This system is very similar to yet predates the one used in Compact Disc players to follow the spiral optical track, where typically a servo motor moves the optical pickup in steps for coarse tracking and a set of coils tilts the laser lens for fine tracking, both guided by an optical sensing device which is the analogue of CED stylus deflection sensing coils.
22.
Such poems emphasise the optical sense and were common to many poems written by the Romantic poets, including his own poem " The Ruined Cottage ", Coleridge's " Dejection : An Ode " and " Rime of the Ancient Mariner " and Percy Bysshe Shelley's " Hymn to Intellectual Beauty " and " The Zucca ".
23.
These short pulses open the new field of ultrafast optics, which is a field of nonlinear optics that gives access to a completely new class of phenomena like measurement of electron movements in an atom ( attosecond phenomena ), coherent broadband light generation ( ultrabroad lasers ) and thereby gives rise to many new applications in optical sensing ( e . g . coherent laser radar, ultrahigh resolution optical coherence tomography ), material processing and other fields like metrology ( extremely exact frequency and time measurements ).
