| Paper | 
        Title | 
        Page | 
    
    
        | CT08 | 
        Adaptive Optics for the LEP 2 Synchrotron Light Monitors
         | 
        77 | 
    
    
        |   | 
        
                - G. Burtin, R.J. Colchester, G. Ferioli, J.J. Gras, R. Jung, J.M. Vouillot
 
                       CERN, Geneva, Switzerland 
          | 
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            |   | 
            
            The image obtained with the LEP synchrotron
            radiation telescopes deteriorates, giving multiple and
            deformed images, when the beam energy goes beyond
            80 GeV at beam currents above 2 mA. This problem is
            due to the deformation of the light extracting beryllium
            mirror, by as little as 1 mm, and had been predicted at
            the design stage. To overcome this problem, several
            changes together with an adaptive optics set-up have
            been introduced. These essentially consist of a
            cylindrically deformable mirror to compensate the
            cylindrical deformation of the beryllium mirror and a
            movable detector to compensate the spherical
            deformation. Both components are continuously
            adjusted as a function of beam current and energy.
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              |