FIERRO, DavideDavideFIERRO0000-0001-6189-2389Sergio D'OrsiMARTY, LaurentLaurentMARTY0000-0002-1264-0641MOLFESE, CESARECESAREMOLFESE0000-0002-2756-9075PERROTTA, FrancescoFrancescoPERROTTA0000-0002-5930-3669SCHIPANI, PietroPietroSCHIPANI0000-0003-0197-589XCapaccioli, MassimoMassimoCapaccioliDe Paris, G.G.De ParisTomelleri, RaffaeleRaffaeleTomelleriRossettini, PierfrancescoPierfrancescoRossettiniFARINATO, JACOPOJACOPOFARINATO0000-0002-5840-83622024-02-092024-02-09201097808194822970277-786Xhttp://hdl.handle.net/20.500.12386/34735The VST primary mirror is a 2.6-m meniscus made of Astro-Sitall. An active optics system is implemented to correct surface errors due to manufacturing or induced by gravity and temperature changes. The primary mirror is axially supported by 84 supports disposed in four concentric rings. Three of the supports, symmetrically placed and much stiffer than the other ones, define the axial plane of the primary mirror acting as fixed points. The remaining 81 supports are force controlled actuators, used to change the shape of the mirror according to wavefront measurements in closed loop operation, or to a look-up table in open loop. This paper describes the solutions adopted for the axial actuator, as well as the test campaign to assess their performance and degree of reliability.STAMPAenConference paper10.1117/12.8566102-s2.0-77956784694https://lens.org/002-973-555-468-55Xhttps://www.spiedigitallibrary.org/conference-proceedings-of-spie/7739/1/The-axial-actuators-for-the-VST-primary-mirror/10.1117/12.856610.short2010SPIE.7739E..33FFIS/05 - ASTRONOMIA E ASTROFISICA