• A.S. Fisher
  SLAC, Menlo Park, California
• A. Goldblatt, T. Lefèvre
  CERN, Geneva

Synchrotron-light telescopes will monitor the profiles of the two LHC proton beams. At collision energy (7 TeV), each telescope will image visible light from a superconducting dipole used to increase beam separation for the RF-cavities. At injection (0.45 TeV), this source must be supplemented by a two-period superconducting undulator 80 cm from the dipole. We will present the mechanical and optical layouts of the telescope. The initial plan to use dipole edge radiation at high beam energy, for its increased visible emission, suffers from significant diffractive blurring. We will instead collect radiation from the first 2 to 3 m of the dipole’s interior. An optical "trombone" delay line will provide the large shift in focus. We will discuss calculations and measurements of blurring by diffraction and by this extended source, and present an alternative optical design using off-axis elliptical mirrors.