The present application relates to an optical system (1) comprising a light beam generator (10) configured to generate a light beam (2) and direct it along an optical path (3), an optical element (19, 24) in said optical path (3) and on which said light beam (2) is incident for redirecting said light beam (2), a sensor (4, 5) attached to said optical element (19, 24), the sensor (4, 5) being configured to generate information indicative of a characteristic of said light beam (2) that is incident on said optical element (19, 24), and a controller (6) configured to adjust one or more characteristics of said optical system (1) in dependence on the information generated by said sensor (4, 5).
