  The versatility of optics enables the design of a wide range of elegant beam
instrumentation. Multiple properties of particle beams can be precisely
measured by various optical techniques, which include: direct sampling of
optical radiation emitted from a charged particle beam; monitoring interactions
with an optical probe such as a laserwire; and by electro-optic conversion of
the beam signal with high-bandwidth fibre readout. Such methods are typically
minimally-invasive and non-destructive, thus permitting diagnostics during
accelerator operation without perturbation of the particle beam or risk of
damage to the instrument. These proceedings summarise three CAS lectures that
introduce the basic principles of optics relevant for instrumentation design,
outline the key laser technologies and setups, and review the state-of-the-art
in laser-based beam instrumentation.
