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Abstract

The main goal of this work is to realize a metal oxide gas sensor with stable operating temperature. This article describes our approach and the technological process used to reach a high and stable operating temperature (650-700°C), with low consumption (100mW) and good thermal homogeneity all over the active area.

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Abstract

The development reported herein is that of a surface micromachining technology using two SU-8 layers as a structural material. Three different processes are presented and discussed: the first process makes use of a solgel as the sacrificial layer; the second process utilizes the SU-8 itself as the sacrificial layer; the third process utilizes silicon dioxide as the first sacrificial layer and the solgel as the second sacrificial layer. These three processes are adapted for one structural layer structure. With a two-layer structure and when release is long, the third process is more adapted.

Abstract

MOEMS-based electrostatic micro-deformable mirrors (MDM) are promising for future AO systems. Original complete polymer mirrors have been designed and realized. Specific control-command strategy is presented and tested; electrostatic MDM are well-suited for open-loop operation.

Résumé

Le stage consiste en la mise au point de procédés de photolithographie de résines SU8 grâce à des équipements de production de marque EVG. L'objectif pour le LAAS-CNRS est la réalisation et la fiabilisation des procédés de résines SU8 sur différentes épaisseurs : 10µm, 25µm, 50µm, 100µm et 500µm. Pour mener à bien ce projet, je dispose d'équipements technologiques en zone de photolithographie et des moyens de caractérisation tels que les profilomètres tactile et optique (mesures d'épaisseurs) et le microscope électronique à balayage (qualification des profils de résine). En finalité, des fiches de procédés sont rédigées et utilisables par quiconque en salle blanche. D'autres études sont menées sur l'influence des paramètres du procédé. En effet, j'étudie l'influence du type de substrat, du type d'UV et de la relaxation.

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Abstract

Future adaptive optics (AO) systems require deformable mirrors with very challenging parameters, up to 250 000 actuators and inter-actuator spacing around 500 &mgr;m. MOEMS-based devices are promising for the development of a complete generation of new deformable mirrors. Our micro-deformable mirror (MDM) is based on an array of electrostatic actuators with attachments to a continuous mirror on top. The originality of our approach lies in the elaboration of layers made of polymer materials. Mirror layers and active actuators have been demonstrated. Based on the design of this actuator and our polymer process, realization of a complete polymer-MDM has been done using two process flows: the first involves exclusively polymer materials while the second uses SU8 polymer for structural layers and SiO2 and sol-gel for sacrificial layers. The latest shows a better capability in order to produce completely released structures. The electrostatic force provides a non-linear actuation, while AO systems are based on linear matrices operations. Then, we have developed a dedicated 14-bit electronics in order to "linearize" the actuation, using a calibration and a sixth-order polynomial fitting strategy. The response is nearly perfect over our 3×3 MDM prototype with a standard deviation of 3.5 nm; the influence function of the central actuator has been measured. First evaluation on the cross non-linarities has also been studied on OKO mirror and a simple look-up table is sufficient for determining the location of each actuator whatever the locations of the neighbor actuators. Electrostatic MDM are particularly well suited for open-loop AO applications.

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