VLT 4LGSF OTA field selector mechanism

VLT 4LGSF OTA Field Selector Mechanism One of the critical elements in the Four Laser Guide Star Facility (4LGSF) for the ESO Very Large Telescope (VLT) is the Optical Tube Assembly (OTA), consisting of a stable 20x laser beam expander and an active tip/tilt mirror, the Field Selector Mechanism (FSM). The driving requirement for the FSM is its large stroke of ±6.1 mrad, in combination with less than 1.5 µrad RMS absolute accuracy. The FSM design consists of a Zerodur mirror, bonded to a membrane spring and strut combination to allow only tip and tilt. Two spindle drives actuate the mirror, using a stiffness based transmission to increase resolution. Absolute accuracy is achieved with two differential inductive sensor pairs. A prototype of the FSM is realized to optimize the control configuration and measure its performance. Friction in the spindle drive is overcome by creating a local velocity control loop between the spindle drives and the shaft encoders. Accuracy is achieved by using a cascaded low bandwidth control loop with feedback from the inductive sensors.

Crédit:

F. Kamphues/TNO/ESO

À propos de l'image

Identification:tno_kamphues_32
Type:Photographique
Date de publication:20 mars 2012 21:03
Taille:4288 x 2848 px

À propos de l'objet

Nom:Laser Guide Star
Type:Unspecified : Technology
Catégorie:Paranal

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