Kind Of Lens Research Articles

The effect of the back optic zone diameter on the treatment zone area and axial elongation in orthokeratology.

To investigate the influence of corneal parameters on the treatment zone area (TZA) after Corneal Refractive Therapy (CRT) with a 5.0-mm back optical zone diameter (BOZD) were worn and to compare changes in the axial length (AL) with traditional 6.0-mm BOZD lenses. This retrospective study involved 146 subjects (7-12years) who wore orthokeratology (ortho-K) lenses for one year: 86 subjects were treated with CRT 5.0-mm lenses, and 60 subjects were treated with CRT 6.0-mm lenses. The TZA was measured after one year of ortho-K treatment. Both TZA and AL elongation after wearing the two kinds of lenses was compared. The parameters were recorded in the CRT 5.0 group: flat K, steep K, corneal toricity, e value, and anterior corneal elevation values at the 3-, 4-, and 5-mm chords along the principal meridians of the superior, inferior, nasal, and temporal sides. The relationships between these data and the TZA were analyzed. The TZA was 12.90±5.15mm2 and 20.61±4.54mm2, and the AL elongation was 0.15±0.18mm and 0.26±0.18mm in the CRT 5.0 group and the CRT 6.0 group, respectively (all p<0.001). The one-year AL elongation was significantly associated with initial age and the TZA (r=-0.394, 0.393; all p<0.001) in the CRT 5.0 group. The following corneal parameters were found to have statistically significant correlations with the TZA: the e value, difference in corneal elevation (nasal-temporal at the 3-, 4-, and 5-mm chord), and the absolute value of elevation difference (nasal-temporal at the 3- and 4-mm chord and inferior-superior at the 3-, 4-, and 5-mm chord). The e value was the only relevant factor for the TZA by multiple regression analysis (unstandardized β=14.219, p=0.008). In the CRT 6.0 group, the one-year AL elongation was statistically significantly associated only with initial age (r=-0.605, p=0.005), but not with the TZA (p=0.161). A smaller TZA induced by a smaller BOZD may be beneficial for retarding AL elongation in children undergoing ortho-K treatment. The morphology and eccentricity of the cornea may show effects on the TZA.

Hide and seek: Writing fiction as a way of finding hidden selves

ABSTRACT This paper is interested in the hidden selves that hover silently in the spaces that all human relationships create. It asks how these hidden self-states can find the light of day and suggests that one way is through fictional creative writing. The author shares a piece of fictional writing in which an elusive character—Isobel—appears. This ethereal and fictional manifestation occurs in the context of excruciatingly painful relational experiences in which the narrator describes repetitive and painful struggles for transformation. Speculative attempts to understand the meaning of the fictional material reveal an emerging forward edge and a fledgling sense of agency. But more. It elaborates how the creative writing process offers a different kind of lens through which to locate, elaborate, see, experience and be empathic with our own and, by extension, with our patients’ hidden self-states.

Roughness classification detection of Swin-Transformer model based on the multi-angle and convertible image environment

ABSTRACT Current machine vision methods for surface measurement rely excessively on feature design to quantify surface morphology and build predictive models, but metric design suffers from human intervention, and data acquisition is heavily dependent on light source environment and shooting angle. This paper uses the Swin-Transformer model to evaluate and classify roughness directly on colour images of milled samples acquired in a convertible image environment. The images used in the experiment are taken in a completely dark environment and in an environment disturbed by light sources, such as LED energy-saving lamps during the day. By using two kinds of lenses and combining custom light sources and ordinary light sources, respectively, and for different angles, it deeply simulates the environment of online inspection of industrial production. The roughness classification results prove that the method has very good robustness to light source environment and shooting angle, avoiding the artificial design and extraction of image features. The accuracy of the validation set of samples can reach 98.94%, while the accuracy of the test set can reach 97.54%. To wrap it up, the method provides an optimised strategy for visual roughness measurement in industrial production.

Highly Concentrated Solar Flux of Large Fresnel Lens Using CCD Camera-Based Method

Fresnel lens is a kind of lens that can concentrate sunlight up to a level of thousands of suns with small space occupation which is widely used in the research of sunlight concentration and transmission systems via optical fiber. Most studies on the concentrated flux of lenses use experimental methods to measure the flux distribution on the receiver of parabolic trough solar concentrators, solar power towers, and parabolic dish concentrators, while for Fresnel lenses, especially large-aperture Fresnel lenses such as the one in this manuscript, the simulation approach was mostly used. In response to this problem, this study has developed an experimental system for measuring the concentrated flux density of Fresnel lenses. A charge-coupled device (CCD) camera was used to capture the image of spot of large-aperture (968 mm) Fresnel lenses in the CCD camera-based method, and a heat flow meter was used to calibrate the spot brightness image obtained by the CCD camera. Experimental data show that the peak flux of concentrated spot can reach 4.06 MW/m2. This method confirms the simulation results of previous studies that using the rays tracing method, that is, the flux level of the Fresnel lenses can reach 5000 suns. The experimental results demonstrated the CCD camera-based method combined with a heat flow meter is competent in measuring the intensity of flux with a level of 5000 suns.

Focusing Characteristics of a Transcranial Ultrasonic Lens of a Point-like Scatterer Array Partially Covering the Head

This lens can focus an incident plane wave to the diffraction limit in the direction perpendicular to the incident direction, but the peak width in the propagation direction is more than five times that. This phenomenon is a characteristic of Fresnel lenses, and this lens, which is a kind of lens, is also not avoided. It can be improved by increasing the width of the lens, whereas it is not practical. In this work, as an alternative method, we propose to arrange a point-like scatterer so as to partially cover the head. It is shown that the proposed method can suppress the spread of the focal spot at the focal point in the propagation direction.

БОЛЕЗНИ, ЭПИДЕМИИ И ПАНДЕМИИ В ГЛОБАЛЬНОЙ ИСТОРИИ. ЧАСТЬ 1

A review of a thematic issue of the Journal of global history presents traditional and new approaches to the study of histories of disease and epidemics. Epidemics and pandemics are presented as a kind of lens within global and other areas of historical scholarship. Different interdisciplinary approaches to the study of these phenomena are also offered.

Spatio-temporal ultrasound beam modulation to sequentially achieve multiple foci with a single planar monofocal lens

Ultrasound focusing is a hot topic due to its multiple applications in many fields, including biomedical imaging, thermal ablation of cancerous tissues, and non destructive testing in industrial environments. In such applications, the ability to control the focal distance of the ultrasound device in real-time is a key advantage over conventional devices with fixed focal parameters. Here, we present a method to achieve multiple time-modulated ultrasound foci using a single planar monofocal Fresnel Zone Plate. The method takes advantage of the focal distance linear dependence on the operating frequency of this kind of lenses to design a sequence of contiguous modulated rectangular pulses that achieve different focal distances and intensities as a function of time. Both numerical simulations and experimental results are presented, demonstrating the feasibility and potential of this technique.

Legible and Thus Legitimate? Reading and Blurring Gender in China, Today and Yesterday

In her keynote address to the conference from which this special issue of China Perspectives has emerged, Prof. Gail Hershatter spoke of gender and “blindspotting”: how practices of looking and bringing something into focus may cause other aspects to simultaneously fade out (Hershatter 2019). This idea builds on her previous work conceptualising gender as a “kind of lens that allows one to zoom in and out,” an anchoring foothold that is “multi-scalar rather than scalable” (Hershatter 2012: 88...

Багательний стиль В. Сильвестрова в контексті ґенези жанру багателі в українській музиці

Research objective is the analysis of the bagatelle style of the V. Silvestrov in the panorama of the basic trends of development of the bagatelle in Ukrainian music in the aspect of individual-compositional interpretation of the genre. The methodology of the research is based on the unity of various relevant methods: the approaches of historical musicology, comparative and system methods, elements of genre and style analysis. The scientific novelty – The article for the first time presents a panorama of the bagatelle genre in the works of Ukrainian composers from the first third of the nineteenth century to the present days. Conclusions. In Ukrainian music we observe a wide range of creative reading of the bagatelle genre in accordance with the author’s style – from the traditional “easy” (or even didactic) miniature to the whole universe, embodied in a small form, in the legacy of V. Silvestrov. Bagatelles of the Ukrainian composers are presented in various modifications – as individual plays, cycles or their parts (including as one of the numbers of the ballet). Side by side with piano bagatelle, there are also exist works for chamber ensemble and string orchestra, as well as bagatelle performances. However, most of the examples of the bagatelle of Ukrainian authors remain within the traditional interpretation of the genre as a small, easy to perform play, most composers turn to the genre of bagatelle rather sporadically, without building a special concept around it. For Silvestrov, the bagatelle becomes a kind of lens through which the artist looks at the world, and bagatelle principle (“bagatellity”) becames an expression of a certain way of thinking, the basis of style, the features of which are embodied not only in the bagatelle themselves, but also extrapolated to other genres. Sylvester bagatelle is a bagatelle in the highest sense, which is far from “trifles”, goes beyond the usual understanding of the genre, becomes, according to the author himself, the “grain of music”, the embodiment of Platonic ideas, acquires the features of a meta genre. The samples of the bagatelle genre in Ukrainian music considered in this publication need a more systematic analysis in the future, one of the tasks of which may be to outline the typology of Ukrainian bagatelle.

Phase-shifting lensless Fourier-transform holography with a Chinese Taiji lens.

Compared to off-axis holography, phase-shifting technology takes full use of the space-bandwidth product of the detector array. Here we introduce the Chinese Taiji into diffractive lenses and generate the phase-shifting focal spots, which not only can be used for a spherical reference wave, but also make it possible to realize the lensless Fourier-transform holography. The experimental results of a 1951 U.S. Air Force resolution test target verify the validity of the above theory in the optical region. Owing to the amplitude-only diffractive lenses, these kinds of lenses will have great potential in x-ray holography or biochemical microscopy for the next generation of synchrotron radiation and free electron lasers in the future.

Research and Design of Compound Fresnel Concentrator

An efficient and compact concentrator Fresnel concentrator is discussed and designed,The central region is a conventional Fresnel lens designed according to Snell's law of refraction,The edge region is designed to be TIR (internal total reflection) prism.According to the Fresnel formula,the best segmentation position and the optimum focal length of two kinds of lens are calculated,and use SolidWorks to build 3D model,The ray tracing simulation of the designed lens is carried out by using TracePro software.The results show that the efficiency is 89.6% and the F/# is 0.5 at high concentration. The efficiency of the traditional Fresnel concentrator is only 66% when the F/# is the same. The design goal of compact structure and high light performance is achieved.

The Grounds of Tort, Part I: Private Wrongs and Practical Reasoning

Tort theory is widely thought to split cleanly into two seams. Some trace tort's foundations to a deontic form of morality; others to an instrumental, policy-oriented system of loss allocation. Civil Recourse Theory (CRT) resists this binary. It argues that torts comprise a basic legal category, and that this category constitutes an autonomous domain of normativity. But while the theory rightly rejects the binary between corrective justice theory on the one hand and the law-and-economics framework on the other, its insistence on tort law's deontic character is more difficult to sustain, and ultimately cannot be vindicated by doctrinal, historical, or institutional arguments considered apart from their philosophical foundations. Using the familiar question whether tort directives are guidance rules or liability rules as a kind of lens, or prism, this paper shows how requirements of practical reasoning undermine CRT's account of private wrongs. If tort's directives are reasons for action, placing them within the normative domain is not something we can do for free: if we are going to claim that they exert robust normative force, we must account for the grounds of this force and why we need to posit it in the face of simpler, less extravagant explanations of a relatively straightforward system of dispute resolution. CRT tries to satisfy its explanatory burden by co-opting Hart's internal point of view, but this leveraging strategy cannot succeed. The internal point of view interprets legal directives as guides to action, but in tort law, as in private law more generally, legal directives merely demand conformity, not compliance. With the connection between its interpretation of tort directives and the internal point of view thus severed, CRT faces a dilemma: it is either critically incomplete in its account of the grounds of private wrongs, or it is insufficiently responsive to the realities of legal practice. In closing, I suggest that the theory's proponents do better by resisting the temptations of middle-of-the-road metaphysics and instead recognize either the moral or the positivist roots of private wrongs.

Flat polarization-controlled cylindrical lens based on the Pancharatnam–Berry geometric phase

The working principle of ordinary refractive lenses can be explained in terms of the space-variant optical phase retardations they introduce, which reshape the optical wavefront curvature and hence affect the subsequent light propagation. These phases, in turn, are due to the varying optical path length followed by light at different transverse positions relative to the lens center. A similar lensing behavior can, however, be obtained when the optical phases are introduced by an entirely different mechanism. Here, we consider the ‘geometric phases’ that arise from the polarization transformations occurring in anisotropic optical media, named after Pancharatnam and Berry. The medium anisotropy axis is taken to be space-variant in the transverse plane and the resulting varying geometric phases give rise to the wavefront reshaping and lensing effect, which however also depends on the input polarization. We describe the realization and characterization of a cylindrical geometric-phase lens that is converging for a given input circular-polarization state and diverging for the orthogonal one, which provides one of the simplest possible examples of optical elements based on geometric phases. The demonstrated lens is flat and only a few microns thick (not including the supporting substrates); moreover, its working wavelength can be tuned and the lensing can be switched on and off by the action of an external control electric field. Other kinds of lenses or more general phase elements inducing different wavefront distortions can be obtained by a similar approach. Besides their potential for optoelectronic technology, these devices offer good opportunities for introducing college-level students to an advanced topic of modern physics, such as the Berry phase, with the help of interesting optical demonstrations.

New method for lens thickness measurement by the frequency-shifted confocal feedback

We describe a new method for lens thickness and air gap measurement based on the frequency-shifted confocal feedback. The light intensity fluctuation is eliminated by the heterodyne modulation and the detection sensitivity is improved prominently by the frequency-shifted feedback effect. The measurement results for different materials and kinds of lenses are presented in the paper, including K9 plain glasses, fused silica plain glass, and K9 biconvex lens. The uncertainty of the axial positioning is better than 0.0005mm and the accuracy reaches micron range. It is promising to be applied in the multi-layer interface positioning and measurement area.

Smart multifunction diffractive lens experimental validation for future PV cell applications.

Recently, diffractive optical elements (DOE's) have attracted more attention for applications to third generation PV cells. Some DOE types can provide multiple functions such as spectrum splitting and beam concentration (SSBC) simultaneously. An off-axis diffractive lens has been designed and its ability to achieve the SSBC proved experimentally. This lens can be used to separate the solar spectrum in the Vis-NIR range into two bands with a low concentration factor, and about 70% optical efficiency. It is expected that this kind of lens can be integrated with the lateral multijunction PV cells to build an effective compact solar system.

PECULIARITIES OF DESIGNING OF FACES AND FOUNDATION OF THE CHEOPS PYRAMID

This article contains the results of calculation of geometric characteristics of faces and foundation of the Cheops pyramid, assuming that they are a kind of lenses that concentrate energy of the Earth and the Sun inside the pyramid.

Development of a Mechanical Actuator for Active Lenses

SummaryVariable focus lenses can vary their shape and consequently their focus when a stimulus is applied. This kind of lenses, on some applications, has advantages over the regular lenses because of their smaller size and weight. Different types of stimulus can be used to change the shape of these lenses; the element that applies the stimulus is called actuator. Lenses deformed by a mechanical force are interesting devices that work in a way similar to human eyes. The muscles around a human eye compress or relax its lens every time a focus change is needed. On this paper we describe a voice coil actuator that applies mechanical force over a flexible polymeric lens, changing its shape and consequently its focus. The applied force, the deformation of the lens and its convergence power are functions of the driving current in the voice coil actuator. The maximum force applied by the actuator is 0.48N. The convergence power is also dependent of optical and viscoelastic properties of the lens material.

Whose Design? Physical, Philosophical and Theological Questions Regarding Hawking and Mlodinow’s Grand Design

Stephen Hawking and Leonard Molodinow’s (HM) The Grand Design1 faces some of the big questions of the human thought: “Why is there something rather than nothing? Why do we exist? Why this particular set of laws and not some other?” (p. 10, p. 171). Their answer is rooted in the concepts of “scientific determinism” (p. 30, p. 34) and “model-dependent realism” (p. 7). According to this epistemological view, “our perception—and hence the observations upon which our theories are based—is not direct, but rather is shaped by a kind of lens, the interpretive structure of our human brains” (p. 46), so “a well-constructed model creates a reality of its own” (p. 172). This background helps to understand some of the most controversial assertions of the book. In physics, scientists may prefer one model from another when the former explains more experiments and does it better.

Optical Quality and Vision with Iris-Coloring Soft Contact Lenses

To study the influence of iris-coloring soft contact lenses, designed for changing apparent iris color, on optical quality and vision. Eighty subjects were included in this study. All participants were classified as emmetropic, with monocular best-corrected visual acuity of 20/20 or better. For 40 subjects, we measured the optical quality (aberrations, the Strehl ratio, and the objective scattering index) and visual performance before and after wearing the cosmetic soft contact lenses. We also measured the optical quality and visual performance for the other 40 subjects but with a different kind of lens (fantasy soft contact lenses). Iris-coloring soft contact lenses significantly increased coma-like and total higher-order aberrations and objective scattering index (p < 0.05). We also found a significant deterioration in the Strehl ratio. The contrast sensitivity function significantly decreased only after wearing the fantasy soft contact lenses (p = 0.047). Iris-coloring soft contact lenses deteriorate the optical quality and worsen the contrast sensitivity function. Iris-coloring soft contact lens wearers should be informed about the effects on optical quality and visual function.

소프트콘택트렌즈의 유형에 따른 각막형태의 변화

목적: 콘택트렌즈의 함수율, 재질, 굴절력의 차이에 따른 착용전후의 각막의 형태 변화를 살펴보고자 하였다. 방법: 5가지 유형의 콘택트렌즈를 사용하여 렌즈 착용 전후의 두께차이를 비교하였다. 각막의 중심부와 각막 중심에 떨어진 거리와 방향에 따른 렌즈 착용 전, 후의 각막의 두께, 각막 전, 후면 곡률, 고위수차의 변화를 조사하였다. 측정에 사용된 장비로는 ORB ScanII(Bausch & Lomb Inc, ver 3.14)로 각막 지형도 및 각막 두께를 측정하였으며, 고위수차(high order aberration) 분석을 위하여 Zywave(Bausch & Lomb Inc, ver 5.20)를 사용 하였다. 결과: 산소투과가 낮은 하이드로겔 재질의 소프트 콘택트렌즈(T2 lens)에서 각막의 두께가 증가하는 경향이 두드러지게 나타났다. 각막 중심에서 가장 많은 변화를 보였으며, 중심에 가까울수록 변화정도가 증가하였다. 각막의 방향에 있어서는 코 쪽이 가장 많이 변하였다. 결론: 본 연구에서 사용한 함수율, 재질, 디자인이 다른 5종의 콘택트렌즈 중 Dk가 28이상의 산소투과도를 가진 렌즈에서는 각막의 형태 변화가 적었으며, 산소투과도가 매우 낮은 렌즈에서 가장 많은 각막형태의 변화가 나타났다. Purpose: This study was to investigate changes in the thickness of cornea, curvature of cornea, and aberration depending on the water contents, materials, and refractive power of contact lens. Methods: The differences in the corneal thickness between pre- and post-wearing the lenses were compared using 5 kinds of lenses. The changes in the corneal thickness, the curvatures of the anterior and posterior cornea, and high order aberration (HOA) before and after wearing the lenses were investigated at the center of the cornea, and the different distance and the direction away from the center of the cornea. For the equipments of measurement, ORB ScanII (Bausch & Lomb Inc, ver 3.14) was used to measure the corneal topography and thickness, and Zywave (Bausch & Lomb Inc, ver 5.20) was used to analyze the high order aberration. Results: Five (S1, S2, S3, T1, T2) of the lens was used for this study, excluding the lens T2 lens has four lenses and the thickness of the corneal shape, but the impact is minimal. In the case of the hydrogel soft contact lenses (T2 lens) with low oxygen permeability, the corneal thickness showed distinct increasing patterns. The high order aberration and coma aberration were most changed in the silicon hydrogel toric lens, while the depth of anterior was most changed in the hydrogel toric lens. Conclusion: Among the 5 kinds of contact lenses with different water contents, materials, and refractive power used for this study, the corneal shape change was small for the lenses with an oxygen permeability (Dk) of more than 28, and the largest for the lenses with a very low oxygen permeability.