Relevant bibliographies by topics / Refraction

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Academic literature on the topic 'Refraction'

Author: Grafiati
Published: 4 June 2021
Last updated: 31 July 2024

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Journal articles on the topic "Refraction"

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Aldridge, David F., and Douglas W. Oldenburg. "Refractor imaging using an automated wavefront reconstruction method." GEOPHYSICS 57, no. 3 (March 1992): 378–85. http://dx.doi.org/10.1190/1.1443252.

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The classical wavefront method for interpreting seismic refraction arrival times is implemented on a digital computer. Modern finite‐difference propagation algorithms are used to downward continue recorded refraction arrival times through a near‐surface heterogeneous velocity structure. Two such subsurface traveltime fields need to be reconstructed from the arrivals observed on a forward and reverse geophone spread. The locus of a shallow refracting horizon is then defined by a simple imaging condition involving the reciprocal time (the traveltime between source positions at either end of the spread). Refractor velocity is estimated in a subsequent step by calculating the directional derivative of the reconstructed subsurface wavefronts along the imaged interface. The principle limitation of the technique arises from imprecise knowledge of the overburden velocity distribution. This velocity information must be obtained from uphole times, direct and reflected arrivals, shallow refractions, and borehole data. Analysis of synthetic data examples indicates that the technique can accurately image both synclinal and anticlinal structures. Finally, the method is tested, apparently successfully, on a shallow refraction data‐set acquired at an archeological site in western Crete.
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Boengas, Sawitri, and Rivan Virlando Suryadinata. "Perbedaan Hasil Pemeriksaan Tajam Penglihatan dan Refraksi pada Anak Usia 4-12 tahun pada Pemeriksaan Non Sikloplegik dan Sikloplegik." Surya Medika: Jurnal Ilmiah Ilmu Keperawatan dan Ilmu Kesehatan Masyarakat 17, no. 1 (December 20, 2021): 1–6. http://dx.doi.org/10.32504/sm.v17i1.483.

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ABSTRACTBackground of Study: Globally, there are 19 million children with visual impairment, 12 million are caused by uncorrected refractive errors. Uncorrected refractive errors in children have the potential to cause amblyopia, severe visual impairment and even blindness. Refractive errors in children must receive proper management. Cycloplegic refraction is a gold standart method for children to minimize the effect of strong accommodation in childhood. The purpose of the study: to analyze the differences between the results of the visual acuity examination and refractive examination between the non-cycloplegic and the cycloplegic examination in children aged 4-12 years. Methods: This study is an analytical observational study through recording medical records of patients 4-12 y.o between November 2020-October 2021, which were carried out with non-cycloplegic and cycloplegic refraction. Data were analyzed by SPSS with WilcoxonTest. Results: There were 106 eyes of children consisting of 62(58%) boys and 44(42%) girls. Based on statistical tests, there was no difference in natural visual acuity on non-cycloplegic and cycloplegic examinations. There were differences between non-cycloplegic and cycloplegic refractions. The difference in refraction results towards the positive spherical 75(70,75%) children towards the negative spherical 21(19.81%) children, only 10(9,4%) children showed the same results between the two refractive stages. Conclusion: There was no difference in children's visual acuity between the non-cycloplegic examination and the cycloplegic examination, but there were differences in the results of non-cycloplegic and cycloplegic refraction in children aged 4-12 years. Therefore, the determination of the size of the glasses in children must be done through cycloplegic refraction.Keywords : Refraction, Cycloplegic Refraction, Visual Acquity, Children
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Mohamed, Fathimath Nestha, and Rokiah Omar. "A situational analysis of clinical refraction services in the capital city of the Maldives." Medical hypothesis discovery and innovation in ophthalmology 10, no. 4 (February 24, 2022): 146–55. http://dx.doi.org/10.51329/mehdiophthal1433.

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Background: Uncorrected refractive error is a leading cause of visual impairment globally. This study aimed to determine the current state of clinical refraction services and barriers to service provision in the capital city of the Maldives. Methods: This cross-sectional, descriptive-analytical study used a purposive sampling technique. The list of facilities providing refraction services in the city of Malé was compiled through a desk review and finalized after verification by personnel from the Ministry of Health. The availability of human resources and infrastructure was measured using a pre-coded questionnaire that also listed barriers to service provision, followed by on-site observations and subsequent data analysis. Results: Three clinical ophthalmology departments within hospitals, two ophthalmology hospitals, and nine primary eye care centers were selected for this study. The private sector (n = 12, 85.7%) was the primary provider of refractive error services. All facilities possessed the essential equipment required for refraction. Only optometrists and ophthalmologists conducted refraction. Contact lens assessment and low vision services were not available at any facility. The number of refractions conducted in Malé annually was 145,392. Human resources and management-related factors were the major barriers to the provision of clinical refraction services (n = 21, 44.7%). Conclusions: Accessibility to refractive error management and low vision services is needed in Malé to meet current population needs. Existing resources, including humans and equipment, require augmentation regarding service provision and enhancement. Knowledge of these barriers could lead to the upscaling of refraction services in Malé, Maldives by health policy makers.
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Ejukonemu, Barbie O. M. "Refracting The Diseased Eye." Bayero Journal of Nursing and Health Care 3, no. 2 (September 11, 2022): 893–97. http://dx.doi.org/10.4314/bjnhc.v3i2.9.

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Refractive error refers to ocular refractive status where images of objects of regard do not fall on the retina in a relaxed eye - the ametropic eye. Thus, objects are perceived as blur. Refractive error is an aberration in an otherwise normal physiological phenomenon and not a disease. Uncorrected refractive errors are the second most causes of blindness after cataract and the cause of almost half of visual impairment. Clinical refraction is a careful scientific procedure employed to correct refractive error. Given that refractive error is the most common reason patients present to the eye care practitioner, a lot of attention must be given to refraction. When an irreversible eye disease co-exist with refractive error, then correction of refractive error under this circumstance; refracting the diseased eye (RDE) become very challenging and painstaking. There will be likelihood of irregularities in the transparent refractive surfaces of the eye due to disease or surgery which make refraction difficult both for the patient and the examiner. Personal clinical experience of the author who is a low vision consultant and review of related literature from textbooks and journals are brought to bear in this article. This paper is a review of the RDE algorithm with delineation of these steps to enable an effective refractive endpoint for the eye with disease. The paper will enable young Optometrists to deal with refractive error masquerading irreversible eye disease. It is also an essential reading for the low vision Optometrist in mastering the art and science of low vision refraction.
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Dent, B. "Practical 3D refraction statics." Exploration Geophysics 20, no. 2 (1989): 207. http://dx.doi.org/10.1071/eg989207.

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Analysis of refracted first breaks has traditionally assumed that the data have been collected using special geometries that enhance the results, e.g. reversed profiles with regularly spaced geophones in-line between two shots. The geometries used to collect most 3D reflection data are quite different. Thus refraction analysis to obtain statics using traditional methods requires both approximations and selection of a subset of the data. The surface-consistent method allows use of nearly all the data, thus providing the high redundancy required for statistical robustness. A large survey incorporating both a new 3D survey and older 2D lines yielded refraction statics that greatly improved the final results.The surface-consistent method assumes that the refractor can be approximated by a horizontal plane under each station. When the refracting surface is steeply dipping, this assumption may break down. The Generalized Reciprocal Method is a traditional refraction analysis technique that gives improved results for steeply-dipping refracting surfaces. The surface-consistent method can also be made less sensitive to dip by a generalization, i.e. assume a dipping plane under each station. The refracting surface between the stations can be approximated by interpolation of these planes using the "linear projection" technique. A comparison of results using the two surface-consistent methods on synthetic data generated from a model of a buried, steep-walled valley shows the superior results obtainable.
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Carpena-Torres, Carlos, Laura Batres, María Serramito, and Gonzalo Carracedo. "Repeatability of Subjective Refraction in Different Age Groups." Photonics 11, no. 7 (July 2, 2024): 634. http://dx.doi.org/10.3390/photonics11070634.

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Background: The purpose of this study was to assess the inter-examiner repeatability of subjective refraction across diverse age cohorts, an aspect not previously investigated. Methods: A cross-sectional, randomized study enrolled 86 participants (mean age: 37.0 ± 18.0 years), distributed into three groups: youth, non-presbyopic adults, and presbyopic adults. Each participant underwent three subjective refractions by three different optometrists on separate days. Repeatability analysis encompassed all refractive variables (M, J0, and J45). Results: There were no significant differences between optometrists in all refractive variables for either the overall sample or across age groups (p ≥ 0.05). Additionally, no correlation was found between participants’ age and the mean difference in refractive variables across optometrists (p ≥ 0.05). The 95% confidence interval of repeatability (r) for the total sample was ±0.70 D for M, ±0.29 for J0, and ±0.21 D for J45. Conclusions: Based on these findings and previous research, it is suggested to establish 95% limits of agreement of ±0.75 D for M, and between ±0.25 D and ±0.50 D for both J0 and J45 when validating new refraction systems compared to subjective refraction as the gold standard, regardless of the age of the subjects evaluated.
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Leffler, Christopher T., Martin Wilkes, Juliana Reeves, and Muneera A. Mahmood. "Postoperative Refraction in the Second Eye Having Cataract Surgery." ISRN Ophthalmology 2011 (December 10, 2011): 1–6. http://dx.doi.org/10.5402/2011/273923.

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Introduction. Previous cataract surgery studies assumed that first-eye predicted and observed postoperative refractions are equally important for predicting second-eye postoperative refraction. Methods. In a retrospective analysis of 173 patients having bilateral sequential phacoemulsification, multivariable linear regression was used to predict the second-eye postoperative refraction based on refractions predicted by the SRK-T formula for both eyes, the first-eye postoperative refraction, and the difference in IOL selected between eyes. Results. The first-eye observed postoperative refraction was an independent predictor of the second eye postoperative refraction () and was weighted more heavily than the first-eye predicted refraction. Compared with the SRK-T formula, this model reduced the root-mean-squared (RMS) error of the predicted refraction by 11.3%. Conclusions. The first-eye postoperative refraction is an independent predictor of the second-eye postoperative refraction. The first-eye predicted refraction is less important. These findings may be due to interocular symmetry.
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Kumar, Rajesh S., Caitlin A. Moe, Deepak Kumar, Mahalakshmi V. Rackenchath, Sathi Devi A. V., Sriharsha Nagaraj, Dionna M. Wittberg, Robert L. Stamper, and Jeremy D. Keenan. "Accuracy of autorefraction in an adult Indian population." PLOS ONE 16, no. 5 (May 19, 2021): e0251583. http://dx.doi.org/10.1371/journal.pone.0251583.

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Purpose Autorefractors allow non-specialists to quickly assess refractive error, and thus could be a useful component of large-scale vision screening programs. In order to better characterize the role of autorefraction for public health outreach programs in resource-limited settings, the diagnostic accuracy of two autorefractors was assessed relative to subjective refraction in an adult Indian population. Methods An optometrist refracted a series of patients aged ≥50 years at an eye clinic in Bangalore, India using the Nidek ARK-900 autorefractor first, followed by the 3nethra Royal autorefractor, and then subjective refraction. The diagnostic accuracy of each autorefractor for myopia, hyperopia, and astigmatism was assessed using subjective refraction as the reference standard, and measures of agreement between refractions were calculated. Results A total of 197 eyes in 104 individuals (mean age 63 ± 8 years, 52% female) were evaluated. Both autorefractors produced spherical equivalent estimates that were on average more hyperopic than subjective refraction, with a measurement bias of +0.16 D (95%CI +0.09 to +0.23D) for Nidek and +0.42 D (95%CI +0.28 to +0.54D) for 3nethra. When comparing pairs of measurements from autorefraction and subjective refraction, the limits of agreement were approximately ±1D for the Nidek autorefractor and ±1.75D for the 3Nethra autorefractor. The sensitivity and specificity of detecting ≥1 diopter of myopia were 94.6% (95%CI 86.8–100%) and 92.5% (95%CI 88.9–97.5%) for the Nidek, and 89.2% (95%CI 66.7–97.4) and 77.5% (95%CI 71.2–99.4%) for the 3Nethra. The accuracy of each autorefractor increased at greater levels of refractive error. Conclusions The sensitivity and specificity of the Nidek autorefractor for diagnosing refractive error among adults ≥50 years in an urban Indian clinic was sufficient for screening for visually significant refractive errors, although the relatively wide limits of agreement suggest that subjective refinement of the eyeglasses prescription would still be necessary.
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Kim, Dong Seon, Bo Hyun Park, Han Jo Kwon, Sung Who Park, and Ik Soo Byon. "Predictive Accuracy of Refraction after Transscleral Fixation of Intraocular Lenses in Trabeculectomized Eyes with Glaucoma." Journal of the Korean Ophthalmological Society 64, no. 11 (November 15, 2023): 1022–29. http://dx.doi.org/10.3341/jkos.2023.64.11.1022.

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Purpose: To investigate the predictive accuracy of refraction and any change in intraocular pressure (IOP) after transscleral fixation of intraocular lenses (IOLs) in trabeculectomized eyes with glaucoma.Methods: We retrospectively reviewed the medical records of glaucoma patients who underwent trabeculectomy, followed by transscleral fixation of dislocated IOLs combined with vitrectomy. The refraction predicted by the SRK/T formula and the postoperative refraction were converted into spherical equivalents. Predictive refraction accuracies were analyzed when the differences between the two values were within ± 0.5 diopters (D) and ± 1.0 D. The IOP was measured before and after surgery.Results: Eleven eyes of 11 men (mean age, 67.27 ± 10.55 years) were included. The mean axial length was 23.64 ± 1.26 mm; the mean predicted and postoperative refractions were -0.02 ± 0.46 D and -0.80 ± 0.98 D, respectively (p = 0.029). The refractive outcome was more myopic (by -0.78 ± 1.11 D) than predicted. The predictive accuracies were 36.4% and 72.7% when the differences were ± 0.5 and ± 1.0 D, respectively. The IOP did not change during follow-up (13.18 ± 4.56, 12.82 ± 5.88, and 12.73 ± 4.58 mmHg at baseline, 1 week, and 3 months, respectively).Conclusions: In trabeculectomized eyes, transscleral IOL fixation did not affect the IOP, but the refractive outcome was more myopic than predicted. This difference should be considered when choosing IOL target power.
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Ocansey, Stephen, Rufaida Amuda, Carl Halladay Abraham, and Emmanuel Kwasi Abu. "Refractive error correction among urban and rural school children using two self-adjustable spectacles." BMJ Open Ophthalmology 8, no. 1 (April 2023): e001202. http://dx.doi.org/10.1136/bmjophth-2022-001202.

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ObjectiveSelf-refracting spectacles (SRSs) have different optical and mechanical designs, which may affect the refractive outcome, depending on the experience of the end user. This study compared the performance of two SRS among children in Ghana.Methods and analysisA cross-sectional study of two Alvarez variable-focus SRS designs was conducted. A total of 167 children (mean age 13.6±1.6 years) identified as having refractive error were recruited from 2465 students who underwent screening. Subjects completed self-refraction using FocusSpecs, and Adlens, autorefraction and cycloplegic subjective refraction (CSR) (gold standard). Wilcoxon signed-rank test was used to compare visual outcomes and accuracy of refraction and graphically illustrated using Bland-Altman plots.ResultsEighty (47.9%) urban and 87 (52.1%) rural children were analysed and only about one-quarter 40 (24.0%) wore spectacles. The proportion who achieved visual acuity of ≥6/7.5 with FocusSpec, Adlens, autorefraction and CSR among urban schools were 92.6%, 92.4%, 60% and 92.6%, while those in rural schools were 81.6%, 86.2%, 54.0% and 95.4%, respectively. The mean±SD spherical equivalent errors for urban and rural schools using FocusSpec, Adlens and CSR were −1.05±0.61 D, –0.97±0.58 D and −0.78±0.53 D; and −0.47±0.51 D, –0.55±0.43 D and −0.27±0.11 D, respectively. The mean differences between the two self-refraction spectacles for urban and rural schools were not statistically different (p>0.00) but differed significantly when both were compared with the gold standard (CSR) (p<0.05).ConclusionBackground and refraction experience of school children did not significantly affect self-refraction.
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Dissertations / Theses on the topic "Refraction"

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Li, Tsan Hang. "Theoretical study of negative refractive electromagnetic and acoustic media /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202004%20LIT.

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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 124-126). Also available in electronic version. Access restricted to campus users.
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Lehman, Joseph Christian. "Sphero-cylindrical Refraction with Spherical Lenses." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587510615809807.

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Beaman, Heather. "Reflection-Refraction." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1888.

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I find my inspiration by looking at the world around me. I take snapshots, compose photographs, and collect physical objects from my surroundings. I interpret these materials by layering printmaking, mixed media, and alternative photographic processes. I use the simplification of the human form when developing the composition. As my work takes shape, I present a universal person placed in a situational narrative. Layering the human figure with my travels and experiences creates a pause or an intimate moment that the viewer shares with the art work.
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Hartwig, Andreas. "The influence of optics, peripheral refraction and posture on refractive error development." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/the-influence-of-optics-peripheral-refraction-and-posture-on-refractive-error-development(f0382767-3194-4631-8cab-d473d64900bd).html.

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The aim of the present project was to analyse the link between peripheral posture, optics, optics and refractive error progression. Preliminary studies were conducted to ensure that peripheral aberrometry is valid for further analysis. The repeatability of the IRX-3 for peripheral aberrometry was asgood as for central measurements and the recalculation of elliptical pupils did not seem to be necessary for measurements up to 20 degrees eccentricity. Higher order aberration measurements werecomparable to other studies. Eye and head movements as well as working distance did not differ significantly between myopes and non-myopes. However, there was some evidence, that forward bending of the head during reading increases in association with higher refractive error progression rates. The link between central higher order aberrations and refractive error development was analysed by comparing higher order aberrations between isometropes and anisometropes. This analysisdid not show any significant association of higher order aberrations on the development, as no major differences were found between the two groups. For central vision, changes in biometric parameters during accommodation were analysed. It was found that biometric parameters change similarly in myopes and non-myopes. Peripheral accommodation was found to differ between myopes and emmetropes indicating that there might be an influence of peripheral refraction on myopisation. However, associationbetween peripheral refraction or peripheral aberrations and refractive error progression were not significant. The reason for this observation might be the low refractive error progression (0.04± 0.29 D in myopes and -0.12 ± 0.38 D in emmetropes) during one year in the study population.
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Rodgman, D. N. "Refraction in volume graphics." Thesis, Swansea University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638701.

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In this study, we have proposed several methods for sampling field-based representations of refraction attributes, and analysed these methods in terms of the quality and accuracy of the results produced. We have identified two types of anomalies that affect the correctness of some methods, and found that the best of these methods is capable of producing images of equal quality to surface-graphics techniques. Our approach produces good results with functionally defined models, and discrete volumetric data, in the absence of noise. We have also established that this approach allows the modelling and rendering of types of objects that cannot be represented in surface graphics (e.g. objects with a continuous, non-uniform refractive index). Where noise is present in volumetric data, it significantly affects the correctness of rendering refraction, usually resulting in images of poor quality. A number of methods for smoothing have been examined, including low-pass filtering and various types of nonlinear diffusion. We have shown that regularised anisotropic nonlinear diffusion is a powerful and effective method for processing noisy volumetric data sets in order to improve the quality of images featuring refraction. High quality images featuring refraction often take a long time to render. We have presented the design and implementation of a parallel, open source volume graphics rendered which supports refraction and multi-volume scenes. A large number of issues related to a efficient operation of a parallel renderer have been examined, and a high-performance, scaleable parallel renderer has been developed, which performs efficiently on both networked clusters, and shared memory multi-processor machines.
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Turpin, Avilés Alejandro. "Conical refraction: fundamentals and applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/322801.

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El fenomen de la refracció cònica en cristalls biaxials és conegut des del 1832, quan William Hamilton va predir matemàticament que un feix de llum idealment col·limat travessant un cristall biaxial paral·lelament a un dels eixos òptics del cristall, es refracta com un conus asimètric i emergeix del cristall com un cilindre de llum, la secció transversal del qual forma un anell de llum. La posterior observació del fenomen només uns mesos després per part de Humphrey Lloyd, va convertir la refracció cònica en un dels primers fenòmens observats després de la seva predicció, així com va donar el triomf de la teoria ondulatòria de la llum sobre la teoria corpuscular. A finals dels anys 70 del segle passat, Belsky i Khapalyuk van presentar la formulació difractiva del fenomen per a feixos amb simetria cil·líndrica, la qual va estar re-formulada per Berry durant la passada dècada. En aquesta tesi, explorem la refracció cònica d’una manera àmplia, alhora que profunda. Primerament, demostrem que, després d’un cert desenvolupament, la teoria de Berry pot ser utilitzada per estudiar la propagació de qualsevol feix, independentment del seu estat de polarització o perfil transversal, tant al llarg de l’eix òptic com a fora del mateix i per a qualsevol nombre de cristalls biaxials en cascada. Aquesta teoria difractiva també és utilitzada per a demostrar que, només ajustant la raó entre el radi de l’anell de refracció cònica i l’amplada del feix d’entrada, es poden aconseguir feixos molt dispars i que donen lloc a singularitats òptiques i vector beams molt interessants. Seguidament, demostrem que la refracció cònica pot ser entesa com la transformació de les ones incidents en dues ones còniques, la interferència de les quals dóna lloc als típics anells dobles al pla focal. A més a més, proposem una teoria alternativa que permet calcular el patró final després del cristall de qualsevol tipus de feix d’entrada, només tenint en compte refracció de vectors d’ona incidents i ho apliquem al cas particular de tenir múltiples cristalls en cascada. En particular, demostrem un sistema de multiplexació i de-multiplexació de senyals monocromàtiques per a aplicacions en les comunicacions òptiques en espai lliure basat en tres cristalls biaxials en cascada. Tot l’estudi anterior serveix per a la realització de noves propostes per a trampes òptiques per a àtoms neutres i partícules absorbents. En aquest sentit, demostrem tant teòricament com experimental que les estructures fosques que es generen amb refracció cònica són de gran utilitat per a atrapar àtoms ultra-freds, en col·laboració amb el grup del Prof. Gerhard Birkl a la Technische Universität Darmstadt. Tanmateix, utilitzem la particular distribució de polarització dels anells de refracció cònica per a construir una ampolla òptica re-configurable en temps real i que permet carregar i descarregar partícules macroscòpiques absorbents. També ens endinsem en el món de l’òptica quàntica a través de l’estudi de la generació de segon harmònic tant de tipus I com de tipus II a partir d’un feix de refracció cònica i demostrem que les propietats del feix de segon harmònic són pràcticament iguals a les del feix fonamental. Finalment, fem una proposta teòrica per a dissenyar un dispositiu capaç de detectar entrellaçament quàntic en moment lineal entre fotons bessons on l’element clau és un cristall biaxial.
The conical refraction phenomenon in biaxial crystals is known since 1832 when William Hamilton predicted mathematically that and ideally collimated light beam passing through a biaxial crystal parallel to one of the crystal optic axes would refract as an slanted cone within the crystal and emerge as a hollow light cylinder, whose transverse profiles forms a light ring. The afterwards observation of the phenomenon by Humphrey Lloyd made the conical refraction phenomenon to become one of the first phenomenon that were observed after their prediction, as well as the one who tip the scales towards the wave theory of light against the corpuscular theory. In the late 70s, Belsky and Khapalyuk presented the diffractive formulation of the phenomenon for cylindrically symmetric beams, this formalism being reformulated by Berry during the last decade. In this thesis, we explore conical refraction in deep and present some applications of this phenomenon. Firstly, we show that, after some theoretical development, Berry’s formalism can be used to predict the transformation of beams along any propagation direction, no matter the state of polarization or transverse profile they posses and the number of crystals in cascade used. The diffractive theory is also used to demonstrate that, by simply tuning the ratio between the conical refraction ring radius and the waist radius of the input beam, a rich variety of light beams and optical singularities can be generated. Then, we show that conical refraction can be understood as the transformation of the input plane waves into a pair of conical waves whose interference leads to the characteristic concentric bright rings at the focal plane. Additionally, we propose an alternative theory that allows calculating the resulting pattern beyond the biaxial crystal for any input light beam by considering splitting of input wave-vectors and we apply this simple formalism to predict the resulting pattern for a cascade of crystals. In particular, we demonstrate a multiplexing and de-multiplexing system for monochromatic signals for free space optical communications applications based on three biaxial crystals in cascade. The latter results are used to propose and realize different optical architectures for optical trapping of both ultra-cold atoms and absorbing particles. In this sense, show both theoretically and experimentally that dark optical geometries generated with conical refraction are of complete usefulness to trap Bose–Einstein condensates, in collaboration with the group of Prof. Gerhard Birkl at the Technische Universität Darmstadt. Additionally, we use the particular polarization distribution along the conical refraction rings to build a reconfigurable optical bottle capable to load and unload macroscopic absorbing particles at wish, in collaboration with the group of Prof. Wieslaw Krolikowski at the Australian National University. We also explore the world of quantum optics throughout the analysis of both type I and type II second harmonic generation of a conically refracted beam and we demonstrate that the second harmonic beam keeps most of the properties of the fundamental harmonic beam. Finally, we present a theoretical proposal to design an optical device able to detect linear momentum entanglement between twin photons, a biaxial crystal being the key element of the device.
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Trendall, Chris. "Ray tracing refraction in hardware." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ49742.pdf.

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Valle, G. Raul del. "Model parameterization in refraction seismology." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66057.

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Wu, Qi. "Negative refraction by photonic nanostructures." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337163.

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Martos, Justin Riley. "Fault Mapping with the Refraction Microtremor and Seismic Refraction Methods along the Los Osos Fault Zone." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/873.

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The presence of active fault traces in proximity to any new infrastructure project is a major concern for the design process. The relative displacements that can be experienced in surface fault rupture during a seismic event must be either entirely avoided or mitigated in some way. Blind faults present a significant challenge to engineers attempting to identify these hazards. Current standards of practice employed to locate these features are time consuming and costly. This work investigates the geophysical methods of refraction microtremor (ReMi) and seismic refraction with regard to their applicability in this task. By imaging a distinct lateral variation in the shear wave velocity (Vs) profile across a short horizontal distance, these methods may provide a means of constraining traditional investigation techniques to a more focused area. The ReMi method is still very new, but holds key advantages over other geophysical methods in its ease of application and ability to achieve good results in highly urban settings. It is one of the few geophysical techniques that does not suffer in the presence of high amplitude ambient vibrations. The seismic refraction method is here applied in an attempt to corroborate data obtained through the ReMi analysis procedure. Sensitivity, precision parametric studies are carried out in order to learn how to best apply the ReMi method. Both tests are then applied at a previously trenched fault trace to determine whether the data can be matched to the subsurface information. Finally, the methods are deployed at a location with an inferred fault trace where little to nothing is known about the subsurface. The precision study indicates a coefficient of variation for the ReMi method on the order of 7%. At the known fault trace both methods generally agree qualitatively with available subsurface data and each other. Using the ReMi method, a marked shift is observed in the Vs profile laterally across the fault trace. In the case of the inferred fault trace, the same type of lateral variation in the V­­s profile is observed using the ReMi method. The seismic refraction at this site does not agree with the ReMi data, but seems reasonable given the visible geomorphology. Receiver arrays placed in close proximity to the inferred fault trace recorded erratic signals during seismic refraction testing, and displayed abnormal response modes after transforming the ReMi data to frequency-slowness space. These anomalies may possibly be attributed to the presence of abnormal subsurface structural geometry indicative of faulting.
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Books on the topic "Refraction"

1

Eleftheriades, G. V., and K. G. Balmain, eds. Negative-Refraction Metamaterials. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2005. http://dx.doi.org/10.1002/0471744751.

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E, Garcia George, ed. Handbook of refraction. 4th ed. Boston: Little, Brown, 1989.

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Michaels, David D. Basic refraction techniques. New York: Raven Press, 1989.

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1955-, Benjamin William J., and Borish Irvin M, eds. Borish's clinical refraction. Philadelphia: W.B. Saunders, 1998.

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Hisako, Motoo, ed. Reflection and refraction. Hong Kong: Asia One Books, 2012.

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J, Lehmann O., ed. Clinical optics and refraction. Oxford: Butterworth-Heinemann, 1998.

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C, Still D., ed. Eye examination and refraction. 2nd ed. Oxford ; Malden, MA: Blackwell Science, 1998.

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R, Fletcher, and Still D. C, eds. Eye examination and refraction. Oxford: Blackwell Scientific, 1991.

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Caroline, Christie, ed. Clinical optics and refraction: A guide for optometrists, contact lens opticians, and dispensing opticians. Edinburgh: Butterworth-Heinemann, 2007.

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Maksymilian, Pluta, Szyjer Mariusz, Society of Photo-optical Instrumentation Engineers. Poland Chapter., Institute of Applied Optics (Poland), Society of Photo-optical Instrumentation Engineers., and Komitet Badań Naukowych (Poland), eds. Refractometry: 16-20 May 1994, Warsaw, Poland. Bellingham, Wash., USA: SPIE, 1995.

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Book chapters on the topic "Refraction"

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Xu, Liu-Jun, and Ji-Ping Huang. "Theory for Thermal Wave Refraction: Advection Regulation." In Transformation Thermotics and Extended Theories, 219–32. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-5908-0_16.

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AbstractIn this chapter, we study thermal waves of conduction and advection and further design advection-assisted metamaterials to realize the positive, vertical, and negative refraction of thermal waves. These results have a phenomenological analog of electromagnetic wave refraction despite different mechanisms. The negative refraction of thermal waves means that the incident and refractive thermal waves are on the same side of the normal, but the wave vector and energy flow are still in the same direction. As a model application, we apply the refractive behavior to design a thermal wave concentrator that can increase wave numbers and energy flows. This work provides insights into thermal wave manipulation, which may have potential thermal imaging applications.
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Keighley, H. J. P., F. R. McKim, A. Clark, and M. J. Harrison. "Refraction." In Mastering Physics, 140–50. London: Macmillan Education UK, 1986. http://dx.doi.org/10.1007/978-1-349-86062-3_15.

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Keighley, H. J. P., F. R. McKim, A. Clark, and M. J. Harrison. "Refraction." In Mastering Physics, 140–50. London: Macmillan Education UK, 1986. http://dx.doi.org/10.1007/978-1-349-08849-2_15.

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Sadun, Alfredo A., and James D. Brandt. "Refraction." In Optics for Ophthalmologists, 41–63. New York, NY: Springer New York, 1987. http://dx.doi.org/10.1007/978-1-4612-4810-1_2.

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Gooch, Jan W. "Refraction." In Encyclopedic Dictionary of Polymers, 615. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9869.

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Zaitsev, Alexander M. "Refraction." In Optical Properties of Diamond, 1–11. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-662-04548-0_1.

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Canavan, Brendan. "Refraction." In Contemporary Consumption, Consumers and Marketing, 83–98. 1 Edition. | New York : Routledge, 2021.: Routledge, 2020. http://dx.doi.org/10.4324/9781003013532-6.

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Weik, Martin H. "refraction." In Computer Science and Communications Dictionary, 1450. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_15861.

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Kushner, Burton J. "Refraction." In Strabismus, 23–29. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-63019-9_3.

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Gooch, Jan W. "Refraction." In Encyclopedic Dictionary of Polymers, 920. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_14660.

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Conference papers on the topic "Refraction"

1

Daniels, Wilfried, José Proença, Dave Clarke, Wouter Joosen, and Danny Hughes. "Refraction." In CompArch '15: Federated Events on Component-Based Software Engineering and Software Architecture. New York, NY, USA: ACM, 2015. http://dx.doi.org/10.1145/2737166.2737168.

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Guyton, David L. "Automated Refraction." In Ophthalmic and Visual Optics. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/ovo.1991.thc1.

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Approximately twenty automated refractors are now available, including manual objective refractors, automatic retinoscopes, and remote-controlled refractors. Problems from alignment, irregular refraction and instrument accommodation are still not fully solved.
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Zaghloul, A. I., and Youn Lee. "Simulation of refraction focusing using negative-refractive-index metamaterials." In 2008 IEEE Antennas and Propagation Society International Symposium and USNC/URSI National Radio Science Meeting. IEEE, 2008. http://dx.doi.org/10.1109/aps.2008.4619991.

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Yu, Wenkang, and Fengxun Gong. "Analysis and Correction of Atmospheric Refraction Effects on MLAT." In SAE 2023 Intelligent Urban Air Mobility Symposium. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-01-7070.

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<div class="section abstract"><div class="htmlview paragraph">The non-uniformity of the atmospheric medium induces the refraction effect in signal propagation, causing the bending of propagation paths and a propagation velocity slower than the speed of light. Consequently, it affects the time of arrival and, in turn, influences the performance of Multilateration systems(MLAT). This research analyze the influencing factors of atmospheric refraction and employs Innsbruck sounding data to fit a refractive index profile. The proposed model demonstrates superior performance in predicting the refractive index for the Innsbruck region compared to the three traditional models: the three-segment model, the exponential model, and the double exponential model. Furthermore, this study unveils the impact of atmospheric refraction on time difference observations and the mechanism leading to positioning errors. To address this, a novel atmospheric refraction correction algorithm based on the Taylor method is introduced and its effectiveness is verified.</div></div>
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Bower, Michael O. "Continuous refraction profiling: A new standard for refraction surveys." In SEG Technical Program Expanded Abstracts 1988. Society of Exploration Geophysicists, 1988. http://dx.doi.org/10.1190/1.1892524.

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Li, Chunfei, and Yuxiao Wang. "Saturable refraction and reverse saturable refraction in optical materials." In SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, edited by Suganda Jutamulia and Toshimitsu Asakura. SPIE, 1998. http://dx.doi.org/10.1117/12.326825.

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Lustig, Eran, Ohad Segal, Soham Saha, Eliyahu Bordo, Sarah N. Chowdhury, Yonatan Sharabi, Avner Fleischer, et al. "Time-Refraction Optics at Single Cycle Modulation." In CLEO: Fundamental Science. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/cleo_fs.2023.ftu3d.1.

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We present an experimental study of optical time-refraction in single-cycle time-interfaces. Specifically, we study the propagation of a probe pulse through a sample undergoing large refractive index changes induced by an intense ultra-short modulator pulse.
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Bullimore, Mark A., Craig W. Adams, Robert E. Fusaro, Marcella Bauman, Russell M. Cotteral, Joy Ng Sarver, J. Daniel Twelker, and Andrew D. Graham. "Patient Acceptance of Auto-Refractor and Clinician Prescriptions: A Randomized Clinical Trial." In Vision Science and its Applications. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/vsia.1996.sua.4.

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Auto-refractors are frequently used to provide a starting point for subjective examinations. Ancillary personnel use auto-refractors to obtain rapid estimates of patients' refractive errors which can then be refined by clinicians. Automated refraction has also found use in studies of refractive error (e.g., Zadnik et al., 1993), due to its superior repeatability to clinician refraction (Zadnik et al., 1992; Adams et al., 1995).
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Li, Qi, and Qiushi Ren. "Correlation among auto-refractor, wavefront aberration, and subjective manual refraction." In Photonics Asia 2004, edited by Britton Chance, Mingzhe Chen, Arthur E. T. Chiou, and Qingming Luo. SPIE, 2005. http://dx.doi.org/10.1117/12.575900.

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Hanafy, Sherif, and Gerard Schuster. "Parsimonious refraction interferometry." In SEG Technical Program Expanded Abstracts 2016. Society of Exploration Geophysicists, 2016. http://dx.doi.org/10.1190/segam2016-13688399.1.

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Reports on the topic "Refraction"

1

Hahn, Kim H. Y., and Jihyun Kim. Amber Refraction. Ames: Iowa State University, Digital Repository, 2013. http://dx.doi.org/10.31274/itaa_proceedings-180814-564.

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Yang, Chen-Jen, and Samson A. Jenekhe. Group Contribution to Molar Refraction and Refractive Index of Conjugated Polymers. Fort Belvoir, VA: Defense Technical Information Center, September 1996. http://dx.doi.org/10.21236/ada314812.

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Morel-à-l'Huissier, P., J. H. Karl, A. Tréhu, Z. Hajnal, R F Mereu, R. P. Meyer, J L Sexton, C. P. Ervin, A G Green, and D. Hutchinson. 1986 Great Lakes seismic refraction survey [GLIMPCE]: line A - refraction mode. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1990. http://dx.doi.org/10.4095/128170.

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Asudeh, I., F. Anderson, J. Parmelee, S. Vishnubhatla, P. Munro, and J. Thomas. A Portable Refraction Seismograph Prs1. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1992. http://dx.doi.org/10.4095/133234.

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Spence, G. D., T. Yuan, J. A. Hole, I. Asudeh, R M Ellis, R. M. Clowes, K. M M Rohr, and R. D. Hyndman. Queen Charlotte Refraction Experiment, 1988. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1992. http://dx.doi.org/10.4095/133461.

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Kunasz, P. Laser line transport with refraction. Office of Scientific and Technical Information (OSTI), August 1989. http://dx.doi.org/10.2172/7245398.

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Martin, Lee U., and William P. Hooper. Optical Refraction Measurements Across Chesapeake Bay. Fort Belvoir, VA: Defense Technical Information Center, April 2002. http://dx.doi.org/10.21236/ada400983.

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Pullan, S., H. A. MacAulay, J. A. M. Hunter, R. L. Good, R M Gagne, and R. A. Burns. Permafrost distribution determined from seismic refraction. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1987. http://dx.doi.org/10.4095/126967.

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Richards, Gordon, Christina Peters, Bee Martin, J. Bryce Kalmbach, John Parejko, Ian Sullivan, and Franz E. Bauer. Leveraging Differential Chromatic Refraction in LSST. LSST AGN Science Collaboration, 2018. http://dx.doi.org/10.17918/k90k-ey97.

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Keener, James. Potential Measurement Errors Induced by Atmospheric Refraction. Fort Belvoir, VA: Defense Technical Information Center, March 1997. http://dx.doi.org/10.21236/ada341850.

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