PURPOSE: To assess the optical performance of four extended range of vision (ERV) intraocular len... more PURPOSE: To assess the optical performance of four extended range of vision (ERV) intraocular lenses (IOLs) and predict the visual quality of the average pseudophakic patient. METHODS: Four ERV IOLs (LuxSmart, Bausch & Lomb; Vivity, Alcon Laboratories, Inc; Tecnis Eyhance, Johnson & Johnson Vision; and Isopure, PhysIOL) were inserted in an on-bench model eye. Their performance was assessed using through-focus modulation transfer function (MTF)–based metrics, through-focus point spread function, and halo analysis for three pupils (2.0, 3.0, and 4.5 mm). The expected visual acuity and the range of vision was estimated from the through-focus area under the MTF curve. A monofocal IOL (Tecnis ZCB00; Johnson & Johnson Vision) was included as reference. RESULTS: The Tecnis ZCB00 showed the highest image quality at far for all pupil conditions, closely followed by the Tecnis Eyhance. The LuxSmart and Vivity performed similarly in the intermediate range (−1.00 to −2.00 diopters [D]) with a 3...
Education and Training in Optics & Photonics Conference 2021, 2021
The 3rd central IDL Event in Spain probably gathered the largest number of activities for the 16t... more The 3rd central IDL Event in Spain probably gathered the largest number of activities for the 16th May commemoration in 2021. Conferences, debates, workshops, exhibitions, light shows, and photo contests, adapted to severe constraints due to the pandemic, achieved the participation of a wide and diverse audience.
The optical quality of three multifocal intraocular lenses (MIOLs) was measured in vitro using th... more The optical quality of three multifocal intraocular lenses (MIOLs) was measured in vitro using the area under the modulation transfer function (MTFa) and energy efficiency (EE). We evaluated those metrics through-focus (TF) by axially scanning the image space with three wavelengths (R, G, B). High linear correlation between MTFa and EE was found for all cases. Correlations between optical in vitro results (polychromatic TF-MTFa and TF-EE) and clinical visual acuity (VA) defocus curves for the three MIOLs allowed us to derive mathematical expressions. Both metrics proved to be equivalent to predict postoperative VA.
Resumen Las cuatro experiencias que presentamos en este artículo utilizan el portafolio como méto... more Resumen Las cuatro experiencias que presentamos en este artículo utilizan el portafolio como método para ayudar al estudiante en el aprendizaje de conocimientos y competencias transversales. En tres de ellas el portafolio se integra como un elemento que ayuda al estudiante a organizar su trabajo en la asignatura, a reflexionar sobre su aprendizaje y a valorar sus resultados. El portafolio también se presenta como un instrumento de evaluación sumativa y formativa. En la última experiencia el portafolio tiene como objetivo ofrecer al estudiante la oportunidad de reflexionar sobre el grado en que desarrolla las competencias transversales. En este caso el alumno dispone de un Wiki en el que puede recopilar de forma ordenada tanto las reflexiones como las evidencias que demuestran la consecución de dicho aprendizaje.
Resumen Preguntarse por la calidad del aprendizaje en Educación Superior (E.S.) no es una cuestió... more Resumen Preguntarse por la calidad del aprendizaje en Educación Superior (E.S.) no es una cuestión nada simple. Como toda apreciación de naturaleza evaluadora, fundamentalmente depende de los referentes empleados en hacerlo y del modo cómo se realiza. Ello convierte a dicha noción en un concepto complejo y controvertido debido a las distintas aproximaciones posibles sobre el mismo. Por lo tanto, preguntarse acerca de "qué calidad" y "para quién" es un punto de partida obligado. En términos de la idea de calidad que utilizamos, hay dos aspectos que son de interés, la percepción de los estudiantes sobre la misma y las pruebas 1 Este texto corresponde a una síntesis reelaborada del Proyecto:
Objective.To evaluate the degree of axial elongation with soft radial refractive gradient (SRRG) ... more Objective.To evaluate the degree of axial elongation with soft radial refractive gradient (SRRG) contact lenses, orthokeratology (OK), and single vision (SV) spectacle lenses (control) during a period of 1 year before treatment and 2 years after treatment.Methods.This was a prospective, longitudinal, nonrandomized study. The study groups consisted of 30, 29, and 41 children, respectively. The axial length (AL) was measured during 2 years after recruitment and lens fitting.Results.The baseline refractive sphere was correlated significantly (Spearman’s Rho (ρ) correlation = 0.542;P< 0.0001) with the amount of myopia progression before baseline. After 2 years, the mean myopia progression values for the SRRG, OK, and SV groups were −0.56 ± 0.51, −0.32 ± 0.53, and −0.98 ± 0.58 diopter, respectively. The results represent reductions in myopic progression of 43% and 67% for the SRRG and OK groups, respectively, compared to the SV group. The AL increased 27% and 38% less in the SRRG and ...
Ninth International Topical Meeting on Education and Training in Optics and Photonics, 2005
The student portfolio is an ideal tool to assess competencies. In a portfolio, students must be a... more The student portfolio is an ideal tool to assess competencies. In a portfolio, students must be able to show their progress towards the acquisition of learning outcomes. Students must convince teachers of their learning. The implementation in our case (first year wave optics course) consists in a collection of all the work done during the semester. It contains summaries of text books, resolved problems,
In laser materials processing applications it is often necessary to work with uniform intensity d... more In laser materials processing applications it is often necessary to work with uniform intensity distributions. This goal is quite difficult to achieve when dealing with high power laser beams, and becomes critical for a successful application involving surface heat treatment of non-metallic materials. We have designed and tested a very simple beam shaper for transforming the initial intensity distribution of
ABSTRACT This paper describes a model for the analysis of the quality of teaching and learning in... more ABSTRACT This paper describes a model for the analysis of the quality of teaching and learning in higher education. Empirically validated through an extensive student-focused survey, this model puts forward a concept of quality that challenges that which is commonly used in ...
This work describes the phase transitions occurring at the film-substrate interface of amorphous ... more This work describes the phase transitions occurring at the film-substrate interface of amorphous germanium films upon nanosecond laser-pulse-induced melting of the surface. Films with thickness ranging from 50 to 130 nm deposited on glass substrates were studied. Real-time reflectivity measurements with subnanosecond time resolution performed both at the air-film and film-substrate interfaces were used to obtain both surface and in-depth information of the process. In the thicker films (⩾80nm), the enthalpy released upon solidification of a shallow molten surface layer induces a thin buried liquid layer that self-propagates in-depth towards the film-substrate interface. This buried liquid layer propagates with a threshold velocity of 16±1m∕s and causes, eventually, melting at the film-substrate interface. In the thinnest film (50 nm) there is no evidence of the formation of the buried layer. The presence of the self-propagating buried layer for films thicker than 80 nm at low and in...
Rapid solidification dynamics in amorphous germanium films melted by nanosecond laser pulses has ... more Rapid solidification dynamics in amorphous germanium films melted by nanosecond laser pulses has been analyzed by means of single-shot subnanosecond time resolved reflectivity measurements using a streak camera based setup. The results show that once a minimum melt depth is induced, a bulk solidification process followed by the release of the solidification enthalpy dominates the solidification scenario. Moreover, the laser-melted material solidifies completely before being remelted as a consequence of the solidification enthalpy release, something only observed, up to date, upon irradiation with picosecond laser pulses.
We report on the mechanisms responsible for the formation of optical waveguides upon femtosecond ... more We report on the mechanisms responsible for the formation of optical waveguides upon femtosecond laser irradiation of an alkaline lead-oxide silicate glass. MicroRaman spectroscopy and nonlinear fluorescence were employed to probe the local glass network structure and the formation of optically active defects respectively. At low laser pulse energies, the laser modified region is formed by a single light guiding region, whereas for pulses above 14 μJ the modified region is formed by a central dark zone, which does not guide light, accompanied by light guiding zones located in the surrounding of the dark one. This behavior is different from that observed in common silica glass systems but agrees with recent results obtained in phosphate and heavy metal oxide glasses. However, our results show that, unlike the latter glass, local densification of the glass occurs in the whole laser modified region, i.e., in the dark and the guiding zones. The suppression of light guiding in the dark r...
We study the feasibility of femtosecond laser writing of optical waveguides in bulk 35PbO∙35Bi2O3... more We study the feasibility of femtosecond laser writing of optical waveguides in bulk 35PbO∙35Bi2O3∙15Ga2O3∙15GeO2 glass, motivated by the extended transparency interval of heavy metal oxide glasses in the mid-infrared regime. Its large linear and nonlinear refractive indices cause critical self-focusing to occur even at low laser energies, leading to filamentary propagation and material damage. However, the vicinity of the laser-damaged region shows a considerable increase in the refractive index, which we attribute to a collateral, stress-induced densification due to the high pressures generated in the focal region. These regions of increased refractive index are strongly birefringent and sufficiently large to support efficient light propagation in transversally written structures. Optical waveguides with a refractive index increase ⩾10−3 and minimal mode ellipticity have been obtained.
A new integration method suited for spatially coherent high-power laser beams is demonstrated. Th... more A new integration method suited for spatially coherent high-power laser beams is demonstrated. The integrator system is based on a mirror with two facets, one of which can vibrate under the action of a piezoelectric translator. After reflection in the faceted mirror, the beam intensity distribution is modified to obtain greater uniformity. However, because of the coherence of the reflected beamlets, this distribution is affected by an interference pattern. The active integration consists of a periodic displacement of the moving facet that causes the interference pattern to vibrate, and its contribution to the intensity profile therefore averages out (fringe visibility within a 5% range). The combination of a faceted mirror and a simple imaging system results in an intensity profile with good uniformity over large spot sizes. Both simulated and experimental results are presented, the latter showing that a final uniformity within a 10% range can be achieved and it is limited mainly by diffraction at the edges of the facets.
It is shown that optical surfaces traditionally ground in conventional glasses with high coeffici... more It is shown that optical surfaces traditionally ground in conventional glasses with high coefficients of thermal expansion may be polished by irradiation with a space-and time-controlled uniform CO 2 laser beam. Comparisons of a theoretical simulation model of the laser-driven heating process with the experimental results allow us to determine the conditions for successful and reliable use of this technique. The technique can be applied indiscriminately to preheated samples made of different glasses, with any topography, and, of any size in a limited range that depends only on the available laser power.
An analysis is given of how nonuniformities in the laser beam intensity translate into variations... more An analysis is given of how nonuniformities in the laser beam intensity translate into variations on the induced temperature distribution on an irradiated sample. The study involves materials with different thermal conductivities. By use of a reshaped irradiating beam obtained with a multifaceted integrating mirror, a three-dimensional numerical calculation allows us to establish both surface and in-depth temperature distributions. The results show that in the case of materials such as glass ͑i.e., with low thermal conductivity͒ large thermal gradients occur both on the surface and in depth during irradiation. However, the lateral heat flow is high enough to strongly reduce the surface gradients as soon as the laser irradiation ends. Conversely, in good thermal conductors such as nickel, the laser intensity nonuniformities induce a thermal peaking of the surface with lateral thermal gradients that are by no means negligible. Experimental evidence during laser glass polishing that confirms the numerical assessments are also provided.
This article studies the relationship between two metrics, the area under the modulation transfer... more This article studies the relationship between two metrics, the area under the modulation transfer function (MTFa) and the energy efficiency (EE), and their ability to predict the visual quality of patients implanted with multifocal intraocular lenses (IOLs). The optical quality of IOLs is assessed in vitro using two metrics, the MTFa and EE. We measured them for three different multifocal IOLs with parabolic phase profile using image formation, through-focus (TF) scanning, three R, G, B wavelengths, and two pupils. We analyzed the correlation between MTFa and EE. In parallel, clinical defocus curves of visual acuity (VA) were measured and averaged from sets of patients implanted with the same IOLs. An excellent linear correlation was found between the MTFa and EE for the considered IOLs, wavelengths and pupils (R2 > 0.9). We computed the polychromatic TF-MTFa, TF-EE, and derived mathematical relationships between each metrics and clinical average VA. MTFa and EE proved to be equi...
PURPOSE: To assess the optical performance of four extended range of vision (ERV) intraocular len... more PURPOSE: To assess the optical performance of four extended range of vision (ERV) intraocular lenses (IOLs) and predict the visual quality of the average pseudophakic patient. METHODS: Four ERV IOLs (LuxSmart, Bausch & Lomb; Vivity, Alcon Laboratories, Inc; Tecnis Eyhance, Johnson & Johnson Vision; and Isopure, PhysIOL) were inserted in an on-bench model eye. Their performance was assessed using through-focus modulation transfer function (MTF)–based metrics, through-focus point spread function, and halo analysis for three pupils (2.0, 3.0, and 4.5 mm). The expected visual acuity and the range of vision was estimated from the through-focus area under the MTF curve. A monofocal IOL (Tecnis ZCB00; Johnson & Johnson Vision) was included as reference. RESULTS: The Tecnis ZCB00 showed the highest image quality at far for all pupil conditions, closely followed by the Tecnis Eyhance. The LuxSmart and Vivity performed similarly in the intermediate range (−1.00 to −2.00 diopters [D]) with a 3...
Education and Training in Optics & Photonics Conference 2021, 2021
The 3rd central IDL Event in Spain probably gathered the largest number of activities for the 16t... more The 3rd central IDL Event in Spain probably gathered the largest number of activities for the 16th May commemoration in 2021. Conferences, debates, workshops, exhibitions, light shows, and photo contests, adapted to severe constraints due to the pandemic, achieved the participation of a wide and diverse audience.
The optical quality of three multifocal intraocular lenses (MIOLs) was measured in vitro using th... more The optical quality of three multifocal intraocular lenses (MIOLs) was measured in vitro using the area under the modulation transfer function (MTFa) and energy efficiency (EE). We evaluated those metrics through-focus (TF) by axially scanning the image space with three wavelengths (R, G, B). High linear correlation between MTFa and EE was found for all cases. Correlations between optical in vitro results (polychromatic TF-MTFa and TF-EE) and clinical visual acuity (VA) defocus curves for the three MIOLs allowed us to derive mathematical expressions. Both metrics proved to be equivalent to predict postoperative VA.
Resumen Las cuatro experiencias que presentamos en este artículo utilizan el portafolio como méto... more Resumen Las cuatro experiencias que presentamos en este artículo utilizan el portafolio como método para ayudar al estudiante en el aprendizaje de conocimientos y competencias transversales. En tres de ellas el portafolio se integra como un elemento que ayuda al estudiante a organizar su trabajo en la asignatura, a reflexionar sobre su aprendizaje y a valorar sus resultados. El portafolio también se presenta como un instrumento de evaluación sumativa y formativa. En la última experiencia el portafolio tiene como objetivo ofrecer al estudiante la oportunidad de reflexionar sobre el grado en que desarrolla las competencias transversales. En este caso el alumno dispone de un Wiki en el que puede recopilar de forma ordenada tanto las reflexiones como las evidencias que demuestran la consecución de dicho aprendizaje.
Resumen Preguntarse por la calidad del aprendizaje en Educación Superior (E.S.) no es una cuestió... more Resumen Preguntarse por la calidad del aprendizaje en Educación Superior (E.S.) no es una cuestión nada simple. Como toda apreciación de naturaleza evaluadora, fundamentalmente depende de los referentes empleados en hacerlo y del modo cómo se realiza. Ello convierte a dicha noción en un concepto complejo y controvertido debido a las distintas aproximaciones posibles sobre el mismo. Por lo tanto, preguntarse acerca de "qué calidad" y "para quién" es un punto de partida obligado. En términos de la idea de calidad que utilizamos, hay dos aspectos que son de interés, la percepción de los estudiantes sobre la misma y las pruebas 1 Este texto corresponde a una síntesis reelaborada del Proyecto:
Objective.To evaluate the degree of axial elongation with soft radial refractive gradient (SRRG) ... more Objective.To evaluate the degree of axial elongation with soft radial refractive gradient (SRRG) contact lenses, orthokeratology (OK), and single vision (SV) spectacle lenses (control) during a period of 1 year before treatment and 2 years after treatment.Methods.This was a prospective, longitudinal, nonrandomized study. The study groups consisted of 30, 29, and 41 children, respectively. The axial length (AL) was measured during 2 years after recruitment and lens fitting.Results.The baseline refractive sphere was correlated significantly (Spearman’s Rho (ρ) correlation = 0.542;P< 0.0001) with the amount of myopia progression before baseline. After 2 years, the mean myopia progression values for the SRRG, OK, and SV groups were −0.56 ± 0.51, −0.32 ± 0.53, and −0.98 ± 0.58 diopter, respectively. The results represent reductions in myopic progression of 43% and 67% for the SRRG and OK groups, respectively, compared to the SV group. The AL increased 27% and 38% less in the SRRG and ...
Ninth International Topical Meeting on Education and Training in Optics and Photonics, 2005
The student portfolio is an ideal tool to assess competencies. In a portfolio, students must be a... more The student portfolio is an ideal tool to assess competencies. In a portfolio, students must be able to show their progress towards the acquisition of learning outcomes. Students must convince teachers of their learning. The implementation in our case (first year wave optics course) consists in a collection of all the work done during the semester. It contains summaries of text books, resolved problems,
In laser materials processing applications it is often necessary to work with uniform intensity d... more In laser materials processing applications it is often necessary to work with uniform intensity distributions. This goal is quite difficult to achieve when dealing with high power laser beams, and becomes critical for a successful application involving surface heat treatment of non-metallic materials. We have designed and tested a very simple beam shaper for transforming the initial intensity distribution of
ABSTRACT This paper describes a model for the analysis of the quality of teaching and learning in... more ABSTRACT This paper describes a model for the analysis of the quality of teaching and learning in higher education. Empirically validated through an extensive student-focused survey, this model puts forward a concept of quality that challenges that which is commonly used in ...
This work describes the phase transitions occurring at the film-substrate interface of amorphous ... more This work describes the phase transitions occurring at the film-substrate interface of amorphous germanium films upon nanosecond laser-pulse-induced melting of the surface. Films with thickness ranging from 50 to 130 nm deposited on glass substrates were studied. Real-time reflectivity measurements with subnanosecond time resolution performed both at the air-film and film-substrate interfaces were used to obtain both surface and in-depth information of the process. In the thicker films (⩾80nm), the enthalpy released upon solidification of a shallow molten surface layer induces a thin buried liquid layer that self-propagates in-depth towards the film-substrate interface. This buried liquid layer propagates with a threshold velocity of 16±1m∕s and causes, eventually, melting at the film-substrate interface. In the thinnest film (50 nm) there is no evidence of the formation of the buried layer. The presence of the self-propagating buried layer for films thicker than 80 nm at low and in...
Rapid solidification dynamics in amorphous germanium films melted by nanosecond laser pulses has ... more Rapid solidification dynamics in amorphous germanium films melted by nanosecond laser pulses has been analyzed by means of single-shot subnanosecond time resolved reflectivity measurements using a streak camera based setup. The results show that once a minimum melt depth is induced, a bulk solidification process followed by the release of the solidification enthalpy dominates the solidification scenario. Moreover, the laser-melted material solidifies completely before being remelted as a consequence of the solidification enthalpy release, something only observed, up to date, upon irradiation with picosecond laser pulses.
We report on the mechanisms responsible for the formation of optical waveguides upon femtosecond ... more We report on the mechanisms responsible for the formation of optical waveguides upon femtosecond laser irradiation of an alkaline lead-oxide silicate glass. MicroRaman spectroscopy and nonlinear fluorescence were employed to probe the local glass network structure and the formation of optically active defects respectively. At low laser pulse energies, the laser modified region is formed by a single light guiding region, whereas for pulses above 14 μJ the modified region is formed by a central dark zone, which does not guide light, accompanied by light guiding zones located in the surrounding of the dark one. This behavior is different from that observed in common silica glass systems but agrees with recent results obtained in phosphate and heavy metal oxide glasses. However, our results show that, unlike the latter glass, local densification of the glass occurs in the whole laser modified region, i.e., in the dark and the guiding zones. The suppression of light guiding in the dark r...
We study the feasibility of femtosecond laser writing of optical waveguides in bulk 35PbO∙35Bi2O3... more We study the feasibility of femtosecond laser writing of optical waveguides in bulk 35PbO∙35Bi2O3∙15Ga2O3∙15GeO2 glass, motivated by the extended transparency interval of heavy metal oxide glasses in the mid-infrared regime. Its large linear and nonlinear refractive indices cause critical self-focusing to occur even at low laser energies, leading to filamentary propagation and material damage. However, the vicinity of the laser-damaged region shows a considerable increase in the refractive index, which we attribute to a collateral, stress-induced densification due to the high pressures generated in the focal region. These regions of increased refractive index are strongly birefringent and sufficiently large to support efficient light propagation in transversally written structures. Optical waveguides with a refractive index increase ⩾10−3 and minimal mode ellipticity have been obtained.
A new integration method suited for spatially coherent high-power laser beams is demonstrated. Th... more A new integration method suited for spatially coherent high-power laser beams is demonstrated. The integrator system is based on a mirror with two facets, one of which can vibrate under the action of a piezoelectric translator. After reflection in the faceted mirror, the beam intensity distribution is modified to obtain greater uniformity. However, because of the coherence of the reflected beamlets, this distribution is affected by an interference pattern. The active integration consists of a periodic displacement of the moving facet that causes the interference pattern to vibrate, and its contribution to the intensity profile therefore averages out (fringe visibility within a 5% range). The combination of a faceted mirror and a simple imaging system results in an intensity profile with good uniformity over large spot sizes. Both simulated and experimental results are presented, the latter showing that a final uniformity within a 10% range can be achieved and it is limited mainly by diffraction at the edges of the facets.
It is shown that optical surfaces traditionally ground in conventional glasses with high coeffici... more It is shown that optical surfaces traditionally ground in conventional glasses with high coefficients of thermal expansion may be polished by irradiation with a space-and time-controlled uniform CO 2 laser beam. Comparisons of a theoretical simulation model of the laser-driven heating process with the experimental results allow us to determine the conditions for successful and reliable use of this technique. The technique can be applied indiscriminately to preheated samples made of different glasses, with any topography, and, of any size in a limited range that depends only on the available laser power.
An analysis is given of how nonuniformities in the laser beam intensity translate into variations... more An analysis is given of how nonuniformities in the laser beam intensity translate into variations on the induced temperature distribution on an irradiated sample. The study involves materials with different thermal conductivities. By use of a reshaped irradiating beam obtained with a multifaceted integrating mirror, a three-dimensional numerical calculation allows us to establish both surface and in-depth temperature distributions. The results show that in the case of materials such as glass ͑i.e., with low thermal conductivity͒ large thermal gradients occur both on the surface and in depth during irradiation. However, the lateral heat flow is high enough to strongly reduce the surface gradients as soon as the laser irradiation ends. Conversely, in good thermal conductors such as nickel, the laser intensity nonuniformities induce a thermal peaking of the surface with lateral thermal gradients that are by no means negligible. Experimental evidence during laser glass polishing that confirms the numerical assessments are also provided.
This article studies the relationship between two metrics, the area under the modulation transfer... more This article studies the relationship between two metrics, the area under the modulation transfer function (MTFa) and the energy efficiency (EE), and their ability to predict the visual quality of patients implanted with multifocal intraocular lenses (IOLs). The optical quality of IOLs is assessed in vitro using two metrics, the MTFa and EE. We measured them for three different multifocal IOLs with parabolic phase profile using image formation, through-focus (TF) scanning, three R, G, B wavelengths, and two pupils. We analyzed the correlation between MTFa and EE. In parallel, clinical defocus curves of visual acuity (VA) were measured and averaged from sets of patients implanted with the same IOLs. An excellent linear correlation was found between the MTFa and EE for the considered IOLs, wavelengths and pupils (R2 > 0.9). We computed the polychromatic TF-MTFa, TF-EE, and derived mathematical relationships between each metrics and clinical average VA. MTFa and EE proved to be equi...
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