Collision avoidance device for measuring instruments and measuring instrument with such collision prevention device

A collision preventing apparatus (2; 3) for measuring devices for measuring dimensions of a workpiece by relative movement of the workpiece and a non-contact sensor (18) by a drive system (200) full, a holder (20) which is fixed to the non-contact sensor (18), a collision detecting section (30) which covers the non-contact sensor (18), a holding device (70) which holds the collision detecting section (30) in such a way that it is displaceable with respect to the support (20), and instructs a switch (50) which detects a relative displacement between the holder (20) and the collision detecting section (30) and the drive system (200) to stop the relative movement of the workpiece and the non-contact sensor (18) or the workpiece and non-contact sensor (18) in a retreating direction in which the workpiece and the non-contact sensor (18) away from each other to move, wherein said holding means comprises a first holding device (40) which holds the collision detecting section (30) in such a way that he in a first ...