(EN) The invention relates to a device (10) for blocking optical workpieces (L), said device comprising a first moving device (12) for rotating a workpiece (L), which is blocked on a blocking piece (B), about a workpiece rotational axis (14) and a nozzle (16) for dispensing a pressure medium high-pressure stream (H) in a direction that is essentially transverse to the workpiece rotational axis onto a point of incidence (A) in an edge region between the blocking piece and the workpiece. The device also comprises a second moving device (18) for generating a relative movement between the nozzle and the workpiece. The aim of the invention is to enable the blocking of the workpieces as securely, damage-free, and quickly as possible. This is achieved in that the second moving device has a nozzle guiding portion (20) on which the nozzle is mounted and by means of which the nozzle can be positioned with respect to the blocking piece in a cam-controlled manner in order to aim the pressure medium high-pressure stream towards the point of incidence in a defined manner.