Calibración de Microscopios Confocales

El microscopio confocal ha sido durante mucho tiempo un instrumento de observación tridimensional con múltiples aplicaciones especialmente dentro de la biología. Sin embargo en los últimos años ha comenzado a ser utilizado como instrumento de medida en diferentes áreas de la ingeniería. En la actualidad existen muchas especificaciones de productos (dimensionales, angulares, acabado superficial) en las escalas micrométricas y nanométricas que pueden o podrían ser verificadas utilizando este instrumento. Pero para que esta verificación sea válida dentro de un sistema de calidad el microscopio confocal debe ser trazable. Esta ponencia presenta una solución sencilla a este problema implementada en el Centro Láser de la Universidad Politécnica de Madrid (UPM) que ha permitido dotar de trazabilidad a las medidas dimensionales realizadas en el plano XY y en el eje Z de su microscopio confocal. The confocal microscope has been a three-dimensional observation instrument with multiple applications especially in biology. However in recent years has begun to be used as a measuring instrument contact in various engineering fields. At present there are many product specifications (size, angular, surface roughness) in the micrometer and nano scales that can or could be verified using this instrument. But this verification is only valid within a quality system if the confocal microscope is traceable. This paper presents a simple solution to this problem implemented in the Laser Centre of the Polytechnic University of Madrid (UPM). This solution provides traceablity to the size measurements made in the XY plane and the Z-axis

Micromecanizado Láser de Componentes de Gran calidad de Acabado Superficial

El uso de láseres pulsados con anchos temporales de nanosegundos y longitudes de onda en el rango Ultravioleta, permiten un preciso control del material abferido, convirtiendo dicha técnica en una herramienta fundamental para mecanizados que requieren de una gran calidad y acabado, con relaciones de aspecto muy altas. Este trabajo presenta un análisis paramétrico de la influencia de las distintas variables de proceso para diferentes tipos de materiales (metálicos, dieléctricos, materiales orgánicos, etc) en la calidad y acabado final. The use of nanoseconds U.V. lasers permits a precise control in ablation’s processes. As a result this tool plays a fundamental role in machining where a high quality and good aspect ratios are required. This paper presents a parametric analysis of the influence of some processing parameters for different types of materials

Selective ablation with UV lasers of a-Si:H thin film solar cells in direct scribing configuration

Monolithical series connection of silicon thin-film solar cells modules performed by laser scribing plays a very important role in the entire production of these devices. In the current laser process interconnection the two last steps are developed for a configuration of modules where the glass is essential as transparent substrate. In addition, the change of wavelength in the employed laser sources is sometimes enforced due to the nature of the different materials of the multilayer structure which make up the device. The aim of this work is to characterize the laser patterning involved in the monolithic interconnection process in a different configurations of processing than the usually performed with visible laser sources. To carry out this study, we use nanosecond and picosecond laser sources working at 355nm of wavelength in order to achieve the selective ablation of the material from the film side. To assess this selective removal of material has been used EDX (energy dispersive using X-ray) analysi

Laser Shock Microforming of Thin Metal Sheets with Q-Switched ns Lasers

The increasing demands in MEMS fabrication are leading to new requirements in production technology. Especially the packaging and assembly require high accuracy in positioning and high reproducibility in combination with low production costs. Conventional assembly technology and mechanical adjustment methods are time consuming and expensive. Each component of the system has to be positioned and fixed. Also adjustment of the parts after joining requires additional mechanical devices that need to be accessible after joining

Microconformado de Materiales Metálicos mediante Pulsos Láser en el Dominio de ns

La demanda de miniaturización introducida, entre otros, por la industria de fabricación de MEMS (Micro Electro Mechanical Systems), hace necesario caracterizar y validar los procesos que emplean el láser en el microconformado de materiales metálicos a escala submilimétrica. Como alternativa al microconformado térmico, que hace uso de las deformaciones de origen térmico inducidas por la radiación láser, el microconformado mediante pulsos láser en el dominio de ns hace posible el conformado de materiales metálicos manteniendo, o incluso mejorando, las propiedades mecánicas de los mismos debido a la inducción de tensiones residuales de compresión en la superficie de la pieza tratada. Se presenta en este trabajo el estudio teórico y experimental del microconformado láser mediante la caracterización de diversas pruebas elementales. Miniaturization of components demanded by MEMS (Micro Electro Mechanical Systems) industry, makes necessary the validation of the manufacturing processes applied to submillimetric metallic materials in which laser is used. As an alternative to thermal microforming in which laser induced thermal fields are responsible for the forming phenomena, the use of ns laser pulses makes possible microforming of metallic materials preserving, or even improving, their mechanical properties, due to the induction of residual stresses in the surface. In the present paper experimental tests and FEM simulation results on nanosecond time scale laser microforming are presented

Avances en la fabricación de células y módulos fotovoltaicos de silicio en capa fina mediante láser

El láser es un instrumento omnipresente en la fabricación de módulos fotovoltaicos. Los láser estándar para la interconexión monolítica de dispositivos de lámina delgada de a-Si son láser de estado sólido bombeados por diodo (DPSS) emitiendo en longitudes IR (λ=1064 nm) y en VIS (λ=532 nm). En este trabajo mostramos estudios de ablación de algunos materiales fotovoltaicos (óxidos conductores transparentes (OCT) y a-Si) con láser emitiendo en UV en el régimen de nanosegundos (ns). La afección térmica resultante en la ablación es menor, y por tanto se reduciría el riesgo de cortocircuitos en la interconexión monolítica, convirtiendo a las fuentes láser UV como herramientas prometedoras como alternativa a las fuentes estándar. Laser is an essential tool for photovoltaic modules manufacturing. Nowadays DPSS working at IR ( λ=1064 nm) and VIS (λ=532 nm) wavelengths are standard tools for thin film module fabrication. In this work we present ablation studies of some photovoltaic materials (transparent conductive oxides (TCO) and a-Si) using nanoseconds (ns) laser sources emitting in the UV. The thermal affection is minimized, and therefore it would be reduced the short-circuit formation risk in the monolithic interconnection, demonstrating the potential use of ns laser sources emitting in the UV as promising alternative tools to the standard laser sources

Silicon PV module customization using laser technology for new BIPV applications

It is well known that lasers have helped to increase efficiency and to reduce production costs in the photovoltaic (PV) sector in the last two decades, appearing in most cases as the ideal tool to solve some of the critical bottlenecks of production both in thin film (TF) and crystalline silicon (c-Si) technologies. The accumulated experience in these fields has brought as a consequence the possibility of using laser technology to produce new Building Integrated Photovoltaics (BIPV) products with a high degree of customization. However, to produce efficiently these personalized products it is necessary the development of optimized laser processes able to transform standard products in customized items oriented to the BIPV market. In particular, the production of semitransparencies and/or freeform geometries in TF a-Si modules and standard c-Si modules is an application of great interest in this market. In this work we present results of customization of both TF a-Si modules and standard monocrystalline (m-Si) and policrystalline silicon (pc-Si) modules using laser ablation and laser cutting processes. A discussion about the laser processes parameterization to guarantee the functionality of the device is included. Finally some examples of final devices are presented with a full discussion of the process approach used in their fabrication

Laser Shock Microforming of Thin Metal Sheets: Physical Principles, Modelling and Experimental Implementation

The increasing demands in MEMS fabrication are leading to new requirements in production technology. Especially the packaging and assembly require high accuracy in positioning and high reproducibility in combination with low production costs. Conventional assembly technology and mechanical adjustment methods are time consuming and expensive. Each component of the system has to be positioned and fixed. Also adjustment of the parts after joining requires additional mechanical devices that need to be accessible after joining. Accurate positioning of smallest components represents an up-to-date key assignment in micro-manufacturing. It has proven to be more time and cost efficient to initially assemble the components with widened tolerances before precisely micro-adjusting them in a second step

Study of a-Si crystallization dependence on power and irradiation time using a CW green laser

An advantage of laser crystallization over conventional heating methods is its ability to limit rapid heating and cooling to thin surface layers. Laser energy is used to heat the a-Si thin film to change the microstructure to poly-Si. Thin film samples of a-Si were irradiated with a CW-green laser source. Laser irradiated spots were produced by using different laser powers and irradiation times. These parameters are identified as key variables in the crystallization process. The power threshold for crystallization is reduced as the irradiation time is increased. When this threshold is reached the crystalline fraction increases lineally with power for each irradiation time. The experimental results are analysed with the aid of a numerical thermal model and the presence of two crystallization mechanisms are observed: one due to melting and the other due to solid phase transformation

Simulación del comportamiento del subsistema de potencia del satélite Lian-He bajo unos parámetros de misión típicos = Simulation of the Lian-Hé satellite power subsystem under typical LEO mission requirements

En el proceso de diseño de sistemas espaciales, el subsistema de generación y distribución de potencia resulta crítico. Para percibirlo basta con pensar en la dependencia energética de gran parte de los demás subsistemas. En el presente informe se describirá en detalle el modelizado del sistema de generación y distribución de potencia del satélite Lian-He. También se realizarán análisis para comprobar durabilidad de la batería durante la misión, así como la robustez del diseño en caso de fallo de algún panel solar. El presente trabajo es parte del contenido docente de la asignatura de Generación y Gestión de Potencia Eléctrica correspondiente al Máster Universitario en Sistemas Espaciales (MUSE), impartido en el curso 2016-2017. Los tutores de este trabajo han sido los profesores Elena Roibás-Millán, Javier Cubas y Santiago Pindado. The proper design of the power subsystem in a space mission is a critical factor, as the correct performance of all the other subsystems of a satellite depend on the power generation and distribution. In the present work, the power subsystem of Lian-Hé satellite (generation, storage and distribution), is thoroughly described and analyzed for a typical LEO misión requeriments. Besides, a failure analysis of key parts of the subsystem such as oneot two solar panels, or half of the battery strings has been included in the work. This work was carried out as part of the subject Power Subsystems of the Master in Space Systems(MUSE)of Universidad Politécnica de Madrid. The supervisors of this work were professors elena Roibás-Millán, Javier Cubas and Santiago Pindado