This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 within the LDRD program.

1. Preparación de pulidora y purines En primer lugar preparar el sistema de pulido convergente (específicamente llamado C onvergent, me nitial superficie Independiente, S ingle iteración, R ogue Pulidora libre de partículas o CISR (pronunciado &#39;tijera&#39;)) 7,17 mediante la instalación de la plataforma y el tabique, el acondicionamiento de la almohadilla, diluir y estabilizar químicamente la suspensión, y la incorporación de la suspensión dentro del sistema de filtración. <ol><li> En la pulidora CISR, se adhieren una almohadilla de poliuretano en la base regazo granito. Se adhieren almohadilla de uno de los bordes primero y aplicar presión en la dirección hacia el borde opuesto para reducir al mínimo los espacios de aire. Recorte el pad sobresaliente y luego utilizar una hoja de afeitar y el rodillo para perforar y extraer las burbujas de aire si es necesario. </li><li> Para el primer uso y después de cada ~ 100 hr de pulir, condición diamante el teclado usando un acondicionador de diamantes CMP (50 mm de diámetro; 0,6 psi de presión aplicada; de permanencia de 5 minutos en cada lugar regazo radial con incrementos de espaciado 25 mm; rotación vuelta 25 rpm) con agua DI que fluye. </li><li> Entre iteraciones para pulir, eliminar los purines y productos de vidrio residuales de la almohadilla con un limpiador-in situ por ultrasonidos (~ 2 minutos de permanencia en cada lugar radial; rotación vuelta 5 rpm) con agua DI que fluye. </li><li> Por el peso del tabique de forma única, se adhieren cinta de espuma de doble cara y luego el material septum (por ejemplo, vidrio pre-corte u otro material resistente al desgaste). Recortar cualquier cinta de espuma en voladizo para que coincida con la forma del material tabique y peso. Tenga en cuenta el diseño del tabique (tanto la forma y el peso) cambia para diferentes tamaños de la pieza y vuelta 7,17. </li><li> Preparar pulido suspensión para Baume 4 concentración (específicamente mezcle por volumen ~ 1 parte de óxido de cerio para pulir los purines y ~ 9 partes de agua desionizada (DI) en una bu 11 Lcket). Compruebe Baume usando un flotador Baume. Añadir ~ 5 ml de KOH (10 M) para ajustar el pH a 9,5 y añadir 120 ml (~ 1% en volumen) de surfactante patentada 19. Vuelva a ajustar el pH y Baume cada 24 horas de pulido. </li><li> Instale el cubo con la suspensión preparada en el sistema de filtración. A continuación, instale los filtros de partículas CMP deseados en el sistema de filtración. Deje recirculación suspensión dentro del sistema de filtración durante varias horas. </li><li> Distribución de tamaño de partícula medida de suspensión (por ejemplo, usando sola partícula técnicas de detección óptica) para asegurar el extremo de la cola de la distribución es adecuada libre de partículas pícaro 9,20. </li></ol> 2. Preparación de la pieza (Aguafuerte y bloqueo) Antes de pulir, grabar químicamente la pieza de tierra fina como se recibe a reducir la cantidad de remoción de material necesario para eliminar la sub-superficie de molienda daños 21. Entonces, bloquear la pieza de trabajo (si la relación de aspecto (es decir, longitud / espesor) es&gt; 10), utilizando una nueva técnica de bloqueo botón de pitch (PBB) para evitar que la pieza de trabajo se doble durante el bloqueo y pulido 22. <ol><li> Grabar la pieza de trabajo molido fino (específicamente un 265 x 265 x 8 mm 3 de vidrio de sílice fundida plana) en un tanque lleno de HF: NH 4 F (6: 1 de grabado de óxido tamponado (BOE) 3x diluyó con agua DI) durante 6 horas eliminación 10 micras de vidrio de la superficie de la pieza de trabajo. ¡CUIDADO! BOE es extremadamente peligroso; utilizar equipo de protección personal (EPP) apropiado. Retire la pieza del tanque de grabado y agresivamente enjuagar la pieza con agua DI y permita que la pieza se seque al aire verticalmente. </li><li> Inspeccione la pieza de trabajo por daños profunda durante el proceso de molienda mediante una inspección de la luz brillante en un cuarto oscuro. Si no se encuentra daño profundo, continúe con el siguiente paso, de lo contrario enviar la pieza de nuevo para volver a la molienda. </li><li> Calentar el bloqueo de tono en una pistola de pegamento a ~ 95 ºC y colocar gotas (también llamadas botones) de lanzamiento (~ 0,06 g) sobre la faz de laplaca de bloqueo en una matriz de 9 x 9 (81 botones con 26 mm de distancia). Para diferentes piezas de trabajo de tamaño, consulte diseñar reglas para el número ideal, tamaño y espaciamiento de botón de pitch 22. Coloque la placa de bloqueo con los botones aplicados boca arriba en un horno precalentado a 70 ºC. </li><li> Aplique la cinta a la cara de la pieza de trabajo que no está para ser pulido. Evitar la generación de burbujas de aire o excesivamente estirar la cinta. </li><li> Coloque la pieza de trabajo con la cara cara de la cinta hacia abajo sobre los botones de la placa de bloqueo en el horno. Cubra la pieza-button-bloque para minimizar el flujo convectivo. Después de 1,5 horas, ajuste horno se enfríe 10 ºC / hora a temperatura ambiente. Después de enfriar, el espesor de paso en la pieza de trabajo debe ser bloqueado ~ 1 mm. </li></ol> 3. convergente Pulido <ol><li> Encienda el sistema de humedad en la cámara ambiental de pulidor CISR para prevenir lodo se seque durante el pulido y reducir al mínimo las partículas canallas rascándose la pieza de trabajo. </li><li> Insde altura y montar el tabique específicamente diseñado y preparado en pulidora. Instale PBB pieza en pulidor CISR y bajar la pluma para sostener la pieza de trabajo. </li><li> Polaco pieza de trabajo en CISR durante 4 horas a una velocidad de rotación de vuelta y la pieza de trabajo emparejado de 25 rpm con un golpe radial de ~ 75 mm y con un flujo de la suspensión de sistema de filtración de 1 gal / min. NOTA: La placa de bloqueo también sirve como el peso de la carga en la pieza de trabajo correspondiente a 0,6 psi presión aplicada. </li><li> Apague el regazo y la pieza de rotación y el flujo de lodo. Retire PBB pieza de pulidor CISR y sumerja en agua llena de baño DI. Limpie la superficie de la pieza con un paño sala limpia mientras está sumergido. Retire PBB pieza de baño y rociar enjuague con agua DI. </li><li> Deblock pieza de trabajo mediante la inserción de una cuña en la interfaz pieza de bloque. Retire la cinta de superficie de la pieza. Agresivamente enjuagar la pieza con agua DI y secar al aire. </li><li> PBB la cara opuesta de la pieza de trabajo como se describe en la Sección 2. A continuación, repita poel que se crea el procedimiento como se describe en la Sección 3. </li></ol> 4. Metrología e Inspección <ol><li> Medida de frente de onda reflejada (es decir, forma de superficie) de ambos lados de la pieza de trabajo, así como de frente de onda de transmisión usando un interferómetro. </li><li> Monte la pieza en brillante estación de inspección de la luz y medir las propiedades cero / excavación utilizando métodos estándares de fabricación óptico. Un corto grabado BOE de la pieza de trabajo, tal como se describe en el paso 2.1, se puede utilizar para exponer arañazos ocultos para piezas utilizadas en aplicaciones de láser de alta fluencia. Para la medición de arañazos finos o rugosidad en la pieza de trabajo, se pueden utilizar microscopía óptica estándar o interferometría de luz blanca. </li><li> Tienda completó pieza de trabajo en un contacto minimización recipiente con la cara de la pieza de trabajo. </li></ol>

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The authors have nothing to disclose.

Como se explica en la Introducción, la implementación exitosa de Convergente Pulido con respecto a la superficie cifra implica eliminar o minimizar todos los fenómenos que influyen espacial no uniformidad de material excepto el de desajuste pieza vueltas debido a la forma de la pieza. Si uno cualquiera de estos fenómenos no se mitiga adecuadamente, ya sea a través de control de procesos o a través de ingeniería apropiado de la pulidora, a continuación, el punto de convergencia deseado no puede conseguirse o mant...

Los principales pasos en un proceso típico de fabricación óptica incluyen formación, rectificado, pulido de abertura total, y, a veces pequeña herramienta de pulido 1-3. Con el aumento de la demanda de componentes ópticos de alta calidad para sistemas de imagen y láser, se han producido avances significativos en la fabricación de óptica en los últimos decenios. Por ejemplo, la precisión, la eliminación de material determinista ahora es posible durante la configuración y los procesos de molienda con los avances en la computadora de control numérico de máquinas de conformación (CNC) de vidrio. Del mismo modo, las tecnologías de pulido pequeña herramienta (por ejemplo, superficie óptica controlada por ordenador (CCOS), ion calcular, y el acabado magnetoreológico (MRF)) han dado lugar a la eliminación de material determinista y control de forma de superficie, impactando fuertemente la industria de fabricación de óptica. Sin embargo, el paso intermedio del proceso de acabado, pulido de abertura total, aún carece de alto determinismo, por lo general requieren opticia expertons para llevar a cabo múltiples, a menudo largos y ciclos iterativos con múltiples cambios en el proceso para alcanzar la cifra de superficie deseada 1-3. El gran número de métodos de pulido, las variables del proceso, y la compleja química y las interacciones mecánicas entre la pieza de trabajo, lap y purines 4.3 han hecho que sea difícil para transformar pulido óptico de un &quot;arte&quot; a una ciencia. Para lograr determinista pulido plena abertura, la velocidad de eliminación de material debe ser bien entendido. Históricamente, la tasa de eliminación de material ha sido descrita por la ecuación Preston ampliamente utilizado 5 <img alt="Ecuación 1" fo:content-width="1in" fo:src="/files/ftp_upload/51965/51965eqn1.jpg" src="/files/ftp_upload/51965/51965eqn1.jpg" width="100px" /> (1) donde dh / dt es la tasa de eliminación de espesor medio, p k es la constante de Preston, σ S sela presión aplicada, y V r es la velocidad relativa media entre la pieza y la vuelta. La Figura 1 representa esquemáticamente los conceptos físicos que influyen en la tasa de eliminación de material tal como se describe la ecuación Preston, incluyendo las variaciones espaciales y temporales en la velocidad y la presión, las diferencias entre el la presión aplicada y la distribución de la presión que las experiencias de la pieza, y los efectos de fricción 6-8. En particular, la distribución de la presión real experimentada por la pieza de trabajo se rige por una serie de fenómenos (descritos en detalle en otra parte 6-8) que afecta fuertemente resultante figura superficie de la pieza de trabajo. También, en la Ecuación Preston, los efectos microscópicos y moleculares de nivel se pliegan en gran medida en el macroscópica constante Preston (k p), que influye en la tasa global de material de eliminación, micro-rugosidad, e incluso arañazos en la pieza de trabajo. Diversos estudios han ampliado el modelo de Preston para dar cuenta<html> para lechada microscópica interacciones partícula-pad-piezas de trabajo para explicar la tasa de remoción de material y microrrugosidad 9-16. Para lograr el control determinista de la figura superficie durante el pulido abertura total, cada uno de los fenómenos descritos anteriormente tiene que ser entendido, cuantificado y luego controlada. La estrategia detrás de pulido es convergente para eliminar o minimizar las causas indeseables de la eliminación de material no uniforme, ya sea a través del diseño pulidor de ingeniería o de control de procesos, de tal manera que la eliminación es impulsado sólo por la falta de coincidencia de la pieza vueltas debido a la forma de la pieza 7,17- 18. La figura 2 ilustra cómo la forma de la pieza puede llevar a la convergencia basada en el concepto desajuste pieza vueltas. Considere la posibilidad de una vuelta plana y una pieza de trabajo hipotética de forma compleja se muestra en la parte superior izquierda. El desajuste altura de la interfase (referido como la brecha,? H ol) influye en la distribución de la presión de interfaz (σ) como: contenido &quot;fo: keep-together.within-page =&quot; always &quot;&gt; <img alt="Ecuación 2" fo:content-width="1in" fo:src="/files/ftp_upload/51965/51965eqn2.jpg" src="/files/ftp_upload/51965/51965eqn2.jpg" width="100px" /> (2) donde h es una constante que describe la velocidad a la que la presión disminuye con un aumento en la brecha? h oL 6. En este ejemplo, la pieza de trabajo tiene la presión más alta local en el centro (véase la parte inferior izquierda de la Figura 2), y por lo tanto esta ubicación observará la tasa de eliminación de material inicial más alta durante el pulido. Como se retire el material, el diferencial de presión a través de la pieza de trabajo se reducirá debido a una disminución en el desajuste pieza de trabajo-regazo, y la pieza de trabajo convergerá a la forma de la vuelta. En la convergencia, la distribución de presión pieza de trabajo, y por lo tanto, la eliminación de material, será uniforme a través de la pieza de trabajo (ver lado derecho de la Figura 2). Este ejemplo se ilustra para una vuelta plana, however, el mismo concepto se aplica a una vuelta esférica (ya sea cóncava o convexa). Una vez más, este proceso de convergencia sólo funciona si se han eliminado todos los demás fenómenos que afectan espacial no uniformidad material. Las mitigaciones de procedimiento y de ingeniería específicas implementadas en el protocolo Pulido convergente se describen en la Discusión. El protocolo se describe en el siguiente estudio es el proceso convergente Pulido específicamente para un cuadrado fusionado pieza de vidrio de sílice 26,5 cm a partir de una superficie de molido fino. En 8 horas de pulido (4 horas / superficie), esta pieza de trabajo puede alcanzar una planitud pulida de ~ λ / 2 con una calidad de superficie muy alta (es decir, de baja densidad cero).

<table border="0" cellpadding="0" cellspacing="0" width="634">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:251px;">Name of Material/Equipment</td>
			<td style="width:245px;">Company</td>
			<td style="width:139px;">Catalog Number</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MHN 50 mil Polyurethane Pad&#160;</td>
			<td>Eminess Technologies</td>
			<td>PF-MHN15A050L-56</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cerium oxide polishing slurry</td>
			<td>Universal Photonics</td>
			<td>HASTILITE PO</td>
		</tr>
		<tr height="21">
			<td dir="LTR" height="21" style="height:21px;width:251px;">Septum Glass (waterjet cut)</td>
			<td dir="LTR" style="width:245px;">Borofloat ; Schott&#160;</td>
			<td dir="LTR" style="width:139px;">NA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Diamond conditioner</td>
			<td>Morgan Advanced Ceramics&#160;</td>
			<td>CMP-25035-SFT</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultrasonic Cleaner</td>
			<td>Advanced Sonics Processing System</td>
			<td>URC4</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Purification Optima Filter cartridge</td>
			<td>3M</td>
			<td>CMP560P10FC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blocking Pitch</td>
			<td>Universal Photonics</td>
			<td>BP1</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blocking Tape</td>
			<td>3M</td>
			<td>#4712</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cleanroom Cloth</td>
			<td>ITW Texwipe</td>
			<td>AlphaWipe TX1013</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Single Particle Optical Sensing</td>
			<td>Paritcle Sizing Systems</td>
			<td>Accusizer 780 AD</td>
		</tr>
	</tbody>
</table>

convergent polishing: a simple, rapid, full aperture polishing process of high quality optical flats &amp; spheres

Convergent pulido es un novedoso sistema de pulido y método para el acabado de la óptica de vidrio planas y esféricas en la que una pieza de trabajo, independientemente de su forma inicial (es decir, forma de superficie), convergerá a la figura superficie final con una excelente calidad de la superficie bajo un conjunto fijo de inmutable pulir parámetros en una sola iteración de pulido. Por el contrario, los métodos convencionales de pulido de apertura completa a menudo requieren múltiples ciclos largos, iterativos, que implican pulir, metrología y cambios en el proceso de alcanzar la cifra de superficie deseada. El proceso de pulido convergente se basa en el concepto de pieza de trabajo vueltas desajuste altura resultante en diferencial de presión que disminuye con la extracción y los resultados en la pieza de trabajo convergentes a la forma de la vuelta. La implementación exitosa del proceso convergente Pulido es el resultado de la combinación de una serie de tecnologías para eliminar todas las fuentes de no uniforme de remoción de material espacial (excepto la pieza vueltasdesajuste) de forma de superficie convergencia y de reducir el número de partículas de canallas en el sistema para densidades de arañazos y baja rugosidad. El proceso convergente Pulido se ha demostrado para la fabricación de dos pisos y esferas de diferentes formas, tamaños y relaciones de aspecto sobre diversos materiales de vidrio. El efecto práctico es que los componentes ópticos de alta calidad se pueden fabricar más rápidamente, más repetidas ocasiones, con menos de metrología, y con menos mano de obra, lo que resulta en menores costos unitarios. En este estudio, el protocolo convergente de pulido se describe específicamente para la fabricación de 26,5 cm cuadrado fusionados pisos de sílice a partir de una superficie de molido fino a un ~ λ figura superficie pulida / 2 después de pulir 4 hr por unidad de superficie en un pulidor de diámetro 81 cm.

El protocolo convergente de pulido descrito anteriormente permite que un suelo de sílice fundida pieza de trabajo (en este caso un cuadrado de 26,5 cm) a pulir, en una única iteración de 4 hr por unidad de superficie, a una planitud de pico a valle de ~ λ / 2 (~ 330 nm) para piezas de trabajo baja relación de aspecto y 1λ ~ (~ 633 nm) para piezas de trabajo alta relación de aspecto (véase la Figura 3). Una vez más, este proceso converge repetidamente piezas de trabajo a la misma figura superfic...

Watch this Scientific Journal Video about Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres at JoVE.com

Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats &amp; Spheres

A novel optical polishing process, called &#8220;Convergent Polishing&#8221;, which enables faster, lower cost polishing, is described. Unlike conventional polishing processes, Convergent Polishing allows a glass workpiece to be polished in a single iteration and with high surface quality to its final surface figure without requiring changes to polishing parameters.

Convergentes Pulido: Una simple, rápida, completa Apertura Pulido Proceso de alta calidad óptica Pisos y Esferas

Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial ...

convergent-polishing-simple-rapid-full-aperture-polishing-process

Research

JoVE Journal

Engineering

11.0K vistas.  Lawrence Livermore National Laboratory. A novel optical polishing process, called “Convergent Polishing”, which enables faster, lower cost polishing, is described. Unlike conventional polishing processes, Convergent Polishing allows a glass workpiece to be polished in a single iteration and with high surface quality to its final surface figure without requiring changes to polishing parameters.

Video: Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres

Fabrication of Silica Ultra High Quality Factor Microresonators

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date1-2. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.3-7
The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q&gt;100 million).1-2,8-9 However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment.
Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment.
Introduction
An optical resonator efficiently confines light at specific wavelengths, known as the resonant wavelengths of the device. 1-2 The common figure of merit for these optical resonators is the quality factor or Q. This term describes the photon lifetime (&tau;o) within the resonator, which is directly related to the resonator's optical losses. Therefore, an optical resonator with a high Q factor has low optical losses, long photon lifetimes, and very low photon decay rates (1/&tau;o). As a result of the long photon lifetimes, it is possible to build-up extremely large circulating optical field intensities in these devices. This very unique property has allowed these devices to be used as laser sources and integrated biosensors.10
A unique sub-class of resonators is the whispering gallery mode optical microcavity. In these devices, the light is confined in circular orbits at the periphery. Therefore, the field is not completely confined within the device, but evanesces into the environment. Whispering gallery mode optical cavities have demonstrated some of the highest quality factors of any optical resonant cavity to date.9,11 Therefore, these devices are used throughout science and engineering, including in fundamental physics studies and in telecommunications as well as in biodetection experiments. 3-7,12
Optical microcavities can be fabricated from a wide range of materials and in a wide variety of geometries. A few examples include silica and silicon microtoroids, silicon, silicon nitride, and silica microdisks, micropillars, and silica and polymer microrings.13-17 The range in quality factor (Q) varies as dramatically as the geometry. Although both geometry and high Q are important considerations in any field, in many applications, there is far greater leverage in boosting device performance through Q enhancement. Among the numerous options detailed previously, the silica microsphere and the silica microtoroid resonator have achieved some of the highest Q factors to date.1,9 Additionally, as a result of the extremely low optical loss of silica from the visible through the near-IR, both microspheres and microtoroids are able to maintain their Q factors over a wide range of testing wavelengths.18 Finally, because silica is inherently biocompatible, it is routinely used in biodetection experiments.
In addition to high material absorption, there are several other potential loss mechanisms, including surface roughness, radiation loss, and contamination loss.2 Through an optimization of the device size, it is possible to eliminate radiation losses, which arise from poor optical field confinement within the device. Similarly, by storing a device in an appropriately clean environment, contamination of the surface can be minimized. Therefore, in addition to material loss, surface scattering is the primary loss mechanism of concern.2,8
In silica devices, surface scattering is minimized by using a laser reflow technique, which melts the silica through surface tension induced reflow. While spherical optical resonators have been studied for many years, it is only with recent advances in fabrication technologies that researchers been able to fabricate high quality silica optical toroidal microresonators (Q&gt;100 million) on a silicon substrate, thus paving the way for integration with microfluidics.1
The present series of protocols details how to fabricate both silica microsphere and microtoroid resonant cavities. While silica microsphere resonant cavities are well-established, microtoroid resonant cavities were only recently invented.1 As many of the fundamental methods used to fabricate the microsphere are also used in the more complex microtoroid fabrication procedure, by including both in a single protocol it will enable researchers to more easily trouble-shoot their experiments.

We describe the use of a carbon dioxide laser reflow technique to fabricate silica resonant cavities, including free-standing microspheres and on-chip microtoroids. The reflow method removes surface imperfections, allowing long photon lifetimes within both devices. The resulting devices have ultra high quality factors, enabling applications ranging from telecommunications to biodetection.

La fabricación de sílice de alta calidad Ultra microresonators Factor

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the ...

Investigación

Ingeniería

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material fabrication techniques are able to mimic the complexity of these structures while maintaining scalability. The Vaporization of a Sacrificial Component (VaSC) process is able to do so. This process uses sacrificial fibers as a template to form hollow, cylindrical microchannels embedded within a matrix. Tin (II) oxalate (SnOx) is embedded within poly(lactic) acid (PLA) fibers which facilitates the use of this process. The SnOx catalyzes the depolymerization of the PLA fibers at lower temperatures. The lactic acid monomers are gaseous at these temperatures and can be removed from the embedded matrix at temperatures that do not damage the matrix. Here we show a method for aligning these fibers using micromachined plates and a tensioning device to create complex patterns of three-dimensionally arrayed microchannels. The process allows the exploration of virtually any arrangement of fiber topologies and structures.

The Vaporization of a Sacrificial Component (VaSC) process is used to fabricate microvascular structures. This procedure uses sacrificial poly(lactic) acid fibers to form hollow microchannels with precise 3D geometric positioning provided by laser micromachined guide plates.

Proceso de fabricación microestructuras tridimensionales mediante vaporización de un componente de sacrificio

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material ...

Construction of a High Resolution Microscope with Conventional and Holographic Optical Trapping Capabilities

High resolution microscope systems with optical traps allow for precise manipulation of various refractive objects, such as dielectric beads 1 or cellular organelles 2,3, as well as for high spatial and temporal resolution readout of their position relative to the center of the trap. The system described herein has one such "traditional" trap operating at 980 nm. It additionally provides a second optical trapping system that uses a commercially available holographic package to simultaneously create and manipulate complex trapping patterns in the field of view of the microscope 4,5 at a wavelength of 1,064 nm. The combination of the two systems allows for the manipulation of multiple refractive objects at the same time while simultaneously conducting high speed and high resolution measurements of motion and force production at nanometer and piconewton scale.

The system described herein employs a traditional optical trap as well as an independent holographic optical trapping line, capable of creating and manipulating multiple traps. This allows for the creation of complex geometric arrangements of refractive particles while also permitting simultaneous high-speed, high-resolution measurements of the activity of biological enzymes.

Construcción de un microscopio de alta resolución con capacidades de captura óptica convencional y holográfica

High resolution microscope systems with optical traps allow for precise manipulation of various refractive objects, such as dielectric beads 1 or cellular ...

The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry

Thermal noise in high-reflectivity mirrors is a major impediment for several types of high-precision interferometric experiments that aim to reach the standard quantum limit or to cool mechanical systems to their quantum ground state. This is for example the case of future gravitational wave observatories, whose sensitivity to gravitational wave signals is expected to be limited in the most sensitive frequency band, by atomic vibration of their mirror masses. One promising approach being pursued to overcome this limitation is to employ higher-order Laguerre-Gauss (LG) optical beams in place of the conventionally used fundamental mode. Owing to their more homogeneous light intensity distribution these beams average more effectively over the thermally driven fluctuations of the mirror surface, which in turn reduces the uncertainty in the mirror position sensed by the laser light.
We demonstrate a promising method to generate higher-order LG beams by shaping a fundamental Gaussian beam with the help of diffractive optical elements. We show that with conventional sensing and control techniques that are known for stabilizing fundamental laser beams, higher-order LG modes can be purified and stabilized just as well at a comparably high level. A set of diagnostic tools allows us to control and tailor the properties of generated LG beams. This enabled us to produce an LG beam with the highest purity reported to date. The demonstrated compatibility of higher-order LG modes with standard interferometry techniques and with the use of standard spherical optics makes them an ideal candidate for application in a future generation of high-precision interferometry.

Large laser-interferometers are being constructed to create a new type of astronomy based on gravitational waves. Their sensitivities, as for many other high-precision experiments, are approaching fundamental noise limits such as the atomic vibration of their components. We are pioneering technologies to overcome these limits using novel laser beam shapes.

La Generación de orden superior Laguerre-Gauss haces ópticos de Interferometría de alta precisión

Thermal noise in high-reflectivity mirrors is a major impediment for several  types of high-precision interferometric experiments that aim to reach the  ...

Fabrication Process of Silicone-based Dielectric Elastomer Actuators

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bio-inspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to precisely-defined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied.

This manuscript shows the fabrication process for the manufacture of dielectric elastomer soft actuators based on silicone membranes. The three key stages of production are presented in detail: blade casting of thin silicone membranes; pad printing of compliant electrodes; and the assembly of all the components.

Proceso de fabricación de elastómeros dieléctricos actuadores basados ​​en silicona

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an ...

Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 &#176;C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 &#176;C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 &#176;C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 &#176;C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example.

A protocol for high-temperature and high-pressure gas adsorption measurements on zeolite H-ZSM-5 using an adsorption measurement device based on a langatate crystal microbalance is presented. Prior to the adsorption measurements, the synthesis of zeolite H-ZSM-5 on the langatate crystal microbalance sensor by the steam-assisted crystallization (SAC) method is demonstrated.

Dispositivo de adsorción Basado en una microbalanza de cristal Langatate de alta temperatura y alta presión de adsorción de gas en la zeolita H-ZSM-5

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate ...

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

Challenges in Rheological Characterization of Highly Concentrated Suspensions &amp;#8212; A Case Study for Screen-printing Silver Pastes

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

Desafíos en reológico caracterización de suspensiones de alta concentración - Un estudio de caso para pastas de plata serigrafía

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

Method for Recording Broadband High Resolution Emission Spectra of Laboratory Lightning Arcs

Lightning is one of the most common and destructive forces in nature and has long been studied using spectroscopic techniques, first with traditional camera film methods and then digital camera technology, from which several important characteristics have been derived. However, such work has always been limited due to the inherently random and non-repeatable nature of natural lightning events in the field. Recent developments in lightning test facilities now allow the reproducible generation of lightning arcs within controlled laboratory environments, providing a test bed for the development of new sensors and diagnostic techniques to understand lightning mechanisms better. One such technique is a spectroscopic system using digital camera technology capable of identifying the chemical elements with which the lightning arc interacts, with these data then being used to derive further characteristics. In this paper, the spectroscopic system is used to obtain the emission spectrum from a 100 kA peak, 100 &#181;s duration lightning arc generated across a pair of hemispherical tungsten electrodes separated by a small air gap. To maintain a spectral resolution of less than 1 nm, several individual spectra were recorded across discrete wavelength ranges, averaged, stitched, and corrected to produce a final composite spectrum in the 450 nm (blue light) to 890 nm (near infrared light) range. Characteristic peaks within the data were then compared to an established publicly available database to identify the chemical element interactions. This method is readily applicable to a variety of other light emitting events, such as fast electrical discharges, partial discharges, and sparking in electrical equipment, apparatus, and systems.

Emission spectroscopy techniques have traditionally been used to analyze inherently random lightning arcs occurring in nature. In this paper, a method developed to obtain the emission spectroscopy from reproducible lightning arcs generated within a laboratory environment is described.

Método para la grabación de espectros de emisiones de alta resolución de banda ancha de arcos relámpagos de laboratorio

Lightning is one of the most common and destructive forces in nature and has long been studied using spectroscopic techniques, first with traditional ...

Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model

Vanadium dioxide is a material that has a reversible metal-insulator phase change near 68 &#176;C. To grow VO2 on a wide variety of substrates, with wafer-scale uniformity and angstrom level control of thickness, the method of atomic-layer deposition was chosen. This ALD process enables high-quality, low-temperature (&#8804;150 &#176;C) growth of ultrathin films (100-1000 &#197;) of VO2. For this demonstration, the VO2 films were grown on sapphire substrates. This low temperature growth technique produces mostly amorphous VO2 films. A subsequent anneal in an ultra-high vacuum chamber with a pressure of 7x10-4 Pa of ultra-high purity (99.999%) oxygen produced oriented, polycrystalline VO2 films. The crystallinity, phase, and strain of the VO2 were determined by Raman spectroscopy and X-ray diffraction, while the stoichiometry and impurity levels were determined by X-ray photoelectron spectroscopy, and finally the morphology was determined by atomic force microscopy. These data demonstrate the high-quality of the films grown by this technique. A model was created to fit to the data for VO2 in its metallic and insulating phases in the near infrared spectral region. The permittivity and refractive index of the ALD VO2 agreed well with the other fabrication methods in its insulating phase, but showed a difference in its metallic state. Finally, the analysis of the films&#39; optical properties enabled the creation of a wavelength- and temperature-dependent model of the complex optical refractive index for developing VO2 as a tunable refractive index material.

Thin films (100-1000 &#197;) of vanadium dioxide (VO2) were created by atomic-layer deposition (ALD) on sapphire substrates. Following this, the optical properties were characterized through the metal-insulator transition of VO2. From the measured optical properties, a model was created to describe the tunable refractive index of VO2.

Deposición de capa atómica de dióxido de vanadio y un modelo óptico dependiente de la temperatura

Vanadium dioxide is a material that has a reversible metal-insulator phase change near 68 &#176;C. To grow VO2 on a wide variety of substrates, with ...

Predicting Catalyst Extrudate Breakage Based on the Modulus of Rupture

The mechanical strength of extruded catalysts and their natural or forced breakage by either collision against a surface or by a compressive load in a fixed bed are important phenomena in catalyst technology. The mechanical strength of the catalyst is measured here by its bending strength or flexural strength. This technique is relatively new from the perspective of applying it to commercial catalysts of typical sizes used in the industry. Catalyst breakage by collision against a surface is measured after a fall of the extrudates through the ambient air in a vertical pipe. Quantifying the impact force is done theoretically by applying Newton's second law. Measurement of catalyst breakage due to stress in a fixed bed is done following the standard procedure of the bulk crush strength test. Novel here is the focus on measuring the reduction in the length to diameter ratio of the extrudates as a function of the stress.

Here we present a protocol to measure the modulus of rupture of an extruded catalyst and the breakage of said catalyst extrudates by collision against a surface or by compression in a fixed bed.

Rotura de extrusión de catalizador predicción basada en el módulo de ruptura

The mechanical strength of extruded catalysts and their natural or forced breakage by either collision against a surface or by a compressive load in a ...