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Title: A new UHV micro positioning system for high load

Abstract

In this work we report the design and performance of a novel compact in-vacuum actuator, designed to be compatible with all the motions required for the scissor-type ESRF mirror bender. These mirror benders include several linear actuators, which drive the mirror bending torques, as well as the main alignment motions such as pitch and translation along the normal to the mirror surface. The motions are provided by compact linear actuators, which consist of motor, reduction, spindle and nut, encapsulated on a closed air volume to provide vacuum compatibility. The actuator includes a hydroformed bellows to transmit the force to the actuator tip, and an electrical feedthrough for the motor cables. The design boundaries for these actuators are quite tight, as they must be integrated in a narrow volume, must be UHV compatible and must provide high resolution, for a relatively high load. As a result, they have limited mechanical performance, and in some cases poor reliability. To overcome these problems, we designed and implemented a different concept. In the proposed concept, the motor rotation is converted onto a linear motion by means of a cam instead of a spindle and a nut. This allows for much shorter and stiffer transmissionmore » system, with similar dimensions. The vacuum compatibility is intrinsic for this solution, since the whole mechanism of the actuator is UHV compatible. All motions are preloaded and guided by vacuum compatible (hybrid metal-ceramics) ball bearings. This allows the system reaching a repeatability and backlash well within the micron. The absence of friction allows for a high reliability and releases the maintenance needs of the system. The transmission is intrinsically irreversible, and the system can hold a load of 250 N within a few nanometers without any holding current on the motors. This allows the system to move reliably also in micro-stepping mode, providing a resolution well below the half-step nominal resolution of 100 nm. Performances have been tested on a prototype. We report the results of the tests obtained in air and in vacuum after bake-out. Two units of the new actuator have been installed at the photoemission beamline of ALBA (CIRCE) and are routinely used to align the 3 µm spot on the field of view of the Photoemission Electron Microscope. The absence of any noticeable backlash, or any friction effect and the reliability of the micro-stepping motion has simplified very much the alignment of the photon beam, reducing the alignment process to few minutes. The excellent performances and relatively high load capacity of this new compact actuator make of it a versatile element to be integrated in other systems requiring reliable in-vacuum positioning.« less

Authors:
; ;  [1]
  1. ALBA Synchrotron, Carretera BP 1413, de Cerdanyola del Vallès a Sant Cugat del Vallès, Km. 3,3, 08290 Cerdanyola del Vallès, Barcelona (Spain)
Publication Date:
OSTI Identifier:
22608360
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1741; Journal Issue: 1; Conference: SRI2015: 12. international conference on synchrotron radiation instrumentation, New York, NY (United States), 6-10 Jul 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ACTUATORS; ALIGNMENT; BALL BEARINGS; CAPACITY; COMPATIBILITY; COMPUTER-AIDED MANUFACTURING; DESIGN; ELECTRON MICROSCOPES; EUROPEAN SYNCHROTRON RADIATION FACILITY; MIRRORS; PHOTOEMISSION; PHOTON BEAMS; PHOTONS; POSITIONING; RELIABILITY; RESOLUTION; ROTATION; TRANSMISSION

Citation Formats

Colldelram, Carles, E-mail: ccolldelram@cells.es, Nicolas, Josep, E-mail: jnicolas@cells.es, and Nikitina, Liudmila, E-mail: lnikitina@cells.es. A new UHV micro positioning system for high load. United States: N. p., 2016. Web. doi:10.1063/1.4952847.
Colldelram, Carles, E-mail: ccolldelram@cells.es, Nicolas, Josep, E-mail: jnicolas@cells.es, & Nikitina, Liudmila, E-mail: lnikitina@cells.es. A new UHV micro positioning system for high load. United States. doi:10.1063/1.4952847.
Colldelram, Carles, E-mail: ccolldelram@cells.es, Nicolas, Josep, E-mail: jnicolas@cells.es, and Nikitina, Liudmila, E-mail: lnikitina@cells.es. 2016. "A new UHV micro positioning system for high load". United States. doi:10.1063/1.4952847.
@article{osti_22608360,
title = {A new UHV micro positioning system for high load},
author = {Colldelram, Carles, E-mail: ccolldelram@cells.es and Nicolas, Josep, E-mail: jnicolas@cells.es and Nikitina, Liudmila, E-mail: lnikitina@cells.es},
abstractNote = {In this work we report the design and performance of a novel compact in-vacuum actuator, designed to be compatible with all the motions required for the scissor-type ESRF mirror bender. These mirror benders include several linear actuators, which drive the mirror bending torques, as well as the main alignment motions such as pitch and translation along the normal to the mirror surface. The motions are provided by compact linear actuators, which consist of motor, reduction, spindle and nut, encapsulated on a closed air volume to provide vacuum compatibility. The actuator includes a hydroformed bellows to transmit the force to the actuator tip, and an electrical feedthrough for the motor cables. The design boundaries for these actuators are quite tight, as they must be integrated in a narrow volume, must be UHV compatible and must provide high resolution, for a relatively high load. As a result, they have limited mechanical performance, and in some cases poor reliability. To overcome these problems, we designed and implemented a different concept. In the proposed concept, the motor rotation is converted onto a linear motion by means of a cam instead of a spindle and a nut. This allows for much shorter and stiffer transmission system, with similar dimensions. The vacuum compatibility is intrinsic for this solution, since the whole mechanism of the actuator is UHV compatible. All motions are preloaded and guided by vacuum compatible (hybrid metal-ceramics) ball bearings. This allows the system reaching a repeatability and backlash well within the micron. The absence of friction allows for a high reliability and releases the maintenance needs of the system. The transmission is intrinsically irreversible, and the system can hold a load of 250 N within a few nanometers without any holding current on the motors. This allows the system to move reliably also in micro-stepping mode, providing a resolution well below the half-step nominal resolution of 100 nm. Performances have been tested on a prototype. We report the results of the tests obtained in air and in vacuum after bake-out. Two units of the new actuator have been installed at the photoemission beamline of ALBA (CIRCE) and are routinely used to align the 3 µm spot on the field of view of the Photoemission Electron Microscope. The absence of any noticeable backlash, or any friction effect and the reliability of the micro-stepping motion has simplified very much the alignment of the photon beam, reducing the alignment process to few minutes. The excellent performances and relatively high load capacity of this new compact actuator make of it a versatile element to be integrated in other systems requiring reliable in-vacuum positioning.},
doi = {10.1063/1.4952847},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1741,
place = {United States},
year = 2016,
month = 7
}
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