Ivan Moreno

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• Profesor
• Profesor at Universidad Autónoma de Zacatecas "Francisco García Salinas"

Light-emitting diodes (LEDs) come in many varieties and with a wide range of radiation patterns. We propose a general, simple but accurate analytic representation for the radiation pattern of the light emitted from an LED. To accurately render both the angular intensity distribution and the irradiance spatial pattern, a simple phenomenological mode...

We analyze the first-order design of light sources consisting of multiple light-emitting diodes (LEDs) to uniformly illuminate a near target plane by considering each single LED as an imperfect Lambertian emitter. Simple approximate equations and formulas are derived for the optimum LED-to-LED spacing, i.e., the optimum packaging density, of severa...

A metalens is an ultra-thin lens made of a metasurface, with focusing and imaging functions, and with promising applications in miniature optical systems, such as mobile devices. This paper gives an introduction to the optics of metalenses. First, we examine the focusing and imaging characteristics of metalenses. And then, as an essential step, we...

This book provides an overview of the basic optics of the metalens, providing an introduction for students, scientists and engineers. The scope of this book is to introduce the optical fundamentals and basic optical design methods of a metalens, where light propagation can be modelled by simple, and yet useful basic optics (e.g., the refraction law...

ABSTRACT: The phase-shift, transmittance, and polarization properties of meta-atoms are investigated, motivated by their use as building blocks of metasurfaces used in metalenses, holograms, and beam shaping. We studied dielectric nanorod meta-atoms of several geometries, which included cylinders, triangles, squares, hexagons, octagons, and truncat...

Designing lenses for wavelengths below 121 nm is challenging due to the strong absorption of optical materials. This study introduces a metalens composed of ring-shaped silica nano-elements that efficiently focus extreme ultraviolet (EUV) radiation. Each ring features an air or vacuum core (n=1) surrounded by silica with a refractive index (n<1), o...

Citation: García-Moreira, D.P.; Pacheco, N.; Hernández-Guzmán, H.; Bahammou, Y.; Tagnamas, Z.; Moreno, I.; López-Vidaña, E.C. Evaluation of Various Drying Methods for Mexican Yahualica chili: Drying Characteristics and Quality Assessment. Processes 2024, 12, 1969. Abstract: As one of the main chili varieties in Mexico, Yahualica chili requires year...

In this study, a novel adaptive solar dryer with a coating of polymer-dispersed liquid crystals (PDLC) was designed, built, and characterized to evaluate its optical properties and thermal performance by modulating the transmission of solar radiation toward the drying chamber. PDLC films can electrically switch between opaque and transparent states...

Articulo de divulgación científica sobre metasuperficies. Revista eek', vol. 10, issue 3, pag. 7-8: https://issuu.com/cozcyt2021/docs/eek58

The phase-shift, transmittance, and polarization properties of meta-atoms are investigated, motivated by their use as building blocks of metasurfaces used in metalenses, holograms, and beam shaping. We studied dielectric rod meta-atoms of several geometries, which included: cylinders, squares, polygons, and truncated cones. By analyzing light propa...

The phase-shift, transmittance, and polarization properties of meta-atoms are investigated, motivated by their use as building blocks of metasurfaces used in metalenses, holograms, and beam shaping. We studied dielectric rod meta-atoms of several geometries, which included: cylinders, squares, polygons, and truncated cones. By analyzing light propa...

Color is one of the most critical food quality parameters since it impacts consumer acceptability. The influence of peach drying at varied temperatures (50, 55, and 60 °C), air velocities (0.3, 0.6, and 0.9 m·s−1), and processing periods (6, 6.5, and 7 h) on colorchange, water activity, total soluble solids, and browning index was studied. A 2^3 ra...

While transmission-mode metalenses have been extensively studied, reflection-mode metalenses remain almost unexplored, presenting advantages in terms of improved efficiency and reduced complexity. In this Letter, we investigate a multilayer dielectric metalens operating in reflection mode at visible wavelengths without a metallic layer. Simulations...

In this video, we can observe the interaction of a plane wave incident from the top onto a reflective metalens “without metallic layers”. This metalens consists of dielectric multilayer meta-atoms. After interacting with the metalens, the flat wavefront is reflected back with a hyperbolic phase profile and is focused. This effect is achieved by alt...

While transmission-mode metalenses have been extensively studied, reflection-mode metalenses remain almost unexplored, presenting advantages in terms of improved efficiency and reduced complexity. In this letter, we investigate a multilayer dielectric metalens operating in reflection mode at visible wavelengths without a metallic layer. Simulations...

While transmission-mode metalenses have been extensively studied, reflection-mode metalenses remains almost unexplored, presenting advantages in terms of improved efficiency and reduced complexity. In this work we investigate a multilayer dielectric metalens operating in reflection mode without a metallic layer. Simulations and analysis demonstrate...

Peach is a fruit highly appreciated by consumers; however, it is highly perishable, so drying is an alternative to preserve its physical and chemical properties. In this study, the effect of drying in natural and forced convection at three different temperatures (40 °C, 45 °C and 50 °C) and solar drying with two air velocities (1 m/s and 3 m/s) on...

We propose and analyze a metalens whose meta-atoms (nanoscatterers) are integrated by a stack of quarter-wave dielectric layers. Each multilayer meta-atom is a nanopillar, which consists of alternating layers of high- and low-refractive-index materials. We show that the nanopillars of a multilayer metalens may have a smaller aspect ratio than the n...

Current advances in metalenses are leading to the development of new compact optical systems, mainly in imaging applications. Here, we focus the study of metalenses in nonimaging optics applications. In this work we present the study and design of a total internal reflection (TIR) metalens by using finite difference time domain (FDTD) electromagnet...

We develop a design method of flat optics for illumination. We describe a metalens design method for uniform illumination based on the ray mapping algorithm between a point source and a target. Based on metasurface refraction equation and a suitable ray mapping, a first order differential equation that represents the characteristics of the desired...

In this work, we present a study by finite-difference time-domain FDTD simulations of metalenses with hyperbolic phase profile, formed by multilayer cylindrical scatters. The multilayers are constructed by alternating high refractive material (α-Si) and a low refractive (GaN). In this way, it is shown that these multilayer scatters improve some pro...

The regulation of the spatial energy distribution of a light source with high efficiency is a classical and challenging issue in the field of nonimaging optics. In this work we derive the partial differential equation that the metasurface phase function must satisfy to produce a desired illumination pattern by refraction, it is a Monge-Ampére equat...

The great potential of the convolutional neural networks (CNNs) provides novel and alternative ways to monitor important parameters with high accuracy. In this study, we developed a soft sensor model for dynamic processes based on a CNN for the measurement of suspended solids and turbidity from a single image of the liquid sample to be measured by...

Ray tracing in a metasurface is the process to obtain the three-dimensional (3D) light path under reflection and transmission, which may be helpful in the optical design of metalenses and other metaoptical devices. In this work, first we deduce the 3D vector form of Snell's law for metasurfaces by using a geometric approach. And then, we deduce the...

Aggregates of superparamagnetic colloids confined in liposomes in the presence of a controllable external magnetic field are studied here by computer simulation. A model of a hard sphere with a central dipole has been used to simulate secondary particles of colloids confined to move within a liposome, which is modelled as a hard spherical cavity. W...

We have implemented an exact ray trace through a plano-freeform surface for an incident plane wavefront. We obtain two caustic surfaces and provide the critical points related to the ray tracing process. Additionally, we study the propagation of the refracted wavefronts through the plane-curved surface. Finally, by using the Ronchi-Hartmann type nu...

Appendix B of paper: Ivan Moreno and P. X. Viveros-Méndez, "Modeling the irradiation pattern of LEDs at short distances," Opt. Express 29, 6845-6853 (2021)

A method for modeling the irradiance spatial distribution by light-emitting diodes (LEDs) on near distance targets has been developed. The model can easily handle the complex simulation of non-homogenous emitting LEDs, multichip LEDs, LED arrays, and phosphor coated LEDs. The LED irradiation profile is obtained by image processing one photograph of...

A multichip light-emitting diode (LED) should not be treated as a point source at short-distance illumination. For that, we propose a general, simple, but accurate mathematical model of the irradiance spatial distribution for multichip LEDs, valid at very short distance illumination. This model provides the irradiance profile as a function of both...

Convolutional neural networks (CNNs) and digital holographic interferometry (DHI) can be combined to improve the calculation efficiency and to simplify the procedures of many DHI applications. In DHI, for the measurements of concentration differences between liquid samples, two or more holograms are compared to find the difference phases among them...

So far, metalenses have only been studied in imaging optics, where a point from the object space is mapped to a corresponding point in the image space. Here we explore metalenses and metamirrors for dealing with the optimal transfer of light energy. Owing to its compactness and high design flexibility, metasurface-based flat optics may open new opp...

Light stimulation and biofloc technology can be combined to improve the efficiency and sustainability of tilapia production. A 73-day pilot experiment was conducted to investigate the effect of colored light on growth rates and nutritional composition of the Nile tilapia fingerlings (Oreochromis niloticus) in biofloc systems. The effect of colored...

Many emerging light-emitting diode (LED) applications require short-distance illumination. For that, we derive an exact formula of the illumination profile produced by Lambertian LEDs, in which all parameters are fundamental constants. Moreover, we propose a general, simple, but accurate mathematical model of the irradiance pattern, valid for Lambe...

Una metalente es una lente súper plana o súper delgada. Las metalentes tienen grabada una nano-estructura de diminutos elementos ópticos que redirigen la luz y la enfocan a un punto. Cada uno de estos elementos es un nano-resonador o nano-esparcidor óptico. Una matriz de miles o millones nano-esparcidores ópticos forman la metalente, cada uno separ...

This research evaluates the effect of wavelengths of the light on growth rates of Nile tilapia fry in the order of improving sustainability in aquaculture production. For this purpose, four tanks of water with tilapias were studied. Three tanks were illuminated with LED lamps each one with monochromatic peak wavelengths (𝜆): Blue light (BL) tank wi...

To date, many studies on the optimization of the spectral power distributions (SPDs) have been conducted to maximize the energy performance and color quality of white light-emitting diodes (LEDs). Here, not only for LEDs but for any light source, we numerically calculate the SPDs which maximize luminous efficacy of radiation (LER) in function of th...

Ceramic phosphor plates of cerium (Ce³⁺)‐doped oxyfluoride were fabricated by the solid‐state reaction method. These phosphors exhibit efficient emission, with the novel feature of color tuning by varying both the doping concentration and excitation wavelength. As the Ce³⁺ concentration increases, the excitation spectrum broadens by a factor of 1.6...

A new method for improving color rendering index (CRI) and low correlated color temperature (CCT) in high power white light emitting diodes (WLEDs) is proposed. We used a configuration of phosphor-in-glass (PIG) and studied light output changes with the increment in concentration of yellow emitting Y3Al5O12:Ce³⁺ (YAG: Ce³⁺) phosphor. The PIG was co...

Photographs of the lights seen from outer space at night are analyzed. We perform a multifractal analysis in red-green-blue color channels of lights spatial distribution of the largest cities and most populous cities in the World.

We use the digital holographic interferometry (DHI) technique to display the early ignition process for a butane-air mixture flame. Because such an event occurs in a short time (few milliseconds), a fast CCD camera is used to study the event. As more detail is required for monitoring the temporal evolution of the process, less light coming from the...

Street lighting, which is one of the main players in energy waste and light pollution at night, still faces the challenge of efficient lighting of roadways with curved and twisted shapes. To meet this challenge, we propose an effective and efficient adaptive light-emitting diode (LED) luminaire. This LED lamp delivers a roadway-shape light pattern,...

Strong emission of green light in ceramic glass was obtained. The intensity of the emitted signal changes with the heat treatment temperature.

Light-emitting diode (LED) sources have evolved to encompass a wide range of non-conventional and novel approaches in many illumination applications. This paper surveys some optical aspects of nonconventional LED based illumination.

Strong green-yellow emission in Eu2+ doped glass ceramic as a function of rare earth concentration was obtained. Proof of concept for solid state white lighting with high power AC LED was fabricated.

We obtain simple exact formulas for both caustic and refracted wavefronts through smooth surfaces by considering an incident plane wavefront propagating along the optical axis, providing a condition for total internal reflection (TIR). On the other hand, a formula to provide the maximum slopes for refracted rays outside of the lens is directly rela...

Energy consumption in mobile systems heavily depends on the display brightness. We investigate the effect of mobile phone screen brightness level on color reproduction of the whole system camera-display.

Determining the invisibility of an optical cloak intended to hide something has become a complex problem in recent years. There are many invisibility mechanisms, the performance is quite different from technique to technique, and it is desirable to have a precise metric for their comparison. Here, we propose a simple metric that assesses the percei...

LED luminaires may deliver precise illumination patterns to control light pollution, comfort, visibility, and light utilization efficiency. Here, we provide simple equations to determine how the light distributes in the streets. In particular, we model the illuminance spatial distribution as a function of Cartesian coordinates on a floor, road, or...

Calculation Code

To characterize the distribution of emittance of a lighting source, we demonstrate a new microscopy technique that does not use any lens, and is not limited to any light power emission, neither to a small depth of field.

A compact encapsulating lens is proposed and analyzed, which simultaneously collimates and mixes the tunable light from red, green and blue (RGB) light-emitting diode (LED) chips. Colored LED chips are embedded within a spherical lens, and a section of the sphere that surrounds chips is mirrored with a diffuse reflector. Color light is mixed by mul...

Combining multiple total internal reflections and segmented diffuse reflection enables a spherical lens package to mix and project light from different color LED chips.

La luz es esencial para ver y vital para el desarrollo humano. Al ocultarse el sol, las lámparas iluminan la oscuridad y permiten la convivencia, la lectura y el estudio. Lo cual tiene un profundo impacto en el desarrollo social, intelectual y económico de las civilizaciones. Pero mucha de la gente del campo, aproximadamente 1500 millones de person...

An efficient LED lamp that illuminates the street with high quality is presented. The luminaire shows high optical efficiency, high optical utilization factor, low glare, and illuminates the street with high uniformity. The concept is simple but effective: a cluster of LEDs with TIR lenses are put inside a reflective box, which is covered with a mi...

For decades, optics for focusing laser and solar light has been developed. Here, we explain the radiometry and discuss the nonimaging optics for efficient concentration of LED light into an intense and small focal spot.

A novel light luminaire is proposed and experimentally analyzed, which efficiently mixes and projects the tunable light from red, green and blue (RGB) light-emitting diodes (LEDs). Simultaneous light collimation and color mixing is a challenging task because most collimators separate colors, and most color mixers spread the light beam. We performed...

Publicado: Julio del 2012 Sección: Explorando en la Óptica, Academia Mexicana de Óptica. Resumen: Es increíble cómo el diodo emisor de luz (LED), que empezó siendo una tenue lucecita en los 60s, ha superado ya a la lámpara incandescente y fluorescente en términos de eficiencia. Cada vez nos estamos acercando más a la era del LED, usamos su luz en m...

An array of spatially distributed light-emitting diodes (LEDs) can produce an illumination pattern that approaches an image by individually modulating each LED. In this letter, I analyze the first-order design of such systems in order to achieve the best match between the illumination distribution and a desired image. In particular, simple formulas...

A novel light luminaire is proposed and experimentally analyzed, which efficiently mixes and projects the tunable light from red, green and blue (RGB) light-emitting diodes (LEDs). Simultaneous light collimation and color mixing is a challenging task because most collimators separate colors, and most color mixers spread the light beam. Our method i...

The knowledge about a seed’s optical parameters is of great relevance in the seed technology practice. Such parameters provide information about its absorption and reflectance, which in turn is related to its color, quality, and health condition. The objective of the present study was to determine the optical absorption coefficient β for maize seed...

Virtually all light-emitting diodes (LEDs) are encapsulated with a transparent epoxy or silicone-gel. In this paper we analyze the optical efficiency of spherical encapsulants. We develop a quasi-radiometric equation for the light transmission efficiency, which incorporates some ideas of Monte-Carlo ray tracing into the context of radiometry. The a...

The aim of this study was to determine the optical properties of raw and dyed maize seeds using photoacoustic spectroscopy. The experimental photoacoustic spectroscopy results are verified by using transmission photometry and the Beer law. The obtained values of the optical absorption coefficient for raw and dyed seeds only change at superficial le...

Solar energy systems use concentrating optics with photovoltaic cells for optimizing the performance. Advanced concentrators are designed to maximize both the light collection and the spatial uniformity of radiation. This is important because irradiance uniformity is critical for all types of photovoltaic cells. This is difficult to achieve with tr...

Assessing how uniform the light distribution is throughout an illuminated target is important in many applications, but traditional methods do not quantify the variability of illuminance as the human visual system (HVS) does. Considering that most light patterns are intended for humans, I propose a simple metric that assesses the uniformity in a si...

A caustic by reflection at an arbitrary surface is commonly known as a catacaustic. We study the formation of the catacaustic by multiple reflections in a reflecting circular surface by considering a point light source placed at an arbitrary point on the optical axis. The geometrical wavefront associated with multiple reflections for a paraxial app...

In this work, multivariate methods such as: principal component analysis (PCA) and partial least square–discriminant analysis (PLS–DA), were applied for the analysis and interpretation of Raman spectra, collected from microorganisms of different species. The main objective was to develop a methodology for a rapid and free of chemical–reagents discr...

We study the formation of the caustic surfaces formed in both convex-plane and plano-convex spherical lenses by considering a plane wave incident on the lens along the optical axis. Using the caustic formulas and a paraxial approximation we derive analytical expressions to evaluate the spherical aberration to third order. Furthermore, we apply the...

The use of digital holographic interferometry for 3D measurements using simultaneously three illumination directions was demonstrated by Saucedo et al. (Optics Express 14(4) 2006). The technique records two consecutive images where each one contains three holograms in it, e.g., one before the deformation and one after the deformation. A short coher...

A light cone efficiently transports, distributes, and concentrates the incoming radiation. I derive a formula for the spatial irradiance (or illuminance) distribution at the exit aperture of a tapered light pipe. The theory is demonstrated by Monte Carlo ray-tracing for lightpipes with light-emitting diodes at the input face. The analysis is based...

There is an enormous range of possible color distributions that may be created with a light cone when the primary source is an array of multicolor light-emitting diodes (LEDs). If one looks through a lightpipe toward an LED array, multiple images of the color LEDs can be observed as in a kaleidoscope. A tapered lightpipe behaves as a three-dimensio...

The photopyroelectric method has been recognized as a reliable and useful tool for the measurement of the thermal properties of condensed matter samples. Usually the photothermal signal is generated using intensity modulated light beams, whose amplitudes are difficult to maintain stable. In this paper we describe a variant of this technique that us...

A lighting cavity is a reflecting box with light sources inside. Its exit side is covered with a diffuser plate to mix and distribute light, which addresses a key issue of luminaires, display backlights, and other illumination systems. We derive a simple but precise formula for the optical efficiency of diffuser plates attached to a light cavity. W...

The output power of a light-emitting diode (LED) not only is affected by aging but also by dirt buildup. Environment and surroundings are typically characterized by the presence of substances, dust, liquids or vapors that may stick to the LED, reducing its light output. Knowing the effect of dirt on light output, manufacturers and users can efficie...

Virtually all light-emitting diodes (LEDs) are encapsulated with a transparent epoxy or silicone gel. Here we analyze the optical efficiency of spherical encapsulants. We develop a quasi-radiometric equation for the light transmission efficiency, which incorporates some ideas of Monte Carlo ray tracing into the context of radiometry. The approach i...

Versatility in the design of optical systems is one of the key features of light-emitting diodes (LEDs) that has attracted considerable attention. In the analysis of systems using LEDs, it is useful to know if the distance is far enough from the LED to allow the radiation pattern to be simulated by the point source approach. We propose three far-zo...

We describe a simple imaging technique that enables a three-dimensional inspection of the angular intensity distribution of a light-emitting diode (LED) over a significant part of the hemisphere. The measurement set-up is very simple: it consists of only a charge-coupled device (CCD) camera and a flat diffuse translucent screen. An LED illuminates...

We describe the differential cell design and the experimental (optical and electronic) setup for the differential front photopyroelectric technique, whose theory has been developed in the first part of this paper (Ivanov et al 2008 J. Phys. D: Appl. Phys. 41 085106). We will show first how the direct (non-differential) front photopyroelectric theor...

In practice, any cluster of light-emitting diodes (LEDs) can be modeled or measured as a directional point source if the detector is far enough away from the cluster. We propose a far-zone condition for measuring or modeling propagation of light from an LED array. An equation gives the far-field distance as a function of the LED radiation pattern,...

Any cluster of light-emitting diodes (LEDs) can be modeled as a directional point source if the far-zone condition is met. A general condition is derived for the distance beyond which the far-zone approximation can be used in measuring or modeling propagation of light from an LED array. A simple equation gives the far-field condition in function of...

An array of spatially distributed LEDs can produce a desired illumination pattern by individually modulating each LED. A target image can be the desired lighting pattern so that the software could find the best solution to match it. Given a desired illuminance distribution on a target surface, the luminous flux of each single LED that most closely...

In general, a caustic by refraction at an arbitrary surface is commonly known as a diacaustic. We study the formation of the diacaustic in a plane interface between an isotropic medium and a uniaxial crystal, for both ordinary and extraordinary rays, when the crystal axis is perpendicular to the plane of incidence and when it lies in the plane of i...

— A method of calculating the luminance and luminance uniformity of a bottom LED backlight is proposed and demonstrated. Both the power consumption and brightness uniformity as a function of screen brightness, screen size, backlight thickness, transmittance of the LCD panel, reflective cavity efficiency, gain, cone angle of the enhancement films, L...

In this paper the theory of the differential front photopyroelectric technique is developed. The thermal effusivity measurements of a sample through photopyroelectric direct (no-differential) experiments do not have sufficient resolution and accuracy to detect small changes in the thermal effusivity. To assess minor variations in this thermal magni...

An algorithm designed for the comparison of photothermal methods is described, based on the knowledge of the value–to–uncertainty ratio of the measured thermal parameters of the investigated object. This comparison allows us to select the best method for the precise determination of thermal properties of materials. The usefulness of the algorithm i...

A direct or bottom LED backlight is a key concept in large area LCD displays because it does not use a light guide, is flat, and is easy to assemble. In this paper, a method of luminance management for a bottom LED backlight is proposed and demonstrated. We analytically calculate both the power consumption and brightness uniformity in function of:...

A single-chip white light LED is commonly modeled by considering the phosphor coating as a homogeneous Lambertian light source. However, this approach leads to an incorrect optical simulation of phosphor-coated multi-chip LEDs due to the presence of a previously unreported spatial distribution of emission spots across the phosphor layer. We introdu...

Since its beginnings, light-emitting diode (LED) has progressed toward greater performance. Today, LEDs are everywhere, in many shapes, and with a wide range of radiation patterns. We propose a general analytic representation for the angular intensity distribution of the light emitted from an LED. The radiation pattern equation is determined by add...

Dispersion in a uniaxial prism provides an example of the application of the law of refraction for a uniaxial crystal. Formulas for the minimum deviation angle for the extraordinary ray are given when the crystal axis lies in the plane of incidence. Three particular cases for the crystal axis position are presented and are shown to have a behavior...

A single-chip white light LED is commonly modeled by considering the phosphor coating as a homogeneous Lambertian light source. However, this approach leads to an incorrect optical simulation of phosphor-coated multi-chip LEDs due to the presence of a previously unreported spatial distribution of emission spots across the phosphor layer. We introdu...