Luis Carretero | Universidad Miguel Hernandez (original) (raw)

Papers by Luis Carretero

Journal of Refractive Surgery, 1997

Many videokeratoscopes use mathematical formulas to calculate corneal radii; calculations depend ... more Many videokeratoscopes use mathematical formulas to calculate corneal radii; calculations depend on slope, curvature, coordinate position, or focal properties of the surface. Accuracy of each type of videokeratoscope must be evaluated. A controversy exists about whether axial or tangential methods best provide a precise description of corneal shape; therefore results with the Topcon CM-1000 using both methods were evaluated. Measurements were done on black polymethylmethacrylate (PMMA) spherical calibrated surfaces. Lenses were first aligned and measured and then misaligned in different directions and measured. Results for each position were compared with the zero or alignment position. Accuracy of the CM-1000 was high even under extreme misalignment conditions. Tolerance to misalignment was high (about 300 mm). Misalignment-induced variations in the output results were small (usually less than 0.05 mm). However, important variations (more than 1.00 diopter [D]) were found for the lowest measured radius (6 mm). In some cases, small differences between axial and tangential radii for the same point could be found. With the exception of extremely low radii of curvature, the CM-1000 was accurate for measuring spherical surfaces. Further investigation remains to be done on aspheric surfaces and in clinical practice.

Results in Physics, 2020

We investigate the dynamics of Si spherical nanoparticles for different infrared wavelengths in a... more We investigate the dynamics of Si spherical nanoparticles for different infrared wavelengths in a system based on two circularly polarized counter-propagating Gaussian beams. Through the analysis of the dipolar and quadrupolar forces, we obtain several conditions under which these nanoparticles describe different types of attractive or repulsive spirals at focus plane depending on the efficiency of the quadrupole trap obtained. We demonstrate that these spirals are generated by the angular momentum transfer from the electromagnetic field to the particles, and this is mainly due to the interference forces dipole-dipole and quadrupole-dipole. Through the adequate selection of the wavelength, angular momentum transfer can only take place with quadrupolardipolar interference forces. We study particle dynamics by solving the deterministic and non-deterministic over-damped Langevin equation.

Journal of the Optical Society of America A, 2008

We rigorously analyze the optical singularities and power flux in the near-field region of the no... more We rigorously analyze the optical singularities and power flux in the near-field region of the novel superlenses reported in [Science 317, 927 (2007)] For this purpose, we derive near-field expressions and a general criterion to classify the optical singularities in the vacuum, which are valid when the (s-or p-polarized) electromagnetic fields are generated by any planar field distribution with Cartesian or azimuthal symmetry. Such general results are particularized to the superlenses [Science 317, 927 (2007)], for which we identify a sequence of optical vortices and saddles that arise from evanescent-field interference. While the saddles are always located around the focal region, the vortex locations depend on the source field. The features of the topological connection between vortices and saddles are also discussed.

Applied Physics B-lasers and Optics, 2003

This work describes the study of free-radical homopolymerization kinetics for a system based on a... more This work describes the study of free-radical homopolymerization kinetics for a system based on acrylamide, triethanolamine, and methylene blue on a polyvinylalcohol matrix, by analyzing temporal variations of the diffraction efficiency. Due to the high viscosity of the material, it has been demonstrated that diffusion processes at the time of recording are negligible. So, the modulation index has been related to the parameters of the system’s components, giving as a result, a method that can be used to estimate the chain-length of the polymer, the kinetic rate constants and absorption-scattering parameters. Depending on the termination step, two models of homopolymerization has been proposed – a bimolecular model (bimolecular termination) and a radicalic model (primary radical termination). Using these methods it was possible to compare the results obtained for the kinetic parameters of the photopolymerization process when the intensity and the concentration of each component were ...

Optics Communications, 2000

We present a model describing real-time evolution of diffraction efficiency for a slanted grating... more We present a model describing real-time evolution of diffraction efficiency for a slanted grating recorded in holographic photopolymers when the reading is performed with the same wavelength as the recording. This model combines initiation kinetics of polymerization and the coupled-wave theory, explaining the effects of thickness, intensity and the final modulation index. The model is validated by the fit of

Journal of Modern Optics, 1998

... S. BLAYAt, L. CARRETEROS, A. FIMIA?, R. MALLAVIA?, R. F. MADRIGAL?, R. SASTREg and F. AMAT-GU... more ... S. BLAYAt, L. CARRETEROS, A. FIMIA?, R. MALLAVIA?, R. F. MADRIGAL?, R. SASTREg and F. AMAT-GUERRIg ?Departamento de Ciencias Experimentales y Technologia, UniversidadMiguel Hernandez, Avenida Ferrocarril s/n, Apdo 03202, Elche (Alicante), Spain ...

Proc. SPIE, 2005

In recent years the interest shown in dry photopolymer films as holographic recording materials h... more In recent years the interest shown in dry photopolymer films as holographic recording materials have increased dramatically. The main reasons for this are the special properties of these media, such as high diffraction efficiency, low noise, real-time processing and low ...

Optics Express, 2003

The holographic parameters of purple membranepolyacrylamide films obtained from a mutant form of ... more The holographic parameters of purple membranepolyacrylamide films obtained from a mutant form of Halobacterium salinarum (originally Halobacterium halobium) were measured. The synthesized films have an absorption of around 2.5 at 532 nm and a pH of 8.65. The results show that diffraction efficiencies of about 1.2 % (measured at 633 nm) can be achieved with writing intensities in the range of 200-400 mW/cm 2 (532 nm), and these values remain constant after saturation. Pump-probe experiments were also used to measure the M state lifetime and our PM films were found to have the lowest M state lifetime described at this pH.

Chemical Physics Letters, 2003

The merit function for electrooptic applications of dipyrromethene–BF2 complexes were optimized u... more The merit function for electrooptic applications of dipyrromethene–BF2 complexes were optimized using the electron density derivatives respect to an applied electric field. These derivatives were evaluated using ab initio quantum mechanical methods and as a result we present new complexes with second-order nonlinear optical properties and ground state dipole moment two times higher than the reference molecule (disperse red 1).

Applied Physics B-lasers and Optics, 2006

Recently the capability of photopolymerizable sol–gel materials to angular multiplex holographic ... more Recently the capability of photopolymerizable sol–gel materials to angular multiplex holographic gratings has been demonstrated [1, 2]. In this study, holographic transmission gratings were recorded using angular multiplexing in a silica glass doped photopolymer holographic recording material. The time interval between exposures and the angular selectivity were analyzed, in particular their effects on the dynamic range. By using the optimal parameters gratings of similar response were achieved with values of M/#=4.8, as well as good values of diffraction efficiency with high photosensitivity.

Journal of The Optical Society of America A-optics Image Science and Vision, 2008

Journal of Modern Optics, 1998

... S. BLAYAt, L. CARRETEROS, A. FIMIA?, R. MALLAVIA?, R. F. MADRIGAL?, R. SASTREg and F. AMAT-GU... more ... S. BLAYAt, L. CARRETEROS, A. FIMIA?, R. MALLAVIA?, R. F. MADRIGAL?, R. SASTREg and F. AMAT-GUERRIg ?Departamento de Ciencias Experimentales y Technologia, UniversidadMiguel Hernandez, Avenida Ferrocarril s/n, Apdo 03202, Elche (Alicante), Spain ...

Micromachines

We theoretically analyze the methodology for obtaining vectorial three-dimensional bullets, concr... more We theoretically analyze the methodology for obtaining vectorial three-dimensional bullets, concretely Airy–Gauss bullets. To do this, binary micro zonal plates (BZP) were designed in order to obtain different Airy–Gauss bullets with sub-diffraction main lobe width. Following the vectorial diffraction theory, among the electrical field, we extend the theory to the magnetic field, and thus we analyze several properties such as the Poynting vector and the energy of Airy–Gauss vectorial bullets generated by illuminating the designed BZP with a temporal Gaussian circular polarized pulses.

IEEE Photonics Journal

We analytically calculate the forces generated on the near field by a focused azimuthally polariz... more We analytically calculate the forces generated on the near field by a focused azimuthally polarized Hermite-Gauss beam after passing a complex mask formed by two annular pupils. The resultant optical tractor beam shows two transport channels that move trapped objects upstream or downstream along the conveyor. From the analysis of the phase diagrams, we theoretically demonstrate that, depending on illumination intensity, the 3-D behavior of nanoparticles in this conveyor shows a limit cycle between transport channels. This limit cycle appears as a consequence of diffraction that produces spatially limited optical forces. We theoretically demonstrate the possibility of using the limit cycle to design a particle exchanger between channels.

Optics and Lasers in Engineering

Journal of Refractive Surgery, 1997

Many videokeratoscopes use mathematical formulas to calculate corneal radii; calculations depend ... more Many videokeratoscopes use mathematical formulas to calculate corneal radii; calculations depend on slope, curvature, coordinate position, or focal properties of the surface. Accuracy of each type of videokeratoscope must be evaluated. A controversy exists about whether axial or tangential methods best provide a precise description of corneal shape; therefore results with the Topcon CM-1000 using both methods were evaluated. Measurements were done on black polymethylmethacrylate (PMMA) spherical calibrated surfaces. Lenses were first aligned and measured and then misaligned in different directions and measured. Results for each position were compared with the zero or alignment position. Accuracy of the CM-1000 was high even under extreme misalignment conditions. Tolerance to misalignment was high (about 300 mm). Misalignment-induced variations in the output results were small (usually less than 0.05 mm). However, important variations (more than 1.00 diopter [D]) were found for the lowest measured radius (6 mm). In some cases, small differences between axial and tangential radii for the same point could be found. With the exception of extremely low radii of curvature, the CM-1000 was accurate for measuring spherical surfaces. Further investigation remains to be done on aspheric surfaces and in clinical practice.

Results in Physics, 2020

We investigate the dynamics of Si spherical nanoparticles for different infrared wavelengths in a... more We investigate the dynamics of Si spherical nanoparticles for different infrared wavelengths in a system based on two circularly polarized counter-propagating Gaussian beams. Through the analysis of the dipolar and quadrupolar forces, we obtain several conditions under which these nanoparticles describe different types of attractive or repulsive spirals at focus plane depending on the efficiency of the quadrupole trap obtained. We demonstrate that these spirals are generated by the angular momentum transfer from the electromagnetic field to the particles, and this is mainly due to the interference forces dipole-dipole and quadrupole-dipole. Through the adequate selection of the wavelength, angular momentum transfer can only take place with quadrupolardipolar interference forces. We study particle dynamics by solving the deterministic and non-deterministic over-damped Langevin equation.

Journal of the Optical Society of America A, 2008

We rigorously analyze the optical singularities and power flux in the near-field region of the no... more We rigorously analyze the optical singularities and power flux in the near-field region of the novel superlenses reported in [Science 317, 927 (2007)] For this purpose, we derive near-field expressions and a general criterion to classify the optical singularities in the vacuum, which are valid when the (s-or p-polarized) electromagnetic fields are generated by any planar field distribution with Cartesian or azimuthal symmetry. Such general results are particularized to the superlenses [Science 317, 927 (2007)], for which we identify a sequence of optical vortices and saddles that arise from evanescent-field interference. While the saddles are always located around the focal region, the vortex locations depend on the source field. The features of the topological connection between vortices and saddles are also discussed.

Applied Physics B-lasers and Optics, 2003

This work describes the study of free-radical homopolymerization kinetics for a system based on a... more This work describes the study of free-radical homopolymerization kinetics for a system based on acrylamide, triethanolamine, and methylene blue on a polyvinylalcohol matrix, by analyzing temporal variations of the diffraction efficiency. Due to the high viscosity of the material, it has been demonstrated that diffusion processes at the time of recording are negligible. So, the modulation index has been related to the parameters of the system’s components, giving as a result, a method that can be used to estimate the chain-length of the polymer, the kinetic rate constants and absorption-scattering parameters. Depending on the termination step, two models of homopolymerization has been proposed – a bimolecular model (bimolecular termination) and a radicalic model (primary radical termination). Using these methods it was possible to compare the results obtained for the kinetic parameters of the photopolymerization process when the intensity and the concentration of each component were ...

Optics Communications, 2000

We present a model describing real-time evolution of diffraction efficiency for a slanted grating... more We present a model describing real-time evolution of diffraction efficiency for a slanted grating recorded in holographic photopolymers when the reading is performed with the same wavelength as the recording. This model combines initiation kinetics of polymerization and the coupled-wave theory, explaining the effects of thickness, intensity and the final modulation index. The model is validated by the fit of

Journal of Modern Optics, 1998

... S. BLAYAt, L. CARRETEROS, A. FIMIA?, R. MALLAVIA?, R. F. MADRIGAL?, R. SASTREg and F. AMAT-GU... more ... S. BLAYAt, L. CARRETEROS, A. FIMIA?, R. MALLAVIA?, R. F. MADRIGAL?, R. SASTREg and F. AMAT-GUERRIg ?Departamento de Ciencias Experimentales y Technologia, UniversidadMiguel Hernandez, Avenida Ferrocarril s/n, Apdo 03202, Elche (Alicante), Spain ...

Proc. SPIE, 2005

In recent years the interest shown in dry photopolymer films as holographic recording materials h... more In recent years the interest shown in dry photopolymer films as holographic recording materials have increased dramatically. The main reasons for this are the special properties of these media, such as high diffraction efficiency, low noise, real-time processing and low ...

Optics Express, 2003

The holographic parameters of purple membranepolyacrylamide films obtained from a mutant form of ... more The holographic parameters of purple membranepolyacrylamide films obtained from a mutant form of Halobacterium salinarum (originally Halobacterium halobium) were measured. The synthesized films have an absorption of around 2.5 at 532 nm and a pH of 8.65. The results show that diffraction efficiencies of about 1.2 % (measured at 633 nm) can be achieved with writing intensities in the range of 200-400 mW/cm 2 (532 nm), and these values remain constant after saturation. Pump-probe experiments were also used to measure the M state lifetime and our PM films were found to have the lowest M state lifetime described at this pH.

Chemical Physics Letters, 2003

The merit function for electrooptic applications of dipyrromethene–BF2 complexes were optimized u... more The merit function for electrooptic applications of dipyrromethene–BF2 complexes were optimized using the electron density derivatives respect to an applied electric field. These derivatives were evaluated using ab initio quantum mechanical methods and as a result we present new complexes with second-order nonlinear optical properties and ground state dipole moment two times higher than the reference molecule (disperse red 1).

Applied Physics B-lasers and Optics, 2006

Recently the capability of photopolymerizable sol–gel materials to angular multiplex holographic ... more Recently the capability of photopolymerizable sol–gel materials to angular multiplex holographic gratings has been demonstrated [1, 2]. In this study, holographic transmission gratings were recorded using angular multiplexing in a silica glass doped photopolymer holographic recording material. The time interval between exposures and the angular selectivity were analyzed, in particular their effects on the dynamic range. By using the optimal parameters gratings of similar response were achieved with values of M/#=4.8, as well as good values of diffraction efficiency with high photosensitivity.

Journal of The Optical Society of America A-optics Image Science and Vision, 2008

Journal of Modern Optics, 1998

... S. BLAYAt, L. CARRETEROS, A. FIMIA?, R. MALLAVIA?, R. F. MADRIGAL?, R. SASTREg and F. AMAT-GU... more ... S. BLAYAt, L. CARRETEROS, A. FIMIA?, R. MALLAVIA?, R. F. MADRIGAL?, R. SASTREg and F. AMAT-GUERRIg ?Departamento de Ciencias Experimentales y Technologia, UniversidadMiguel Hernandez, Avenida Ferrocarril s/n, Apdo 03202, Elche (Alicante), Spain ...

Micromachines

We theoretically analyze the methodology for obtaining vectorial three-dimensional bullets, concr... more We theoretically analyze the methodology for obtaining vectorial three-dimensional bullets, concretely Airy–Gauss bullets. To do this, binary micro zonal plates (BZP) were designed in order to obtain different Airy–Gauss bullets with sub-diffraction main lobe width. Following the vectorial diffraction theory, among the electrical field, we extend the theory to the magnetic field, and thus we analyze several properties such as the Poynting vector and the energy of Airy–Gauss vectorial bullets generated by illuminating the designed BZP with a temporal Gaussian circular polarized pulses.

IEEE Photonics Journal

We analytically calculate the forces generated on the near field by a focused azimuthally polariz... more We analytically calculate the forces generated on the near field by a focused azimuthally polarized Hermite-Gauss beam after passing a complex mask formed by two annular pupils. The resultant optical tractor beam shows two transport channels that move trapped objects upstream or downstream along the conveyor. From the analysis of the phase diagrams, we theoretically demonstrate that, depending on illumination intensity, the 3-D behavior of nanoparticles in this conveyor shows a limit cycle between transport channels. This limit cycle appears as a consequence of diffraction that produces spatially limited optical forces. We theoretically demonstrate the possibility of using the limit cycle to design a particle exchanger between channels.

Optics and Lasers in Engineering