state of rest,’ which have so far been taken as exogenous to the market process. These exogenous shocks include knowledge generation and preference shifting. However, I argue that these can and ought to be understood as market phenomena, and so belong within the scope of praxeological analysis. To capture these types of human action, I propose that a new and truly ‘final’ state of rest be introduced, which we term the ‘nirvana state of rest.’ This new state represents a ‘true’ final state, in which human action ceases because all needs, and thus all motivation to act, are completely and perpetually assuaged. Introducing this state into the analysis, we can break free from myopic analyses of mere present states of knowledge and values to observe and explain general tendencies in market processes, prices, and entrepreneurship. I also show how quarrels within Austrian circles might be resolved through this expanded, macroscopic lens.

Contemporary populist politics through the macroscopic lens of Randall Collins’s conflict theory

This paper draws on Collins’s conflict theory to understand the contemporary surge of populism. It puts forward an account centred on citizenship rights and the state, and on ‘my nation first’ politics in four countries: the US, Sweden, India and China. Collins has identified a capitalist crisis, the dynamics of geopolitical legitimacy, and state-penetrating bureaucracy as three central processes in modern societies. Especially the last of these focuses attention on the conflict between cosmopolitan elites and ‘the people’, construed in exclusionary terms, which is on the rise in all of the four cases discussed here. The paper analyses the similarities and differences between them, and sketches the prospects for populist politics.

Magic lantern shows through a macroscopic lens: topic modelling and mapping as methods for media archaeology

ABSTRACTThis article explores trends across Lucerna, an online web resource for magic lantern materials, by combining two digital approaches: topic modelling and geospatial mapping. Topic modelling identifies words that occur most frequently together in a large corpus of texts through a form of statistical analysis. Using this method, I studied 2,000 descriptions of magic lantern shows given between 1874 and 1903. While there were records from Canada, India, and New Zealand in this data set, most of these lantern shows occurred in England. The groupings of words, or ‘topics’, reflected the prevalence of the Church Army, Band of Hope, and Sunday Schools in Lucerna’s textual record. Mapping these patterns revealed that descriptions of magic lantern shows were relatively uniform across the UK, suggesting that magic lantern shows in urban and rural spaces were represented similarly in periodical literature. Since the topics did not vary by region, I studied how the most prevalent topics differed by host organization and how they changed over time. The article finds that descriptions of lantern shows given by evangelistic organizations shared vocabulary with those hosted by Sunday Schools and temperance societies. It also shows that evangelistic shows tended to avoid the language of entertainment, echoing earlier discourse about the magic lantern on the mission field, and that the decline in topics related to Sunday Schools over time corresponds with the rise of educational lantern lectures, particularly those given by secular institutions like the Royal Albert Memorial Museum in Exeter. Overall, the article suggests that topic modelling can be used to excavate the performance history of lantern shows by foregrounding latent linguistic similarities in published descriptions of these events.

Zoom systems with tuneable lenses and linear lens movements

BackgroundClassical zoom lenses are based on movements of sub-modules along the optical axis. Generally, a constant image plane position requires at least one nonlinear sub-module movement. This nonlinearity poses a challenge for the mechanical implementation.Tuneable lenses can change their focal length without moving along the optical axis. This offers the possibility of small system lengths.Since the focal range of tuneable lenses with significant aperture diameters is still limited, the use of tuneable optics in zoom lenses is usually restricted to miniaturized applications.MethodsTo solve the challenge of the nonlinear movement in classical zoom lenses and the limitations of tuneable lenses for macroscopic applications we propose a combination of both concepts. The resulting ‘Hybrid Zoom Lens’ involves linear movements of sub modules as well as changing the focal length of a tuneable lens.The movements of the sub-modules and the focal length tuning of the lens are already determined by the collinear layout of the zoom lens. Therefore, we focus on collinear considerations and develop a method that allows a targeted choice of specific collinear layouts for our ‘Hybrid zoom lenses’.ResultsBased on examples and an experimental setup we demonstrate the feasibility of our approach. We apply the proposed method to examples of classical zoom lenses and zoom lenses based exclusively on tuneable lenses. Thereby we are able to show possible advantages of our ‘Hybrid zoom lenses’ over these widespread system types.ConclusionsWe demonstrate important collinear considerations for the integration of tuneable lenses into a zoom lens. We show that the combination of classical zoom lens concepts with tuneable lenses offers the possibility to reach smaller system lengths for macroscopic zoom lenses while requiring only a small focal tuning range of the tuneable lens.

Lensfree OLEDs with over 50% external quantum efficiency via external scattering and horizontally oriented emitters

High efficiency is important for successful deployment of any light sources. Continued efforts have recently made it possible to demonstrate organic light-emitting diodes with efficiency comparable to that of inorganic light-emitting diodes. However, such achievements were possible only with the help of a macroscopic lens or complex internal nanostructures, both of which undermine the key benefits of organic light-emitting diodes as an affordable planar light source. Here we present a systematic way to achieve organic light-emitting diodes with ultrahigh efficiency even only with an external scattering film, one of the simplest low-cost outcoupling structures. Through a global, multivariable analysis, we show that scattering with a high degree of forwardness has a potential to play a critical role in realizing ultimate efficiency. Combined with horizontally oriented emitters, organic light-emitting diodes equipped with particle-embedded films tailored for forward-intensive scattering achieve a maximum external quantum efficiency of 56%.

Efficient Computational Methods for Optical Components

When performing computations to answer questions surrounding the design of optical components, several different numerical methods can be useful. Which method to choose depends on the size of the component and the nature of the electromagnetic wave propagation. Very accurate general-purpose methods, so called full-wave methods, are frequently used when designing micro- and nano-optical devices, whereas approximate methods such as ray tracing are needed when designing macroscopic lens systems. The following tutorial gives a quick background of the traditional methods and then demonstrates the newer beam envelope method and its virtues in computational optics.

Macroscopic ice lens growth in hardened concrete

Spalling of concrete has been observed in water retaining concrete structures exposed to long periods of freezing weather. A hypothesis is that poor quality concrete, inadequate compaction or aging make hardened concrete susceptible to macroscopic ice lens growth, i.e. ice segregation. To simulate winter conditions, the top surface of concrete specimens was subjected to freezing, whereas the bottom surface was submerged in heated water. Given constant thermal conditions, ice segregation occurred in sound concrete with w/c-ratio 0.9 and higher. In concrete with internal frost damage, ice segregation occurred within a few days regardless of the w/c-ratio. Ice segregation also occurred in specimens with paper sheets cast into the concrete to form cavities. However, the period of freezing required to facilitate ice segregation increased with decreasing w/c-ratio. The risk of macroscopic ice lens growth in actual structures cannot be overlooked since unfavourable temperature and moisture conditions may exist in winter.

City branding research and practice: An integrative review

Closing the gap between theory and practice presents a major challenge for branding. However, a disconnect has formed between city branding research and practice. This article argues that the divergent evolutionary paths of city branding research and practice contribute to this disconnect. Specifically, we review the evolution of city branding research and practice through a macroscopic lens in order to delineate major shifts in the philosophies and assumptions shaping each trajectory. In terms of practice, we map the development of city brand management over five waves covering primitive attempts to adjust what cities mean to people, boosterish city promotion, entrepreneurial urban governance, formalised city marketing and, finally, a rhetorical city brand focus. We then identify four major waves in city branding research: (i) initial possibilities, (ii) application and adaption of existing branding theory, (iii) development of a critical lens and (iv) progressive approaches that intersect with the co-creation branding paradigm. As well as providing a basis for mutual understanding and collaboration between researchers and practitioners, examination of both evolutionary paths indicates major research gaps in the city branding literature that appear particularly pertinent to bridging the city branding theory-practice gap.

Generalized propagation of light through optical systems. II. Numerical implications.

We present an algorithm implemented in a MATLAB toolbox that is able to compute the wave propagation of coherent visible light through macroscopic lenses. The mathematical operations that complete the status at the end of the first paper of this sequence, where only limited configurations of the propagation direction were allowed toward arbitrarily directed input beam computations, are provided. With their help, high numerical aperture (NA) field tracing is made possible that is based on fast Fourier routines and is Maxwell exact in the limit of macroscopic structures and large curvature radii, including reflection and transmission. Whereas the curvature-dependent terms in the Helmholtz equation are under analytical control through the first perturbation order in the curvature, they are only included in the propagation distance in the current investigation for the sake of reasonable time consumption. We give a number of examples that demonstrate the strengths of our approach, describe essential differences from other approaches that were not obvious when Paper 1 was written, and list a number of drawbacks and possible simplifications to overcome them.

Effects of varying interfacial surface tension on macroscopic polymer lenses

We investigate macroscopic polymer lenses (0.5- to 2.5-cm diameter) fabricated by dropping hydro- phobic photocurable resin onto the surface of various hydrophilic liquid surfaces. Due to the intermolecular forces along the interface between the two liquids, a lens shape is formed. We find that we can vary the lens geometry by changing the region over which the resin is allowed to spread and the surface tension of the substrate to produce lenses with theoretically determined focal lengths ranging from 5 to 25 mm. These effects are varied by changing the container width, substrate composition, and substrate temperature. We present data for five different variants, demonstrating that we can control the lens dimensions for polymer lens applications that require high surface quality. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Deep-UV microsphere projection lithography.

In this Letter, we present a single-exposure deep-UV projection lithography at 254-nm wavelength that produces nanopatterns in a scalable area with a feature size of 80 nm. In this method, a macroscopic lens projects a pixelated optical mask on a monolayer of hexagonally arranged microspheres that reside on the Fourier plane and image the mask's pattern into a photoresist film. Our macroscopic lens shrinks the size of the mask by providing an imaging magnification of ∼1.86×10(4), while enhancing the exposure power. On the other hand, microsphere lens produces a sub-diffraction limit focal point-a so-called photonic nanojet-based on the near-surface focusing effect, which ensures an excellent patterning accuracy against the presence of surface roughness. Ray-optics simulation is utilized to design the bulk optics part of the lithography system, while a wave-optics simulation is implemented to simulate the optical properties of the exposed regions beneath the microspheres. We characterize the lithography performance in terms of the proximity effect, lens aberration, and interference effect due to refractive index mismatch between photoresist and substrate.