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. Preparação de polidor e Slurry Primeiro prepare o Sistema de Polimento Convergente (especificamente chamado C onvergent, eu nitial Superfície Independent, S ingle iteração, R ogue-Particle gratuito polidor ou CISR (pronuncia-se &#39;tesoura&#39;)) 7,17 instalando o pad e septo, condicionando a almofada, diluição e estabilização química da pasta, e a incorporação da lama dentro do sistema de filtragem. <ol><li> No polidor CISR, aderir uma almofada de poliuretano para a base colo granito. Aderem almofada uma aresta primeiro e aplicar pressão em direcção à aresta oposta para minimizar os espaços de ar. Apare o pad saliente e depois usar uma lâmina de barbear e de rolos para perfurar e retirar as bolhas de ar, se necessário. </li><li> Na primeira utilização e depois de cada ~ 100 hr de polimento, condição diamante almofada usar um condicionador de diamante CMP (50 mm de diâmetro; 0,6 psi de pressão aplicada; 5 min de permanência em cada local colo radial com incrementos de espaçamento de 25 mm; rotação lap 25 rpm) com água DI fluindo. </li><li> Entre iterações de polimento, remover quaisquer chorume e produtos de vidro residuais do bloco usando um produto de limpeza in-situ de ultra-som (~ 2 min de permanência em cada local radial; rotação colo 5 rpm) com água DI fluindo. </li><li> Sobre o peso do septo forma exclusiva, aderir fita de espuma dupla face e, em seguida, o material de septo (por exemplo, vidro de pré-corte ou outro material não-uso). Aparar qualquer fita adesiva de espuma que pende para coincidir com a forma do material de septo e peso. Observe o projeto septo (forma e peso) muda para diferentes tamanhos de peça e colo 7,17. </li><li> Prepare polimento lama a Baume 4 concentração (especificamente misturar em volume ~ 1 parte de óxido de cério pasta de polimento e ~ 9 partes de água deionizada (DI) de água em um 11 L bucket). Verifique Baume usando uma bóia Baume. Adicionar ~ 5 ml de KOH (10 M) para ajustar o pH para 9,5 e adicionar 120 ml (~ 1 vol%) de surfactante proprietária 19. Reajuste pH e Baume cada 24 horas de polimento. </li><li> Instale balde com a pasta preparada em sistema de filtração. Em seguida, instalar os filtros de partículas CMP desejados em sistema de filtração. Vamos recircular pasta dentro do sistema de filtração por várias horas. </li><li> Distribuição de tamanho de partícula medida de suspensão (por exemplo, usando técnicas de sensoriamento única partícula de óptica) para garantir o fim da cauda da distribuição é adequadamente desonestos 9,20 livre de partículas. </li></ol> 2. Preparação de Peça (Gravura e de bloqueio) Antes de polir, gravar quimicamente a peça solo bem como recebido para reduzir a quantidade de remoção de material necessário para eliminar o sub-superfície dano 21 moagem. Em seguida, o bloco da peça de trabalho (se a relação de aspecto (isto é, comprimento / espessura) é&gt; 10), utilizando uma nova técnica de bloqueio botão pitch (PBB) para evitar que a peça de flexão durante o bloqueio e polimento 22. <ol><li> Etch a peça moído fino (especificamente um 265 x 265 x 8 mm3 vidro de sílica fundida plana) em um tanque cheio com HF: NH 4 F (6: 1 tamponada etch óxido (BOE) 3x diluída com água DI) durante 6 horas removendo 10 um de vidro a partir da superfície da peça de trabalho. CUIDADO! BOE é extremamente perigoso; usar equipamento de proteção individual (EPI). Retire peça do tanque de etch e enxaguar agressivamente a peça com água DI e permitir que a peça secar ao ar verticalmente. </li><li> Inspecione a peça por danos profunda durante o processo de moagem usando uma inspeção luz brilhante em um quarto escuro. Se nenhum dano profundo for encontrado, prossiga para a próxima etapa, outra peça enviar de volta para re-moagem. </li><li> Aqueça o bloqueio gramado em uma pistola de cola para ~ 95 ºC e coloque gotas (também chamados de botões) de campo (~ 0,06 g) sobre a face daplaca de bloqueio em uma matriz de 9 x 9 (81 botões com espaçamento de 26 mm). Para diferentes peças de tamanho, referem-se a criar regras para o número, tamanho ideal, e espaçamentos de botão passo 22. Colocar a placa de bloqueio com os botões aplicados voltada para cima no forno pré-aquecido a 70 ºC. </li><li> Aplicar fita para a face da peça de trabalho que não está a ser polida. Evitar a formação de bolhas de ar ou excesso de alongamento da fita. </li><li> Coloque a peça de trabalho com a face para baixo sobre o lado da fita botões na placa de bloqueio no forno. Cubra a peça-button-bloco para minimizar o fluxo convectivo. Após 1,5 horas, arrefecer a definir forno 10 ° C / h até à temperatura ambiente. Após arrefecimento, a espessura da peça de trabalho sobre o arremesso bloqueado deve ser ~ 1 mm. </li></ol> 3. Convergente Polimento <ol><li> Ligue sistema umidade na câmara ambiental de CISR polidor para evitar suspensão de secagem durante o polimento e minimizar partículas desonestos riscar a peça. </li><li> Insde altura e montar o septo especificamente concebido e preparado para polidor. Instale PBB peça em polidor CISR e menor crescimento para segurar a peça. </li><li> Peça polonês em CISR durante 4 horas a uma velocidade de rotação combinado colo ea peça de 25 rpm com um curso radial de ~ 75 mm e com um fluxo de lama do sistema de filtração de 1 gal / min. NOTA: A placa de bloqueio também serve como o peso de carga sobre a peça de trabalho que corresponde a 0,6 psi de pressão aplicada. </li><li> Desligue rotação colo e peça e fluxo de lama. Remover PBB peça de CISR polidor e mergulhe-o DI de água cheia de banho. Limpe a superfície da peça com sala limpa pano enquanto submerso. Remover PBB peça de banho e spray enxágüe com água DI. </li><li> Deblock peça através da inserção de um calço na interface peça-block. Remover a fita a partir da superfície da peça de trabalho. Agressivamente lavar peça com água DI e ar seco. </li><li> PBB a face oposta da peça de trabalho, conforme descrito na Seção 2. Em seguida, repita poprocedimento institui como descrito na Seção 3. </li></ol> 4. Metrologia e Inspeção <ol><li> Medida de frente de onda reflectida (ou seja, figura superfície) de ambos os lados da peça de trabalho, bem como frentes de onda transmitida utilizando um interferómetro. </li><li> Mount peça na estação de inspeção brilhante luz e medir as propriedades scratch / escavação usando métodos padrão de fabricação óptica. Um etch BOE curta da peça de trabalho, tal como descrito na etapa 2.1, pode ser usado para expor arranhões ocultos para peças utilizadas em aplicações de laser de elevada fluência. Para a medição de multa arranhões ou rugosidade da peça, podem ser utilizados microscopia óptica padrão ou luz branca interferometria. </li><li> Loja concluído em uma peça de contacto minimização recipiente com a face da peça de trabalho. </li></ol>

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The authors have nothing to disclose.

Como discutido na Introdução, a implementação bem sucedida de Convergente Polimento em relação à superfície figura envolve eliminar ou minimizar todos os fenômenos que influenciam espacial não-uniformidade de material excepto a peça-lap incompatibilidade devido a forma da peça. Se qualquer um desses fenômenos não está devidamente mitigado, seja por meio de controle de processo ou através de engenharia apropriada do polidor, então o ponto de convergência desejado não pode ser alcançado ou mantido; por...

As principais etapas de um processo típico de fabrico óptico incluem modelagem, moagem, polimento de abertura total, e às vezes pequena ferramenta de polimento 1-3. Com o aumento da demanda por componentes ópticos de alta qualidade para sistemas de imagem e laser, tem havido avanços significativos na fabricação óptica ao longo das últimas décadas. Por exemplo, a precisão, a remoção de material determinista é agora possível, durante a concepção e processos de moagem com os avanços na Numérico Computadorizado (CNC máquinas de moldagem) de vidro Controlados. Da mesma forma, as tecnologias de polimento pequena ferramenta (por exemplo, controlado por computador superfície óptica (CCOS), figurando ion, e acabamento magneto-reológico (MRF)) levaram a remoção de material determinista e figura superfície de controle, assim, impactando fortemente a indústria de fabrico óptico. No entanto, a etapa intermediária do processo de acabamento, polimento de abertura total, ainda carece de alta determinismo, geralmente exigindo opticia qualificadosns para realizar múltiplas, muitas vezes, os ciclos iterativos longos com várias mudanças de processos para alcançar a figura superfície desejada 1-3. O grande número de métodos de polimento, variáveis ​​de processo e do complexo químico e interações mecânicas entre a peça, colo e lama 3-4 fez-se um desafio para transformar polimento óptico de uma &quot;arte&quot; para a ciência. Para alcançar determinista polimento abertura total, a taxa de remoção de material deve ser bem compreendido. Historicamente, a taxa de remoção de material que tem sido descrito pela equação Preston amplamente utilizado 5 <img alt="Equação 1" fo:content-width="1in" fo:src="/files/ftp_upload/51965/51965eqn1.jpg" src="/files/ftp_upload/51965/51965eqn1.jpg" width="100px" /> (1) onde dh / dt é a taxa média de remoção de espessura, k é a constante p Preston, σ é oa pressão aplicada, e V r é a velocidade relativa média entre a peça eo colo. A Figura 1 apresenta esquematicamente os conceitos físicos que influenciam a taxa de remoção de material, como descrito a Equação de Preston, incluindo as variações espaciais e temporais na velocidade e pressão, diferenças entre o pressão aplicada e a distribuição da pressão que as experiências da peça, e os efeitos de fricção 6-8. Em particular, a distribuição da pressão real experimentada por a peça de trabalho é regulada por um certo número de fenómenos (descritas em detalhe noutro local 6-8) que afecta fortemente resultante figura superfície da peça de trabalho. Além disso, na Equação Preston, os efeitos ao nível molecular são microscópicas e dobrada em grande parte a constante macroscópica Preston (k p), o que influencia a taxa de remoção de material global, micro-rugosidade, e mesmo riscar sobre a peça de trabalho. Vários estudos têm expandido o modelo de Preston para dar conta<html> para o chorume microscópica interações partícula-pad-de peças para explicar taxa de remoção de material e microrugosidades 9-16. Para conseguir o controle determinista da figura de superfície durante polimento abertura total, cada um dos fenômenos descritos acima precisa ser entendido, quantificados e então controlada. A estratégia por trás Convergente Polishing é eliminar ou minimizar as causas indesejáveis ​​de remoção de material não-uniforme, seja através de projeto polidor de engenharia ou por controle de processo, de modo que a remoção é impulsionado apenas pelo descompasso peça voltas devido a forma da peça 7,17- 18. A Figura 2 ilustra como a forma da peça de trabalho pode conduzir a uma convergência com base no conceito da peça incompatibilidade voltas. Considere um lap plana e uma peça de trabalho hipotético de forma complexa mostrado no canto superior esquerdo. O desfasamento da altura de interface (referida como o intervalo, ÔH oL) influencia a distribuição da pressão de interface (σ) como: conteúdo &quot;fo: manter-together.within-page =&quot; always &quot;&gt; <img alt="Equação 2" fo:content-width="1in" fo:src="/files/ftp_upload/51965/51965eqn2.jpg" src="/files/ftp_upload/51965/51965eqn2.jpg" width="100px" /> (2) em que H é uma constante que descreve a taxa à qual a pressão diminui com um aumento no intervalo ÔH oL 6. Neste exemplo, a peça de trabalho tem a mais alta pressão local no centro (ver parte inferior esquerda da Figura 2), e, portanto, esta localização irá observar a maior taxa de remoção de material inicial durante o polimento. Como o material é removido, o diferencial de pressão através da peça de trabalho irá diminuir devido a uma diminuição na incompatibilidade da peça voltas, e a peça de trabalho irá convergir para a forma do colo. Na convergência, a distribuição da pressão da peça, e, consequentemente, a remoção de material, será uniforme em toda a peça de trabalho (ver lado direito da Figura 2). Este exemplo é ilustrado por uma volta plana, however, o mesmo conceito se aplica para uma volta esférica (ou côncava ou convexa). Mais uma vez, esse processo de convergência só funciona se todos os outros fenómenos afectam espacial material não-uniformidade ter sido eliminado. As atenuações processuais e de engenharia específicas implementadas no protocolo Polishing Convergente são descritos na discussão. O protocolo descrito no estudo seguinte é o processo convergente Polimento especificamente para um quadrado de vidro de sílica fundida peça 26,5 centímetros a partir de uma superfície de chão finos. Em 8 horas de polimento (4 horas / superfície), esta peça pode atingir um nivelamento polido de ~ λ / 2 com altíssima qualidade de superfície (ie, baixa densidade zero).

<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>
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		<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

Convergente Polimento é um novo sistema de polimento e método para acabamento planas e esféricas óptica de vidro em que uma peça de trabalho, independentemente da sua forma inicial (ou seja, a figura de superfície), irá convergir para figura superfície final com excelente qualidade de superfície abaixo, um conjunto imutável fixa de polimento parâmetros em uma única iteração de polimento. Em contraste, os métodos de polimento abertura total convencionais requerem múltiplas, ciclos iterativos, muitas vezes longos envolvendo polimento, metrologia e mudanças de processo para conseguir a figura superfície desejada. O processo convergente polimento é baseado no conceito da peça voltas incompatibilidade resultante altura em que a pressão diferencial diminui com a remoção e resulta na peça convergindo para a forma do colo. A aplicação bem sucedida do processo convergente polimento é um resultado da combinação de uma série de tecnologias para remover todas as fontes de não-uniforme espacial remoção de material (excepto para a peça de trabalho voltasdesencontro) para a figura superfície convergência e reduzir o número de partículas desonestos no sistema para baixas densidades zero e baixa rugosidade. O processo convergente Polishing foi demonstrado para a fabricação de ambos os apartamentos e esferas de diversas formas, tamanhos e proporções em vários materiais de vidro. O impacto prático é que os componentes ópticos de alta qualidade podem ser fabricados mais rapidamente, mais repetidamente, com menos de metrologia, e com menos trabalho, resultando em menores custos unitários. Neste estudo, o protocolo convergente polimento é descrito especificamente para a fabricação de 26,5 centímetros quadrados fundidos apartamentos de sílica a partir de uma superfície de chão finos de uma ~ λ / 2 figura superfície polida após o polimento da superfície por 4 h em um polidor de 81 centímetros de diâmetro.

O protocolo descrito acima Polimento convergente permite que uma peça de trabalho de sílica fundida terra (neste caso um 26,5 centímetros quadrados) a ser polido, em uma única iteração de 4 horas por unidade de área, para uma planicidade pico a vale de λ ~ / 2 (~ 330 nm) para baixas peças relação de aspecto e ~ 1λ (~ 633 nm) para peças com uma elevada relação de aspecto (ver Figura 3). Mais uma vez, este processo converge repetidamente peças para a mesma figura superfície final sem a ne...

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.

Convergente Polimento: Um simples, rápido, de abertura total Polimento Processo de alta qualidade ótica Flats &amp; Spheres

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 visualizações.  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.

Vídeo: 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.

Fabricação de Sílica Ultra microresonators alto fator de qualidade

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

Engenharia

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.

Processo de fabricação de microestruturas tridimensionais usando vaporização de um componente sacrificial

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.

Construção de um microscópio de alta resolução com recursos de captura óptica convencional e holográfico

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.

A geração de alta ordem Laguerre-Gauss feixes óticos para High-precision Interferometria

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.

Processo de fabricação de base de silicone dielétricos Elastomer Atuadores

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 adsorção Baseado em um Langatate Microbalança de Cristal de alta temperatura de adsorção de gás de alta pressão em 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 ...

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.

Desafios na reológico Caracterização de suspensões altamente concentrado - um estudo de caso para-impressão da tela de prata Cola

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 gravação de banda larga de alta resolução espectros de emissão de laboratório arcos relâmpago

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.

Deposição de camada atômica de dióxido de vanádio e um modelo ótico de temperatura-dependente

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.

Prever Catalyst Extrudate ruptura baseia o 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 ...